Air quality worsened Monday as a thin haze of pollution crept over Bay Area skies.
Cities around the region recorded moderate levels of air pollution just after dawn, with conditions reaching levels unhealthy for sensitive groups. Those with respiratory illnesses are being encouraged to limit prolonged outdoor exertion.
Vallejo recorded the poorest air quality in the region as conditions there inched closer to unhealthy air quality levels. Berkeley, East Oakland and San Jose also saw declines after a stretch of clear skies.
But Monday’s slight smog is not a major cause for concern, air quality officials said.
The rise in smoke and other particulates is likely due to local residential wood burning, not fumes from wildfires smoldering in the Sierra Mountains, said Erin DeMerritt, a spokeswoman for the Bay Area Air Quality Management District.
Getting ?’s RE: smoke in #BayArea Here’s the latest #smoke model. Wildfires are still burning in the Sierra w/ winds aloft push it toward SF, but it is light. Onshore returns tonight and remains light.
Got questions on Air Quality, see https://t.co/A0HwR4zjMj @AirDistrict#CAwx pic.twitter.com/6EBTejOqyk
— NWS Bay Area (@NWSBayArea) November 2, 2020
“It’s not uncommon to see elevated particulate matter readings this time of year,” said DeMerritt, who added that smoke particles tend to build up in the air on cooler nights before the winter rains arrive.
Smoke from the Creek Fire and other active wildfires in the Sierras remained aloft in the atmosphere above the Bay Area and is not expected to have a significant impact air quality throughout the region, National Weather Service meteorologists said.
Rain — the kind that can wash smoke and other pollutants out of the air — is not expected within the coming week.
NWS models showed a small chance of rain for Sonoma, Napa and Marin counties beginning on Friday and Saturday, but even that hopeful sign appeared to evaporate Monday, meteorologists said.
Nora Mishanec is a San Francisco Chronicle staff writer. Email: nora.mishanec@sfchronicle.com