What is behind the record number of wood-burning bans?

For local firewood seller Glenn Kantock, the goal of the Bay Area no-burn rule is obvious — to put an end, once and for all, to wood burning.

This year, he said, the Spare the Air effort has a powerful conspirator and, no, it's not PG&E.

"It just so happens that nature is cooperating with them," said Kantock, the owner of All Seasons Firewood in Santa Rosa.

"This year, at the time that people need to use the wood the most, they can't use it or are afraid to use it," Kantock said.

Less than halfway into the Bay Area Air Quality Management District's four-month Winter Spare the Air season, the number of 24-hour wood-burning bans is off the charts, though district officials would not say whether wood-burning violations were up over last year.

Saturday's no-burn alert marks the 21st, compared to the previous record of 15 during the entire 2011-2012 season. Also, there thus far have been 10 days that the Bay Area's air quality has exceeded federal safety levels, compared to 13 for the entire 2008-2009 season, which was the first Spare the Air season.

When a Spare the Air day is called, it's illegal for Bay Area residents and businesses to use fireplaces, wood stoves, pellet stoves, outdoor fire pits or any other wood-burning devices.

Kantock said the record number of no-burn alerts has caused a great deal of frustration among his customers, as well as some of his employees.

"What's lacking is a clear explanation or definition of why we need Spare the Air days," he said, adding that some feel there's "no compassion" toward those who rely on wood heat even though the no-burn rule does exempt those who rely on wood burning as their only source of heat.

Business has been slow this season, Kantock said.

On Friday, David Goins of Healdsburg filled his trailer with a a half-cord, or 64 cubic feet, of firewood from Kantock's stock. Firewood is the only source of heat in Goins' Chalk Hill Road farmhouse, which sits just north of the air quality district's northern boundary, just above Windsor.

This is the domain of the Northern Sonoma County Air Pollution Control District, which does not prohibit the use of wood-burning stoves and fireplaces.

The Winter Spare the Air season, which lasts from Nov. 1 to Feb. 28, is an effort to reduce air pollution during winter months. Alerts often are called when there is a high-pressure system sitting over much of the Bay Area, which creates a temperature inversion that forms an atmospheric layer and traps pollutants.

During Christmas week, the Bay Area's air quality exceeded federal health standards three time — on Sunday, Monday and Christmas Day.

Ralph Borrman, an air quality district spokesman, said district officials weigh a number of factors when calling a no-burn alert. These include weather conditions, the persistence of the inversion layer and the level of particulate matter, or PM, that's in the atmosphere.

Saturday's alert marks the sixth consecutive alert. Earlier in December, during a dry cold snap, there was a run of 11 consecutive 24-hour alerts.

"We really haven't had rain ... that speaks to the general weather pattern," Borrman said. "It's not only impacting the Bay Area but also Central California. We have never really experienced something longer than four days at a time. It is an unusual winter weather pattern this year."

The health effects of wood smoke in the Bay Area during such weather conditions are real, said Dr. Al Haas, chief of Kaiser Permanente's allergy department in Santa Rosa.

"We have a million reasons for wanting the rain," said Haas. "We're just seeing unusually challenging conditions. One of the ways we have of dealing with it is calling Spare the Air days. Without it, it would be a lot worse."

Haas said that during days when there's a high concentration of particulate matter in the atmosphere, the emergency department usually sees more patients with acute asthma. He said there's also evidence of "increased mortality" among patients who are 65 and older.

Wood smoke produces particles of different sizes, Haas said. Larger particles end up in people's eyes and nasal passages, while smaller particles get down into the bronchial tubes and even further down into lung tissue known as alveoli, little sacs where gas exchange takes place, he said.

Lodged in our bronchial tubes or alveoli, the particles can interfere with our ability to breathe and inflame the respiratory tract.

Over time, the particles can exacerbate asthma symptoms, Haas said, adding that there seems to be a cumulative effect, where a number of consecutive days of exposure can worsen the impact on a person's health.

"It's worse than if you just have a day or two," he said.

Of the nine counties in the Bay Area air district, the skies over Sonoma County are among the most heavily polluted during winter.

Last year, the air district issued 45 Spare the Air violations from 272 complaints lodged by local residents. While other counties saw more complaints — 467 in Marin, 459 in San Mateo, 371 in Contra Costa — they had far fewer verified violations.

Those who violate the rule will be given the option of taking a wood-smoke awareness class, online or by mail, or paying a $100 fine.

"Repeat violators who continue to burn in violation of the alert face increasing penalties, $500 or more depending on the circumstances," Borrman said.

Often, a high number of public complaints in a certain area or neighborhood will trigger an inspection. Inspectors will patrol the area looking for actual wood-burning violations. Inspectors don't usually visit the sites of complaints, because the district doesn't have enough resources to visit the site of every complaint lodged.

"We focus our patrols where there have been a certain number of complaints," he said.

Karen Holbrook, Sonoma County's interim public health officer, said people with pre-existing lung disease and heart disease, children and older adults are the most likely to be affected by particle pollution.

"However, even healthy people may experience temporary symptoms from exposure to particle pollution," she said, including irritation of the airways, coughing or difficulty breathing.

Additional possible effects of particle pollution include adverse birth outcomes such as low birth weights, decreased lung growth in children, lung cancer and early deaths.

Holbrook said that when particle pollution is high, people should reduce the amount of time spent outside and engage in easier outdoor activities, such as walking instead of running.

Haas recommended those who suffer from respiratory ailments spend time on the coast, where there's "a little more wind and it's cleaner."