Increased indoor humidity may decrease #Coronavirus #COVID-19 transmission

Note: The suggestions in this guest essay may or may not be useful in your personal situation. It is provided here for review and discussion. There is some supporting evidence that increased heat and humidity will have an adverse affect on the Coronovirus, as does UV-C light, but each personal situation is unique, and other factors may dominate transmission likelihoods. Use your own best judgment. – Anthony

Guest essay by Leo Goldstein

Bullet points:

  • COVID-19 spreads mostly indoors by person to person and person to surface to person transmission
  • Increasing humidity indoors to 50%-60% is a safe and promising method to fight COVID-19 spread

Increasing Indoor Humidity to Constrain COVID-19

Indoor temperature, humidity, and ventilation must be increased in public and private buildings in all COVID-19 affected areas. Here, indoor temperature of at least 75°F (24°C) and relative humidity levels of 50%-60% are recommended.


It is a common knowledge, confirmed by the rigorous body of research, that low temperatures and low humidity contribute to flu-like virus epidemics, while high temperatures and high humidity reduce or even prevent flu-like epidemics. Good ventilation (rapid exchange of indoor air, which potentially contains viruses, with clean outside air) is another important factor that decreases the virus spread. COVID-19 is caused by a coronavirus SARS-CoV-2. Coronaviruses and Influenza viruses are enveloped RNA viruses from the respiratory virus group.  Therefore, the knowledge gained by the vast amount of prior studies of such viruses is fully applicable to the current epidemic.

People in the US and other developed countries spend most of their time indoors. The typical indoor conditions are characterized by very low relative humidity, lower than optimal temperature, and bad ventilation. Today, the seasonality of flu-like illnesses is better explained as an indirect impact of cold weather. Heating without humidification dries indoor air, and the low humidity contributes to virus survival, infectivity preservation, and transmission. There is evidence that these indoor environment conditions have been worsening over the last 10-15 years.

The suggested temperature and humidity for decreasing the spread of viruses is within most existing regulations. However, the humidity of many indoor environments typically goes unchecked and frequently falls below 30%, per Quinn and Shaman (1).  Reisman and Das (2) shows that an increase of humidity in schools, from ordinary ~28% to ~45%, decreases influenza-like illnesses among children by 2.3 times in wintertime. Thus, increasing indoor humidity levels and temperatures, as stated above, would yield immediate benefits beyond just slowing the spread of COVID-19. These measures also seem to have no downsides, at least over a few weeks’ period.

There is no need to wait until summer or even mid-April. Hygrometers cost about $20 and humidifiers are also inexpensive.  In the absence of a humidifier, one can leave a pot of water simmering.

Immediate Recommendations

Inhibition of influenza viruses by environmental conditions is closest correlated with absolute humidity, per Shaman and Kohn (3). Absolute humidity is determined by relative humidity and temperature.

There is similarity of shedding, transmission, and infection mechanisms between the relevant corona- and Influenza viruses (Dormalen et al. (3), Iljaz (9), Prussin et al. (11), Pica and Bover (12)). That allows applying results from the previous studies of such viruses the COVID-19 epidemic. The previous studies (including Dormalen et al. (5), Noti (6), Iljaz (7), Yang and Marr (8)) are unanimous that increase in humidity sharply decreases transmission, survival, and infectivity of these viruses up to ~50% through multiple biological, chemical, and physical mechanisms. The positive effects are not so uniform above 50%, but the bottom line is that increase in humidity above 50% still restraints spread of the Influenza and coronaviruses. This said, SARS-CoV-2 and SARS-CoV have been described as relatively tough viruses.

These recommendations can be implemented by individuals in their homes as well as in their businesses.  However, to slow down the epidemics, they should be implemented by the whole community in the same time. Today, that means endorsement by governments.

The issue of low-quality indoor air might have been worsened recently. Energy conserving buildings are tightly sealed, have practically no passive ventilation, and often poor active ventilation. There is an energy conservation movement to keep wintertime indoor temperature at 68°F (20°C), and to drop temperatures even lower when the space is unoccupied.  Repeating this cycle dries out the air even more and creates ideal conditions for Influenza and coronaviruses to survive, stay infective, and even aerosolize. It is also beneficial for computer equipment to be kept at lower temperature and humidity levels.

The geography of the spread of COVID-19 seems compatible with the hypothesis that low-quality indoor environment is a large contributing factor.

Advanced Discussion

Important Analysis Factor

Comparing the COVID-19 spread in the West with that in Asia, like South Korea and Japan, there is one measure that has been undertaken in the East, but not in the West: contact tracing. Japan traced individual cases of COVID-19. In the US and EU, even anonymized infection tracing was not seriously considered. That might be the case due to Big Tech’s refusal to share their users’ location data with doctors and/or government agencies, even upon the user’s consent or request.

Beyond Humidity Levels of 50%-60%

The peer reviewed research indicates that corona- and Influenza viruses lose their viability outside of the human body with an increase in relative humidity even above 50%-60%. This begs the question: should indoor relative humidity recommendations, in the areas affected by the COVID-19 epidemic, be increased even higher, perhaps to 70-90%?

The ordinary recommendations for indoor humidity levels are between 40-60%. These recommendations balance different requirements. Even in hospitals, humidity is a balancing act, intended to minimize potential growth of viruses (higher RH inhibits enveloped RNA viruses), fungi (lower RH inhibits fungi), & bacteria (vary). However, when the dominant threat is a coronavirus, other concerns can put on the back burner for a few weeks, in order to slow this epidemic.

A humidity level of over 70% is uncomfortable for many and often develops an unpleasant smell. But we can tolerate these and other discomforts, for a few weeks, to fight the spread of COVID-19.

Other Indoor Climate Parameters

There is also an option to increase the temperature and/or relative humidity in spaces, when those spaces are unoccupied.  This could be done in office buildings at night and in residences during the day, when everyone is at work.

Increasing indoor ventilation may be the hardest indoor environmental recommendation to implement. Since not all windows (especially in commercial buildings) can be opened, non-traditional methods might be used. For example, where office windows cannot be opened, one might cut holes in them.

In many cases, it might be easier to use germ-killing air purification than to increase ventilation. See Ijaz (10) for air purification techniques.

Ozone generators should be re-considered. They kill germs in the air and on the surface.

Generally, there are many indoor parameters and measures that are not acceptable long term might be used for a few weeks in affected areas.

Aircrafts have very dry and cold air and a high density of passengers. They are not just virus carriers, but also incubators. (Based on Olsen (13), Booth (14).)

Notice that air cooling also decreases relative humidity. If this issue is not addressed, this epidemic might decrease in the late spring, then peak back in the summer due to elevated AC use.

Here, the term affected area is left to interpretation by the decision makers. It might include areas affected by the panic.

Annotated References

Peer Reviewed Studies

  1. Indoor temperature and humidity in New York City apartments during winter

Ashlinn Quinn, Jeffrey Shaman, Science of Total Environment, 2017

Levels of humidity seen here are consistent with increased influenza virus survival.

Mean indoor vapor pressure (a measure of absolute humidity) was 6.7 mb in the surveyed homes during the winter season.

This corresponds to RH=30% at 75°F.

2. Humidity as a non-pharmaceutical intervention for influenza A

Jennifer M. Reiman, Biswadeep Das, Center for Clinical and Translational Science, Mayo Clinic, PLOS ONE, 2018

There were 2.3 times as many ILI [influenza-like illness] cases in the control rooms compared to the humidified rooms, and whether there is a causal relationship, and its direction between the number of cases and levels of influenza virus in the rooms is not known. Additional research is required, but this is the first prospective study suggesting that exogenous humidification could serve as a scalable NPI for influenza or other viral outbreaks. …

This epidemiological correlation suggests that deliberate increases in AH could be a potential NPI to reduce the spread of influenza and other viruses. One approach is to maintain relative humidity (RH) between 40–60%, the proposed optimal range for reducing growth opportunities for viruses, bacteria, and fungi [15]. Our previous study, demonstrated that classroom humidification to RH of 40–60% may be a feasible approach to increase indoor AH to levels with the potential to reduce influenza virus survival (a target of 10mb) and transmission …

Elevated classroom humidification was maintained at an average of 9.89 mb in humidified rooms compared to 6.33 mb in control rooms

A grab bag of viruses. Control group relative humidity was 28%, while experimental groups achieved 42-45% humidity.

3. Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1

Neeltje van Doremalen, et all., National Institute of Allergy and Infectious Diseases, Azaibi Tamin, et all., CDC, The New England Journal of Medicine, 2020

We found that the stability of SARS-CoV-2 was similar to that of SARS-CoV-1 under the experimental circumstances tested [including various surfaces and aerosol]. This indicates that differences in the epidemiologic characteristics of these viruses probably arise from other factors, including high viral loads in the upper respiratory tract and the potential for persons infected with SARS-CoV-2 to shed and transmit the virus while asymptomatic.

4. Absolute humidity modulates influenza survival, transmission, and seasonality

Jeffrey Shaman (Columbia University) & Melvin Kohn (John Hopkins), Proceedings of the National Academy of Sciences, 2009

This paper summarizes the field: Absolute Humidity constraints Influenza Virus Transmission (IVT) and Influenza Virus Survival (IVS). The results are applicable to coronaviruses as well.

Previous studies indicate that relative humidity (RH) affects both influenza virus transmission (IVT) and influenza virus survival (IVS). Here, we reanalyze these data to explore the effects of absolute humidity on IVT and IVS. We find that absolute humidity (AH) constrains both transmission efficiency and IVS much more significantly than RH. In the studies presented, 50% of IVT variability and 90% of IVS variability are explained by AH, whereas, respectively, only 12% and 36% are explained by RH.

Includes physics of droplets: gravitation, speed, size, and evaporation. Cough droplets with viruses evaporate faster at lower humidity.  They also become smaller and stay airborne for a longer time. Absolute Humidity also better correlates with an increase in both temperature and relative humidity.

5. Stability of Middle East respiratory syndrome coronavirus (MERS-CoV) under different environmental conditions

N van Doremalen, T Bushmaker, V J Munster, Laboratory of Virology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Eurosurveillance, 2013

[Aerosolized] MERS-CoV decreased only 7% in viability at 40% RH, whereas the viability at 70% RH decreased significantly with 89% (unpaired one-tailed Student’s t-test, p=0.0045). The viability of A/Mexico/4108/2009 (H1N1) virus decreased under both conditions with 95% for 40% RH and 62% for 70% RH respectively

MERS-CoV was very stable in aerosol form at 20°C – 40% RH. The decrease in viability at 20°C – 70% RH (89%) was comparable to that of A/Mexico/4108/2009 (H1N1) virus. Severe acute respiratory syndrome coronavirus (SARS-CoV) has been reported to stay viable for up to five days at 22 to 25°C and 40 to 50% RH and increase in temperature and humidity resulted in a rapid loss of viability [19]. Although a comparison between different experimental studies should be approached cautiously, the relative stability of MERSCoV at 20°C – 40% RH and the rapid decrease in virus viability at higher temperatures and higher humidity suggests that MERS-CoV and SARS-CoV share relatively similar stability characteristics.

