A UK study has suggested that the benefits of exercise far outweigh the harm caused by air pollution.1
The research, which included work from the University of Cambridge and Imperial College London, found that the amount of air pollution required to negate the benefits of exercise, was only present in 1% of cities worldwide. The statistics for air pollution levels around the world were taken from the World Health Organization.
The study used computer models to achieve their results, and found that, in an average city, physical activity will remain beneficial in smoggy environments for up to seven hours on a bike, or 16 hours when walking. However, in heavily polluted cities such as Delhi, these numbers are reduced to 30 minutes and 90 minutes respectively.
While results from computer models need to be examined and interpreted with caution, providing the data they were based upon was accurate they can be very reliable. However, with this being a model we don't know just how true to life the results are.
The study also did not examine the differences between children and adults, or people with health conditions, as they may have different "tipping points" (the point where exercise is negated by air pollution levels).
With that said, the results should reassure anybody who is worried about the impact of air pollution on their health. Indeed, the study suggests it is unlikely that exercising outside in busy cities will have any detrimental effect on your health.
1 Tainioa M, de Nazelleb AJ, Götschic T et al. Can air pollution negate the health benefits of cycling and walking? Preventive Medicine. Published online May 6 2016.
Benefits of cycling and walking 'outweigh air pollution risk' in cities. The Guardian, 6 May 2016
Air pollution: Benefits of cycling and walking outweigh harms - study. Daily Mirror, 6 May 2016.
Why walking is good for you... even in the smog: Health benefits of a stroll found to outweigh harm caused by chemicals and dust pumped out by traffic. Mail Online, 6 May 2016