City cycling 'could do damage to heart' due to polluting chemicals, new research claims

Cycling in heavy pollution could affect heart's ability to respond to different levels of exertion, say Dublin scientists

by Sarah Barth   December 29, 2013  

Cyclists at traffic lights (©Toby Jacobs)

Cycling in cities could do more damage than good to a rider’s heart due to dangerous pollutants in the air, a new study based on cycling in Dublin has found. 

The Dublin study is not the first to suggest that air pollution in cities may pose a health risk to cyclists back in 2011 we reported on a study conducted by Proffessor John Grigg for Barts and The London School of Medicine which found that London cyclists inhaled 2.3 times more black carbon than pedestrians. That same year a study in Ottawa suggested that cyclists could experience short term heart irregularities in urban cyclists exposed to high levels of pollution.

The problem for cyclists is that when they exert themselves breathe more heavily than pedestrians, meaning their exposure to miniscule particles of polluting chemicals is increased.

The Scientists who have studied cyclists in Dublin say that these chemicals reduce the ability of the heart to respond to different rates of exertion (a similar finding to the 2011 Ottawa study).

They noted that: “These [findings] indicate that exercise while commuting has an influence on inhaled particulate matter, associated with acute declines in heart rate variability, especially in pedestrians and cyclists.”

As well as exhaust fumes, studies have shown that vehicle brakes and tyres also generate potentially dangerous particles, which can penetrate the lungs due to their tiny size and work their way into the bloodstream.

The Dublin study of 32 fit healthy cyclists was led by Marguerite Nyhan of Trinity College Dublin, who advised riders to choose relatively traffic-free routes for their health.

A spokesman for Sustrans, a charity that campaigns for cycling and walking, said: “Air pollution is a concern and Sustrans is calling on the government to ban unfiltered diesel vehicles from Britain’s cities. However, the benefits of cycling and walking far outweigh the health risks.”

Professor Ross Anderson of the government’s advisory committee on the medical effects of air pollutants told the Sunday Times (£): “While the health benefits of cycling are likely to be beneficial, the balancing of risks is problematic. Other epidemiological evidence suggests that traffic pollution has lasting health effects.”

While any exposure to pollution is unlikely to be a good thing it it worth noting that the studies from Dublin, London, and Ottawa were based on a small sample sizes - 32 in Dublin, 42 in Ottawa. it's also worth noting that accordint to a  Danish study car occupants are most at risk of inhaling harmful traffic pollution being exposed to up to four times the levels of pollutants that cyclists are.

Currently the best advice for urban cyclists who want to reduce their exposure to harmful pollutants is to opt for quieter routes on less busy roads. One other suggestion resulting fromt he Ottawa study is that cyclists should keep at least 15 feet back from a car or lorry's exhaust pipe. The closer you get to the exhuast the finer the particulates of the most harmful pollutants - but as they get further from the exhaust they tend to clump together in to heavier particles which fall to the ground and are thus less likely to be breathed in.

As we reported last year, Glasgow is the most polluted city in the UK, and the fifth worst in the whole of Europe, a study has shown.

The report from the European Environment Agency (EEA) measured the toxic gas nitrogen dioxide, caused by exhaust fumes and industrial pollution.

Only ten cities, of which Glasgow was one, breached the limits for the harmful gas. Levels in Glasgow were 46.3 microgrammes per cubic metre, above the legal European limit of 40mg/m3.

According to government information, nitrogen dioxide is pretty nasty stuff:
   

Nitrogen dioxide (NO2) is one of a group of gases called nitrogen oxides. Road transport is estimated to be responsible for about 50% of total emissions of nitrogen oxides, which means that nitrogen dioxide levels are highest close to busy roads and in large urban areas. Gas boilers in buildings are also a source of nitrogen oxides.
There is good evidence that nitrogen is harmful to health. The most common outcomes are respiratory symptoms such as shortness of breath and cough. Nitrogen dioxide inflames the lining of the lung and reduces immunity to lung infections such as bronchitis. Studies also suggest that the health effects are more pronounced in people with asthma compared to healthly individuals.
In recent years the average level of nitrogen dioxide within London has not fallen as quickly as predicted. This largely appears to be the result of diesel cars creating more nitrogen dioxide than was anticipated.
Nitrogen dioxide also reacts with hydrocarbons in the presence of sunlight to create ozone, and contributes to the formation of particles*.

