Regional Air Pollution in Poland

I know the topic of air pollution has been touched on in some other threads, but it would be nice to understand variations among the Polish regions.

I've been tracking the air quality in Poland over te past few weeks using online maps (Weather Bug).

The western third of Poland is usually far less polluted than the rest of the country, with very heavy pollution on southern central Poland.

Why is the air in far-western Poland so much less polluted than in the rest of the country?

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South of Poland is the most polluted part of the country. Silesia and party Lesser Poland are historically industrial regions. Coal mines are still a big deal here. People heat houses with coal and.. burn trash (a habit the government is trying to regulate by fines). Hence the smog.

I use Plume mobile app to monitor the air quality, by the way.