I want to pull two quotes from the article.
> “Our findings emphasise that exercise remains beneficial even in polluted environments,” lead researcher Professor Po-Wen Ku said in a statement. [...] “We don’t want to discourage people from exercising outdoors,” said Co-author Professor Paola Zaninotto.
The health effects of exercise outdoors are combined from two effects:
- Positive effects due to exercise. These start out strong but level off after a while.
- Negative effects due to pollution. These increase almost linearly with time spent outside.
One might ask, is there an amount of daily exercise at which the negative effects overpower the positive ones? Yes, in a handful of cities around the world, after a few hours of exercise, the pollution makes additional outdoors exercise actually harmful.
But almost everywhere a marginal minute of exercise provides a positive effect on health regardless of time already spent exercising, and there is nowhere in the world where something like an hour of exercise a day is a net negative. Get out there. Pick an active means of commuting (cycling, running, walking, skiing, rollerblading, skateboarding, unicycling) and don't worry so much about pollution unless you live in one of those single-digit cities which I forget where they are, but probably concentrated in Asia.
(I feel bad about typing this out without linking to the source. I'm looking for it in my notes!)