*tiny bits of solids or liquids suspended in the air, that can settle in the airway and deep in the lungs and cause health problems.

12 user comments

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I actually dont care any more...hate to admit that.

I've tried it, essentially cycling to work amongst hung over and late motorists distracted by looking at phones or doing their make-up resulted in far too many near misses and for what?

I drive now, making sure of course to make a very visible point of driving very carefully around my fellow cyclists.

I hope the muppets behind will get the hint that others do actually recognise that any inocuous lump clad in lycra is actually a human being with an extremely fragile life that I temporarily have responsibility for as I pass.

I've had it with half arsed government attempts at encouraging sustainable transport solutions and endless reports screaming out the frickin' obvious benefits of people not sitting on arses all day long.

Bring on the smog, the clogged highways, the broken roads, obesity, the NHS timebomb with the multi billion pound price tag and everything else that the national obsession with the car entails.

Perhaps then our MP's will get it...of course it will be the fault of the previous government as the latest smug waste of space sidles up to you and asks you where your vote is going Yawn

Just how many times can you lead a horse to the trough before you get fed up and leave the wretched thing to its fate? At Wits End

Controversial I know and it pains me to write this but just what are we supposed to do to get anything to change?!

Hating our selfish and ignorant car culture

posted by ironmancole [124 posts]
30th December 2013 - 1:35

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Quote:
Cycling in cities could do more damage than good to a rider’s heart thanks to dangerous pollutants in the air, a new study has found.

Haven't found any studies on bicycle emissions, but am fairly sure that it's motorised vehicles that are throwing out PM2.5/10 (the apparent focus of Ms Nyhan's research), CO, NOx, and VOCs, not bicycles. So let's try changing that quote a little.
Quote:
Driving in cities could do more damage than good to a rider’s heart thanks to dangerous pollutants in the air, a new study has found.

There, that's better. Now we have a fair idea of where the problem is coming from. You'd think that the best way out of this is to stay off that nasty, unhealthy bicycle, and get into a nice, healthy car. Whoopsadaisy. From 1995, "The exposure of cyclists, car drivers and pedestrians to traffic-related air pollutants (van Wijnen JH, Verhoeff AP, Jans HW, van Bruggen M.)
Quote:
Despite the much higher concentrations in the personal air samples of car drivers, the uptake of CO, benzene, toluene and xylenes of cyclists sometimes approached that of the car drivers. The uptake of NO2 of cyclists was clearly higher than that of car drivers.

And from 2001, Differences in cyclists and car drivers exposure to air pollution from traffic in the city of Copenhagen. (Rank J, Folke J, Jespersen PH.)
Quote:
The concentrations of particles and BTEX in the cabin of the cars were 2-4 times greater than in the cyclists' breathing zone, the greatest difference being for BTEX. Therefore, even after taking the increased respiration rate of cyclists into consideration, car drivers seem to be more exposed to airborne pollution than cyclists.

Now I didn't buy the full articles, and am quoting highlights of the abstracts. But I'm seeing a trend here. Pollution seems to be worse inside a motorised vehicle than outside it, particularly for the type of pollution looked at in detail for Ms Nyhan's research, and without the added benefit of a cardiovascular workout as well. But no articles saying driving to work is bad for your health. Can't help wondering why cyclists have been singled out to be advised to stay off busy roads. Suggestions on a postcard please.

While I'm here...

Quote:
There is good evidence that nitrogen is harmful to health.

Never mind. We're all screwed. The air around us is about 80% nitrogen.

posted by Argos74 [289 posts]
30th December 2013 - 2:28

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Far sooner take the much smaller risk from pollution and traffic as a cyclist than the risk of gatting an inactivity based illness.

society needs to take the same line with cars and pollution as they have done with smoking and stop/contain the offenders, not blame the innocent third parties

posted by gazza_d [200 posts]
30th December 2013 - 9:31

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Thanks to Argos74 for pointing out some of the skewed perspective on this. Once again we're told not to do the healthy, congestion-busting cycling thing and jump in our cars.
Angry

gazza_d wrote:
Far sooner take the much smaller risk from pollution and traffic as a cyclist than the risk of gatting an inactivity based illness.