Suggests that coronaviruses are more sensitive to humidity than influenza viruses. This applies to aerosol forms as well as to surface born (fomite).

6. High humidity leads to loss of infectious influenza virus from simulated coughs

John D. Noti,  Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC), PLOS ONE, 2013,  Included into CDC NIOSHTIC-2, 2013

Total virus collected for 60 minutes retained 70.6–77.3% infectivity at relative humidity ≤23% but only 14.6–22.2% at relative humidity ≥43%. Analysis of the individual aerosol fractions showed a similar loss in infectivity among the fractions. Time interval analysis showed that most of the loss in infectivity within each aerosol fraction occurred 0–15 minutes after coughing.

Maintaining indoor relative humidity >40% will significantly reduce the infectivity of aerosolized virus.

Loss of infectivity is only one of the effects that decrease transmission. The infectivity is at a minimum at RH=43% (here, rounded up to 50%), then slightly increases and then drops again at RH>70%

The effect of increasing humidity on viral survival differed among several reported studies as Hemmes et al. [3], Hood [4] and Harper [5] concluded that survival was maximum at 10–25% RH and minimal at high >50% RH whereas, Shechmeister [6] and Shaffer et al. [7] found survival was maximal at 20–25% RH, minimal at 50% RH, and moderate at 70–80% RH.

7. Survival Characteristics of Airborne Human Coronavirus 229E

M. K. Ijaz, Journal of General Virology, Society for General Microbiology, 1985

The survival of airborne human coronavirus 229E (HCV/229E) was studied under different conditions … High RH [=80%] at 20 °C, on the other hand, was found to be the least favourable to the survival of aerosolized virus and under these conditions the virus half-life was only about 3 h;

8. Dynamics of Airborne Influenza A Viruses Indoors and Dependence on Humidity

Wan Yang & Linsey C. Marr, Virginia Tech, PLOS ONE, 2011

… we further model the dynamics of droplets emitted from a cough in an indoor environment and illustrate the evolution of infectious IAV [influenza A viruses] concentrations and size distributions, considering removal by gravitational settling, ventilation, and viral inactivation. We are thus able to determine the magnitude by which humidity affects airborne concentrations of infectious IAVs. … Higher RH favors removal of infectious IAVs. 

Maintaining a high indoor RH and ventilation rate may help reduce chances of IAV infection.

9. The Effects of Temperature and Relative Humidity on the Viability of the SARS Coronavirus

K. H. Chan, et all., University of Hong Kong, Hindawi – Advances in Virology, 2011

Interestingly, during the outbreak of SARS in Guangzhou, clinicians kept the windows of patient rooms open and well ventilated and these may well have reduced virus survival and this reduced nosocomial transmission. SARS CoV can retain its infectivity up to 2 weeks at low temperature and low humidity environment

Our studies indicate that SCoV is relatively more stable than the human coronaviruses 229E or OC43 … SARS CoV can survive at least two weeks after drying at temperature and humidity conditions found in an air-conditioned environment.

This is applicable to SARS-CoV dried in cold dry office conditions.

10. Generic aspects of the airborne spread of human pathogens indoors and emerging air decontamination technologies

M. Khalid Ijaz, et all, American Journal of Infection Control, 2016

Environmental factor Viruses
Temperature As temperature increases, survival decreases DNA viruses are more stable than RNA viruses at higher temperatures
RH Enveloped viruses (most respiratory viruses, influenza) survive longer at lower RH (20%-30%) Nonenveloped viruses (adenovirus, rhinovirus, and polio virus) survive longer in higher RH (70%-90%)
Atmospheric gases Ozone inactivates airborne viruses to a greater degree than bacteria or fungi
Light and irradiation UV light is harmful (RH-dependent)


Table 3 Current and emerging technologies for decontamination of indoor air for human pathogens
Technology Description Pathogen tested Remarks
UV irradiation Upper-room 254 nm UVC light UV light (254 nm) at 3 levels of RH Influenza A virus (H1N1, PR-8) Virus susceptibility to UV increased with decreasing RH
UV light (254 nm) … a coronavirus as surrogate for SARS, … High RH did not protect viral aerosols
Ozone generator Gaseous ozone and aerosolized virus were generated continuously into the chamber Bacteriophages: single-strand RNA [like influenza & coronaviruses] and DNA, double-strand RNA and DNA 95% of virus aerosol was <2.1 µm in diameter Viruses were more susceptible to ozone at higher RH

11. Survival of the Enveloped Virus Phi6 in Droplets as a Function of Relative Humidity, Absolute Humidity, and Temperature

Aaron J. Prussin, II, et all., American Society of Microbiology, Applied and Environmental Microbiology, 2018

Shaman and Kohn (12) have concluded that the relationship is stronger with AH than with RH. According to their analysis of virus survival in aerosols (24) and transmission in guinea pigs (16), AH explains 50% and 90% of the variability in influenza virus transmission and survival, respectively … In a study examining influenza virus survival in droplets at elevated temperatures (55 to 65°C), McDevitt et al. (27) also reported that AH is a better predictor than RH for virus inactivation. …

Due to the challenges and biosafety concerns of working with the influenza virus and coronavirus, this study employed the enveloped bacteriophage Phi6, which has been suggested as a surrogate for the influenza virus (31, 32) and SARS coronavirus (33). Our results provide novel information about the complex interplay between temperature, humidity, and the survival of viruses in droplets.

Shows optimum humidity levels at 75-80% and temperature above 25 degrees Celsius.

12. Environmental factors affecting the transmission of respiratory viruses

Natalie Pica, Nicole M Bouvier, Mount Sinai School of Medicine, Science Direct, 2012

► Respiratory viruses are spread from person to person via various modes of transmission, including direct and indirect contact, droplet spray, and aerosol

Modes of person-to-person transmission of respiratory viruses

Contact transmission In both modes of contract transmission (direct and indirect), contaminated hands play an important role in carrying virus to mucous membranes.
Direct transmission Virus is transferred by contact from an infected person to another person without a contaminated intermediate object (fomite).
Indirect transmission Virus is transferred by contact with a contaminated intermediate object (fomite).
Droplet spray transmission Virus transmits through the air by droplet sprays (such as those produced by coughing or sneezing); a key feature is deposition of droplets by impaction on exposed mucous membranes.
Aerosol transmission Virus transmits through the air by aerosols in the inspirable size range or smaller; aerosol particles are small enough to be inhaled into the oronasopharynx and distally into the trachea and lung.

(Adapted from Centers for Disease Control and Prevention (CDC); URL:


airborne routes (droplet spray and aerosol) seemed to be more important in SARS coronavirus spread


Influenza viruses Orthomyxoviridae Contact, droplet spray and/or aerosol (conflicting data)
SARS coronavirus Coronaviridae Droplet spray and aerosol, possibly contact

In the early 1960s, Schulman and Kilbourne developed an influenza virus transmission model in mice. Although mouse-to-mouse transmission is relatively inefficient, they still observed a significant decrease in transmission efficiency with increasing relative humidity (RH) …

Transmission of viruses via airborne routes may be affected by ambient humidity, which affects not only the virus’ stability but also respiratory droplet size, as water content evaporates. In turn, droplet size influences whether the particle will quickly settle to the ground or remain airborne long enough to be inhaled into the respiratory tract of a susceptible host. For influenza virus, mathematical modeling suggests that RH is an important variable in airborne transmission of influenza virus; high RH favors removal of infectious particles both by increasing the settling of large, water-laden droplets and by hastening virus inactivation

13. Transmission of the Severe Acute Respiratory Syndrome on Aircraft

Sonja J. Olsen, Ph.D., The New England Journal of Medicine, 2003

This paper suggests that aircraft might be not only carriers, but incubators of the coronaviruses because of the human density and low humidity levels.

14. Detection of Airborne Severe Acute Respiratory Syndrome (SARS) Coronavirus and Environmental Contamination in SARS Outbreak Units

Timothy F. Booth, et all, Oxford Journal of Infectious Disease, 2005

Previous studies of human coronavirus 229E (a common cold virus) showed that experimental aerosols could persist and retain viability for as long as 6 days at 20C and 50% relative humidity [20]. These conditions are representative of typical indoor environments. Although such experiments may overestimate the ability of a virus to survive in real environments (for example, they do not take into account air turnover rates in buildings), one would expect SARS CoV to have similar airborne survival characteristics, given that these viruses are in the same family and have broadly similar physicochemical properties

Popular Medical Advice

This Inexpensive Action Lowers Hospital Infections And Protects Against Flu Season

Leah Binder, Forbes, 2019

Since that study was published, there is now more research in peer-reviewed literature observing a link between dry air and viral infections, such as the flu, colds and measles, as well as many bacterial infections, and the National Institutes of Health (NIH) is funding more research. Taylor finds one of the most interesting studies from a team at the Mayo Clinic, which humidified half of the classrooms in a preschool and left the other half alone over three months during the winter. Influenza-related absenteeism in the humidified classrooms was two-thirds lower than in the standard classrooms—a dramatic difference.

How humidity could help fight coronavirus

Emily Bamforth,, 2020

Humidity could be helpful in relieving the symptoms of coronavirus, as well as preventing it from spreading

Just Dumb

New York City Health, Frequently Asked Questions (FAQs) for Residential Buildings Coronavirus Disease (COVID-19)

Should temperature or humidity in buildings be adjusted to prevent the transmission of COVID-19? • There is no data to suggest that adjusting the temperature or humidity of a building would be an effective way to reduce transmission of COVID-19. The Health Department does not recommend that buildings increase humidity levels to control COVID-19 transmission.

Such obscurantism might have contributed to New York becoming the new COVID-19 epicenter. New York and New Jersey have more than half of the 68,581 COVID-19 cases, confirmed in the US by March 26, 2020.

Conflict of Interest Statement

The Author declares absence of conflicts of interest.

Note from Anthony: I’ve been sick myself the last few days, but I can’t tell if it was flu or seasonal allergy issues, or COVID-19. Time will tell.

What I can tell you though, is that I got one of these, and it has helped my sneezing and coughing. It has a UV-C light to kill germs, and that type of UV light may kill the Coronavirus according to this article.

There are also models that add heat and humidity to the indoor air:

As suggested in the article above by Leo Goldstein, there may be value against COVID-19 in increased humidity, increased temperature, and use of UV-C light in a circulating air filter

Best of luck in these trying times to all!

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Robert Terrell
March 28, 2020 12:05 pm

I have wondered about this ever since I saw a report that said warmer weather and higher humidity would signal an end to infections, just as it does with the seasonal flu. Also, I once considered adding UV-C lights to the air plenums in my HVAC system, to fight off colds and flus. It doesn’t kill them, but it prevents them from reproducing, which is just as good. We need more research on this. Adding these lights is fairly easy and not too expensive.

Henry Pool
Reply to  Robert Terrell
March 28, 2020 4:23 pm

Colds and flus are viruses. They don’t reproduce outside of human cells. UV-C lights in air handling systems will not have any effect on their reproduction.

