Reduced wood burning is partially responsible for the Bay Area having one of its cleanest air quality seasons for smoke and other air-borne fine particles, a regional pollution agency reported Wednesday.
Soot concentrations in the nine Bay Area counties violated the federal public health standard on just one day during the Spare the Air season that ran from Nov. 1 to Feb. 28.
That ties the 2010-11 season as the record low during the 13 years the Bay Area Air Quality Management District has tracked fine particle pollution -- thinner than a human hair and able to lodge deep in human lungs.
The federal government sets a fine particle health standard because the pollution can trigger asthma and emphysema attacks and lead to heart attacks in the sick and elderly.
Bay Area regulators attributed the improved air quality at least in part to the effectiveness of a controversial five-year-old rule that outlaws wood fires on declared Spare the Air days.
"Thanks to reductions in wood burning as a result of our Spare the Air program, we had just one violation in the federal health standard this winter," said Jack Broadbent, executive officer of the district. "Wood smoke has continued to decrease in the region, but it still poses a formidable public health threat to our neighborhoods and communities."
Weather is a big variable in soot levels from year to year. Cold stagnant air can trap smoke near the ground, while wind and rain often sweeps away pollution.
January this year had many nights with cold air, conducive to trapping smoke, and yet the district had only one day violating the health standard, said Kristine Roselius, a spokeswoman for the nine-county air district.
The district this season issued 10 Spare the Air alerts banning fires, 15 alerts in the season before and four in the 2010-11 season.
The district cited 178 burn violators this season, less than the 234 violation average for the past five seasons, and far less than 359 violations two seasons ago.
The pollution agency was tougher on first-time offenders this season. Instead of getting warnings with no penalties, as in the past, first-time offenders were required to take and pass a smoke education class online or pay a $100 fine. Second-time offenders are fined $500.
Roselius said it's hard to say if the tougher penalties deterred burn violations.
She said violations were down in part to media and public attention to the many chilly January nights that produced a string of Spare the Air alerts.
"We had several alerts in a row," Roselius said. "There was a lot of public awareness about the Spare the Air program."
Sonoma County topped the Bay Area with 45 violators for the season, followed by Marin with 32, Santa Clara with 23, San Mateo with 22 and Contra Costa with 21.
The public made 2,316 complaint calls this season about illegal burners.
Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.