Where the particulates are (and aren't)

This press release from NASA has the usual FUD in it, particularly with the “health-sapping” title. But what I find most interesting is the lack of 2.5 μm particulates in the USA and Australia. Yet another USA map further down (link)  in the article shows an entirely different view for the same period. It shows a lot of particulates in the San Joaquin valley of California where there is little industry, and a lot of farming, suggesting dust from ag operations. Likewise, the Sahara is full of dust, and dust laden winds coming off the Sahara and towards Cape Verde islands may have a role in hurricane formation. Dust is important in the scheme of things meteorological, as another NASA press release says it’s important enough to launch a broad study of.

Global satellite-derived map of PM2.5 averaged over 2001-2006.  <b>Credit:</b> Dalhousie University, Aaron van Donkelaar

Global satellite-derived map of PM2.5 averaged over 2001-2006. Credit: Dalhousie University, Aaron van Donkelaar - click to enlarge

New Map Offers a Global View of Health-Sapping Air Pollution

In many developing countries, the absence of surface-based air pollution sensors makes it difficult, and in some cases impossible, to get even a rough estimate of the abundance of a subcategory of airborne particles that epidemiologists suspect contributes to millions of premature deaths each year. The problematic particles, called fine particulate matter (PM2.5), are 2.5 micrometers or less in diameter, about a tenth the fraction of human hair. These small particles can get past the body’s normal defenses and penetrate deep into the lungs.

To fill in these gaps in surface-based PM2.5 measurements, experts look toward satellites to provide a global perspective. Yet, satellite instruments have generally struggled to achieve accurate measurements of the particles in near-surface air. The problem: Most satellite instruments can’t distinguish particles close to the ground from those high in the atmosphere. In addition, clouds tend to obscure the view. And bright land surfaces, such as snow, desert sand, and those found in certain urban areas can mar measurements.

However, the view got a bit clearer this summer with the publication of the first long-term global map of PM2.5 in a recent issue of Environmental Health Perspectives. Canadian researchers Aaron van Donkelaar and Randall Martin at Dalhousie University, Halifax, Nova Scotia, Canada, created the map by blending total-column aerosol amount measurements from two NASA satellite instruments with information about the vertical distribution of aerosols from a computer model.

Their map, which shows the average PM2.5 results between 2001 and 2006, offers the most comprehensive view of the health-sapping particles to date. Though the new blending technique has not necessarily produced more accurate pollution measurements over developed regions that have well-established surface-based monitoring networks, it has provided the first PM2.5 satellite estimates in a number of developing countries that have had no estimates of air pollution levels until now.

The map shows very high levels of PM2.5 in a broad swath stretching from the Saharan Desert in Northern Africa to Eastern Asia. When compared with maps of population density, it suggests more than 80 percent of the world’s population breathe polluted air that exceeds the World Health Organization’s recommended level of 10 micrograms per cubic meter. Levels of PM2.5 are comparatively low in the United States, though noticeable pockets are clearly visible over urban areas in the Midwest and East.

“We still have plenty of work to do to refine this map, but it’s a real step forward,” said Martin, one of the atmospheric scientists who created the map.”We hope this data will be useful in areas that don’t have access to robust ground-based measurements.”

Piecing Together the Health Impacts of PM2.5

U.S. satellite-derived map of PM2.5 averaged over 2001-2006. <b>Credit:</b> Dalhousie University, Aaron van Donkelaar

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U.S. satellite-derived map of PM2.5 averaged over 2001-2006. Credit: Dalhousie University, Aaron van Donkelaar


Screen capture from animation, based on data from the Goddard Chemistry Aerosol and Transport model, simulates the global movement of black carbon soot from August 1, 2009 to November 19, 2009.  Black carbon is shown in white.

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Screen capture from animation, based on data from the Goddard Chemistry Aerosol and Transport model, simulates the global movement of black carbon soot from August 1, 2009 to November 19, 2009. Black carbon is shown in white. Credit: NASA/Goddard Space Flight Center/Scientific Visualization Studio

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Heavy haze hugged the southern face of the Himalaya in mid-December 2009.

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Haze hugged the southern face of the Himalaya in mid-December 2009. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this true-color image on December 14. Credit: NASA/Goddard/MODIS

For more info on this image, visit the Earth Observatory. Take a deep breath. Even if the air looks clear, it’s nearly certain you’ve inhaled millions of PM2.5 particles. Though often invisible to humans, such particles are present everywhere in Earth’s atmosphere, and they come from both natural and human sources. Researchers are still working to quantify the precise percentage of natural versus human-generated PM2.5, but it’s clear that both types contribute to the hotspots that show up in the new map.