Rud Istvan
Reply to  Henry Pool
March 28, 2020 5:24 pm

No. UVc will disable enveloped viruses like corona. Dries/disrupts the enveope and its proteins. It will have little effect on the capsid coat of naked viruses like rhino, by far the most common cold viruses. Hence installing them on aircraft isn’t helpful.

Phil Rae
Reply to  Rud Istvan
March 29, 2020 12:05 am


I’d have thought UV-C would likely damage the RNA enclosed by the capsid & that wouldn’t be good news for the virus! Isn’t this a more potent inactivation than “drying/disrupting the envelope”? The RNA genetic material of the virus is presumably more vulnerable to the ionizing effects of UV-C than the protein coat.

Since viruses are effectively obligate intracellular parasites, they presumably don’t have any repair enzymes to fix corrupted RNA so the net impact of UV-C would be to disrupt transcription leaving the virus inactivated.

Rainer Bensch
Reply to  Phil Rae
March 29, 2020 3:56 am

Repair? I think they mutate this way.

Phil Rae
Reply to  Rainer Bensch
March 29, 2020 6:35 am

Viral mutations arise naturally, regardless of external influences like UV radiation . The same is true of mammalian cells and for that reason among others, we have various repair mechanisms to eliminate mutations and repair damage caused spontaneously or by an external source & correct induced errors in DNA/RNA (mainly thymine/uridine dimers).

UV-C is a potent means to kill bacteria & viruses because it is so damaging to the viral/bacterial RNA/DNA. Generally, the mutations are severe enough to compromise the viability of the virus 🦠

Nicholas McGinley
Reply to  Henry Pool
March 29, 2020 12:42 am

What Henry said is correct.
What Robert said is wrong.
Robert got it backwards: UV light will kill viruses, but since they do not reproduce outside of host cells, it makes no sense to say those lights stop them from reproducing only.
The question is the intensity of the UV, how long it will shine on a virus suspended in an air stream moving by rapidly, etc.
I have one of those lights in my AC system, but the bulb is burned out.
Before replacing it, I looked into the evidence that such lights have been proven to reduce diseases or kill anything.
I did not find anything conclusive, and many people seem to think they are a useless gimmick.
I would like to see any scientific studies done that demonstrate having a UV light in your air handler will be killing viruses.
Of course, if someone comes into your home with a virus and expels enough of it to be drawn into the air handler, what are the chances you have not already breathed it in prior to it making any difference?
And if you are the one that is in your home most of the time, no small kids around, etc…what is the point?
You cannot give a virus to yourself, and if your partner has one, chances are you are getting it directly, not after it passes through the air handler.
Might be better to get a HEPA filter in any case.
And for anyone in who has an AC unit running…you will have a hard time raising the humidity to 60 % while it is running, and it will start to feel increasingly uncomfortable if you do succeed. A pot of simmering water raising the humidity of a whole home?
No way.
I have dehumidifiers, and one of them can pull a gallon of water from the air in a hour or two, even when the RH is only about 50%.
When the AC has been off and the RH is 70% or higher, the tank in a dehumidifier will fill up in no time.
I have had my AC drip pan drain get clogged and had the water come dripping into the garage, and had to put a bucket under it until I was able to get the drain unclogged (it happens regularly in Florida, and there is a law that the overflow has to drip the water “someplace obvious”, so it will be seen), and my AC will fill a five gallon bucket in a few hours. If it is more humid to start with, it just collects the water faster, since any moisture will collect on those cold coils as it passes…more moisture in the air will condense more rapidly…just like the sweat on a cold drink will be much heavier when it is very humid. In Florida Summer, a cold drink will make a huge puddle in no time.

I think people would be better advised to spray lots of Lysol around the house.
And ditto with hospitals.
I just cannot see a hospital raising the dew point of the air that high, even if they had a way to do it without simply turning off the AC.
Sick people do not do well when it is very hot and uncomfortable, I do not think. If it is 70% RH and very warm, people in bed will be sweating, and people with a fever will be sweating profusely.
Hospitals go to a lot of trouble to avoid that.

Charles Ellison
Reply to  Robert Terrell
March 29, 2020 11:05 am

Raising the humidity would add protection to the fatty coat. Lowering the humidity and raising the temperature above 77 degrees would be more beneficial. In an enclosed area raising the temperature would lower the humidity. (Law of psychics.) Above information from report available from Johns-Hopkins.

March 28, 2020 12:38 pm

When will people realise that “epicentre” is not a just clever way of saying “centre”. It doesn’t make you sound clever, just ignorant.

Reply to  Disputin
March 28, 2020 4:28 pm

Different meaning. Center means, well center. A point equidistant from the edges.
Epi-center means starting point.

Reply to  MarkW
March 28, 2020 5:23 pm

Did you make that all on your own?

Until alarmist COVID reporting became the new global warming , epicentre was a term only heard in connection with seismology. It meant : a point, directly above the true center of disturbance.

The press have now adopted this as a scary term for a country or region currently hit by a large number of SARS-CoV2 infections.

Reply to  Greg
March 28, 2020 6:13 pm

Both are fine as per Collins dictionary … one is formal use the other informal
You are arguing over nothing

Reply to  LdB
March 28, 2020 7:10 pm

2. informal
the absolute centre of something

So we still don’t see “Epi-center means starting point.”

BTW ” as per Collins” , per already means as, “as per” is repetition, like “the hoi polloi”. Terms intended to sound learned which end up doing the opposite.

Nicholas McGinley
Reply to  LdB
March 29, 2020 12:46 am

Like saying “It begs the question”, when what is meant is not that, but simply to raise the question?

March 28, 2020 12:42 pm

“In Detroit, we are seeing a lot of patients that are presenting to us with severe disease, rather than minor disease,” said Chopra, who worried about a “tsunami” of patients.

Louisiana has surpassed 2,700 infections, with 119 residents dead from COVID-19 — an increase of 36 fatalities from a day earlier, according to the health department. Gov. John Bel Edwards said Louisiana has the third-highest rate of cases per capita and the second-highest death rate per capita, with the region on track to run out of ventilators by the first week of April.

Joel O'Bryan
Reply to  ren
March 28, 2020 1:34 pm

Louisiana is getting slammed for Mardi Gras festivities in February and early March. Expect Florida to follow close behind resulting from the mid-March Spring break kiddees.

China got slammed in February for its late January Chinese New Year migrations and family gatherings.

Epidemiologists understand this phenomenon. It is likely STDs follow those same patterns in sexually active and promiscuous groups therein.

Clyde Spencer
Reply to  Joel O'Bryan
March 28, 2020 3:39 pm

Unfortunately, a lot of the young people participating in the mid-March Spring break in Florida were from out of state, and will be bringing ‘presents’ back to their families throughout the country.

Joel O'Bryan
Reply to  ren
March 28, 2020 1:40 pm

Detroit likely got seeded early with SARS-CoV-2 because of extensive travel contacts by corporate Fiat-Chrysler execs and engineers cross-flow with Italy.

Henry Pool
Reply to  ren
March 28, 2020 4:24 pm

Louisiana has high humidity.

Greg Goodman
Reply to  Henry Pool
March 28, 2020 6:00 pm

It’s indoor humidity which is under discussion. If you heat air without adding extra water RH drops.

Leo Goldstein:

Notice that air cooling also decreases relative humidity. If this issue is not addressed, this epidemic might decrease in the late spring, then peak back in the summer due to elevated AC use.

How does that work ? You cool air and RH goes up, not down . That is why you get water pouring out of the heat exchangers in AC units because the air gets to 100% RH and condensation happens. That reduces *absolute* humidity NOT RH. You should correct that part of the article.

It now seems common practice for people to expect to walk round in a tee-shirt all year round at home, instead of letting the body aclimatise to the seasons wrapping up in winter. This means living in unnaturally dry air for half the year. Big surprise if this is period when these *seasonal* illnesses occur.

Apart from being an added stress on the mucus membranes, which struggle to remain sufficiently damp, it may also affect the way they absorb infected aerosols.

A dehydrated membrane will suck up and moisture droplets they contact with ( and any viruses contained therein ). Apart from being generally unhealthy , I suspect that is the major factor relating to infections.

Personal anecdote: I don’t heat my living space until it gets down to about 10 deg C ( 50 F ) , I stop when it gets to 12-14 deg C. I DON’T GET colds seasonal flu.

The best way not gets colds is to stay cold 😉

This is a very important factor , thanks for such detailed and well sources article.

Henry Pool
Reply to  Greg Goodman
March 28, 2020 6:10 pm

It doesn’t matter if the humidity is indoor, or it is outdoor. The problem New Orleans has is that the transmission occurred outside during Carnival, where the humidity is high.

Reply to  Henry Pool
March 28, 2020 7:22 pm

How do you know where transmission occurred ? Did you study it? Don’t people meet before going out?

What is the typical indoor and outdoor humidity in New Orleans in February?

Afternoon is typically mid 50s RH. Same as my house right now.

Nicholas McGinley
Reply to  Greg Goodman
March 29, 2020 1:03 am

Air conditioners lower the amount of moisture in the air, and they also lower the relative humidity.
If they did not, the air would not feel nearly as comfortable.
How well sweat will cool our body (and we are always sweating, whether or not it accumulates enough to be noticeable) is directly related to relative humidity, not absolute humidity, although the two are definitely related.
I have several dehumidifiers in my house, and i can tell you, when the AC comes on, it lowers the relative humidity substantially.
Say the air inside is 82° and the RH is 75%, when I am out of the house all day and the AC is turned off.
I get home and turn it on. The temperature goes down to about 70-72° (I do not believe in being uncomfortable inside my house…I can go out to the pool or garden for that), and the RH to about 45-50% (I can tell because my dehumidifiers have a readout on them that says what the RH is). But If I wanted to lower the RH to a similar level and keep the temp at 82°, that would require removing far more water from the air.

By the way…the best way to avoid getting a cold is to avoid people who have a cold.
You do not get viruses for the air, no matter the temp.
I do not get cold either, and I never let my house get really cold (or hot).
But I would never try to argue that it is because of where I keep my thermostat setting.
That is malarkey.

Charles Ellison
Reply to  Nicholas McGinley
March 31, 2020 10:56 am

Nice article but difficult to understand due to failure to “once over” for misspelled words which change the meaning intended. Temperatures listed should be adjusted to “apparent” temperature instead of actual temperature. Setting the thermostat to a cooling temperature of 78 degrees will eventually feel like 72 when the humidity is reduced to the 40% shown. Here is the problem with most residences. The installer of the conditioning equipment do not engineer the system to fit the area to be controlled. Oversizing either causes problems. Oversizing a heating system will cause cool spots within the area due to short run time. It could be a room or even several rooms. Oversizing an A/C unit will result in higher humidity due to the short run times. (This is the way to engineer cold rooms in a produce house, one who sells lettuce and similar vegetables, to keep from removing the moisture from the products cooled. This also applies to fresh meat coolers.) With the necessity of complete control of the air within a residence, a full set of engineering data should be used to determine the equipment to be installed. Variable equipment would be a big plus in controlling the air. A little under-sizing is better than any over-sizing.

