As temperatures begin to drop and the winter season approaches, the South Coast Air Quality Management District this week issued its first-ever mandatory "no burn alerts" prohibiting residents in some areas from lighting up their wood-burning fireplaces.

In an effort to reduce harmful pollutants that become trapped during particular weather conditions, the Diamond Bar-based smog control agency began implementing the mandatory program on Nov. 1 for the second consecutive year. It will run through February.

The AQMD on Sunday issued a one-day restriction for fireplace use for the downtown Los Angeles area, West Hollywood, Burbank and most of the eastern San Fernando Valley.

On Monday, residents of Riverside, Mira Loma and other nearby communities faced a $50 fine for burning wood or artificial logs both inside or outdoors through midnight early Tuesday morning. To avoid a citation for first-time offenses, residents can participate in wood smoke awareness courses.

"We typically have a no-burn alert when we have a low atmospheric inversion," said Sam Atwood, AQMD spokesman. "This acts as a cap and it traps pollutants close to the ground that allows the concentration to go to unhealthy levels."

Along with pollutants, that inversion layer also traps fog, he said.

"If people are seeing dense fog that lasts for several hours, that's probably a sign that there's an inversion layer," he said.

Atwood didn't expect that the agency would issue any alerts on Tuesday due to a low-pressure system that will lift the inversion and improve air quality, he said.

Low atmospheric inversion traps fine particulate matter known as PM2.5, which is produced from motor vehicles, power plants, wood-burning and other sources.

The tiny particles can lodge deep in the lungs, enter the blood stream and into other vital organs, said Elizabeth Jonasson, campaign and outreach associate for the Coalition for Clean Air.

It can trigger asthma in those sensitive to the pollutants and other complications for people with cardiovascular issues, Jonasson said.

"Longer term, particularly for people living in air basins that are already quite contaminated, like the Los Angeles air basin and the Valley, you're already exposed to terrible air quality on a constant basis and this is just an added layer of bad air that we're breathing," she said in reference to wood-burning.

The pollutants have an impact for not only those outdoors, but for those actually using the fireplaces indoors, where concentrations can be even higher, Jonasson said.

According to the California Air Resources Board, pollution from all sources in Southern California could lead to roughly 5,000 premature deaths annually.

To curb exposure to the particulate matter, the AQMD issues no-burn alerts when concentration levels reach harmful levels, according to the agency.

The agency expects to issue 15 to 20 alerts during the winter months. Residents are encouraged call to 1-800-CUT-SMOG to report suspected violations.

A second offense will result in a $150 fine, or residents can choose to install a permanent gas-fueled fireplace. A third offense could lead to a $500 penalty, or the resident can fund a project to help the environment, according to the AQMD.

Residents can check for local no-burn alerts by entering their zip codes at www.aqmd.gov/noburn. To sign up to receive no-burn alerts, go to http://aqmd.enviroflash.info.

maritza.velazquez@sgvn.com

626-544-0817