The State of the Air 2013 report by the American Lung Association released last week gave the county an F grade for both ozone and particulate pollution in the three-year period from 2009-11.
The grade means that during the three-year period, the county annually averaged more than 3.3 days of unhealthy air, as determined by a five-stage index that rates air from good to hazardous for both smog and particulate pollution.
Regions that received an A grade recorded no days of air labeled unhealthy or worse.
San Joaquin County averaged 6.8 days per year with high smog levels and 11.5 days with high levels of particles in the air — making it 38 out of 277 metropolitan areas in the nation in terms of smog, and 12 of 277 when it comes to particle pollution.
Will Barrett, policy manager for the ALA’s Sacramento office, said surveys completed since 2000 show that San Joaquin County has made strides in improving its air quality.
San Joaquin County received a passing grade for the year-round average of particles in the air, making it the only county in the Central Valley to pass the measure.
Bakersfield, at the southern end of the valley, was ranked worst among the metropolitan areas in the nation for particle pollution and third-worst for smog, according to the report.
Barrett said the region “still faces some of the most daunting challenges in the nation” when it comes to cleaning its air, including agricultural activity, high traffic volume, wood-burning in the winter and a bowl-like shape that traps pollutants on warm days with little wind.
“The Central Valley is a unique place because of the geography and the climate and the growing population,” he said. “The pollutants can get trapped in the bowl of the valley and stay there for days on end.”
Those airborne particles and smog can contribute to serious health problems, according to San Joaquin County health officer Karen Furst.
Pollution is one of many contributing factors for asthma, a respiratory ailment that makes it difficult to breathe.
San Joaquin County had seven residents die from asthma in 2010, down from a 10-year peak of 15 in 2007, according to Furst.
She also said that asthma affects 20.1 percent of San Joaquin County residents 18 and older. The population of the county is 685,306, according to the 2010 U.S. Census.
“That’s significant,” she said. “And comparing (San Joaquin County) to the other Central Valley counties, our prevalence is fairly high.”
She said particulate matter in the air can also be dangerous for people with heart conditions.
“Let’s say there’s a fire and there’s lots of particles in the air,” Furst said. “They’re more likely to end up in the emergency room.”
Several steps have been taken to make people more aware of the dangers of unhealthy air, Furst said, including a color-coded air quality index published daily by the San Joaquin Valley Air Pollution Control District and a corresponding flag system at schools.
“People (can) watch these indicators … and make their decision about their activities during the day,” she said. “They need to change their activity for the day so they’re not exposing themselves.”
Barrett said a number of trends suggest that future skies will be clearer in the Central Valley, especially when it comes to the cars and trucks that contribute “the vast majority” of smog-forming pollutants.
“Much more efficient engines are going into cars,” he said. “We’re also starting to see many more hybrid options, electric plug-in vehicle options. San Joaquin Regional Transit District is putting in two all-electric buses into service this month.”
Air district spokesman Anthony Presto also said the State of the Air report fails to tell the whole story, saying businesses have invested $40 billion in air quality improvement measures since the valley air district formed in 1992.
But Barrett said more progress must be made for San Joaquin County and the rest of the valley to receive passing grades.
“In the valley we face some of the most significant hurdles to clean air,” Barrett said. “The challenges in this region are much more difficult, and speak to the need to transition to cleaner fuels and cleaner vehicles.”
• Contact Jon Mendelson at 830-4231 or firstname.lastname@example.org.