D. Boss
Reply to  Greg Goodman
March 29, 2020 5:21 am

Yes, the above article, and most of the so called papers are gibberish in regards to R.H. (Relative Humidity). The critical factor is Absolute Humidity. I just saw an article and paper on this, but can’t locate it right now.

The critical factor is about 12,000 ppmv water vapor. Or approx 9 g/m³. Stay above this absolute humidity and the virus is attenuated.

Here is an excellent online calculator for converting your ambient temperature and relative humidity to absolute humidity:

Right now beside my computer is a thermometer and hygrometer, and I have 77F and 49% RH, and my pressure is 1018.8 mb (or hectopascal). Enter these into the above web calculator and my absolute humidity is 15,482 ppmv.

The article and papers above are correct in that a virus’ life outside a host is attenuated with higher humidity – just do not use Relative Humidity as your yardstick.

Nicholas McGinley
Reply to  D. Boss
March 29, 2020 6:39 pm

See below, it depends on the virus.
People who are sick shed virus, and measuring how long viruses live on surfaces is not the same thing as measuring the likelihood of someone passing a virus along to other people in a house or a hospital or an office.
It seems logical it will not hurt, but how much difference will it make?
70% RH is fine when it is cool, but that humidity level when it is warm is very uncomfortable.
The only way we can be sure not to get this virus is to not be near people who have it.
If someone is in the same room with you and they have it, I am not buying the argument you can avoid contracting it by changing the humidity in the building.
And how long are we gonna do that?
This seems likely to be an ongoing thing.
Now, making it humid in Winter…that makes sense…and it will make the living space more comfortable, and make a cool or cold room seem warmer at the same temperature…same as higher humidity does when it is hot.
Hospitals are not going to make the air humid and uncomfortable.
Many people who are sick would be very negatively affected by also being hot and sweaty. People with heart conditions for example.

March 28, 2020 12:49 pm

Its interesting how different agencies differ in facts. This information for instance says the air should be dry.

The following is from Irene Ken physician, whose daughter is an Asst. Prof in infectious diseases at
Johns Hopkins University
* The virus molecules remain very stable in external cold, or artificial as air conditioners in houses and cars.

They also need moisture to stay stable, and especially darkness. Therefore, dehumidified, dry, warm and bright environments will degrade it faster.

* UV LIGHT on any object that may contain it breaks down the virus protein. For example, to disinfect and reuse a mask is perfect. Be careful, it also breaks down collagen (which is protein) in the skin.

Joel O'Bryan
Reply to  Sciwiz
March 28, 2020 2:21 pm

UV light penetrates the viral membrane and protein capsid and far more quickly induces molecular defects in the nucleic acid coding via strand breaks and oxygen radical formation (leading to extensive oxidation defects in the nucleotides and cross-linking) than any consequential protein damage. By the time UV has begun to make detectable protein damages, the RNA strand is so heavily damaged the virus is long-past being viable. The shorter the wavelength, the deeper the UV penetrates. UV-C is particularly damaging, but there is little UV-C flux at sea level.

Roger Knights
Reply to  Leo Goldstein
March 28, 2020 7:48 pm

A-HA! (I had encountered this contradictory humid/dry advice elsewhere, but now you’ve resolved it for me.)

Reply to  Leo Goldstein
March 28, 2020 8:43 pm

Fear is an animal emotion. I doubt that and strand of RNA knows fear. Maybe you could say what really is the case.

The envelop of enveloped RNA viruses is lipid. Why does that make “moisture” a problem? Since moisture is not clear whether it refers to water content ( humidity ) or RH, it would be best to avoid that term in this context.

It is necessary to distinguish between survivability of the virion itself and it success in transmission and reproduction which depends heavily on the host. I suspect most of the RH argument relates to the performance of mucus membranes in different environments.

Nicholas McGinley
Reply to  Leo Goldstein
March 29, 2020 2:18 am

I had raised this exact point in some of the early discussions of this virus here at WUWT.
Some viruses seem to survive better on fomites when the humidity is low, and others survive better when it is high.
There are no general rules which hold true in all cases, and there can be wide variations in the survival characteristics of even closely related viruses.
And it has been noted that there is no central repository of information on how well various viruses survive under what specific conditions.

See here:
For humidity…
“Effect of relative humidity (RH) varies within virus type. It is believed that the survival of enveloped viruses on inanimate surfaces is better when RH levels are below 50%. On the other hand, RH levels higher than 80% are considered to be more beneficial to the survival of non-enveloped viruses. In general, viruses with higher lipid content tend to be more persistent at a lower RH, whilst viruses with lesser or no lipid content are more stable at a higher RH (Assar and Block 2000; Moce-Llivina et al. 2006). However, there are exceptions.

Studies have shown that HAV is able to survive better at low levels of RH, which is in contrast to the behaviour of other enteroviruses (Mbithi et al. 1991; Stine et al. 2005). When its persistence in high and medium RH (85.7–90.3% and 45.1–48.4%) was compared, HAV survived longer on lettuce in dry conditions. Based on the calculated inactivation rates, a 99.9% reduction in HAV could take 822 days in pre-harvest conditions of contaminated vegetables (Stine et al. 2005). In contrast, Abad et al. (1994) found that survival of HAV was enhanced at high RH.

Data regarding rotavirus survival was determined to be contradictory. Moe and Shirley (1982) showed that a field strain of human rotavirus could survive longer when RH was kept either low or high than when RH has medium range. Sattar et al. (1986) reported that human rotavirus survived for a shorter period of time at high RH. Abad et al. (1994) also observed that human rotavirus and poliovirus exhibited greater persistence at high RH on non-porous material. The survival of adenovirus was not affected by RH. At 5°C RH had a little effect on survival time of norovirus, but its survival was longest at 20°C and low RH.

Sattar et al. (1987) investigated rhinovirus on surfaces. Humidity was used as a variable factor. The study found that rhinovirus exhibits optimum survival at 50% RH.”

For temperature…
“However the degree of virus survival on surfaces is affected by temperature, it depends also on the virus type and RH. Viral particles are able to persist from days to months over a range of temperatures in the environment, and being preserved by refrigeration or freezing (Cliver 2009).

Temperature is one of the most important of determining norovirus survival in the environment. Recent studies indicate that noroviruses can survive for a prolonged period of time at a low temperature and can be transmitted to a susceptible population via different environmental media including surfaces (Mattison et al. 2007). Doultree et al. (1999) found that FCV dried onto glass and stored at 4°C displays a 4.75 log reduction over 56 days. FCV survival was lower at room temperature, but still prolonged. The number of infectious FCV declined to undetectable levels by 21–28 days. FCV was not detected at 37°C after 1 day. Comparative analyses indicated that FCV survival was greater at 4°C than at room temperature. Therefore, outbreaks caused by noroviruses are much more prevalent in the winter than in the summertime (Doultree et al. 1999; Mattison et al. 2007).

Rotavirus particles are able to survive storage in ambient tropical temperatures for more than 2 months (Fischer et al. 2002). Moe and Shirley (1982) reported that rotavirus infectivity decreases more rapidly under all RH at 37°C than at 4 or 20°C. According to a study done by Sattar et al. (1986), rotaviruses can persist longer at a lower temperature (4°C) and RH (25–50%), with approximately 10% infectious virus remaining after 10 days, in comparison to less than 1% after 2 days at 22°C and 85% RH. Abad et al. (2001) investigated the survival of an astrovirus at 4 and 20°C with a high RH (90 ± 5%). At 4°C, the virus was able to persist for 60 days desiccated on non-porous material and for 90 days on porous material. Faster decay was observed at 20°C. Short-term survival of astrovirus was compared to that observed for other enteric viruses significant for health, such as rotavirus, adenovirus, poliovirus and HAV. Overall, astrovirus persisted better than poliovirus and adenovirus, although they exhibited a shorter survival than the rotavirus and HAV.

Amongst other factors, the effect of freezing on enteric viruses in berries and herbs was tested by Butot et al. (2008). This study revealed that freezing does not significantly reduce the viability of norovirus, HAV and rotavirus. Only infectivity of FCV on strawberries can be decreased. Freezing for 3 months had a limited effect on HAV and rotavirus in all tested food products. A higher decay rate was observed in frozen raspberries and strawberries contaminated with FCV due to the acidic pH (Butot et al. 2008). No reduction of MNV-1 PFUs was observed on frozen onions or spinach during storage for 6 months (Baert et al. 2008). Kurdziel et al. (2001) reported a reduction of <2 log10 units of poliovirus on frozen strawberries after 15 days of storage. So far, no data about survival of other viruses during freezing are available."


This is a very interesting paper, and it includes a large number of links and references.
There is also a section on sunlight and UV.

Well worth taking the time to read it and follow some of the links for further information.

Reply to  Nicholas McGinley
March 29, 2020 3:48 am

Damn, you mean there’s no simplistic answer with a straight line trend fit ?!

The sooner as we can get back to climatology the better.

Thanks for a detailed comment.

Nicholas McGinley
Reply to  Greg
March 29, 2020 6:50 pm

Note that these studies all look at surfaces, not virions floating in the air.
I think having a very strong airflow pulling air through a properly designed filter will make more difference, and I agree that transmission likely occurs by breathing droplets directly, or by fomites on surfaces that are then touched and infect a person when they subsequently touch their face.
Personally, my focus is on keeping people who might be infected out of my house, and spraying disinfectant (Lysol is listed as killing corona virus), and washing hands especially after being outside. When I come in from a place where other people are, all clothes come off and right in the washing machine before i take three steps.
Shoes I spray with Lysol.
Hands I wash before entering a store and after leaving, with 92% isopropyl alcohol, and then a dilute solution of iodine in a squeeze bottle.
Povidone iodine is proven to provide about an hour of residual antiviral activity on the hands.
And I spray everything I bought with Lysol once it is in the trunk of the car.
Then close it up fast.

Humidifying when heat is on is supposed to be done anyway…it is bad for your mucous membranes to be so dry, and humidity makes any space feel warmer at an equivalent temperature.

Reply to  Sciwiz
March 28, 2020 6:30 pm

This information for instance says the air should be dry.

What “agency” is this from. Looks like comment from someone’s mother.
What is your source ( link ) ? Sounds like a journo reporting what he thought a professors though she said.

Most people think warm air is “dry”.

March 28, 2020 12:51 pm

An emergency room doctor at NYU Langone Medical Center and Bellevue Hospital in New York says she fears the “worst case” scenario in the fight against coronavirus if shortages of ventilators and protective equipment persist. (March 26)

Terry R Bixler
March 28, 2020 12:53 pm

Good article. Current government recommendations are to stay indoors and set your thermostat low. Seems like this is a way to maximize virus uptake. In my area they have shut down the beaches and many outdoor venues which makes sure that people are indoors. Meanwhile due to obsession with “global warming” suggest little heat. Further it seems that the research and use of hydroxychloroquine has been politicized so that little current information is available. How to maximize harm in the pursuit of power.

