Is cycling in cities with high air pollution a health hazard?

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British scientists assert in a study that even with relatively high levels of particulate matter, the health benefits outweigh the environmental benefits

The question must be allowed, whether frequent cycling in the city because of the fine dust pollution does more harm than good for health. If you don’t move enough and do sports, that is, if you don’t breathe deep air with all the possible pollutants, you risk your health and you will live shorter, that’s what they say everywhere. And so people who want to live healthier or longer are eagerly jogging and cycling in the streets and parks of the cities. The bulk of particulate pollution now comes from traffic.

Those who exert themselves breathe more deeply and thus also bring more fine dust particles deeper into the lungs. From here, the particles can also enter the blood and thus the heart. It is very likely that in polluted air it would be healthier to walk slowly or to use vehicles than to exert oneself physically. Finally, air pollution is said to kill 7 million people a year, and almost 40 million in Germany.000, just as many in Great Britain.

Scientists at Cambridge University have now investigated whether air pollution can negate the health benefits of walking or cycling, or whether the health benefits outweigh them. The encouraging finding for cyclists, but unfortunate for opponents of exercise: in almost all cities, the health benefits of walking and cycling, which reduces the risk of diseases such as diabetes, heart disease or some cancers, outweigh the harmful effects of air pollution. Only in one percent of the most polluted cities according to the WHO Ambient Air Pollution Database could the damage possibly be higher. Even in cities such as Delhi with a PM2.5 fine dust concentration of 153 μg/m3, it took at least an hour of cycling to reach the tipping point beyond which it is no longer health demanding.

The scientists determined air pollution levels based on PM2.5 fine particulate matter (PM2.5), which means that 50% of the particles in the air have a diameter of 2.5 µm. The range was from 5 to 200 μg/m3. Simulations examine the effects of physical activity of varying duration across a broad spectrum of particulate matter concentrations in the air by estimating the inhaled dose of particulate matter. Two limit values are used as a basis, one being the "tipping point", from which further exercise no longer leads to any health benefits, and finally the "Break-Even Point", at which point the risks from air pollution begin to outweigh the health benefits of exercise. Only the long-term consequences of regular activity under constant particulate matter concentrations were considered.

In order to meet the "tipping point" to achieve, had to ride a bicycle for half an hour a day at the PM2.5 concentration of 95 μg/m3. Such a high annual concentration is found in less than 1 percent of cities. The "Break-Even Point" would be reached only with 160 μg/m3. If half an hour is walked, for both thresholds the exposure had to be above 200 μg/m3. At the WHO average value of 22 μg/m3, the "Tipping Point" Be reached after seven hours of cycling and 16 hours of walking daily.

Up to a concentration of 80 μg/m3, which is found in only 2 percent of cities, according to the WHO, the health benefits outweigh the need to fully replace the time spent driving with cycling. Even in cities or areas with high concentrations of 100 μg/m3, daily cycling for 75 minutes or walking for up to 10 hours and 30 minutes reduced the risk of mortality in. Air pollution, scientists say, virtually does not cancel out the health benefits of walking and biking. Only an unusually high level of physical activity, as in the case of bicycle messengers, was able to be "extremely polluted conditions" negate the health benefits.

It is therefore right for practically all cities to encourage people to walk and ride bicycles. This is also better than sitting around at home, they said, because there is no escape from normal air pollution. The scientists emphasize that the results of the study do not mean that nothing more should be done about fine particulate pollution. James Woodcock, one of the authors, says this has supported more investment in infrastructure, "To get people out of their cars and onto their legs or their bikes, which itself reduces air pollution while supporting physical activity".

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