IQAir has shit coverage. I live in Kazakhstan in a city at the eastern part of the country, near the border with Chinese Xinjiang, where PM2.5 levels regularly exceed 1000 µg/m³ (that's right, it's not a typo). The highest concentration I've seen this winter is 1900 µg/m³ just a couple of days ago.

SO₂ pollution is also extreme, with levels of 1000 µg/m³ being exceeded on a regular basis, and 5000-8000 µg/m³ not unheard of. Yes, I am sure of these numbers, it's not a typo.

Right at this moment there's some wind and the pollution has somewhat subsided, but it won't last: it's an exception. For example, the average PM2.5 concentration over the last month is around 250 µg/m³, depending on the exact place.

We have extensive network of air sensors, but it's not currently public (it only started working a couple of months ago and is in the process of being made available to the public). I can only recommend looking at https://aqicn.org, which has much better coverage than IQAir, and speaking of our country specifically, it collects data from our old sensors provided by the government.

Disregard anything that looks suspicious (some of the sensors are not working and show zero levels of pollution -- they're simply broken).

My city is the worst one, but actually most Central Asian cities have terrible air quality due to harsh winters and outdated heating methods with zero emission control. Much, much worse than anything in Poland or Europe generally. You won't see them on IQAir because AFAIK they mostly collect data through their own sensors, which are expensive and not used here.