Alan McIntire
Reply to  Terry R Bixler
March 28, 2020 3:02 pm

I agree there. Getting outdoors should result in getting exercise, and vitamin D from the Sun., both of which should help build up a person’s immune system regardless of any specific disease,

Reply to  Alan McIntire
March 28, 2020 5:19 pm


Bill Parsons
Reply to  Alan McIntire
March 29, 2020 12:06 am

Best advice yet. Get outside and get moving. Doubly important for the elderly who seem to be hardest hit.

I wonder if the array of “underlying conditions” aren’t the primary cause of death in most people, with the coronavirus providing merely the the final load on weakened hearts and lungs.

If a person testing positive for Coronavirus dies, is that being cited as the chief cause of death regardless of the number and severity of his co-morbidities. In other words is there an incentive to overlook a cause of death that does not elicit emergency funding – say, flu for example?

Reply to  Terry R Bixler
March 28, 2020 3:43 pm

The French researcher Didier Raoult that did the hydro chloroquine study is interestingly a climate skeptic.

Reply to  Stevek
March 28, 2020 6:33 pm

Ah, that’s why they disparage his work. Makes a lot more sense.

March 28, 2020 12:54 pm

Nice post with lots of information to digest.

One word of caution, UV light can generate ozone and ozone is damaging to lungs, and rooms being disinfected in this way should be unoccupied. Circulating UV air purifiers will contain some means for ozone destruction.

Kimchi may be a good line of defense.

Michael S. Kelly
Reply to  Scissor
March 28, 2020 8:02 pm

“Circulating UV air purifiers will contain some means for ozone destruction.”

Just release some freon into the room. Problem solved.

March 28, 2020 1:00 pm

Thanks for this Leo. Hopefully someone out there can reach top levels of CDC and get them to include building temperature/humidity recommendations in guidelines. I’m extremely disappointed in the CDC. They really got caught unprepared for this.

Wim Röst
March 28, 2020 1:16 pm

What is the temperature and the moisture content maintained in cruise ships?

Reply to  Wim Röst
March 28, 2020 3:19 pm

The one i was on – January-February, trans-Atlantic cruise, Tilbury to Tilbury, had very dry air in the cabins; I guess below 30% RH [Guess – no instrument on holiday!!].
Mould and fungi are problems at sea.


Zig Zag Wanderer
Reply to  Wim Röst
March 28, 2020 3:38 pm

Fairly low (by my feel) and very dry. I always have a balcony room, and always leave the door open unless it is cold or in a port.

Most ships do not let you turn the a/c off, so I waste it all and they complain about the condensation, so I complain that I can’t turn off the stupid a/c I don’t want. I’m not a fan of a/c until it gets over 30C, which it rarely does at sea, and I love the sea air.

Reply to  Wim Röst
March 28, 2020 6:38 pm

Cruise ships are predominately aimed senior citizens. Old folks get cold easily. You can be sure that they are kept nice and warm …. and thus dry in winter.

Mike Bryant
March 28, 2020 1:19 pm

Turn up your A/C folks… especially you guys in humid areas… keep the faith… Winning!

Reply to  Mike Bryant
March 28, 2020 3:00 pm

That seems to be just the opposite of what that article was recommending.

Joel O'Bryan
March 28, 2020 1:30 pm

One of the world’s leading experts on Influenza virus, Dr Peter Palese at Mount Sinai School of Medicine, was probably the first virologist to extensively study and report the temperature humidity effect on influenza virus viability.

Influenza Virus Transmission Is Dependent on Relative Humidity and Temperature
Anice C Lowen , Samira Mubareka, John Steel, Peter Palese
Published: October 19, 2007
(from the abstract:)

“Using the guinea pig model, we have evaluated the effects of temperature and relative humidity on influenza virus spread. By housing infected and naïve guinea pigs together in an environmental chamber, we carried out transmission experiments under conditions of controlled temperature and humidity. We found that low relative humidities of 20%–35% were most favorable, while transmission was completely blocked at a high relative humidity of 80%. Furthermore, when guinea pigs were kept at 5 °C, transmission occurred with greater frequency than at 20 °C, while at 30 °C, no transmission was detected. Our data implicate low relative humidities produced by indoor heating and cold temperatures as features of winter that favor influenza virus spread.”

Jeffrey Shaman’s publications on influenza were merely just replication work of Peter Palese’s seminal reported work in different settings (apartments, etc).

Sweet Old Bob
Reply to  Joel O'Bryan
March 28, 2020 6:19 pm

” when guinea pigs were kept at 5 °C ” ….
Isn’t that damn cold for guinea pigs ? Wouldn’t they be severely stressed ?

Reply to  Joel O'Bryan
March 28, 2020 7:05 pm

Very odd that a supposed scientific study does not accurately describe the test conditions.

He is supposedly studying two variables. Yet in neither case does he state what both are at the same time. What was the temperature during RH testing? Was it constant or even measured.

What was the RH during temperature testing? Was it constant or even measured.

Ah, poorly written abstract. Paper gives details.

Influenza virus transmission indoors could potentially be curtailed
by simply maintaining room air at warm temperatures (>20
deg. C) and either intermediate (50%) or high (80%) RHs.

Again the idea that room temps could be lower than 20 deg. C seems to be so unthinkable that it is not even worth including in the study. They are quite happy to keep guinea pigs in 5 deg. C but 10 and 15 deg conditions get a total blank.

Ambient temp as I write is 14 deg. C and RH is 57%. I stopped heating about 4 weeks ago, that is natural ambient conditions.

JD Ohio
March 28, 2020 1:35 pm

This article explains a simple reason why moisture inhibits viruses– “Warmer air holds more moisture, which prevents airborne viruses from traveling as far as they would in dry air. In humid conditions, the small liquid droplets in a cough or sneeze gather more moisture as they’re expelled. Eventually too heavy to stay airborne, they drop to the ground.”

Charles Ellison
Reply to  JD Ohio
March 28, 2020 3:13 pm

Saying liquid droplets add moisture is a complete opposite to osmosis. Since the droplets are 100% humid and air in buildings with artificial temperature control is below 60%.

March 28, 2020 1:35 pm

No way to do a study that would prove humidly limits the spread of Covid19. I have family in the Philippines where the climate is hot and humid…and Covid 19 is running rampant….out of control. There will be those who will claim that without the humidity it would have been worse. Right now there is no way it could be any worse there. Doctors and nurse dying…hospitals at full capacity…healthcare system at near collapse. Hotels filling up with the sick, food rationing, military check points. Government handout of rice is spoiled….certain gov officials make huge profits…Meanwhile, “MANILA (UPDATE) – The United States said it was looking for medical professionals, particularly “those working on #COVID19issues” who wish to work in the US on a work or exchange visitor visa (H or J) as the country’s coronavirus cases surged past 100,000.” (google it)

Dr Deanster
Reply to  Codetrader
March 28, 2020 2:55 pm

No offense, … but have you looked at the numbers? Philippines has ~1000 cases and 68 deaths. That is 1000 cases for a population of 104 Million. Granted, my heart goes out to those people effected, … but … Contrast that to poor old Italy, with 92,000 cases in a population of only 61 Million.

The Philippines data is rather supportive of the OP. It doesn’t say there will be no cases, just fewer.

Reply to  Dr Deanster
March 28, 2020 3:33 pm

No Offense but do you actually think that the Philippines government has the ability to test and report actual numbers and are doing it? China sent hundreds of thousands of test kits to the Phils and 60% of them failed. You simply are misinformed! And, if you want to put on the humidifier in your house and sit back and relax…have at it.

Reply to  Codetrader
March 28, 2020 5:49 pm

Yes, it’s difficult to get good data unfortunately.

This piece casts doubt on Wuhan death figures.

Roger Knights
Reply to  Scissor
March 28, 2020 8:05 pm

Thanks—that’s what I suspected. It was bound to come out. And therefore cases will resume rising after the lock-down has been lifted. But China has no choice—it can’t shut down its economy forever.

Let’s hope that the quinine-based treatments, and other treatments now being tested, can keep the death rate under control enough that we in the U.S. can lift the quarantine without dire consequences.

Nicholas McGinley
Reply to  Codetrader
March 29, 2020 2:31 am

Regarding the number of cases and reporting…I have suspected as much from the get-go.
Obviously some countries have systems in place for rapidly reporting and collating such information, and just as obviously many places have no such ability and no such systems in place.
I would not place much stock in any of the numbers, if I had to bet on their veracity.
During a crisis people have more important things to do than make sure people far away have an accurate understanding of the situation.
And that is just one factor…there are many.

Reply to  Dr Deanster
March 28, 2020 7:02 pm

Dr: 9 Filipino doctors dead due to coronavirus

“Hundreds of medical staff are no longer accepting patients because they are undergoing 14-day self-quarantines after suspected exposure, the hospitals said.

Testing remains limited in the Philippines as of Tuesday, only for those with severe symptoms and those considered most vulnerable to COVID-19, such as the elderly, those with life-threatening ailments, and pregnant women.”

Reply to  Codetrader
March 28, 2020 6:24 pm

Codetrader, maybe your family can try these:

Iodine solution as a gargle wash and disinfectant as used in Japan:

NYC hospital using IV Vitamin C Treatment:
Vitamin C tablets will work, too.

Reply to  Jenn
March 28, 2020 6:59 pm

Thanks, I’ll let them know.

March 28, 2020 2:13 pm

HA! First thing I noticed when I clicked the first product link was that it has an AOC filter!! No sign of a USB so it can be hooked up to the internet but I will put it close to the TV and radio. Thanks for the tip Anthony.

Zig Zag Wanderer
Reply to  Doug
March 28, 2020 3:40 pm

You can filter out AOC? I can see that being in demand. She’s pretty annoying…

Rud Istvan
March 28, 2020 2:24 pm

I will repeat (using different language) some facts from my first Wuhan virus guest post. The knowledge was hard earned over a decade as CEO of a small private company owning the patent to a persistent hand sanitizer (3 hours log 3 kill in vitro on Vitroskin for all bacteria, all fungi, all enveloped viruses, and some naked viruses including rhino), and who was thrust into the 2009 swine flu pandemic as a result if it killing our internal FDA regulatory expert.

My bottom line is that higher humidity will NOT help stop the spread of Wuhan coronavirus. Nor will Wuhan abate much in the summer. Miami becoming a new hotspot, or NOLA now, is sufficient evidence that the Fauci’s summer abatement hypothesis is just hope porn.

The issue is route of infection. Simple bottom line observation first. Flu is very strongly seasonal (rare in summer). Colds are weakly seasonal (summer colds are common, but there are more in winter simply because people are indoors together more).

Flu is mainly spread by inhaling infected aspirate—the ‘smoke’ the Bears and Packers exhale in the cold winter months in their outdoor stadium games. These are very fine particles of moisture. In dry winter indoor air they dry rapidly and remain floating in the air for hours. In humid summer air they cannot dry rapidly and sink towards the floor where you don’t inhale them. They do eventually settle, so contact transmission is a minor secondary route of transmission.

