CIIC:Today's featured article/April 12, 2016
From Wiki China org cn
Particulate matters or PM , is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. PM2.5 (细颗粒物) particles are air pollutants with a diameter of 2.5 micrometers or less, small enough to invade even the smallest airways. (More...)
