Physical activity makes you breath more polluted air though.

Yes, but the positive effects of physical activity increase your life expectancy more than the polluted air decreases it.

https://www.researchgate.net/publication/297712056_Can_air_p...

So the solution is to keep polluting?

I don’t understand your point here. If everyone makes the effort to walk/bike more there will be a reduction in pollution.

My point is that I prefer to just walk or be careful and not do too much effort when on bike when there are pollution events in my city. I try to make sure I only have to breath through my nose then.

I believe it's worse here in Europe than in the US as we have a large proportion of diesel cars (though where I live now, most pollution comes from the harbour) and during bad pollution events you don't just smell it but you feel the particle-polluted air aggressing your respiratory system.

Exactly. Every time I see someone jogging/running in the downtown part of the city, surrounded by idling cars, I shake my head.

Would you rather they drive 20 miles first to jog?

The reality for most people in a city is that to exercise they inevitably first need to escape 5 miles worth if clogged up car arteries.

Are you trying to argue that they are inhaling pollution at an extremely high rate by running downtown or do you just not like the fact that I pointed this out?