Common colds are caused by three virus types: naked rhino, enveloped corona, and enveloped adeno.
For all three types by far the main route of transmission is contact, not inhalation. You blow your nose into a tissue, infecting your hand. Or you cover a cough with your hand, infecting it. Then you open a door using its doorknob, infecting its surface. Hours or days later, someone else opens that same door, and then touches their mouth, nose, or eyes and is infected. (Actual clinical studies show the typical person touches those places 15-25 times per hour.) The time cold viruses remain viable on surfaces depends on the virus type, surface and environment (sunlight IS a disinfectant) but is about 4 days worst case. Alcohol hand sanitizers are ineffective against naked rhinos, the most common cold viruses by far. They DO work against enveloped coronas by denaturing the spike protein the virus uses to enter mucosal and epithelial cells.

The Wuhan corona is much nastier than the four common cold coronas. The only difference in transmission is the hard coughing expelling large moist particles. If you socially distance, you won’t breathe them in even if the cough is uncovered. Three feet (one meter) is sufficient—the overabundance of caution rule is now 6 feet. Guess what. Those particles sink to whatever surface. A table top, a grocery store shelf, the can of soup on the shelf. Just like common cold coronas from then on.

The three things to do are: social distancing (protect from cough), wash hands frequently, since little alcohol sanitizer is available, and don’t touch your face unless right after hand washing.

Reply to  Rud Istvan
March 28, 2020 2:55 pm

Experts here in the UK are now recommending it should be around 8 metres, some 25 feet, which sounds hugely excessive and wildly impractical and extremely theoretical


Rud Istvan
Reply to  Tonyb
March 28, 2020 4:26 pm

TonyB, regards. An observation. Nobody can spit 8 meters (heck, even watermelon seeds) let alone cough 8 meters. The analogies to ‘climate change’ highlighted in my first guest post just continue to mount.

Nicholas McGinley
Reply to  Leo Goldstein
March 30, 2020 6:10 am

I think it is likely that the amount of virus shed by people who have this disease is very high.
And if the infective dose is low, that combination means that whatever was being given as advice (which was based on other viruses…not this one) regarding transmission is very likely wrong.
The emerging evidence is that this is a virus that can be spread very easily, and something is causing that.

Reply to  Rud Istvan
March 28, 2020 3:49 pm


I read today that HCoV-NL63 which has been in humans for likely hundreds of years also uses ACE2 to enter cells.

“The virus is able to use Angiotensin-converting enzyme 2 (ACE2) as an entry receptor to bind to and enter target cells.”

Clyde Spencer
Reply to  Rud Istvan
March 28, 2020 3:52 pm

You said, “They do eventually settle, so contact transmission is a minor secondary route of transmission.” Except, perhaps, for ‘rug rats.’ And then adults handling their shoes while taking them off.

Rud Istvan
Reply to  Clyde Spencer
March 28, 2020 4:45 pm

True, that.
My knowledge comes directly from Dr. Fauci. He became in favor of our FDA swine flu EUA after we showed him our influenza persistence in vitro and he said, (paraphrased) KIDS!

Tom Abbott
Reply to  Rud Istvan
March 28, 2020 4:26 pm

Will sticking your hand under running water wash the virus off the hand or does it have some way to cling to the skin and remain even after the flood?

Rud Istvan
Reply to  Tom Abbott
March 28, 2020 4:35 pm

Tom, the surfactants in soaps help loosen bacteria and viruses from your skin so they are more easily mechanically washed off. Evolution obviously made them ‘sticky’ as an evolutionary advantage for them, before we invented soaps.

Joel O'Bryan
Reply to  Rud Istvan
March 28, 2020 5:02 pm

Alcohol hand sanitizers are ineffective against naked rhinos, the most common cold viruses by far. They DO work against enveloped coronas by denaturing the spike protein the virus uses to enter mucosal and epithelial cells.

This statement is incorrect. Alcohol sanitizers primarily work as lipid solvents, thus they disrupt the lipid envelope of coronaviruses, and influenza viruses; basically disrupting and stripping off the lipid membrane that hold the viral surface structural proteins. It is because of the lack of lipid membrane that Rhino viruses are relatively resistant to alcohol sanitizers.

A little bit of iodine (1% solution) added to the alcohol though is very effective against rhinoviruses.

“Evaluation of virucidal compounds for inactivation of rhinovirus on hands.
Hendley JO, Mika LA, Gwaltney JM Jr. November 1978.
Antimicrob Agents Chemother.

Antimicrobial liquids and foams were applied to the hands to determine their virucidal activity against rhinoviruses. Dilute solutions (1%) of iodine in ethyl alcohol or in water were most effective in causing inactivation of rhinovirus when applied immediately after viral contamination. Iodine also had a residual virucidal activity which persisted on the hands for up to 1 h. Less effective inactivation of rhinovirus was observed with foams containing 0.23% hexachlorophene and 58% ethyl alcohol and another containing 0.2% benzalkonium chloride and 50% ethyl alcohol. Ethyl alcohol alone or in a mixture with benzyl alcohol was the least effective preparation tested.”

Rud Istvan
Reply to  Joel O'Bryan
March 28, 2020 5:41 pm

Yup. Iodine is a VERY effective permanent denaturant. Now how many people would accept a 1% iodophor in alcohol as a solution turning their hands chapped and orange? Heck, tincture of iodine is not in short supply in any store I recently visited. Data. Is used to disinfect OR patient sites once , NOT OR personnel multiple times.

The challenge is which of those known choices can be widely used without major side effects? Been there, done that. Please do not get me started on a decade of that hard won knowledge.

Miklos fom OZ
Reply to  Rud Istvan
March 28, 2020 8:07 pm

Hello Istvan, I hope you not mind me sharing your opinion and comments on my FB page. Highly respect your knowledge and the way you explain complex issues!
Kind Regards,

Nicholas McGinley
Reply to  Rud Istvan
March 30, 2020 5:25 am

The whole world knows masks help prevent the spread of respiratory diseases.

Austria is making it mandatory to wear a mask in supermarkets.
If everyone wears a mask, we can slow the spread.

Nicholas McGinley
Reply to  Rud Istvan
March 30, 2020 5:35 am

More on masks:

Last week I began to speak up more about the obvious disconnect between the advice not to wear masks, and the insistence that medical workers NEED to always have plenty of them.
Now more and more medical authorities are coming around on this.
Do not just go around parroting what others have said about masks not being helpful…that is nonsense, and the public health officials who are actively scolding people not to wear any sort of mask ought to be fired, IMO.
The droplets come out of the mouth and nose, and are breathed into the mouth and nose.
Even a dishtowel is known to block 50% of airborne particulates.
Vacuous cleaner bags are over 90% effective.
Anything is better than nothing, but few things are as effective as blocking transmission as an N-95 mask properly worn.
Even improperly worn it is obviously better than nothing.
How can you not breathe in virus if someone who has it coughs or sneezes and you are in the cloud?
Everyone has to wear a mask.
The sooner we get this straight, the sooner we can slow how this is spreading.
Masks are more effective than hand washing ten times a day.

Nicholas McGinley
Reply to  Nicholas McGinley
March 30, 2020 5:36 am

Vacuum cleaner bags.
Dang autocorrect.

March 28, 2020 2:52 pm

Interesting. We live next to the sea in the UK and rh outside during the winter has regularly been well over 80 percent whilst indoor it rarely falls below 60 percent . Is this true for most coastal regions here and overseas? If so has it corresponded to a lower incidence of CV in coastal or great lakes areas?

My mother also insisted on opening windows to air the house if anyone was Not well.

In a bad flu season around 40000 Brits will die of flu. There is another category of 140000 deaths each year of avoidable deaths often cited due to poorly heated houses. Costs of heating are Insane these days so cold houses and tightly shut windows to keep the warmth in sounds a lethal combination


Dr Deanster
Reply to  Tonyb
March 28, 2020 3:04 pm

Based on my knowledge, It’s not just high humidity, it’s also high temperature. Those in themselves are bad on the virus, but there is the untold fact that warm weather equals short sleeves and swimsuits, and a lot of Vitamin D, which is crucial to the immune system. While Vit D may not prevent the spread, it will result in more asymptomatic infections and less severe infections, and it helps to prevent cytokines storms. In a modern Western Society, up to 50% of people are Vit D deficient.

Places like U.K. will not benefit as much from just high humidity, it’s stinking cold up there.

Rud Istvan
Reply to  Dr Deanster
March 28, 2020 5:00 pm

That is an interesting observation. We live in south Florida, sun and melanoma central. True doc data, 1/3 of South Floridians are vitamin D deficient thanks to sun covers and sunscreens!
My significant other was tested exactly one point whatever away from medically clinically deficient. She covers up when we long walk our beach, as her skin has suffered already a lot of damage from her younger more risky days. 2000 IU supplement daily is the medically prescribed answer for her.

Reply to  Dr Deanster
March 28, 2020 5:12 pm

Dr Deanster, Way too much fake information on your part! Your are not helping!!

March 28, 2020 3:00 pm

in the Philippines where the climate is hot and humid…and Covid 19 is running rampant….out of control

My understanding is that there are also huge high density slums in the Philippines. They don’t have cars so all their food must be bought at local markets within walking distance. Or I suppose public transit which would be worse.

There are a lot of factors at play besides humidity and temp. My reading of the evidence suggests high temps and humidity may well help. The Philippines may well have been worse if not for high temps and humidity.

Reply to  davidmhoffer
March 29, 2020 9:09 am

David, Your “Understanding” of the Philippines is remarkably ignorant! You have no understanding. 60% of the poor reside in rural areas. Philippines trained Doctors and nurses are in high demand internationally and recruited all over the world. The few “slums” in Manila for example remind me of the homeless camps in LA and Seattle. The Philippines economy is the 10th fasted growing economy in the world. Several of the worlds top 15 largest retail shopping malls are located in Manila, Cebu and Pasig.

The burgeoning middle class in the Philippines is set to exceed the spending power of Italy’s middle class by 2030, in a sign of the Southeast Asian nation’s growing economic might. Along with many of its neighbors, the Philippines has a growing tech-savvy population, an exploding digital economy and an increasingly integrated regional economy. Philippines is on track to be an upper-middle-income country by 2022 which translates to an “economy expanding by about 50 percent.

The average annual percentage of humidity in the Phils is: 75.0%. Today it will be about 95 degrees with Humidity at 78% Today in Miami it will be about 85% with a 78% humility. There are about 1,192 infection in Miami today and another 900 in Broward County due north.

Please let the folks know in south Florida that there is nothing more to fear! Higher temps and humidity are on the way.

Juan Slayton
March 28, 2020 3:10 pm

Notice that air cooling also decreases relative humidity.

I must be missing something here….

charles nelson
Reply to  Juan Slayton
March 28, 2020 3:57 pm

It’s Air -conditioning , 101 – Juan.

Charles Elllison
Reply to  Juan Slayton
March 28, 2020 4:01 pm

Air conditioning removes moisture from the air. Only if said moisture is drained from the area. Humidity is the amount of moisture contained within the space cooled listed in percentage. Example: A ziplock storage bag. Should one fill the bag with room air @ 50% humidity and 75 degrees then put it into the freezer, the bag will shrink. The moisture will be the same quantity but space will be smaller. The humidity will be higher even droplets may be visible. Before sealed combustion chambers on furnaces air within houses could get as low as 20% when the outside humidity might be 60%.