Wind, for example, lifts large amounts of mineral dust aloft in the Arabian and Saharan deserts. In many heavily urbanized areas, such as eastern China and northern India, power plants and factories that burn coal lack filters and produce a steady stream of sulfate and soot particles. Motor vehicle exhaust also creates significant amounts of nitrates and other particles. Both agricultural burning and diesel engines yield dark sooty particles scientists call black carbon.

Human-generated particles often predominate in urban air — what most people actually breathe — and these particles trouble medical experts the most, explained Arden Pope, an epidemiologist at Brigham Young University, Provo, Utah and one of the world’s leading experts on the health impacts of air pollution. That’s because the smaller PM2.5 particles evade the body defenses—small hair-like structures in the respiratory tract called cilia and hairs in our noses—that do a reasonably good job of clearing or filtering out the larger particles.

Small particles can make their way deep into human lungs and some ultrafine particles can even enter the bloodstream. Once there, they can spark a whole range of diseases including asthma, cardiovascular disease, and bronchitis. The American Heart Association estimates that in the United States alone, PM2.5 air pollution spark some 60,000 deaths a year.

Though PM2.5 as a class of particle clearly poses health problems, researchers have had less success assigning blame to specific types of particles. “There are still big debates about which type of particle is the most toxic,” said Pope. “We’re not sure whether it’s the sulfates, or the nitrates, or even fine dust that’s the most problematic.”

One of the big sticking points: PM2.5 particles frequently mix and create hybrid particles, making it difficult for both satellite and ground-based instruments to parse out the individual effects of the particles.

The Promise of Satellites and PM2.5

The new map, and research that builds upon it, will help guide researchers who attempt to address this and a number of other unresolved questions about PM2.5. The most basic: how much of a public health toll does air pollution take around the globe? “We can see clearly that a tremendous number of people are exposed to high levels of particulates,” said Martin. “But, so far, nobody has looked at what that means in terms of mortality and disease. Most of the epidemiology has focused on developed countries in North America and Europe.”

Now, with this map and dataset in hand, epidemiologists can start to look more closely at how long term exposure to particulate matter in rarely studied parts of the world – such as Asia’s fast-growing cities or areas in North Africa with quantities of dust in the air – affect human health. The new information could even be useful in parts of the United States or Western Europe where surface monitors, still the gold standard for measuring air quality, are sparse.

In addition to using satellite data from NASA’s Multi-angle Imaging SpectroRadiometer (MISR) that flies on NASA’s Terra satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies on both NASA’s Aqua and Terra satellites, the researchers used output from a chemical transport model called GEOS-Chem to create the new map.

However, the map does not represent the final word on the global distribution of PM2.5, the researchers who made it emphasize. Although the data blending technique van Donkelaar applied provides a clearer global view of fine particulates, the abundance of PM2.5 could still be off by 25 percent or more in some areas due to remaining uncertainties, explained Ralph Kahn, an expert in remote sensing from NASA’s Goddard Space Flight Center in Greenbelt, Md. and one of the coauthors of the paper.

To improve understanding of airborne particles, NASA scientists have plans to participate in numerous upcoming field campaigns and satellite missions. NASA Goddard, for example, operates a global network of ground-based particle sensors called AERONET that site managers are currently working to enhance and expand. And, later next year, scientists from Goddard’s Institute for Space Studies (GISS) in New York will begin to analyze the first data from Glory, a satellite that carries an innovative type of instrument—a polarimeter—that will measure particle properties in new ways and complement existing instruments capable of measuring aerosols from space.

“We still have some work to do in order to realize the full potential of satellite measurements of air pollution,” said Raymond Hoff, the director of the Goddard Earth Science and Technology Center at the University of Maryland-Baltimore County and the author of a comprehensive review article on the topic published recently in the Journal of the Air & Waste Management Association. “But this is an important step forward.”

Related Links:

Environmental Health Perspectives: PM2.5 Research Article

Remote Sensing of Particulate Pollution from Space: Have We Reached the Promised Land?

