http://www.arb.ca.gov/html/brochure/pm10.htm California Air Resources Board known as PM10 Particulate Matter http://www.arb.ca.gov/html/brochure/pm10.htm California EPA: Air Pollution – Particulate Matter Brochure California Air Resources Board More information about particulate matter and its effects a measure known as PM10 California Environmental Protection Agency California EPA: Air Pollution – Particulate Matter Brochure a measure known as PM10 http://www.arb.ca.gov/html/brochure/pm10.htm