Valley gripped by terrible air pollution. Will storms bring relief this weekend?

Air quality officials hope a change in the weather pattern in the coming days brings relief from the unhealthy air in the San Joaquin Valley.

Stanislaus and Merced counties had unhealthy air readings Wednesday due to high levels of tiny particles, according to the San Joaquin Valley Air Pollution Control District’s real-time monitoring. Fresno, Kern and other counties in the valley’s southern region have been socked in by some of the worst pollution in five years.

To emphasize a point, a Twitter post noted the haze in Fresno was three times worse than Beijing’s pollution.

Jaime Holt, communications director for the air district, said not much improvement was expected from the light storm Wednesday in the northern counties. But a larger system Saturday and Sunday could break an inversion layer that has trapped pollutants in the valley air basin for weeks.

Air conditions considered unhealthy for sensitive groups are predicted Thursday in Modesto, Merced and south to Fresno. No residential wood-burning is allowed except for registered clean-burning devices.

“We need a change in the weather pattern – rain, wind and a low-pressure system coming in,” Holt said. “That will allow particles to move higher in the atmosphere so they are pushed out of the valley.”

Holt said a high-pressure system that’s kept the valley mostly dry since November has put a lid on the region. Pollutants from tailpipes, firewood, New Year’s fireworks and other sources have built up in the stagnant air, as the inversion layer has dropped as low as 1,500 feet above ground.

Most of California has remained relatively warm and dry, while below-freezing temperatures have dominated the rest of the nation.

People with health issues and respiratory problems are advised to take it easy until the San Joaquin Valley air improves. The valley district has daily postings on air quality conditions.

Holt questioned the fairness of comparing the valley conditions to the notorious smog in Beijing, which happened to have moderate air quality this week. “It might have rained in Beijing,” Holt said. “Without a doubt, Beijing has worse air quality than we do.”

This story was originally published January 3, 2018 at 6:21 PM with the headline "Valley gripped by terrible air pollution. Will storms bring relief this weekend?."