New study negates the worry over "deaths due to atmospheric pollution"

Walking and cycling are good for health even in cities with higher levels of air pollution


Smog in Los Angeles - Image NASA GSFC
Smog in Los Angeles – Image NASA GSFC

The health benefits of walking and cycling outweigh the negative effects on health of air pollution, even in cities with high levels of air pollution, according to a study led by researchers from the Centre for Diet and Activity Research (CEDAR) and Medical Research Council Epidemiology Unit at the University of Cambridge. This new evidence strengthens the case for supporting cycling even in polluted cities — an effort that in turn can help reduce vehicle emissions.

Regular physical activity reduces the risk of diseases such as diabetes, heart disease, and several cancers. One way for people to increase their levels of physical activity is through ‘active travel’ — for example walking and cycling; however, concern has been raised about the potential risk due to air pollution while walking and cycling in urban environments.

Air pollution is one of the leading environmental risk factors for people’s health. A recent report from the Royal Colleges of Physicians and of Paediatrics and Child Health suggested that it contributes to around 40,000 early deaths a year in the UK. One of the main sources of air pollution in cities is transport and a shift from cars, motorbikes and buses to active travel would help to reduce emissions. However, people who walk or cycle in such environments will inhale more pollution, which could be detrimental to their health.

Previous studies conducted in Europe, the USA and several other developed countries found that the health benefits of active travel are greater than the risks, but these were undertaken in areas of relatively low air pollution, and the applicability of their results to more polluted cities in emerging economies has been uncertain.

Researchers from CEDAR, a partnership between the Universities of Cambridge and East Anglia, and the Medical Research Council, used computer simulations to compare the risks and benefits for different levels of intensity and duration of active travel and of air pollution in different locations around the world, using information from international epidemiological studies and meta-analyses. The study, published in Preventive Medicine, is the first to model the risks and benefits of walking and cycling across a range of air pollution concentrations around the world.

Using this data, the researchers calculated that in practical terms, air pollution risks will not negate the health benefits of active travel in the vast majority of urban areas worldwide. Only 1% of cities in the World Health Organization’s Ambient Air Pollution Database had pollution levels high enough that the risks of air pollution could start to overcome the benefits of physical activity after half an hour of cycling every day.

Dr Marko Tainio from the MRC Epidemiology Unit at the University of Cambridge, who led the study, says: “Our model indicates that in London health benefits of active travel always outweigh the risk from pollution. Even in Delhi, one of the most polluted cities in the world — with pollution levels ten times those in London – people would need to cycle over five hours per week before the pollution risks outweigh the health benefits.

“We should remember, though, that a small minority of workers in the most polluted cities, such as bike messengers, may be exposed to levels of air pollution high enough to cancel out the health benefits of physical activity.”

Senior author Dr James Woodcock, also from CEDAR, says: “Whilst this research demonstrates the benefits of physical activity in spite of air quality, it is not an argument for inaction in combatting pollution. It provides further support for investment in infrastructure to get people out of their cars and onto their feet or their bikes – which can itself reduce pollution levels at the same time as supporting physical activity.”

The authors caution that their model does not take into account detailed information on conditions within different localities in individual cities, the impact of short-term episodes of increased air pollution, or information on the background physical activity or disease history of individuals. For individuals who are highly active in non-transport settings, for example recreational sports, the marginal health benefits from active travel will be smaller, and vice versa for those who are less active than average in other settings.


The research was undertaken by the Centre for Diet and Activity Research, a UKCRC Public Health Research Centre of Excellence. The work was also supported by the project Physical Activity through Sustainable Transportation Approaches, funded by the European Union.


Tainio et al. Can air pollution negate the health benefits of cycling and walking? Preventive Medicine; May 5, 2016

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May 5, 2016 10:11 am

Wow that is one misleading title:
New study negates the worry over “deaths due to atmospheric pollution”
Is *really* not the same as:
The health benefits of walking and cycling outweigh the negative effects on health of air pollution, even in cities with high levels of air pollution (…) Air pollution is one of the leading environmental risk factors for people’s health.

Reply to  benben
May 5, 2016 10:13 am

And this PRETTY ironic considering that yesterday WUWT complained about the media misquoting science to further its own agenda.

Joseph Murphy
Reply to  benben
May 5, 2016 2:50 pm

Good news Anthony, you have been promoted from meteorologist to journalist. Bad news, your ‘agenda’ of transparent and honest science is destroying your reputation as a journalist.

Tim Hammond
Reply to  benben
May 6, 2016 2:03 am

Except it isn’t remotely a risk. The studies show very weak relative risks and suffer from all sorts of issues, including the typical epidemiological Exposure Fallacy.
Add in the fact that death certificates are mainly fiction and you have no evidence whatsoever that air pollution kills anybody.

