We may have been the first country to have a Clean Air Act, back in 1955, but the UK is not breathing so easily now. According to a report by Government advisory body the Committee on the Medical Effects of Air Pollutants (COMEAP), the health cost of air pollution in the UK is equivalent to every citizen dying six months early.
In London alone, the most recent data shows air pollution contributing to over 4,000 early deaths per year. "It affects us on two levels," explains Professor Jon Ayres, chairman of COMEAP. "Our research tells us that accumulative exposure does increase the risk of developing heart or lung diseases, or make existing ones worse - but we also know that on days when air pollution is higher, there are more cardiovascular- and respiratory-related deaths."
Runners at risk
Anyone is at risk of urban air pollution, but runners are especially vulnerable. "When you run, you shift more air in and out of your lungs and so expose yourself to a larger dose," says Ayres. At rest, the lungs pump eight to 12 litres of air per minute, compared with as much as 150 litres during exercise.
The biggest culprits are vehicle emissions, although any combustion process - from central heating systems to industrial plants - contributes to matter particles or 'particulate pollution'. That's why densely populated urban areas tend to be worst hit, and it's not just the traffic-clogged capital.
A widespread problem
According to Environmental Protection UK, Britain's oldest environment charity and one of the organisations behind the recently launched Healthy Air Campaign, over 250 local authorities in the UK have designated one or more 'air quality management areas'.
"These are areas where air pollution levels exceed nationally set, health-based targets," explains James Grugeon, chief executive of Environmental Protection UK. Toxic gases are another issue - particularly nitrogen dioxide and ozone - and time is of the essence here: "Ozone levels peak in the afternoon," explains Ayres. "It is formed as a result of UV light reacting with vehicle emissions and it irritates the airways, worsening chest problems including asthma."
City pollution combined with vigorous exercise can also exacerbate the symptoms of hay fever, which is believed to affect a quarter of the UK population. So, what's the answer? Jump in the car or resign yourself to the bus?
No. Rest assured you can still have a healthy commute or training session on two legs by making a few changes to your routine. You can also take comfort in the fact that as runners are generally fitter than the average person, they are less likely to have cardiovascular or respiratory problems that might be worsened by air pollution.
"They're also more likely to have a healthy lifestyle, which can, to some extent, mediate the problem," adds Ayres.