The 10th season of an important wintertime pollution-reduction program began Nov. 1.

Because of Valley residents' ongoing efforts and understanding of the importance of changing long-ingrained habits in ways that reduce emissions, Check Before You Burn has resulted in historically clean wintertime air quality in the Valley over the past several years. The wood-burning curtailment program is critical in minimizing levels of harmful particulate matter (PM) in the eight-county air basin.

"Thanks to the public's support and cooperation, this rule is the single most-effective, lowest-cost regulation on record in the Valley," said Seyed Sadredin, the district's executive director and air pollution control officer. "It is absolutely imperative to improve air quality."

Each day, the district issues a wood-burning forecast by county for one of two levels: "Wood-burning prohibited" or "Please Burn Cleanly."

When wood burning is prohibited, all residential wood burning -- including fireplaces, wood-burning inserts and heaters, pellet stoves and outdoor devices such as fire pits -- is prohibited. When the forecast is "Please Burn Cleanly," the district encourages residents to use manufactured fire logs or dry, seasoned wood. Gas fireplace use is always allowed.

Residential wood burning is the single largest source of harmful particulate matter during winter and can pump 17 tons of it into Valley skies daily. Fine-particulate matter (PM2.5) exacerbates respiratory illness, such as asthma; causes lung infections and bronchitis; and has been correlated with increased risk of heart attacks and stroke.

There are two exceptions to wood-burning prohibitions:

If the residence does not have access to natural-gas service, even if propane is used; or If burning solid fuel is the sole source of heat for the residence.

Violators of the program are subject to fines.

Daily wood-burning forecasts are available each day at 4:30 p.m. at valleyair.org/aqinfo/WoodBurnPage.htm, or by calling 1-800 Smog Info (766-4463), or by subscribing to the district's daily air quality forecast at valleyair.org/lists/list.htm.

Details: (559) 230-6000, valleyair.org.