Reply to  Tim Hammond
May 7, 2016 7:18 pm

you have no evidence whatsoever that air pollution kills anybody

Other areas in need of real data:
Second hand tobacco smoke.
Death by red meat.
AGW (of course).
Just a few common ones. The point is there’s no need for any supporting evidence, people just believe what they’re told and it doesn’t seem correctable.

Reply to  benben
May 6, 2016 10:40 am

You will find 0 individual deaths are linked to air pollution.
Yes 0. The same number as man made climate change deaths, which is also 0.
Deaths from pollution estimates are estimates based on fiction born of linear thinking, pollution bad, it kills people.
No, it “may” affect the legnth of their lives or their health later on in life, but killing?
Like man made climate change makes all extreme weather worse, pollution makes all existing medical conditions worse except there is no hard data to back that up.

Owen in GA
May 5, 2016 10:25 am

How did they validate their models. I really don’t like models all the way down “studies”. How was it validated against observational data is the biggest question.

Gary Kerkin
Reply to  Owen in GA
May 5, 2016 1:24 pm

That’s the most important criticism. Where are the results of the clinical studies that verify the modelling? In the absence of other information it all looks like “make work” to keep post-grad students occupied.

Crispin in Waterloo but really in Beijing
Reply to  Owen in GA
May 5, 2016 11:33 pm

There is virtually no data behind any claim for the impact of air quality. I have that on good authority (appeal to authority!) from a long time World Bank consultant who specialises in debunking wild claims for ‘impact’ from projects that seek to reduce the effect. The number of people ‘who die’ is properly reported as 0-40,000 not ‘40,000’ if you look into the chain of models, near the source where the thin data actually exists. Most such claims are just made up.
Bill Mollison told me that, “83% of statistics are made up…”

Reply to  Crispin in Waterloo but really in Beijing
May 6, 2016 12:15 pm

I read that Snoopy said that 86.28% of statistics are made up.
Plainly more accurate than Bill Mollison – two decimal places and all!
Auto – with apologies to Schultz!

May 5, 2016 10:29 am

So I wonder why all those guys who were properly hydrated were having heart attacks out east of Atlanta in 2004.
Atmospheric pollution isn’t just an inhibitor of lung function, molecular toxins have to be removed by the bloodstream and many of the toxins are hazardous to long term health. Additionally there are chemicals from industry that reduce or stop the normal healing function of the lungs. One non-industrial example is roach waste – a very very common city pollutant. It interferes with lung micro-regeneration in the same way that tylenol affects liver micro-regeneration.
Walking and cycling (cycling only if you’re not “obese”) are the two most effective health exercises that mankind can engage in. Both reduce heat by increasing airflow and both pump 50% of the body’s muscle mass. NEITHER is healthy to do in a polluted environment because you’re tripling to quintupling the amount of air you filter through your lungs. Human lungs are a VERY efficient wet-bath filter.
Betcha this article doesn’t take the multiplied air-flow into account.

Tim Hammond
Reply to  prjindigo
May 6, 2016 2:09 am

That’s pretty much all nonsense. “Toxins” are removed all the time by our bodies from all sorts of things. Yet we live.The relative risks in these studies are very, very low and have no correlation to exposure – it is simply assumed that somebody who dies from say a heart attack in an area with higher particulates was exposed to the higher level. But there is no evidence that they were exposed. And since death certificates are just biased guesses, they may not have died from a heart attack anyway.
So we have insignificant increase risk based on data that can’t trusted and exposures that may not have happened. The definition of junk science?

Reply to  prjindigo
May 7, 2016 7:23 pm

Shoot PRJ, I wanted to be the first to reply with “you’re an idiot”. I suppose that will teach me.
Nobody’s stopping you from riding your bike in the rain at night, but stay off the road while you’re doing it.

May 5, 2016 10:53 am

“Life expectancy in Beijing and Shanghai has reached 80 years and it’s 82 in Hong Kong. All have massive pollution problems. Life expectancy in Berlin is 79.8, San Francisco and New York are barely 80 and the list goes on”

Reply to  englandrichard
May 5, 2016 4:24 pm

Ouch, those statistics hurt.
People always think the human body is so fragile, but it is unbelievably resilient.
My dad was a 60 year chain smoker, never jogged or took care of himself, swore and drank rum like a sailor, and after practicing medicine for 45 years still lived to age 82.
You can work out and eat healthy all you want but your genetics plays a big role.

