The Valley's stagnant air has generated a fourth consecutive day of Arizona Department of Environmental Quality high pollution advisory conditions, with state officials concerned over high levels of PM-10 particulates.

PM-10, or course particles measuring 10 microns or less. are typically found in airborne dust. The levels are expected to exceed federal standards, so the high pollution advisory will be in effect all day Friday.

Valley residents are encouraged to carpool, ride the bus or telecommute during pollution advisory periods. Children, senior citizens and those with respiratory illnesses and compromised immune systems are advised to limit their time outdoors.

In addition, because high levels of fine particulates (PM-2.5, or particles measuring 2.5 microns or less as typically found in smoke) have generated a health watch, Maricopa County has banned wood burning, including in stoves and fireplaces, for the day.