Particulate matter (PM) is the term applied to dust and other small particles that are suspended in the air. The Environmental Protection Agency (EPA) regulates PM as a pollutant because it can cause health problems when inhaled. There are two categories of PM— coarse and fine. Coarse PM, typically found near roadways and dusty industries, is made up of particles larger than 2.5 micrometers and smaller than 10 micrometers in diameter. Fine PM, found in smoke and haze, is made up of particles 2.5 micrometers in diameter and… Read More →