May 5, 2016 11:13 am

That release is sort of a mishmash of contradictions. When I see that in environmental studies or abstracts, I immediately suspect that the conclusions of the study did not support either the aim of the grant or the hypothesis of the authors.

May 5, 2016 11:40 am

A simple damp bandanna over one’s mouth and nose is sufficient to filter out particulate matter and is frequently used to mitigate smoke inhalation risks. While particulate size is far larger with smoke than for tailpipe exhaust, the basic principle still applies. If not, then simple walking is inherently risky and cities should be banned for their adverse health risks.

Crispin in Waterloo but really in Beijing
Reply to  AZ1971
May 5, 2016 11:39 pm

Biomass and coal combustion make only very small particles, mostly under 1.0 micron. Nanoparticles at 0.01 microns are removed wit surprising efficiency by condensation of moisture in the upper airways. Little actual particulate pollution reaches the deep lungs. The body is very efficient at removing dust. Seems we evolved with it.

May 5, 2016 12:05 pm

‘A recent report from the Royal Colleges of Physicians and of Paediatrics and Child Health suggested that it contributes to around 40,000 early deaths a year in the UK.’
Yet they can’t produce a single death certificate.

Reply to  Gamecock
May 5, 2016 5:01 pm

You’ll note the use of the weasel word ‘contributes’, which can mean just about anything.

May 5, 2016 12:10 pm

Re: “Regular physical activity reduces the risk of diseases such as diabetes, heart disease, and several cancers.”
Does it? Or have we simply repeatedly shown that physical activity correlates with these other factors.
Being unwell correlates with reduced physical activity. Does that mean that lack of physical activity causes un-wellness.
It seems to me that there is a vast amount of cross-sectional research showing a correlation. But where is the reliable longitudinal intervention trial that would prove that physical activity actually causes these ill-health markers to reduce? Has anybody every conducted such a trial? How would it even be done?
Maybe all that we have so far discovered is that being slim and well tends to go hand in hand with a tendency to engage in activity. Which would hardly be unexpected.
Or that being slim and well tend to make a person less likely to drop out of trials designed to study the impact of increased physical activity.
I just did a quick search on this topic. And apparently there is also significant skepticism in the professional field. (for example):

Reply to  indefatigablefrog
May 5, 2016 12:34 pm

I think that the take-home soundbite from that analysis I have just posted (link above) is this:
“Our opinion is that, given that both physical fitness and adiposity have a marked hereditary component, adolescents who are genetically predisposed to poor physical condition or obesity are less likely to get involved in intense physical activity”.
And, IF that is the correct interpretation then the entire modern belief system regarding exercise and health is yet another example of a “correlation does not imply causation” error leading to a mass-delusion.

Gary Kerkin
Reply to  indefatigablefrog
May 5, 2016 1:28 pm

It is fair to say that reports on diseases, such as, for example, prostate cancer, often include comments such as “regular exercise is indicated.”

May 5, 2016 12:40 pm

Women & “overweight” (BMI classification) women + diabetics may respond differently than non-geriatric males. For extensive coverage of air quality see free full on-line pdf of (2010) ” Particulate matter air pollution and cardiovascular disease: an update to the scientific statement from the american heart association”.

May 5, 2016 1:46 pm

The title “New study negates the worry over “deaths due to atmospheric pollution”” and the subtitle “Walking and cycling are good for health even in cities with higher levels of air pollution” DO NOT MATCH.
I am quite disappointed.
This would be expected from tabloid graun/SkS stuff, not from WUWT.

Steve from Rockwood
May 5, 2016 2:29 pm

“Air pollution is one of the leading environmental risk factors for people’s health. A recent report from the Royal Colleges of Physicians and of Paediatrics and Child Health suggested that it contributes to around 40,000 early deaths a year in the UK.”
Sorry, but these statements are total nonsense. Show me the death certificate of someone who died of “air pollution”. The same statements are used to estimate deaths from coal use. How can researchers separate coal air pollution from other air pollution?

May 5, 2016 2:32 pm

Ya have to wonder if there has ever been a study, that correlates injuries, with age, in regards to bicycle mishaps.
I’ll bet most injuries occur in large cities, to people over 40.
It’s all about reaction time.

Retired Kit P
Reply to  u.k(us)
May 5, 2016 4:21 pm

It is about getting dizzy. When I retired, I donated my mountain bike to a charity. I have no business riding a bike.
We study statistics to prevent accidents. I pointed out to an EMT friend that falls cause broken hips. He pointed out that broken hips causes falls.
A few years ago, I came down off a ladder to join in the conversation about how nice my hard work on a hot day looked. My wife and neighbor helped me to the ground. Got a little dizzy.
I am tempted to take a small hammer whenever a situation will lead to recommendations of getting more exercise. A good smack to the knee cap followed by a recommendation to exercise to exercise for an hour.