MISR Home Page

MODIS Home Page

Smog Bloggers Untangle Air Pollution 365 Days a Year

Particulate Matter and Cardiovascular Disease

Adam Voiland

NASA’s Earth Science News Team

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53 thoughts on “Where the particulates are (and aren't)

  1. US EPA Particulate Matter Trends
    http://www.epa.gov/airtrends/pm.html
    Well over 90% of sites are below the National Standard for Air Quality
    At the bottom of that link is a map of states where you can check individual locations. Pennsylvania is a densely populated state with many coal plants, and downwind from Ill, Oh and Indiana. Yet our particulate matter for almost all locations is below the Nat’l Standard, there is some air pollution, but it is in the cities. Coal power plants are generally located in rural areas, yet there is no widespread pollution in Pa.
    The last Pa Air Quality Report was in 2007.
    http://www.dep.state.pa.us/dep/deputate/airwaste/aq/default.htm
    PM 2.5 in Pa. is below the National Ambient Air Quality Standard. (but only slightly)

  2. Now I know why pictures from Australia always has this amazingly blue sky. But I’m surprised that the desert in Australia (or parts of the US) doesn’t create more particulates in the air when you compare to the Sahara. Are there more dust storms in Sahara? Or is there more fine-grained dust?

  3. Didn’t I read a research paper a few years back that showed an inverse corelation between dust from the Sahara and Atlantic hurricane formation? Us Louisiana boys take an interest in hurricane formation… having been through a couple.

  4. Dust is good! Or at least it is for the Amazon basin which gets wind blown dust from the Sahara at an annual rate of several million tonnes. This dust increases the Amazon soil fertility.
    Quite why Australia has no dust when their deserts are so dusty I cannot understand.

  5. I wish to complain about the exclusion of New Zealand from NASA’s world map. NZ is one of the world’s largest meat exporters and I wish to see what NASA thinks our particulate level is. (It’s probably nil).

  6. So they are dusting off this old scare story? In the UK we are frequently told how air pollution is killing hundreds of thousands of people. Of course, genuine pollution of any type is a bad thing, especially for people with Asthma or other respiratory problems.
    But the people who trumpet loudest about PM2.5s (or PM10s) are the usual Greenie suspects. The “hundreds of thousands” come from their computer “scenarios”. And if you ask them to name some of these people who are dying of particulates, with evidence in terms of certified cause of death, then they tend shuffle their feet and try to change the subject.
    My guess is that the number of people world wide who suffer problems with fugitive PM2.5 particles are a tiny fraction of the people who suffer major health effects from cooking on dung or wood fires because they haven’t got affordable, reliable electricity.

  7. Not another scare story about how WAGTD? AND you mentioned the epedemiologist word! Ahhhggg! I am no tobacco man despite being an ex-pipe/cigar smoker but these are the people who used numbers of deaths of those who died in their 70s & 80s in the Anti-secondhand smoking campaign here in the UK & elsewhere as having died “prematurely”. Dust is everywhere in the atmosphere, how much did Chaiten pump out in Chile for instance, or the unponouncable (Iya-fiala-yokul is the best I got to)one in Iceland, that managed to close a continental scale airspace? I happen to think that the human respiratory system, with a few rare exceptions, is a pretty robust thing, it’s had to be from living in smoke filled caves, & stalking the savannahs around Africa hunting heards of various four-legged larder stocks, to volcanic eruptions filling entire inhabited landscapes!

  8. The American Heart Association estimates that in the United States alone, PM2.5 air pollution spark some 60,000 deaths a year.
    Mmm… A good, round number. But is it an exclusive? or do other “Associations” claim the same by sharing out the same deaths? For some time I have been suspicious of such claims, imaging various entities sharing out the body count — or double-dipping on them.
        I suspect even a highway death can be claimed by many “Associations” to add to the toll they can publish as urgently needing funding. The dead guy in the demolished car was a smoker, a drinker, an over-eater, and had recently snacked on junk food, etc. — ignore that a bridge collapsed when he was driving below it…
        I am both a cynic and an awe-struck believer in the almost magical adaptation of all things living.
        Study the particles in the air by all means; but leave out the body counts. People live in some mighty odd places, but we in general continue to live longer, anyway — and there are microbes which live in conditions where we dare not even venture.
        My conclusion of this study? Worth doing; but spare me the furrowed brows of doom — we got that in spades from the Earth-Has-A-Fever brigade.
        Lighten up and study stuff for its own sake. The populace at large will make its decision on how to treat the conclusions; and make its choices more readily and more sensibly without the Frowns making proclamations. The populace may even choose to ignore such studies; and still live longer.

  9. People live longer now when they have respiratory diseases.
    A combination of better drugs (inhaled broncho-dilators and corticosteroids) and better treatment (respiratory physiotherapy) means that asthmatics and those suffering the effects of congestive lung disease have both longer lives and less suffering. They are not getting fewer in number though and are increasing as a percentage of the population.
    The better treatment does not mean that more should not be done to reduce the pollution. Switching from coal to waste oil mixes in generating plant leads to a fall in the large particle size emitted but an increase in the small[er] particle size[s]. The larger size leads to immediate effects while the smaller size leads to longer term chronic effects.
    Don’t knock something because it is in vogue. Respiratory disease is a small matter to someone who is healthy but totally disabling to someone who suffers from it. especially if the disease was caused by, or made worse by, something that could have been avoided.