Charles Nelson
Reply to  Charles Elllison
March 28, 2020 5:01 pm

Where does condensed water vapour go in your place?

Reply to  Charles Elllison
March 28, 2020 8:09 pm

“Humidity is the amount of moisture contained within the space cooled listed in percentage. ”

Wrong definition. Leo did not say humidity he wrote about RH, which is in relation to amount of water in a saturated vapour.

It’s Air -conditioning , 101 – Juan.

Smugly saying “101” does not prove anything. A/c 101 does not take precidence over the laws of physics.

a/c removes water and hence absolute water content. The quoted phrase refered to RH, it seems the author made the same mistake you just did.

Charles Nelson
Reply to  Greg
March 28, 2020 8:51 pm

Greg. Let me know when you know how to read a psychrometric chart Mate!

Reply to  Charles Nelson
March 29, 2020 4:07 am

You’re still being smart. Assuming you actually know how to read one, maybe you can actual make a concrete argument instead of smug comments which do not make any testable claim.

air at 60F and 30 grains of moisture per pound of dry air has an RH of 40%. Cool it to 45F and it has an RH of 70%.

I studied physics, I missed out on AC 101.

If you actually know something , now would be a good point to state it.

Reply to  Juan Slayton
March 28, 2020 4:39 pm

When the AC is first turned on, the relative humidity stays the same as the temperature drops.
Then outside heat warms the air, without adding any new humidity, which drops RH.
Then the AC cools the air while RH stays constant.
Then outside heat warms the air without adding any new humidity, which drops RH.

Lather, rinse, repeat.

Charles Nelson
Reply to  MarkW
March 28, 2020 5:06 pm

You sound a bit confused about this. It’s actually very straight forward.
When you cool air its capacity to hold water vapour is reduced. When you run your AC in cooling mode water drips out of the condensate drain. The air in the cooled space becomes ‘drier’ when compared with the outside atmosphere.

Nicholas McGinley
Reply to  MarkW
March 30, 2020 6:05 am

A properly functioning air conditioner removes a tremendous amount of moisture from the air…enough so that the air coming out of the registers has lower relative and absolute humidity.
That is why it feels so comfortable.

Roger Knights
March 28, 2020 3:21 pm

In the comments section of an article on the Reason magazine website within the past week (link below), these four comments appeared. The 1st and 3rd cite a study that found that mice in a controlled atmosphere containing polypropylene glycol vapor did not contract an introduced flu virus, but mice in an ordinary atmosphere did.
“lafe.long, March.16.2020 at 3:50 pm
“The Protection of Mice against Infection with Air-borne Influenza Virus by Means of Propylene Glycol Vapor.”

They have now extended their observations to the effect of propylene glycol vapour on influenza virus. Vapour was employed instead of an aerosol because it has been found that the glycols are much more active in this form, very much smaller amounts being required for effective air sterilization.

Preliminary experiments were made to determine the amount of atomized virus suspension required to produce regular infection of mice followed by extensive lung consolidation and death within 4 to 10 days. Mice were then exposed to this lethal concentration of virus in a chamber into which propylene glycol vapour had been introduced; they regularly failed to contract the infection.

Diane Reynolds (Paul.), March.16.2020 at 4:00 pm
So… vaping protects you from virus infection?

lafe.long, March.16.2020 at 4:12 pm
According to this study, at least for mice, it would appear so.

Thirty-two control mice all died in 6-10 days with extensive lung consolidation, whereas 32 mice exposed in the glycol chamber all remained well and showed normal lungs when killed on the 8th day.

Roger Knights, March.16.2020 at 7:48 pm
“So… vaping protects you from virus infection?”

I hope “Are You a Vaper?” gets added to questionnaires given to Covid-19 test-takers and hospitalizations. And that its results indicate a strong prophylactic property. And that the government is then forced to encourage the purchase of e-cigarettes and refills by compensating buyers for their costs. A scene I’d like to see.

Maybe a machine could do the vaporizing, in hospital rooms, say.” [AFTERTHOUGHT: If Propylene Glycol could be vaporized in a humidifier, it would provide constant protection and should be scientifically tested for real-world effectiveness. (It costs $33 / gallon on Amazon.)]

Zig Zag Wanderer
March 28, 2020 3:31 pm

86% humidity and 25C this morning here. Sitting pretty…

Martin A
March 28, 2020 3:36 pm

I read an article (sorry – I did not take a note of where I found it) that said COVID-19 infections are very low in countries where malaria is a problem.

Maybe the high humidity in such countries could explain the low incidence of COVID-19, if it is in fact true?

March 28, 2020 3:52 pm

Just looking at deaths in Texas the doubling rate seems much lower. Perhaps due to temperature, humidity.

Many counties here are under shelter in place, have been for around 10 days in my county.

Reply to  Stevek
March 28, 2020 5:17 pm

Yes, Texas has over 4 times the population of Colorado, for example, and has about the same number of cases and deaths.

charles nelson
March 28, 2020 3:55 pm

When RH falls below comfort levels our nasal passages and exposed mucus membrane dry out.
It is this dryness and lack of mucus which makes us vulnerable to viral invasion.
If the virus itself prefers dry conditions to survive (something which I find surprising and counter intuitive given that every other living organism prefers some moisture)…but if it does, then humidifying your space is a good idea.

Greg Freemyer
Reply to  charles nelson
March 28, 2020 9:05 pm

I think it is more of a goldilocks zone. Too dry and the protective outer layer dries up and virus rapidly decays and virus is destroyed.

Too humid and the virus doesn’t efficiently via the air [like a sneeze or cough would do in the goldilocks zone].

March 28, 2020 4:05 pm


From one of the earliest studies we saw from WUWT links and others concerning the viability of the critters and ways to disinfect surfaces like your lavatories and countertops and doorknobs, there was a definite decrease in viability as temperature rose.

The problem with Miami and NOLA was the influx of carriers celebrating Mardi Gras and the traditional college spring break, plus several cruise ship ports. Up here in the Panhandle, we started early to cut down on the “breakers” once some intell came out, but still have a fair number of cases from all ages. The original ones and fatal ones were from overseas travel ( guess where).

Praying that the high temps will help make it harder for the critter to survive long enough to infect us. Our beaches and indoor eateries have been closed for two weeks. So main thing now is reducing the “carriers” from elsewhere, and our whole state is doing that.

Gums sends..

Gums sends…

March 28, 2020 4:13 pm

” aircraft might be not only carriers, but incubators of the corona viruses because of the human density and low humidity levels.”

the London underground wasn’t shut down – 200km of railway tube; trains pushing colossal amounts of DRY air; people packed like sardines; miles of walkways
( it has to be the most efficient means of spreading an airborne virus to max people in minimum time )

Henry Pool
March 28, 2020 4:20 pm

New Orleans is an emerging “hot spot.” New Orleans has high humidity. Guess that sort of proves that humidity isn’t going to help you.

Reply to  Henry Pool
March 28, 2020 5:19 pm

It could always have been worse without the humidity.

Reply to  Henry Pool
March 28, 2020 5:50 pm

Temperature and Humidity are just one factor. New Orleans is having a problem due to the Mardi Gras which packed thousands of people close together.

Reply to  Stevek
March 28, 2020 8:15 pm

Mardi Gras lasts all week and Louisiana RH is high in the morning but intermediate in pm and evening.

Indoor areas are still heated and thus low RH.

simplistic on-size-fits-all statements do not provide any insight.

Tom in Florida
Reply to  Henry Pool
March 28, 2020 6:48 pm

Humidity cannot overcome places that are sh*t holes.

Paul C
March 28, 2020 4:37 pm

My personal theory on biocidal radiation deactivating airborne virus is that the once common cathode ray tube TVs and monitors which emitted small doses (primarily at switching on/off) of low-powered x-ray (next in spectrum to UV-C) provided a low level of protection which is now absent. If damp killed the flu, the UK wouldn’t have a flu season.

Henry Pool
March 28, 2020 4:37 pm

Fearless Leader wants to shut down NYC/NJ/CT, and open up the rest of the country by Easter. He needs to make up his mind.

Josh Postema
Reply to  Henry Pool
March 28, 2020 5:41 pm

Why should do very place be treated identically? My county has had 22 cases total and none new in over a week. Why should we be held home indefinitely because New York keeps getting new cases?

Henry Pool
Reply to  Josh Postema
March 28, 2020 6:13 pm

Because it’s not just NYC. It’s Chicago, Detroit, Atlanta, Seattle, New Orleans, LA and many other cities.

March 28, 2020 4:58 pm

rud istvan

The three things to do are: social distancing (protect from cough), wash hands frequently, since little alcohol sanitizer is available, and don’t touch your face unless right after hand washing.

Yes: That is the MAJOR RULE to follow!

Thanks for having the energy to repeat this all the time.

The rule you mention probably is 1,000 times more important than the entire guest post.

We could add: all governments worldwide should oblige the supermarkets to protect their cashiers by installing a simple glass panel separating them from possibly infected clients.

J.-P. D.

Reply to  Leo Goldstein
March 28, 2020 7:47 pm

Until a few weeks ago hand sanitiser was soap.

The new fad for hand sanitiser seems to give folks the impression it is better than soap : hey , it’s specialise product, must be good.

hand sanitiser is for when you don’t have access to soap and water ( like carry it in your bag ).

Soap (~pH 9) is quite alkaline and destroys the virion’s lipid protective sheath. Better than washing up liquid (~pH 8)

Our local supermarket ( Fr ) set up plexiglass shields at each till last week.

Reply to  Leo Goldstein
March 28, 2020 8:33 pm

Leo, great article in general. I have been saying RH is a key factor in seasonal illness for years. I am really minimalist in heating my living area and I don’t get ill. The average Joe who lives in 22-25 deg C at home is always catching colds and flu.

You seem to confuse absolute humidity and RH in saying a/c reduces RH. a/c causes condensation in the heat exchanger because RH reaches 100% and condensations occurs.

Is the problem that the air them warms again, dropping RH? One problem is an over powered a/c will not run long enough to reduce RH. I don’t see indications it will lower it too much.

A couple of people have picked up on this. Can you comment ?

Reply to  Leo Goldstein
March 29, 2020 2:29 pm

thanks for the reply.

“but we agree that a/c reduces RH through condensation.”

No, we don’t agree ! a/c reduces AH of incoming air through condensation. Condensation happens because RH is near 100%, not because it is low. So air entering via a/c unit is likely to be very high. This RH may drop as it mixes with warmer air already inside but that implies increasing the RH of the air already inside.

I really don’t see any supporting argument for how a/c reduced RH

March 28, 2020 5:15 pm

Take long boiling hot showers, breathe deeply the humidity.
Eat enough to keep your natural defense mechanisms at fighting strength.
Vitamins ??
Then just “damn the torpedoes”.

Reply to  u.k.(us)
March 28, 2020 7:27 pm

A shower will not raise your body temperature. You’ll just burn your skin.

