The Bay Area Air Quality Management District, also known as the Spare the Air folks, are asking Bay Area residents, the ones with fireplaces anyway, to please refrain from burning wood today, Tuesday December 6th. We know it's cold and all, but the breezeless chill means wood smoke stays near the ground and every time you spark up a yule log, you're basically making all your neighbors walk through a forest fire. That's how pollution works.
It's not an official Spare the Air day — just a nice suggestion from the BAAQMD. So you're technically free to do whatever you want, but if the pollution levels increase they'll call a real Spare the Air day and then we will all be stuck watching the Yule Log HD On Demand on Christmas.