Air Quality

http://www.metoffice.gov.uk/guide/weather/air-quality
The air pollution figure shows the 'Daily Air Quality Index

https://en.wikipedia.org/wiki/Particulates
Particle  Distribution of particles

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/304904/COMEAP_proposed_work_strategy.pdf
Committee on the Medical Effects of Air Pollutants