It’s getting cold, and that means wood smoke is in the air
Wood smoke can be the product of doing business (burning agricultural waste) or just living (using a fireplace). Either way, it’s not good for people’s lungs, and that’s always a concern for Jason Mandly as he works against local air pollution.
“You want to make sure people have a healthy place to live and breathe,” he said.
Mandly is an associate planner for the Butte County Air Quality Management District, a local regulatory agency mandated to protect public health. As of Nov. 1, the district’s Check Before You Light program is in effect. It asks people to voluntarily refrain from using wood stoves on days when the levels of fine particulate matter—the stuff that reduces visibility and makes the air appear hazy—exceed standards outlined by the U.S. Environmental Protection Agency.
On advisory days, the county encourages people to reduce their exposure by avoiding heavy outdoor exercise. Residents should also mind their neighbors when there’s a lot of smoke in the air, said Bob McLaughlin, the county’s assistant air pollution control officer.
“People can choose not to burn,” he said, “or change their burning practices to reduce emissions and contributions to ambient levels of [fine particulate matter].”
When the air quality index (AQI) exceeds 100, the air is considered unhealthy for sensitive groups—people with respiratory conditions, children and the elderly. An AQI value under 50 represents good air quality with little potential to affect health, while an AQI value over 300 represents hazardous air quality, according to the EPA.
“These are particles that are so small, they can get past your body’s natural defenses and penetrate deep into the lungs,” Mandly said.
It’s a problem mostly in the wintertime, and residential chimney smoke is the main culprit. Pollution peaks in the evening hours as it gets cold and people light up their wood stoves; it tends to be worst in town when it’s cold and windless, McLaughlin said.
“It happens when there’s very little air movement,” he said. “Agricultural burning doesn’t significantly contribute because that’s typically located away from town.”
The district maintains permanent air quality monitors in Chico, Gridley and Paradise and just started using portable ones to track pollution in other areas. “We didn’t have enough data from Oroville until recently,” McLaughlin said.
As Chico’s population is the largest in the county, it’s the most polluted by woodsmoke, Mandly said. Within city limits, however, those voluntary Check Before You Light rules are mandated by municipal ordinance. There are certain exemptions for low-income families and people whose only source of heat are wood stoves.
In the summer, unless there’s a wildfire nearby, wood smoke is less of an issue, Mandly said. Ozone pollution from vehicles becomes more of a concern, especially for higher-elevation communities on the Ridge, because it rises with heat.
“Paradise tends to have higher ozone levels than Chico,” he said. “That’s a phenomenon that’s pretty consistent throughout California—the foothills tend to have higher ozone values than the valley floor because the heat kind of lifts it up.”
Butte County started posting health advisories on wood smoke in 2006. Over the last decade, the Air Quality Management District has recorded an encouraging downward trend in levels of fine particulate matter. Last winter, for the first time, Butte County didn’t exceed federal standards on a single day and the district didn’t issue any advisories for wood smoke. The especially rainy El Niño season played a role, Mandly said.
“The months of December and January usually are the peak time of year, when we have those still, cold nights,” he said. “But last year, we had storms all throughout those months.”
Another factor may be the district’s popular wood stove replacement program, through which residents traded in old, inefficient wood stoves for new ones. From 2013 to 2015, the program partially paid for 450 clean-burning, EPA-certified wood, gas or pellet stoves, but it ran out of funding last year. The county currently is exploring grants to resume it.
“If you operate one of the new stoves correctly, you shouldn’t see any smoke come out of the top,” Mandly said.
Check Before You Light also has worked in terms of reducing emissions, specifically on advisory days. When the county calls an advisory, residents cut back on burning enough to reduce emissions of fine particulate matter by an average of about 23 percent, Mandly said.
“We have to express our appreciation to the public for stepping up to the plate and doing what they can to protect air quality and to be good neighbors,” McLaughlin.
The advisory program will remain in effect until Feb. 28. That’s around when the district usually sees an improvement in local air quality. “Some people just use their wood stoves for holiday ambiance,” Mandly said.