For the second day in a row, the Bay Area Air Quality Management District is asking residents to refrain from burning wood.
The season's second "Winter Spare the Air Alert" has been issued for Thursday.
Anticipating high levels of pollution this week, district officials also issued a Spare the Air Alert for today.
District officials said that wood burning, both indoors and outdoors, will be illegal all day today and Thursday.
"Winter air pollution is mainly caused by particulates or soot pollution from wood smoke," district officials said in a statement. "Smoke from wood-burning fires is linked to illnesses such as asthma, bronchitis and lung disease, and is especially harmful for children and the elderly."
The district's Winter Spare the Air season began Nov. 1 and will end on Feb. 29. Residents are advised to check www.sparetheair.org or call (877) 4-NO-BURN to check the daily burn status.