I wonder though how do they compute the number (is it average across points measured in the city?). Because within city borders air quality varies wildly. There are some regions where it is actually pretty good.

But it's a silent killer, so let's dramatize fantasy nuclear accidents instead.

All I know, is that it smells really unhealthy, and the smoke coming out of houses is a deep, black colour, almost like oil.

It's much better this year but incredibly hard to police since officials often don't have jurisdiction where the pm2.5 originated, before getting trapped in the inversion

Which is interesting, as either air quality does not matter that much or those data are just bogus.

Well, air quality matters probably, so we are left with the data. Let's check what is the origin of this information: https://www.iqair.com/poland/lesser-poland-voivodeship/krako...

6 stations. One from "corporate contributor" named Arek (common Polish first name, short from Arkadiusz so does not look like a big corp) plus 5 other individual contributors.

What equipment those 6 stations have? No idea. Are the instruments calibrated properly? No idea. Are they placed in the right spot, not on the balcony near the chimney? No idea. Are they placed evenly across Krakow to give reliable city-wide data? Looking on the provided locations - not really.

Iqair seems to "crowdsource" their measurements so they get "crowdsourced" data, which can be total crap. Do they even verify those data? How? No idea.

So the editorialized title is incorrect. It's not "top 5 worst air quality worldwide", it's only top 5 in this list, which is a small subset of the world's cities.

It's a Swiss company but even Switzerland's largest city, Zürich, is missing.

China sure as hell has more than 8 cities and Russia more than 2.

The point of pollution is that it stinks (literally) and is bad for your health. Pollution kills people, shortens expected life times by years, causes respiratory issues for children, etc. Those are some good reasons to do something about it. There are good alternatives to coal at this point. Mostly this is just inefficient legacy infrastructure that we pay extra for to keep going to "protect jobs". From a macro economic point of view, that stopped making sense quite some time ago. Which is why coal plants are going extinct in a lot of places.

Even gas plants are a big improvement. I think of them as a stop gap solution that might be economically risky long term. Wind, solar, and batteries are cheaper. Maybe with some nuclear here and there (expensive but clean). However, gas plants are undeniably a pragmatic compromise between cost and polluting. Unlike nuclear they are easy to switch off when not needed and can act as a fallback solution when wind/solar fall short in the winter. LNG is not cheap though and that makes gas plants long term risky as renewables plus batteries marginalizes their use to the point where they are deeply unprofitable.

There's a base load argument that often pops up in these discussions. Gas plants are nice because they can be switched off. Base load is basically the type of power that is expensive to switch off. Mainly coal and nuclear. This is actually problematic in a grid with a lot of intermittent power supply (wind/solar). Dispatchability is more important. Gas power is good because it is rapidly dispatchable. Batteries act as a buffer and minimize the need for gas plants to run.

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.