Most of Yolo County does not meet the U.S. Environmental Protection Agency’s national ambient air quality standards, the agency announced in December.
The designation refers particularly to high levels of fine particulate matter, which many studies have linked to significant health problems and early death.
The area the EPA has designated as not meeting the standards now stretches roughly from the northern-most tip of the San Joaquin Valley down to Orange and Riverside Counties.
When the EPA made its final announcement, county officials were “caught off guard,” said executive director of the Yolo-Solano Air Quality Management District Mat Ehrhardt. Officials responded with a letter expressing their disagreement with the EPA’s decision.
The federal standard for particulates in the air is 35 micrograms per cubic meter. The average for Sacramento County was 49 and Yolo County was 30.
Air quality data from the Woodland monitoring station indicated that the county was in compliance with standards, but the EPA reasoned that mobile sources of pollution, such as cars used to commute between Yolo County and Sacramento, add to Sacramento’s already poor air quality, Ehrhardt said.
The Sacramento region in particular has historically been one of the worst air quality areas.
“We have some built-in disadvantages,” said Bill Mueller, manager of the Cleaner Air Partnership of Sacramento.
Cars from commuters and traffic on Interstates 5 and 80 account for 80 percent of the region’s pollution. Other major factors include a large railroad network, wood burning during the winter and frequent wildfires during warmer months.
The Sacramento Valley also faces other unique challenges, said Anthony Wexler, director of the UC Davis Air Quality Research Center.
Because of the large mountains surrounding the valley, the air and pollution get trapped on the valley floor.
“That kind of just makes it more stagnant. It just builds up and builds up and builds up,” Wexler said.
Wexler said the scientific community is beginning to understand how much of a health risk having poor air quality is.
Various studies have linked higher concentrations of particulate matter to heart attacks, increased asthma symptoms and under-developed lungs in children.
But Mueller said there is hope for Greater Sacramento.
“Over the last decade things have improved,” he said. “Because cars are continually getting newer and more fuel efficient … the air quality is improving.“
Mueller said area governments have also added stricter requirements for businesses, and devised a “blueprint” for future land use, a process that involved governments from all over the region and as many 5,000 citizens.
“[The blueprint] was a new sort of outlook on how we ought to grow,” Mueller said.
Programs aimed at cleaner air are already in place. The county has an incentive program for people willing to replace their older, heavily polluting wood burning stoves with newer EPA-certified models, and the city of Davis is working on restricting wood burning to days with good air quality forecasts.
Now that Yolo County has been designated a non-attainment area, county government will have to come up with a plan demonstrating how they will meet the standards by April of 2012, and will be required to implement that plan and attain clean air by 2014.
JON GJERDE can be reached at firstname.lastname@example.org.