NASA’s air pollution website provides lots of information, including satellite images:

https://airquality.gsfc.nasa.gov/

DEFRA provides lots of information about air pollution in the UK:

https://uk-air.defra.gov.uk/

The WHO provides information about the health effects of air pollution:

https://www.who.int/health-topics/air-pollution#tab=tab_1

National Geographic have made a Youtube video about air pollution, aimed at older viewers:

https://www.youtube.com/watch?v=e6rglsLy1Ys

A lecture given by Chris Whitty at Gresham College in 2018:

https://www.gresham.ac.uk/watch-now/air-pollution-its-impact-on-health-and-possible-solutions