  10. > …dust laden winds coming off the Sahara and towards Cape Verde islands may have a role in hurricane formation.
    The dust is settled (sorry) on that item. Dust absorbs sunlight at mid-level altitudes and the energy heats up the surrounding air. The remaining sunlight doesn’t heat up the sea surface as quickly as normal. Hurricane formation needs convection which is enhanced by cooler temperatures aloft and is limited when SSTs under 80°F.
    A recent Atlantic hurricane season was greatly impacted by persistant dust off the Sahara. I tried to make a mental note of which one, but forgot it.

  11. So there are few ground sensors that work properly, satellite measures are also unreliable but stir them all together in a ‘computer model’ and suddenly its useful information?
    There does not appear to be any validation. Surely the first step (as asked already by many above) is to check the obvious such as why Australia’s desert areas seem to have no dust compared to the Sahara? Requests to a few friendly universities worldwide to include dust sampling of air in their regions in their graduate or undergraduate studies and provide the results, would be a rapid and relatively reliable separate validation metric.
    What is it that climatologists have against simple validation tests? Do they see them as threats to their funding?

  12. Yes, the deceptive part of articles like this is labeling all PM2.5’s as ‘pollution’ without any real data on chemical composition, etc. Without a baseline measurement in the Sahara, and without hi-res images that can zero in on cities like Dakar, Senegal, it is really hard to draw any large-scale conclusions.
    On the other hand, we can paraphrase the late Tip O’Neill (‘All politics are local politics’): Most air pollution is a local/regional threat. There is no doubt about the health hazards of the local human-produced air pollution in places like Dakar or Mexico City. Likewise, the vast majority of environmental threats are local/regional.

  13. I suspect the EPA is preparing to punish American farmers for being a potential source of dust. I don’t know how the EPA will cope with dust from dirt roads.

  14. Keep in mind that this probably shows particles that are 2.5 μm or larger. The 2.5 μm size is fairly large for dust. In our clean room here at SNOLab, we monitor particles that are 0.5 μm or larger. — John M Reynolds

  15. I wonder how humans managed to survive all these millenia with all those nasty 2.5 um particles in the air all these centuries? Undoubtedly, the particles are not good for one’s internal health, but a little alarmism can’t hurt either, can it?

  16. That would be my guess. Farmers must be taxed for the dust they throw into the air. And with more corporate ownership of agricultural land, we have far fewer voting bodies to stop it from happening. In Oregon, it is very hard for those living outside of the Portland area to stop measures that in the long run will hurt Oregon. Too many bodies voting from the city compared to rural populations. If they come after all farms big and small, the small farm will suffer the most. The same is true for business-related taxes. Whatever taxes big corporations pay will hurt small businesses the most. However, it still holds that small farms and businesses are where most of the jobs are created. If you want to live longer, stop smoking. But a little dirt won’t hurt you.

  17. Where to start?
    First, the reason the first map shows so little apparent PM2.5 pollution in the US, while the linked map of the US shows much more, is that the color scales of the two maps are different.
    The reason the Central Valley of CA shows large amounts of PM2.5 — in the linked map — is partly because of the agricultural emissions, which include dusts, but also because the central valley, with the Sierras to the east, features inversions where the PM2.5 builds up and doesn’t get blown out of the valley. Also, the nitrate levels in the Central Valley are about the highest in the US, partly because of the inversions, partly for technical reasons of atmospheric chemistry. The nitrates would mostly represent vehicular emissions.
    For those interested in the atmospheric chemistry reasons for the high nitrates, here goes. Ammonium ions are plentiful in the atmosphere. They prefer to link with sulfate ions to create ammonium sulfate. So nitrate levels in the east aren’t as high as in the Central Valley, because there aren’t enough ammonium ions left after sulfate has “grabbed” them. There are very few sources of sulfate in California, so the ammonium ions “mate” with the nitrate ions to form the particulate, ammonium nitrate.

