SAN FRANCISCO (KRON) — Smoke seen and smelled in San Francisco and around the Bay Area Thursday afternoon is related to a prescribed burn taking place in the North Bay, according to the Bay Area Air Quality Management District.

“Smoke from a prescribed burn near San Rafael is impacting Marin County and SF,” the BAAQMD posted. “A temperature inversion is also trapping pollutants from sources like wood burning and vehicle pollution near the ground. If you smell smoke, avoid exposure.”

Firefighters are undertaking wildfire prevention work at China Camp State Park in San Rafael Thursday, according to the San Rafael Fire Department. Thursday’s burn is the second of two prescribed fires and was scheduled for between 9 a.m. and 4 p.m.

“Neighborhoods surrounding China Camp State Park may see and smell smoke,” SRFD said in a tweet.

The Central Marin Fire District also addressed the smoke in the air, putting out a post that advised, “The smoke in Marin County is drift smoke from the China Camp prescribed burn.”

There were no other major fires reported Thursday afternoon in the immediate area. Prescribed burns in Marin County are scheduled to continue Friday.