Smoke from two large wildfires near Big Sur is drifting into San Mateo. Hazy skies and the smell of smoke may persist through Tuesday, Sept. 1.

The Bay Area Air Quality Management District issued an advisory Monday, Aug. 31, warning that air quality could reach unhealthy levels at times on both Monday and Tuesday. The smoke is blowing north from the Timber and Plaskett fires in Monterey County.

The two fires have collectively burned nearly 52,000 acres along the Big Sur coastline, according to Cal Fire. The Timber Fire, burning in the Los Padres National Forest since Aug. 8, has scorched 25,190 acres and is 22% contained as of Monday evening. The Plaskett Fire started Aug. 26, has burned 26,734 acres and is 1% contained.

The air district said the smoke is expected to stay aloft but cautioned that conditions can shift quickly and ground-level smoke is hard to predict.

What residents should do

BAAQMD is advising residents to limit time outdoors and stay inside with windows and doors closed when smoke is visible or the air smells smoky. The district also recommends setting car vents to recirculate and using indoor air filtration.

Residents who need cleaner air can visit a Clean Air Center or a building with filtered ventilation, such as a library or shopping mall, according to the air district. Wildfire smoke contains fine particulate matter and other pollutants that are harmful even during short exposure, with older adults, children and people with respiratory illnesses facing particular risk.

Current smoke levels for San Mateo and surrounding areas are available on the U.S. EPA's Fire and Smoke Map. Residents can also reach BAAQMD at 415-749-5000 (or 1-800-HELP-AIR) or at baaqmd.gov.