Global air pollution maps by the European Space Agency
This is great to have another authoritative and trustworthy source of this data.WHO used to have a really nice map I would often use, but it’s been down ever since China complained that it shows them in bad light.  https://maps.who.int/airpollution/It would consistently show China pollution levels as high which didn’t match the maps distributed by the Chinese government showing lower levels of pollution in the mainland.