The number of burn prohibitions in Stanislaus County almost doubled this past season as the abnormally dry winter kept air pollution levels high.

The San Joaquin Valley Air Pollution Control District reported a dramatic increase in wood-burning curtailments this season as part of the annual Check Before You Burn program, which closed its eleventh year Friday. Check Before You Burn requires wood-burning curtailments on days when levels of fine-particulate matter (PM2.5) are forecast to exceed the federal health standard. Wood-burning forecasts are issued daily for each county.

During the season, which began Nov. 1, 2013, the incidence of wood-burning curtailments throughout the eight-county air basin was up 102 percent over last winter. In the Valley, a total of 376 curtailments were declared among all counties, versus 186 during the 2012-13 season. Violations issued for noncompliance with curtailments were also up, from a total of 384 in 2012-13 to 569 this season.

Stanislaus County had 53 burn prohibitions issued this season, compared to 28 in the 2012-13 season. The air district issued 130 violations this season in Stanislaus County, compared to 69 last season.

The increase in wood-burning curtailments was the same for most of California because of a high pressure system that settled over the state and trapped particulate matter at the ground level.

“This was an unusual winter not only for the Valley but for the entire state,” said Jaime Holt, the Air District’s chief communications officer. “Without these extreme conditions, this winter would have been the cleanest on record for the Valley. Despite our experience this winter, it’s important for people to remember that overall we have experienced significant, long-term improvement in winter air quality, thanks to Valley residents embracing Check Before You Burn and refraining from wood burning.”

PM2.5 is a particularly harmful type of air pollution that is linked to chronic lung disease, respiratory illness, heart attacks and premature death. Check Before You Burn minimizes the build-up of particulates. The District issues wood-burning forecasts by county beginning at midnight for the following 24 hours. Forecasts are derived from analyzing multiple factors, including meteorology, expected emissions and other variables. Despite a decrease in emissions that cause PM2.5 to form, meteorological conditions including record low rainfall, stubborn stagnant inversions and abnormally high temperatures overwhelmed strong air pollution control measures and produced large increases in PM concentrations, Holt said.

The air district is revamping their wood-burning curtailment guidelines that will result in more prohibitions being issued. The air district says the stricter guidelines are necessary to stay within reach of the federal guidelines for healthy air. The restructuring is currently being discussed in a series of workshops and public forums.