Think back to Christmas 2011, a time for festive music, gift giving, lighting the Christmas tree, and of course, the fireplace. There was only one problem with that -- Christmas Eve and Christmas day were both Spare the Air days, making wood burning illegal.
And yet, somehow enough people lit wood fires anyway to make them the two most polluted days of the year.
"On Christmas Day alone this year, we had levels of air pollution that were higher than when we had the Northern California wildfires in 2008," air district spokesperson Lisa Fasano said.
Fasano says the local air district found 77 homes apparently violating the burn ban Christmas weekend. Some even announced they would defy it on the district's Facebook page, calling it an outrage, and an absolute joke.
Many of those people were in west Marin, where chimneys abound, and rolling hills make for chilly nights. That's where air quality inspector Jeremy Kimball is out patrolling the streets.
"We're looking for any smoke coming out of the chimney of any residence," Kimball said.
It doesn't take long to find it. Inspectors are trained to "read" the smoke -- estimating how toxic it is by the thickness and color. They take a picture and make notes about the incident.
Documenting it sometimes goes off without a hitch, but other times don't go as smoothly.
"We have a resident with an ax in his hand standing in his driveway," Kimball said.
Personal safety has become a major concern.
"We write tickets, we document violations, so we're used to walking into situations where we don't feel particularly welcome," Kimball said.
Just how unwelcome is evident from emails the inspectors receive. Residents have called the inspectors "communists," "disciples of Hitler," "a disgrace to this country," "inconsiderate," "obnoxious" and "out of control." In one, the writer said he's "enraged" that they've "ruined every holiday..." Another told them they're going to hell.
"They think that we're, you know, we're the smoke Nazis, that we're invading their privacy," Fasano said.
But there's nothing private about what comes out of your chimney. If the wind isn't blowing, federal research suggests burning one log is like forcing each of your neighbors to smoke 30 cigarettes.
"Wood smoke contains all of the same compounds plus more, and is 12 times more carcinogenic than cigarette smoke," clean air advocate Susan Goldsborough said.
Instead of a chimney, Goldsborough's roof is home to a pair of air monitors.
"There were many days this last winter when our air was much dirtier than the Los Angeles basin," Goldsborough said.
That's because she says wood burning is a way of life in west Marin. Some do it to heat their homes, others as a cozy tradition that's not so cozy for neighbors trying to breathe on a windless night.
"When we're out enforcing this regulation, we're protecting public health," Kimball said.
If you're caught burning wood on a Spare the Air day you could face a fine of $400 or more.