An hour long hot bath may do some good and help you sweat out any infection. But sadly baths are a bourgeois luxury these days.

Reply to  Greg
March 28, 2020 7:54 pm

If you want to breathe water vapour use a pot of hot water and an towel .

Roger Knights
Reply to  Greg
March 28, 2020 8:23 pm

“If you want to breathe water vapour use a pot of hot water and an towel.”

Or a humidifier.

Reply to  u.k.(us)
April 8, 2020 2:18 pm

Absolutely! Each day’s morning routine should start with an Amazon rain-forest shower. Purchase a small temp/humidity meter, (Walmart sells one for about 12 bucks).Bring the meter into the shower. Shower in hot water, keep the temp stable by increasing the hot water as it cools. Stay in there, breathing the humidity and monitoring the levels of heat and humidity for 15-20 mins. Ideally, when finished, both should read in the eighties. This AM, mine read 84 for both. After water is shut off, towel off in the shower.
Remember to breath deeply through nose and mouth. Even if the bath has a fan, be prepared to wipe down the walls, it’s gonna be hot with lots of moisture. Covid -19 is a respiratory disease. It doesn’t like heat&humidity. This may be effective. Beats the hell out of doing nothing!

March 28, 2020 6:12 pm

There is no need to wait until summer or even mid-April. Hygrometers cost about $20 and humidifiers are also inexpensive. In the absence of a humidifier, one can leave a pot of water simmering.

There one other way to achieve a similar result TURN THE HEATING DOWN.

Apparently this is so abhorrent that it does not even occur to the author to mention this possibility.

Nicholas McGinley
Reply to  Greg
March 29, 2020 2:37 am

There is no actual evidence that changing the temp or RH in our homes will have any effect at all.

Reply to  Leo Goldstein
March 29, 2020 2:41 pm

Reisman and Das (2) shows that an increase of humidity in schools, from ordinary ~28% to ~45%, decreases influenza-like illnesses among children by 2.3 times in wintertime.

You were amiss in not clearly specifying it in the article but this is RH not AH.

The peer reviewed research indicates that corona- and Influenza viruses lose their viability outside of the human body with an increase in *relative humidity* even above 50%-60%.

9. The Effects of Temperature and Relative Humidity on the Viability of the SARS Coronavirus
K. H. Chan, et all., University of Hong Kong, Hindawi

BTW that’s “et al” not et all , a mistake you make consistently 😉

Enveloped viruses (most respiratory viruses, influenza) survive longer at lower RH (20%-30%)

There does not seem to be any doubt we are talking about RH here not AH. Thanks for bringing up a very important subject. It’s a shame you don’t seem to have understood it yourself and made the a/c blooper.

Tom in Florida
March 28, 2020 6:46 pm

Do not forget to get the correct a/c filter. A MERV 13 rated filter will trap virus. Anything less and you are just recirculating the virus throughout your home. Most home a/c filters are rated for 90 days however I am changing mine every 30 days. Maybe over cautious but the cost is low enough not to matter.

Reply to  Tom in Florida
March 28, 2020 7:12 pm

My HVAC guy was trying to sell us on a UV light thing that supposedly kills bacteria in the air, it attaches to system so air goes through the light. I’m not sure though if it would do anything.

Tom in Florida
Reply to  Stevek
March 29, 2020 4:58 am

UV lights are proven to work however there are two kinds. The most common is used to prevent mold and mildew on the coils, all good units have these. The other is more expensive and is used to kill living organisms as the air passes by in the return duct. This type is usually an optional add on. Your specific circumstances would dictate if it is worth the extra expense and maintenance cost.

Reply to  Stevek
March 29, 2020 9:55 am

I have a UV light system on my HVAC, will definitely kill viruses in the air, it’s UVC. Installed initially for mold (100+yo house)

March 28, 2020 7:17 pm

According to the Business Insider, people over 75 are almost 100 times more likely to die than people 18-44. For some reason I cannot post the graphic here, but, this tells me that destroying our economy is not a good idea.

Let the young and strong go back to work. They get infected, they get better, we do not put 25 million people into unemployment for a risk of 0.17% of death.

This is a flu/cold that is very hard on old sick people. The Great Depression was very hard on old sick people, and Everyone Else Too!

Reply to  Michael Moon
March 28, 2020 7:51 pm

0.17% of 25 million is still a lot people before you get herd immunity at 60-70% but I agree shutting down the whole damned country is crazy and likely to do more damage to lives than the damned virus.

Nicholas McGinley
Reply to  Michael Moon
March 29, 2020 2:35 am

The binary lived/died question is not the whole story.
Many people who ultimately live only survive after several weeks in a hospital with viral pneumonia.

I am not saying the shutdown is justified or a good idea…but it did not happen simply because some very old people or people who were on their deathbed anyway, were/are going to die.
There is far more to this story than that.

A C Osborn
Reply to  Michael Moon
March 29, 2020 4:12 am

0.17%, I have no idea where you get that value from, but whatever the actual number is you can at least double it for all the non COVID deaths that will occur due to health system oveload.
Unless you are advocating not bothering to treat critical COVID patients at all?

March 28, 2020 9:32 pm

The air purifier you bought does have one admirable feature: “A washable AOC Carbon Filter”

Wonderful ridding your life of nuisance AOC.

Reply to  fah
March 29, 2020 4:11 am

I’ve ordered one. I’m going to put it between the decoder and the screen.

March 29, 2020 12:22 am

Yes, & original post about humidity should be expanded to include the following, at least for influenza viral infections in the research cited below.

In lungs under low humidity there is less activation of Type 1 Interferon & it’s subsequent induction of 100s of interferon influenced genes. Then the unchecked virus is able to stimulate activity of capsase enzymes which in physiological pathways contribute to “… lung pathology & mortality, due to formation of neutrophil extra-cellular traps ….”

As per (2019) report “Low ambient humidity impairs barrier function and innate resistance against influenza infection”; free full text availableon-line.

March 29, 2020 2:21 am

“Videos have emerged of desperate people in Italy begging for help because they have run out of money and food.”

A taste of things to come?

Reply to  mwhite
March 29, 2020 8:23 am

Looking at France after 14 days of restrictions, there is mild improvement in doubling time of new infections but it started at least 2 days BEFORE they came into effect whereas any attribution of this improvement to restricted movement would need typically 5 days incubation to show up.

comment image

Are we destroying the economy for nothing ??

A C Osborn
Reply to  Greg
March 29, 2020 8:53 am

The total lockdown started on the 17th, 12 days ago.
The reason that you won’t see much change in the new cases ROC is because there are thousands of undetected cases that are already in the system but not tested, probably self isolating.
New cases = those found by new tests not people newly infected with the virus.

Reply to  A C Osborn
March 29, 2020 9:46 am

Yes, all these stats hide the true number of cases, with mild or symptom-less cases wisely staying well clear of any hospitals and being told not to go to doctors surgeries.

Obviously there is a sampling bias. Are you saying that the sampling bias has changed in the last 12d in a way which is masking a real change in the rate of contagion?

do you have any evidence for that opinion or is it just total speculation?

A C Osborn
Reply to  Greg
March 29, 2020 11:28 am

We don’t know, we don’t know any changes in sampling rates, whe they were tested before the results come back, who is being sampled, how well the people are adhering to the new regs etc.
So it is a considered opinion based on what has been going on.

Reply to  Greg
March 29, 2020 2:54 pm

So you are agreed that there is no evidence that the shutdown has any measureable effect on contagion. Absence of proof is not proof of absence, but the point I was making is that the data ( cr4ppy as it may be ) does not show any attributable effect.

Since this is the data they are feeding us as proof of the “pandemic” it’s all we have to go on.

If they provided concurrent data on how many tests had been conducted maybe we would have more to work on. We could tell whether they arranged the clamp down announcements to coincide with the day after they had provided 100k new test kits in the hospital system.

The paucity of the data provided is lamentable at a time when they are requiring public cooperation with drastic measures and destroying the economy.

No wonder the arab ‘banlieusards” are giving them the finger.

Nicholas McGinley
Reply to  Greg
March 30, 2020 5:45 am

I know if I stay away from other people as much as possible, I have a reduced chance of being exposed.
As does everyone.
If I stay inside, there is no chance I get infected unless someone or something with virus comes into my house.
No one knows who has it, and everyone that has it can spread it to an unlimited amount of people they encounter.
I have never been worried about getting sick, but in this case, I have come to the conclusion I really do not want to get it and wind up with viral pneumonia.
Average time on a respirator is over 4 weeks for the people who are winding up needing one.

March 29, 2020 4:19 am

Quote from Sputnik News:
“The Russian Federal Agency for Biomedicine has made a preparation for the treatment of coronaviruses based on the antimalarial drug mefloquine, according to the press service of the organization. This preparation blocks the cytopathological effects of coronavirus at the cellular level and stops its multiplication, it is said. In addition, the immunosuppressive effect of mefloquine blocks any inflammation that occurs after a person is infected.”

March 29, 2020 5:59 am

Mold can be a pretty serious issue. It likes humidity at 50% and higher.

Humidity at 30% helps with pests like dust mites/ cock roaches.

I see UV lights installed at various entry ways at hospitals, nursing homes and retirement facilities.

Good cleaning/sanitation is a must.

Bill Parsons
Reply to  john
March 29, 2020 12:17 pm

Our local library locations shut down along with the book drops and offices. Borrow times have been extended and all fines waived.

I wondered what measures they might be taking to disinfect all that paper which was circulating through the public’s hands up until a mid-March, but it appears their strategy is to stop physical material from circulating until they can surmise that the majority of the virus is kaput… four to five days after the apocalypse.

March 29, 2020 6:13 am

If they shut down non vital interstate traffic in NY, NJ, CT, RI plus MA, they would essentially stop the virus AND DRUG TRADE in the NE region at the source.

The cartels would try to adapt but that would only identify who’s doing it via all that electronic monitoring going on.

EMS is already stretched for OD calls and now this…

2 birds one stone.

Reply to  john
March 29, 2020 8:26 am

but then when people start sweating and shivering they will not know whether it’s cold turkey or COVID.

March 29, 2020 11:17 am

What happens if your house has very dry air because of forced hot air heat?
10-20% RH at 70F

34% right now only because it’s raining outside

Carlie Coats
Reply to  Rich
April 1, 2020 5:46 am

I have two of these Honeywell wick-style humidifiers, and they keep my (2500 sq ft) in-house humidity at least 45% even in mid-winter (sometimes evaporating as much as 15 gal of water per day). Note that they have a design whereby air is forced through a wetted wick, and so do not create aerosol droplets that evaporate (leaving a solid-core fine dust); in fact, they probably filter out some indoor air pollution.

Nicholas McGinley
March 30, 2020 5:39 am

It is so obvious.
There are decades of studies proving the value of barrier protection.
It is not a magic bullet, it is another layer of protection…and a very effective one if the right mask is worn:

“Great explanation of why simple masks (ie. not N95) are so effective at stopping #COVID19 and why the continuing silence of medical leaders in US/Canada is baffling”

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