Same here. There's no way I would stop cycling to work and go back to driving the car! Riding my bike is too important, for my physical and mental well-being. And that's before I think about the cost of fuel, repairs and wear & tear...

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posted by Simon E [1946 posts]
30th December 2013 - 10:50

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Simon E wrote:
Thanks to Argos74 for pointing out some of the skewed perspective on this. Once again we're told not to do the healthy, congestion-busting cycling thing and jump in our cars.
Angry

gazza_d wrote:
Far sooner take the much smaller risk from pollution and traffic as a cyclist than the risk of gatting an inactivity based illness.

Same here. There's no way I would stop cycling to work and go back to driving to work! Riding my bike is too important, for my physical and mental well-being. And that's before I think about the cost of fuel, repairs and wear & tear...

Simon E's picture

posted by Simon E [1946 posts]
30th December 2013 - 10:51

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Another option to help reduce your exposure is to ride without exerting yourself much, like I often do Wink

posted by a.jumper [698 posts]
30th December 2013 - 11:41

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Can someone assess the respiratory risk of getting the Tube every day? Actually... no need. Yuck.

Boardman CX Team '14 | Cannondale CAAD8 '12 (written off, SMIDSY) | Scott Sportster '08

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posted by Gizmo_ [826 posts]
30th December 2013 - 12:36

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"There is good evidence that nitrogen is harmful to health".

Really? Nitrogen (N2) makes up 75-80% of every breath we breathe. There is no evidence that Nitrogen is harmful to health.

Nitrogen Dioxide (NO2) might cause a few problems but not nitrogen in itself

lifes goal is not to arrive at the grave in a perfectly preserved body, but to skid in sideways yelling "yeah what a ride!"

posted by wheelsucker [44 posts]
30th December 2013 - 13:56

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Since moving to London I have used a Respro Pollution mask for all rides into London. When I commuted 5 days a week, I had to change the filter and valve every month or so. The colour of the filter was enough to make me change and justified the expenditure. Of course I am aware that these do not stop the smallest particles getting through, however careful you are when you put the thing on. Respro state their masks filter down to 0.3microns. But thats not small enough for the more harmful particles. If anyone knows of a better filter you can use for hard riding without your temp going through the roof please let me know,

Life is like riding a bicycle. To keep your balance you must keep moving.
I thought of that while riding my bicycle.
~ Einstein, in reference to the Theory of Relativity

posted by stealfwayne [61 posts]
30th December 2013 - 15:14

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gazza_d wrote:
Far sooner take the much smaller risk from pollution and traffic as a cyclist than the risk of gatting an inactivity based illness.

society needs to take the same line with cars and pollution as they have done with smoking and stop/contain the offenders, not blame the innocent third parties

Can't argue at all with that logic. Seems the producers of the pollution should be blamed for their damage to other members of society

posted by jarredscycling [445 posts]
30th December 2013 - 16:05

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There have been various bits of research along these lines over the years. I remember one study decades ago finding that [deceased] young people in Los Angeles (who, if I recall correctly, had mostly been non-smokers who died from things like gunshot wounds!) had lungs comparable to long-term smokers, due to the effects of road pollution. And some more recent ones showing car pollution increased your chance of a heart attack at least in the short term.

Of course the real message is "other people's driving could do damage to your heart".

But nobody cares. As with RTA deaths, motorists get special licence to ignore the moral rules that apply to everyone else.

(See also the historical use of lead as an additive in petrol.)

posted by FluffyKittenofT... [667 posts]
30th December 2013 - 20:28

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As I don't drive, my choice is bike or public transport. I would rather put the money into my vehicle and super styling wardrobe and put my fate or being late or not in my own hands than get fat and sweaty with hundreds of other unhappy people.

I do wonder which 'city' this pollution is in? I spend about three minutes in town getting to my office. The rest of my route is 20 minutes of suburban roads with plenty of cross breeze. And this is Manchester, England's second city and capital of the North and capital of the UK after the Great Flood of London 2017. Surprised there is no link to the Daily Mail with this health scare. Rolling Eyes


Leviathan of Riderstate

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posted by bikeboy76 [1252 posts]
31st December 2013 - 1:07

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