San Joaquin Valley residents suffering with chronic breathing conditions should stay indoors this week, health officials said Monday.
“Keep doors and windows shut and don’t let in outside air,” Dr. Mohan Reddy said.
A mix of lingering wildfire smoke, harvest season particulates and increasing ozone pollution, commonly known as smog, caused the San Joaquin Valley Air Pollution Control District to issue an air alert throughout the valley Monday.
The district’s primary concern Monday was the smog, according to Anthony Presto, a district spokesman.
Presto described smog as a corrosive gas that damages lung tissue and said the recent increasing levels triggered Monday’s alert.
According to the U.S. Environmental Protection Agency, smog forms when emissions from vehicles, industrial facilities, electric utilities and gasoline vapors combine and bake in hot weather.
Smog typically reaches unhealthy levels during the summer, when the weather heats up and air flow stagnates, Presto said.
“We’re seeing our biggest surge taking place now because school has started again and there’s an increase in traffic,” Presto said.
Officials took precautions Monday at John C. Fremont Charter School in Merced.
“We had a list of students with respiratory issues and they were let into the air-conditioned library,” said Curt DuBois, the school’s learning director. “We had some students in there, but no major respiratory issues so far that I’m aware of.”
Pollution experts said residents should avoid vehicle idling, carpool with friends and family, use alternative transportation and avoid drive-through services.
“Turn off your engine when picking up or dropping off kids at school, and park and go into the business instead of using the drive-through,” Presto said.
The air alert remains in effect through Wednesday.
Smog is not the only air-quality concern in the Valley this week.
Lingering wildfire smoke from the Rim fire along with fires burning on Mount Diablo and in Tulare County will likely affect breathing in Merced for several days at least, city Fire Chief Mike McLaughlin said.
Although smog levels typically peak during the day and fall at night, smoke from fire does exactly the opposite, authorities said.
“It’s kind of a double-whammy,” Reddy said. “There’s also a lot of harvesting going on, which also has an effect.”
Reddy has specialized in asthma treatment in Merced since 1978.
He said respiratory conditions in the Valley seem less severe this year.
“But we’ll probably have to wait until sometime in October for the air to really clear up,” Reddy said.
Historically, the San Joaquin Valley consistently contends with Los Angeles for the worst air quality in the nation, pollution experts said.
“It’s not a title we enjoy holding,” Presto said.
Los Angeles produces far more pollution than the San Joaquin Valley, but regional winds also circulate more, cleaning out its air basin, he said.
Presto said Valley air conditions have improved steadily since the 1990s when industrial and vehicle emission standards increased.
“We enjoy much better air quality now,” Presto said, “but we still need residents to do everything they can to reduce emissions.”
Staff writer Rob Parsons can be reached at rparsons@ mercedsunstar.com or (209) 385-2482.