  18. I’ll bet anything that if we did away with the EPA the pollution would go down. Bet we’d save a little of that U.S. Federal Reserve Chinese Money too. And green ink.
    PS: Is there any truth to the rumor that pregnant women and school kids in California can only breath bottled air? (sarc off)

  19. These researchers sure are having their fun with other people’s lands. Notice the “global” blaming tone of the article. It just seems more and more to me that we have King George sitting on a throne in a big castle. I’ve lived in both cities and rural areas. I’ve worked in large and small school districts. I’ve been a liberal and a conservative. What I have learned from both sides is that as Kings are wont to do, after they come after rural folks, they will come after you. After they suck you dry, they will come after other countries. King George and his minions will have to go. All of them. And in every country where there is a King George. Vote them all out.
    When our current president was put into office, other countries breathed a sigh of relief, thinking this new president would stay out of their affairs and be more friendly. But this government is paying these people to study YOUR pollution. I think we have nothing other than the same president we had before but with a different skin tone. He will come after you, looking for your [pollution] of mass destruction. If he has any brains at all, he will immediately put a stop to this nonsense.

  20. *Problem*?
    Article – “NASA discovery: solar storms don’t always travel in straight lines
    Posted on September 24, 2010 by Anthony Watts”
    Link for “Continue Reading” Does Not Work
    Link for “Comments” Does Not Work [maybe post on Tips & Notes too . . mod]

  21. note to mods:
    the “read more” link on the solar storm story is broken. The link on the right is broken, also.
    the “comments” link on the solar story story brought me here.

  22. how they managed to not fins Aus had a fair bit??
    10 years of drought, some raging north winds every year..
    dust storms you cant see 50 feet in..
    yes we DO have it.
    the dust didnt come from Farmland as so many love to say, it comes from the dry lake beds and bulldust( microfine red powdery dust, gets into everything!) in the inland.

  23. @Henry — that one is simple. Dust on dirt roads is caused by cars driving on them. They will simply ban cars (except government owned cars, of course) from driving on them.

  24. Henry Chance is correct–the EPA is planning on punishing farmers and ranchers for the dust from “their” gravel roads, as well as any dust stirred up by tilling the soil or by livestock meandering around. It’s a no-win situation for us farmers and rural folks. I will encourage our Attorney General to emulate Texas and sue the EPA, forcing them to show their work and prove their models (or someone else’s) correct.

  25. In my University days in the late 70’s I was taught that the Yellow River was named for its yellow color which it got from the massive amounts of yellow dust that blew in from the dry areas further west. It seems that process began a little before the increase in industrialization of China.
    I think the activities of humans are still a tiny fraction of the natural processes taking place on Earth and the Sun.
    My apologies to the Malthusians looking for justification to reduce our number to pre-Christian times.

  26. Probably the answer to the comments about Australia is that the image was taken recently. Australia is having the highest rainfall 12 month period for the last 30 to 50 years in most areas. Also the majority of onshore winds come from the south east at this time of the year. Northerlies start about November/December.

  27. Web note:
    It appears that the link at the top of this page to “NASA discovery: solar storms don’t always travel in straight lines” does work, but the links on the main WUWT page all return a page not found error…

  28. OT,
    No evidence that dietary saturated fat is a cause of cardiovascular disease,
    So, what has been happening for years is that scientists (I really shouldn’t legitimise them with such a title) have been knowingly misleading us by only publishing the studies that support their own prejudices – any paper that doesn’t agree is not published.
    A doctor friend of mine told me “I have learnt that one of the most difficult things to affect is to have someone unlearn something, even when it is demonstrated that what they have learnt, and have believed, is wrong. I base this on my experience over many years with students and residents.” The American journalist, Upton Sinclair made a similar comment when he once remarked: ‘It is difficult to get a man to understand something when his salary depends on his not understanding it.’ It’s not that every scientist is greedy, but they do have to make a living.
    Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010; First published ahead of print January 13, 2010 as doi: 10.3945/ajcn.2009.27725.
    Sound familiar.
    http://www.second-opinions.co.uk/saturated-fat-does-not-increase-heart-disease.html

  29. Slightly OT, but dust from Africa is probably the main cause of coral bleaching in the Atlantic. Coral bleaching is an old phenomena that happens regularly. During the 80’s researchers uncovered a direct link between dust from Africa and coral die-off in the Bahamas. Of course this does not fit the evil AGW narrative so was forgotten. The amount of known and established science that is being abandoned and reinterpreted to fit the propaganda scares me. I sometimes think we are headed to another dark-ages.

