Under the Clean Air Act, states must develop State Implementation Plans (SIP) to convince the US EPA that they can meet the National Ambient Air Quality Standards (NAAQAS).

The U.S. Environmental Protection Agency (EPA) rejected Arizona’s claim that dust storms caused the high pollution readings in Phoenix in 2008, a decision which could have significant implications for the State.

Arizona is currently not meeting the NAAQAS for fine particulate matter, PM- 10 (one-seventh the width of a human hair). Major concerns for human health from exposure to PM- 10 include: effects on breathing and respiratory systems, damage to lung tissue, cancer, and premature death. The elderly, children, and people with chronic lung disease, influenza, or asthma, are especially sensitive to the effects of particulate matter.