alt Hacker NewsI 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!)
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I remember an interview with the producthead of Google Earth (the desktop client), she said when photographing all the streets, the cars also checked for air pollution: She mentioned a capital in Europe, where the amount of particles under certain sizes differed by 10x from one crossing to the next.
Like I totally agree with encouraging exercise most places, but let’s be careful to not understate the risks of pollution. The paper states that above 35μg/m^3 of PM2.5 pollution, the protective benefits of exercise were “non-significant” against the increased risk of cancer, and they stopped measuring at 50μg/m^3. It’s reasonable to assume that above 50, it’s a net negative to exercise outdoors.
There are lots of places in the world that exceed 35μg/m^3 PM2.5, and quite a few that exceed 50μg/m^3 PM2.5 regularly - the entire SF Bay Area is over 35 right now. Los Angeles and San Diego are both above 50 right now, as are huge swaths of Eastern Europe, Africa, and Asia... it’s a bit more than just a few handful of cities. Exercising near wildfires can be quite unhealthy too. There are places in the world where exercising outdoors is harmful to your health, but most of that is self-regulating.
The other thing to note from the paper is that even the range of 0 to 10 μg/m^3 of PM2.5 causes a 30% decrease in the benefits of exercise. That’s a pretty big reduction of benefits from exercise for the EPA’s “Good” category of air. It’s still a net positive, so you should still exercise, but just a little pollution has pretty big measurable negative effects.
Active commuting is great, you get exercise, and help reduce pollution at the same time. Even if exercise in polluted areas is beneficial, we also definitely need to keep raising awareness and improving air quality, for the time spent not exercising, for people with athsma and heart disease, for the people who can’t and/or don’t exercise. We should worry about it a little, while we exercise. ;)