For nearly two weeks, there’s been no yule log and no chestnuts roasting on an open fire. Though the weather outside is frightful, the Bay Area Air Quality Management District banned wood-burning fires for 11 consecutive days, an unprecedented streak that surpassed the total number of days all last year.

Winter Spare the Air alerts can be issued from November through February when weather patterns that usually disperse unhealthy matter remain stagnant and keep dangerously high levels of air pollution close to the surface. Weak winds and a Tuesday morning fire at a Redwood City scrapyard only added to the dirty air.

The district initiated the ban on wood fires in 2008, following research that wood smoke, like cigarette smoke, contains fine particles that can trigger respiratory problems like asthma and bronchitis, said Ralph Borrmann, the district’s public information officer.

“People have been burning wood for thousands of years. What’s the big issue?” he said. “Look around and see what’s happening overseas. Urban China is engulfed in smog for long periods past winter.”

The ban has had a noticeable effect in the San Geronimo Valley. Usually in these weather conditions, evening fires will produce a thick haze. Usually, “it looks like L.A.,” Robin Carpenter, a Lagunitas resident, said of the smog. But since this year’s alerts were issued, smoke can be seen puffing from only a few chimneys.

The compliance may be due in part to last year’s strict enforcement. The district received 467 complaints about those flaunting regulations, making up more than one-fifth of the total calls across the Bay Area, even though Marin’s population makes up only a small portion of the region’s 7.15 million residents, Mr. Borrmann said. A total of 32 violations were issued in the county last year.

First-time violators can either pay a $100 fine or take a wood smoke awareness class online or by mail. Repeat violators are fined $500 or more. The district does make exceptions for homes without an alternative heating system.

While the air in the valley may look clearer, it certainly feels colder, residents say. Ms. Carpenter has a small propane heater, so she can’t technically fire up the primary heat source, her wood stove. Instead, she and her husband have been carrying a portable heater from room to room.

“We’re really worried about the electric bill,” she said, clearing her throat from what sounded like an oncoming cold.

The couple’s home sits in a wooded area that doesn’t get much sunlight in winter, and as renters, they don’t have the option to update the heating system. So, she has been piling on layers and layers of clothes: wool jackets, wool socks, long johns and caps.

“If folks had to run out of the house in the middle of the night, I’m sure it would be an interesting sight to see what fashion is on parade,” she said, before adding, “The cap thing is very helpful.”

But there may be an early Christmas gift ahead: officials said northwest winds mean the ban would likely be lifted today. Listen to that fireplace roar.