Cycling in cities is bad for your health, warns heart doc

Pollution levels inside cars are often higher than that of city air because pollutants become trapped within vehicles. UPDATED: Cyclists sit higher than motorists and so it's generally thought they breathe in less pollutants than motorists, and expel them quicker thanks to stronger lungs. But new, unpublished lab research by the British Heart Foundation attempts to show that cyclists are doing themselves more harm than good by pedalling along congested roads. The lead researcher wants cyclists off the road, and on to cycle paths away from traffic.
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If cycle paths were located away from roads the health risks would be greatly reduced, reported The Sunday Times yesterday. At 10 metres from traffic, pollution levels drop by 90 percent.

The newspaper carried an interview with David Newby, British Heart Foundation senior lecturer in cardiology at Edinburgh University. He said cycling in cities is "bad for the heart."

Newby is author of a paper soon to be published by medical magazine Circulation.

"Cycling through congested traffic exposes the cyclist to high levels of air pollution, especially as the exercise of cycling increases breathing and the individual's exposure," said Newby.

The heart doc had 15 healthy men cycle on exercise bikes for an hour while being exposed to levels of diluted diesel exhaust comparable to the air they would inhale cycling on a congested city road.

Six hours after exposure to the fumes, damage was detected to the men's blood vessels.

Instead of calling for restrictions on car use, Dr Newby wants cyclists off the roads:

"While they are exercising, cyclists breathe two to three times as much air as car drivers. We need to locate cycle lanes away from major roads."

According to the Sunday Times, the British Committee on the Medical Effects of Air Pollutants, a government advisory body, will publish a report next month highlighting the risks of heart disease from traffic pollution.

Jon Ayres, professor of environmental and occupational medicine at Aberdeen University and chairman of the committee, said:

"Exercising outside (in cities) will be a contributory cause of heart disease in healthy individuals."

This was a lesser factor than a person's blood pressure or cholesterol level but "of the same order as passive smoking," said the professor.

The CTC has responded to yesterday's article, saying health gains from cycling far outweigh pollution risks

"The study was conducted using exercise bikes indoors, and makes no attempt to compare how much pollution gets breathed in by cyclists and drivers in real-world cycling conditions," said a rebuttal from the CTC.

"Other research shows that the air which cyclists breathe is a lot less polluted in the first place than that which accumulates inside a car. This is because cyclists are more likely to ride at the side of the road and to reach the front of stationary traffic queues, whereas vehicle occupants are more likely to be stuck behind the exhaust pipe of the vehicle in front of them. Hence vehicle occupants are exposed to air with pollutant concentrations 2-4 times higher than that breathed by vehicle occupants, depending on the type of pollutant."

CTC’s campaigns and policy manager Roger Geffen said:

“Polluted air affects everyone – drivers and pedestrians as well as cyclists – and is estimated to kill up to 24,000 people every year. Cycling is part of solution to this problem, not the problem itself. It has clear overall benefits for your health, fitness and overall life expectancy, as well as helping society to reduce air pollution in the first place. We should tackling the source, not the symptoms, of this problem, and that means encouraging more people to cycle, rather than frightening them into not doing so with incorrect reporting of this important new research."

The British Heart Foundation has clarified its position. The BHF website states:

“For most cyclists, the benefits to their heart health from regular exercise far outweighs risk from pollution, which has yet to be directly proven."

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