PM2.5
noun/ˌpiː em ˌtuː pɔɪnt ˈfaɪv/
/ˌpiː em ˌtuː pɔɪnt ˈfaɪv/
[uncountable]- tiny pieces of a substance less than 2.5 micrometres long or wide that can be breathed in (the abbreviation for ‘particulate matter 2.5’)
- The main danger lies with PM2.5, tiny soot particles with a diameter of 2.5 microns.
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PM2.5