PM2.5 is one size classification of airborne particulate matter, but has become a popular catch phrase for any small-sized particulate matter relevant both to atmospheric heating/cooling (as a greenhouse "gas") due to their high thermal emissivity and sunlight absorption, and as a pollutant with health consequences. Other particle sizes can use this tag as well, including PM10, PM1, PM0.1

There is no tag wiki for this tag … yet!

Tag wikis help introduce newcomers to the tag. They contain an overview of the topic defined by the tag, along with guidelines on its usage.

All registered users may propose new tag wikis.

(Note that if you have less than 4000 reputation, your tag wiki will be peer reviewed before it is published.)