It's a bit more than a couple days. It's not, like, the whole year, but let's not hyperbolize in the other direction and minimize a very real issue. In Canada last year, there were weeks at a time where it was bad for you to go outside. Some jurisdictions were worse than others. I would say that we had anywhere between 4-6 weeks last year during the summer that exercising outside was probably bad for your health (in the Okanagan Valley).
But something that I find interesting living here is that much of the year, our air quality is a 1 (the best), and on moderately bad days where you can smell smoke but not necessarily see any haze, it'll rank as a 3. When I lived in Montreal, it was a 3 all the time. I mean, maybe that's not actually surprising--Montreal is a city of 4 million people (in the Metro area) and I now live in a city of 40k (the whole valley is 400k).
But yeah, the air is gross in cities, it's probably not good for us, and forest fires are making it worse. That's life now. I don't know what's actually to be done about it short of rewinding the clock 100 years. Hopefully battery tech gets lighter so when we finally do switch to EVs, we not only have reduced vehicle emissions, we also aren't pulverizing the tyres as quickly. Then maybe we'll see some city air quality changes.