Valley air quality reached new heights in 2019

2019-20 winter had lowest particulate matter levels since 1999 and 2019 summer had lowest ozone levels since 1990

By Reggie Ellis

FRESNO – The amount of COVID-19 in the air may be on the rise, but otherwise the San Joaquin Valley’s air hasn’t been this clean in more than two decades.

At its March 19 meeting, the San Joaquin Valley Air Pollution Control District (Air District) said the valley had a record year for clean air days in 2019. Over the last winter, November 2019 through February 2020, the Air District reported the greatest number of “good” and “moderate” air quality days, the lowest number of “unhealthy for sensitive groups” air quality days, and zero “unhealthy” or worse air quality days for particulate matter (PM 2.5), primarily comprised of tiny particles released into the air from burning wood and vehicle and stationary emissions. Those are the best air quality numbers since the Air District began tracking PM 2.5 in 1999.

The Valley also recorded a record low number of days when the federal standard of 35 µg/m3, or micrograms of pollutant per cubic meter, was exceeded for a 24-hour period. In fact, the month of February recorded zero days exceeding the standard, a first for the Valley.

Tulare County Supervisor Kuyler Crocker, who represents Tulare County on the Air District board, said the numbers were promising as this was one of driest winters since 1999, usually an indication of worse air quality.

“This proves the incentives are working,” Crocker said. “People are voluntarily improving tractors and limiting their burning. I’m hoping it will be even better now that we’ve had some storms.”

The Valley’s bowl-shaped geography traps PM 2.5 in the air, which builds up quickly at the ground level and hangs there until rain can wash it out. Particulate matter can have adverse effects on public health, aggravating heart and lung diseases such as asthma, emphysema and chronic bronchitis.

John Klassen, director of air quality and science planning for the Air District, said the numbers are a strong indicator that air quality is improving in the valley. Part of the credit goes to the Air District’s Check Before You Burn campaign. Feb. 29 marked the end of the Valley’s 17th Check Before You Burn season which ended as the cleanest on record despite record-breaking high winds at the beginning of the season. The number of days that exceeded PM2.5 levels were 15 for the winter months, compared with peak of 81 days during the 2001-2002 winter. Even more impressive is that the Valley’s air quality improved during a dry winter with far less than average rainfall. The Valley averaged less than half an inch of rain this winter, compared with an average of almost 4 inches since 2000.

Throughout the season, increased cooperation by Valley residents and the use of much cleaner wood, pellet & natural gas devices, made possible by the District’s Burn Cleaner Program, all played pivotal roles in the vast improvement to wintertime air quality this season.

“Once again, the District thanks residents, businesses, the ag industry and all other Valley stakeholders for helping to achieve our cleanest winter on record,” said Valley Air District Executive Director and Air Pollution Control Officer Samir Sheikh.


In June 2019, the Air District adopted the most restrictive residential wood burning strategy in the nation by lowering the thresholds in three counties with the biggest air pollution challenges: Madera, Fresno and Kern. Under its amendments to Rule 4901, the District issued a daily wood-burning declaration, based on the air quality forecast for each county with one of three specific designations: “No Burning for All,” “No Burning Unless Registered,” or “Burning Discouraged.”

Overall, the District’s residential wood burning strategy has significantly reduced emissions through a combination of regulatory curtailments, strong public education, and voluntary incentives for Valley residents. While state regulations prohibit the installation of wood burning fire places in new homes in nonattainment areas and push for more efficient vehicles, the Air District’s Burn Cleaner Program has funded the replacement of thousands of high polluting wood burning devices with cleaner burning devices, the majority of devices being replaced with natural gas devices.

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