Reply to  u.k(us)
May 5, 2016 4:29 pm

Being age 40 or older & likewise 12 or under were associated with a bit more serious bicycling injuries in a 1997 study. However, it was being male , crashing on paved surfaces & going over 15 miles/hr. that was most predicative of injury over a 3 year Seattle study involving data from 3,390 individuals. Severe injury understandably was 3.6 times more likely when vehicles involved; with fatalities 14 times greater when hit by one. Loss of control accounted for15% of incidents & this, assumedly, more in the 40+ & 12- age groups. Males were 2.4 times more often injured; while going over 15 mph was 40% more likely to be related with serious injury (ex. fracture, rather than scrape). Among those over age 13 some used bicycle helmets already & 45% cycled over 5 hours a week ( 36% went more than 50 miles a week). Proportionally there are so many 20-39 yr. olds represented that 23% got hospitalized to only 16.7% aged 40& over;
it was the 12 & under who most often required hospitalization ( 36.6%).
I did a lot of bicycling commuting in my 20s from a dirt road farm to paved mountain road through winding foot hills into university job in town. We only had enough money to keep one
car & I earned the least, so got to check the air outside – whether surrounded by cars or trees.
Link to above study available if anyone wants to request it.

Reply to  gringojay
May 5, 2016 5:06 pm

@ gringojay ,
Great stuff, but back in the day no self respecting 12 year old would go to the hospital.

Michael Maddocks
May 5, 2016 3:34 pm

Now if all of the money and effort that has gone into the CAGW scam went into developing cleaner combustion technology, how many people that are currently dead would still be alive?

Reply to  Michael Maddocks
May 5, 2016 4:47 pm


Retired Kit P
May 5, 2016 4:01 pm

it is just a theory that moderate levels of air pollution cause ‘premature’ death. Read the studies closely. When all the ‘premature deaths’ occur in chronically ill patients over 75, I have to quibble with the terms kill or premature.
In any case this group are not out cycling. They are in a bed, hopefully made more comfortable with air conditioning.

Reply to  Retired Kit P
May 5, 2016 4:50 pm

Unless they can provide a list of the people allegedly killed, they are lying. It’s no more complicated than that. They are making it up.

May 5, 2016 10:35 pm

Dang! There goes my excuse for not exercising…

Johann Wundersamer
May 5, 2016 10:43 pm

Yes, now the skies are clear over Birmingham and London town,
‘Air pollution is one of the leading environmental risk factors for people’s health. A recent report from the Royal Colleges of Physicians and of Paediatrics and Child Health suggested that it contributes to around 40,000 early deaths a year in the UK.’
Where have that Royal Colleges been during the centuries when cities never came out of fog and smog – waiting for computer models telling the magic 40,000.
Now in clear sight, visible there’s no hazardous pollution at all.
Hard to believe one has the guts to come with such ‘paper’.

Johann Wundersamer
May 5, 2016 11:04 pm

And it was’nt industrialization to invent fog and smog. From bronce age to iron age charcoal piles where distributed over europes landscapes – the denser settlement the thicker air.

Reply to  Johann Wundersamer
May 6, 2016 6:09 am

And Areva didn’t invent dust in Arlit, Niger: some of the sand is very fine with high drag and can float. It’s a major health issue: sand dust is irritant.
Obviously mining for uranium moves minerals around and can worsen the problem, but measures can be taken to stabilize the dunes.

May 5, 2016 11:53 pm

EPA data show REAL air pollutants have been cut 55~99% just since 1980:
You’d be amazed at the number of enviro-wackos that think air pollution has gotten severely worse since 1980…not so much…

May 6, 2016 4:27 am

Astonishing! A study from Cambridge recommends cycling: perhaps punting is good for you too.

May 6, 2016 8:24 am

Paraphrased, the political message from this paper seems to be:
What we told you about vehicle exhausts causing asthma, etc., might have been a pack of lies. But we’re still looking to force you out of your car.

Jack Simmons
May 7, 2016 2:54 am

Where are the bodies?
During the Chinese Olympics, everyone commented on how bad the air pollution was in Beijing. Air pollution was off the scale used by the EPA in this country. See
Yet, there were no deaths attributed to air pollution.
Why is that?
Is it possible all the air pollution standards in the US have nothing to do with health?
Just wondering.

May 7, 2016 6:30 pm

I stop reading after I read this “East Anglia,” I don’t believe anything they say.

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