  30. Alan the Brit says:
    September 24, 2010 at 4:18 am
    Not another scare story about how WAGTD? AND you mentioned the epedemiologist word! Ahhhggg!!
    ====
    REPLY: Alan, please watch that, as I am an epidemiologist! (DrPH is for “Doctor of Public Health”).
    Let me teach you how our minds work:
    a) NASA makes a health-related announcement, although they are not primarily in the business of public health….therefore, I’m immediately suspicious.
    b) NASA makes a claim that seems to have policy implications, see (a) above.
    c) I glance at their presentation….Anthony correctly points out “But what I find most interesting is the lack of 2.5 μm particulates in the USA and Australia.”
    d) What I find even more interesting is the extremes in concentrations across Africa (which has very little particulate-producing industries), Arabian peninsula (presumed to be from dust storms, although they have massive petrochemical emissions & flaring pollution), northern India (not heavily industrialized to my knowledge) and eastern China (where, of course, much of their industry is localized).
    Therefore, I just have to say “Uhhh, what is the relationship to human development, if any?” They have mixed apples & oranges badly, confusing naturally occurring particulate levels that have existed for millions of years with industrial emissions from the last 10 years. Bleh, bad science! India widely uses kerosene for a household fuel and burns tons of “biofuel” (wood and charcoal), creating a massive “brown cloud” of pollution over that part of the world.
    Anthony, our lower particulate levels in the USA are related to air pollution controls on the US steel industry, instituted in the late 1970’s and early 1980’s. This was a primary driver in putting “Big Steel” in Chicago, Gary IN and other locations out of business, moving the plants to S. Korea and elsewhere. No we have nice, clean air and huge populations of impoverished workers who used to find employment in the mills.
    Don’t blame this epidemiologist!

  31. I was looking at this on NASA’s propaganda site, yesterday. Has anyone noticed the strange scales used. The US scale is linear from 0 to 20 micrograms/cubicmeter. The global map is also appears linear from 0 to 20, but then goes way non linear. The scary red in the US map is really pretty insignificant. And 60,000 deaths a year in the US from 2.5 micron particulates, I think the guys who provided that number have stinky fingers.

  32. Though PM2.5 as a class of particle clearly poses health problems, researchers have had less success assigning blame to specific types of particles. “There are still big debates about which type of particle is the most toxic,” said Pope. “We’re not sure whether it’s the sulfates, or the nitrates, or even fine dust that’s the most problematic.”
    ======
    Uhhh….doesn’t Nobel Laureate & Sec’y of DOE Steven Chu advocate geoengineering using sulfate particulates to combat CAGW?
    These people are idiots….

  33. Just noticing that the world map and the US map are entirely consistent. It’s the scale coloring that’s different. In the world map, the fiery red is 80; whereas in the US map it’s only 20.

  34. A few months back, WUWT had a post about, “What will be the next BIG issue” scientist will discover to blame – us – for. I do not recall what I predicted but it should have been dust, and here we go….
    It has not been studied much, so that provides two key ingredients for “it” to be the issue; 1- we do not know much about it so it can easily be made into a terrifying and dreadful thing which then calls for, 2- much grant money to study. A third component, important for the longevity of study and money flow, is that it is ubiquitous, measured in tons, massively dynamic and unknown quantities come from space, all perfect for modeling by super computers, the result of which will tell us……. Well, just go ahead and finish that sentence anyway you want.
    As for why “more” particulates show (and are there) in the images nearer the equator – could it be the upward convection is greater the closer you get to the equator and the greater mixing of atmosphere caused by the westward trade winds? Both of these factors would cause the “dust” to not only be greater (given the differences in the local land-ocean boundaries) but also disperse higher into and remain longer in the atmosphere. Hmm, sounds like a important issue to study. NSF, just deposit that $5 million in my bank account. I’ll draw it down as the study progresses.

  35. Particulates know not geopolitical boundaries. Why doesn’t the picture show the particulates over the oceans? And where are the oceans’ particulate emissions?

  36. A natural experiment in particulates from burning coal and respiratory health occurred during the USA’s early & middle industrial age: @ 1850s to 1930s. Autopsies of city police officers who “walked the beat” and city street car drivers and conductors were found to have high burdens of inert carbon material in their lungs compared to people living in rural areas. Tuberculosis, an infectious disease, way before Koch and his postulates, was called consumption. The public health impact of tuberculosis rose rapidly and it was thought the reason was because of increased movement of rural people to the cities: crowding, coughing, water droplet exposures and city laws prohibiting spitting on the sidewalk. A funny thing happened around the 1920s; the incidence of tuberculosis began to plummet even though Streptomycin and Isoniazid antibiotics were discovered and would not be discovered for another 30 years. Epidemiologists have suggested that better nutrition was the reason for the tuberculosis/consumption incidence drop. Maybe to some extent. But everyone better nourished in 10 years? during the Dust Bowl era? Hardly. What had happened was the conversion of home heating from coal to natural gas in most urban areas. Previous to wholesale conversions, most cold mornings you had to get up, go down to the basement and start the fire in the coal furnace. As we all know, it is during the initial combustion of coal that the most particulates are produced as visible by the smoke early on than later on when the fire is blazing. Coal fired boilers are less polluting once they are hot and the air fuel mix is fine tuned. There are now very few coal fired boilers in the USA outside of utility plants. So, do PM 2.5 particulates have an impact upon respiratory health? yes but, at what concentration. Some commenters observations about the use of biofuel, wood, dung, etc for cooking in large tracts of the developing world, and the inherent polluting nature of early ignition of such fires gives a reason and a solution for controlling air pollution and impacting billions of people’s respiratory health.

