Smoke from two Big Sur wildfires has drifted into San Mateo County, triggering an air quality advisory through Tuesday, Sept. 1. The Bay Area Air Quality Management District (BAAQMD) issued the advisory Monday, Aug. 31.

The district's advisory warns that Burlingame and Hillsborough residents may see hazy skies, smell smoke and breathe air that becomes unhealthy at times on Monday and Tuesday. The BAAQMD said wildfire smoke contains fine particulate matter and other harmful pollutants, and that even short exposure can be harmful.

The smoke is coming from the Timber Fire and the Plaskett Fire in Monterey County. The two blazes have collectively burned more than 40,000 acres along the Big Sur coastline as of Monday, according to Cal Fire figures reported by KRON4. The Timber Fire broke out Aug. 8 in the Los Padres National Forest and had burned 24,970 acres at 21% containment. The Plaskett Fire started Aug. 26, had burned 15,479 acres and was just 1% contained.

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

No Spare the Air Alert is in effect.

Pollution levels are not expected to exceed the national 24-hour health standard, according to the BAAQMD. The district urged residents to take precautions anyway. Older adults, children and people with respiratory conditions such as asthma, emphysema or chronic obstructive pulmonary disease (COPD) face the greatest risk. Smoke can irritate eyes and airways, trigger coughing and worsen breathing problems.

The BAAQMD recommends staying indoors with windows and doors closed when smoke is visible. Residents who must drive should set car vents to recirculate. The district also suggests visiting a library, mall or other location with filtered air if smoke reaches ground level.

Residents can check real-time conditions on the U.S. Environmental Protection Agency's Fire and Smoke Map at fire.airnow.gov. The BAAQMD can be reached at 1-800-HELP-AIR.