Bay Area residents may be affected today by smoke from the Gap Fire in Siskiyou County, Bay Area Air Quality Management District officials said.
Meteorologists expect the air to be unhealthy for anyone sensitive to smog and smoke.
Conditions will improve somewhat today, but residents are urged to take precautions as skies may be hazy and smell like smoke.
Air district officials suggest residents who smell smoke to limit outdoor activities, set home and car air conditioning units to re-circulate and remain indoors with the doors and windows closed if possible.
Smoke can irritate a person's eyes and airways, cause coughing, irritate sinuses and cause a scratchy throat.
Particulate matter in the air can also cause a person with asthma to wheeze.
Seniors, children and people with respiratory illnesses are particularly sensitive to higher air pollution levels and should be extra cautious, according to air district officials.