Smoggy Days Are Here Again, Experts Say : Environment: May inaugurates the eye-watering season. But the county’s air quality has improved over the last 15 years.

Tune up those air conditioners and slam the windows shut. Keep your eyes peeled for dirty brown skies. Get ready to hunker down indoors.

Smog season is back.

Ventura County air-quality experts on Thursday issued their annual warning: From now through October, expect occasional days of throat-burning, eye-watering pollution.

True, the county’s air quality has steadily improved over the last 15 years. And last year was the cleanest on record, with only 10 unhealthful days in which pollution exceeded federal health standards.

But no one can predict how 1993 will turn out.

Smog watchers attribute the cleaner air--especially noticeable during the past five years--to a mix of stringent antipollution laws and cooler, windier weather.

“When you look at the long-term trend, you have to say it’s associated with emission reductions designed to clean our air,” said Richard Baldwin, director of the Ventura County Air Pollution Control District. “But when you look at a single year, you can’t know how much is due to our regulations and how much is due to the weather.”

So if weather patterns change, dumping hot, stagnant stretches on Ventura County, the number of unbearably smoggy afternoons could easily double this year, Baldwin said.

That’s something most Southern Californians seem to expect.

“In the summer, the air gets a little more substance to it,” said Simi Valley Mayor Greg Stratton, whose city gets treated to a double dose of smog as it creeps out of the Oxnard plains and spills over from the San Fernando Valley.

Simi Valley has the worst smog record in the county, as the predominant breezes off the ocean force air pollution to pool in inland areas. The Conejo, Santa Clara and Ojai valleys also collect more than their share of dirty air.

“As someone once said, you can’t trust air you can’t see,” Stratton added philosophically.

Actually, though, the thick brown smudges and hazy gray patches that seem as much a part of summer as watermelon are not officially considered smog. True smog comes from ozone, a colorless gas formed when nitrogen oxides and hydrocarbons react together in heat and sunlight.

Cars top the list of ozone-creating villains, emitting more than half the nitrogen oxides and almost 40% of the hydrocarbons that hover over the county. The petroleum industry, power plants and pesticides together contribute 43 tons of pollutants a day, according to the pollution control district.

Even household chores, like cleaning with organic solvents or painting with hydrocarbon-based varnishes, release substantial amounts of smog-creating compounds into the atmosphere. And finally, nature itself stimulates smog--both pine trees and lightning release ozone naturally, meteorologist Kent Field said.

When ozone builds up in the county’s inland valleys, respiratory ailments tend to worsen. Chronic exposure to smog can damage lungs, and people with lung or heart disease may have trouble breathing.

Health experts recommend remaining inside, with windows closed and air conditioning on, during high-smog days. They also advise drinking plenty of fluids and avoiding cigarettes, traffic and outdoor exercise.

Or there’s always Supervisor Maria VanderKolk’s approach: “It’s sort of like the starving children in China--I try not to get too depressed about it,” she said. “I prefer to think of it as haze.”

While May officially kicks off smog season, so far this year Ventura County’s air has been clean, with no days exceeding federal pollution standards, said Doug Tubbs, who manages the county’s monitoring and technical services.

“It’s kind of exciting to see the big picture. In spite of population growth, we’ve seen an improvement in air quality,” Tubbs said.

July, August and September are usually the worst smog months, as asthmatics and some elderly people can attest. But any high-pressure weather system during the year can cook up enough ozone to create a serious smothering sensation.

“The smog season started about 38 years ago,” said Richard Williams, manager of A & A Emissions Tune-Up in Ventura, who remembers returning from school recess with his eyes watering after being on a playground so smoggy that he couldn’t see across the schoolyard.

Used to seeing the telltale smudge stretch across the horizon, many longtime residents shrug off the advent of yet another smog season.

“Nobody likes smog, but smog is here, and that’s all there is to it,” said Betty Lipman, 69, of Simi Valley. “It’s a health hazard, but so are many other things in life. I just don’t think about it.”

Ventura County’s Smog Declines Fewer days have exceeded federal health standards for ozone in recent years. ‘92: 10 Source: Ventura County Air Pollution Control District