  37. “These small particles can get past the body’s normal defenses and penetrate deep into the lungs. ”
    Big flipping woopie! This sort of EMOTIONALLY CHARGED, “lofty sounding” writing isn’t worth the time to read it.
    A little history lesson for you: Prior to the post WWII development of natural gas for fuel, most homes were heated by:
    1. Burning soft coal. (Cheap).
    2. Burning hard coal.
    3. Burning fuel oil.
    4. Burning wood.
    5. Burning peat.
    DO you have ANY idea of the “fine particulate” involved here? Is there ANY definition of the chemical composition of the “fine particulates”? I used to have a dandy paper on the chemical analysis of micron and sub micron Los Angeles road dust. It was 30+ pages of fine print and a plethora of organic compounds, rivaling any cigarette smoke analysis.
    Estimate, 1 to 3 grams per day brought into the G.I. track and the lungs!
    Surprise, surprise…the human body is SO resilient, it handles these burdens with hardly a “morning cough”.
    The point that should be made on this article, which is SCREAMING AT US…is that the “developed countries” have the least burden of fine particulates. Therefore DEVELOPMENT, in general is good.
    Oh wait, China is a PIT!! Could that be because of running a variety of facilities, the same way we did in say, 1920 or 1930 or 1940? By the 50’s power plants began to have CYCLONES on them, eliminating 70 to 80% of the particulates. Houses were transitioned to CH4, eliminating that emission. By the 60’s, ESP’s on power plants and industrial facilities. By the ’70’s, complete control on “blast furnaces”.
    NOW CHINA: Not only running the power plants, and just barely getting into cyclones, but still HEATING much with COAL and PEAT and even WOOD!
    But the Chinese are stupid! Within 10 years, they’ll have fixed that. The whole of China will turn BLUE.
    The the question remains if the “fine particulates” are such a problem, what will we do for the “third world” areas which have the problem?
    The answer is to MODERNIZE THEM. And that will take OODLES of fossil fuels, refined, stoicheometrically [i fixed the rest but i can’t fix this mod] burned, and “pollution controlled”. THAT takes planning, initiative and investment. And it is NOT DONE WITH WINDMILLS AND SOLAR PANELS.
    Signed:
    A. Square.

  38. The San Joaquin Valley had extensive areas of barchan and linear dunes during the Pleistocene and most of the Holocene. Barchan dunes are also known as “crescent” dunes. These fields show clearly on earlier USGS topographic maps, which alas are not as easy to locate as they once were. As recently as about 1,800 years ago active dune formation was occurring in the region as far north as the San Joaquin – Sacramento river delta. Aspects of soil chemistry, especially soil pH, also correlate with the particulate map of California. The pH of the soil tends to increase as you travel south in the valley. This, BTW, is in turn an indirect measure of the increase in the risk of Valley Fever (Coccidio mycosis) exposure. One interesting fact is that since these dune fields had stabilized and been vegetated by the historic period (about 1700 C.E.), California is presently present cooler and wetter, even with post-LIA warming, with quieter airs than it has been over most of the Pleistocene. Another (as far as I have been able to determine) unused piece of data that is implicit in the older USGS maps is geomorphological evidence regarding the changes in prevailing wind directions over the last few thousand years.

  39. Wow!, that’s a Scheherezade tale:
    One Thousand and One Nights (Arabic: كتاب ألف ليلة وليلة‎ Kitāb ‘alf layla wa-layla; Persian: هزار و یک شب Hezār-o yek šab)
    Kind of an abrasive machine to grind occidental cultures: Hurricanes + Sand = WMD !

  40. Just to add to Alan the Brit, this region is constantly active.
    KVERT: ACTIVE VOLCANOES OF KAMCHATKA АND NORTHERN KURILES
    http://www.kscnet.ru/ivs/kvert/volcanoes/index_eng.html
    http://www.kamchatka.org.ru/volcano.html
    http://earthobservatory.nasa.gov/IOTD/view.php?id=42758
    All one has to do is take a look at SI / USGS Weekly Volcanic Activity Reports to see a lot of particulate spewed forth from all the various regions.
    http://www.volcano.si.edu/reports/usgs/index.cfm?wvarweek=20100908
    http://www.volcano.si.edu/reports/usgs/

  41. Glaciers deposits, wind, loess and pahas are conspiring to cause airborne particulate pollution and, wait for it,……. Catastrophic Anthropogenic Climate Disruption.

