Health watch in effect for Maricopa County
PHOENIX -- A health watch for particulates in the air is in effect Friday for Maricopa County.
Environmental quality regulators said open burning and use of wood burning fireplaces are generally prohibited. People with respiratory problems are advised to avoid heavy or prolonged outdoor exertion.
Particulates are extremely small solid particles and liquid droplets that come from automobile exhaust, burning and dust. High levels typically occur when the air is stagnant.