With cold temperatures and little wind, air quality officials declared Tuesday a Spare the Air day, banning wood and other fires.
First-time offenders who light fires despite the ban will receive tickets instead of warning letters for the first time since 2008 when the Bay Area Air Quality Management District began Spare the Air days to limit air pollution.
"We think enough people should know they shouldn't burn wood on Spare the Air days," district spokesman Aaron Richardson said.
The district, which includes the swath of Sonoma County roughly south of Windsor, issued 346 warning letters last year, he said.
Tuesday's ban, the third this year, was brought on by stagnant weather conditions that often trap air pollution, such as wood smoke, close to the ground, Richardson said.
Residents in the district are prohibited from burning wood, manufactured fire logs or any other solid fuel in fireplaces, woodstoves, outdoor fire pits or other wood-burning devices.
Homes where woodstoves or fireplaces are the only source of heat are exempt.