  42. I can believe that Australia on average has very low dust and particulate concentrations.
    When flying light aircraft and gliders I find the visibility usually to be very good, usually well in excess of 20-30 nautical miles and quite often you can see clearly to the hoizon 100nm away. No and again the vis is bad from bushfire smoke or dust from the inland but usually only for a day or two at a time in limited areas with weeks in between events.

  43. Espen says:
    September 24, 2010 at 2:59 am
    “Now I know why pictures from Australia always has this amazingly blue sky. But I’m surprised that the desert in Australia (or parts of the US) doesn’t create more particulates in the air when you compare to the Sahara. Are there more dust storms in Sahara? Or is there more fine-grained dust?”
    Think again:
    http://www.google.co.uk/images?hl=en&q=Dust+storms+Australia&um=1&ie=UTF-8&source=univ&ei=Zy6dTN6dO8yVswby0pXmDg&sa=X&oi=image_result_group&ct=title&resnum=6&ved=0CDoQsAQwBQ&biw=1438&bih=722

  44. the abundance of PM2.5 could still be off by 25 percent or more in some areas due to remaining uncertainties
    Yes, and it may be especially ‘off’ by a lot more than that at Redding, CA, allegedly due to the excessive amount of ‘drippy’ jet trails left by a company someone here identified as Evergreen in a recent article published in the newspapers. Evergreen is the company that sprayed the dispersants, according to these articles, in the Gulf during the BP Oil spill. Many groups in the affected areas are up in arms over the alledged affects of these jet sorties.
    Don’t step on our Blue Suede Skies, thank you, Just Beat It, and furthermore, don’t go away mad, just go away, but dont’ let the Particulate Door hit you in the South Part of the Donkey going North on the way out.

  45. Robuk says: (September 24, 2010 at 7:24 am) OT. No evidence that dietary saturated fat is a cause of cardiovascular disease,
    Was this the original distortion of science that has ripped through the (Western at least) world, Robuk? I think you are right on topic.

  46. http://news.nationalgeographic.com/news/2010/01/100922-volcanoes-eruptions-neanderthals-science-volcanic-humans/
    Neanderthals and volcanoes: A recent study by Naomi Cleghorn and others that appeared in Current Anthropology lays the blame for the extinction of the Neanderthals on the Campanian Ignimbrite (amongst others). By examining ash layers in Russian caves that were frequented by Neanderthals, it appears that ~40,000 years ago a number of volcanic ashes accumulated, right before Neanderthals go extinct. The volcanic ash layer related to the Campanian Ignimbrite appears to lack much plant life (pollen, etc.), suggesting that much plant life in Europe was killed due to the eruption, thus likely leading to a decline in the large mammals that the Neanderthals hunted. The fact that the Neanderthal populations were concentrated in Europe – versus the dispersed human populations in Asia and Africa along with Europe—may have lead to their demise.
    Naomi Cleghorn
    http://www.uta.edu/ra/real/editprofile.php?pid=4919&onlyview=1
    Current Anthropology
    http://www.journals.uchicago.edu/toc/ca/current
    Neanderthals
    http://archaeology.about.com/od/hominidancestors/a/neander.htm
    Campanian Ignimbrite
    http://www.ncbi.nlm.nih.gov/pubmed/18937961

  47. This study from the UNSW of the 2009 dust storms gives a breakdown of particle size, composition and location of the dust coming from the Lake Eyre Basin. My feeling is that Australia’s age means that most of its fine regolith has already been dumped into the Tasman sea a long time ago and that it takes an uncommon low pressure system to drive winds strong enough to raise dust from (and this is the key factor) large basins like Lake Eyre recently drying out from rare flooding. The fine clay particles in the basin would have been brought from the sub- surface in water suspension , dried on the surface to be carried aloft by the next storm. So the sequence has to be, Inland basin flooding- surface drying- strong storm(s) from South Australia for the fine particles to carried any distance, and this combination of events is rare.
    Otherwise, as stated earlier, our air is reasonably clear. The number of amateur astronomers spread across this continent would testify to that.

  48. Curious, Salt Lake City has a bright brown spot, as Dallas has a red spot, and the North East has a big blot. However, Houston, the oil capital of America with 3 million people, is only a small yellow dot.

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