‘Unhealthy’ air plagues San Francisco during fires

With the Kincade Fire in northern Sonoma County growing to more than 74,300 acres, as well as new fires across the East Bay, San Francisco’s skies turned hazy Monday, posing a potential health risk to the region.

As of noon, the Environmental Protection Agency’s Air Now site registered air quality in San Francisco worse than usual, rating 54 (or “moderate”) on the 500-point air quality index scale. But the Air Now forecast for San Francisco predicts that the index will rise to over 150 this afternoon, a number considered “unhealthy” for anyone to breathe.

According to the agency guidelines, people with heart or lung disease, older adults, and children should “avoid prolonged or heavy exertion.”

Air quality has already declined into the “unhealthy” scale in parts of the East Bay near the site of fires in Vallejo and Lafayette, as well as in parts of Sonoma and Napa counties closer to the Kincade Fire.

The Bay Area Air Quality Management District warns that winds from the northeast are pushing smoke into San Francisco and the East Bay, and that “air quality is expected to be mostly in the unhealthy for sensitive groups (USG)” category for most of the Bay Area with higher spikes in smoke pollution possible.

The district predicts that air quality in the city will improve on Tuesday, slipping back into the USG range and then petering out to “moderate” for the rest of the week.

However, like predicting the weather, forecasted air quality isn’t exact. Bay Area residents should prepare for conditions to possibly worsen.

“Small particles and toxic chemicals from wood smoke can cause serious health problems,” the district guidelines warn. When wood smoke mixes with vapors created by burning insulation, paint, and other chemical compositions of homes and businesses set ablaze, the results are grim.

Ventilation masks rated N95 or above can help protect from the effects of smoke inhalation. However, the Food and Drug Administration advises that, while such respirators block “at least 95 percent of very small test particles,” even a properly fitted mask won’t completely block out contaminants.

The best protection against unhealthy air is to remain indoors and avoid physical exertion as much as possible.