Record Clean Air Possible as Weather Smacks Smog

Skies over Ventura County are remarkably smog free as emissions cuts and favorable La Nina weather join to blow away pollution at a pace that could make this year the cleanest in three decades, officials said.

Across the county, air pollution is in retreat as smog season--the midyear stretch when an opaque pall of ozone and particle haze historically pervades inland valleys--reaches the halfway mark this weekend.

If the trend continues, this year may end up the cleanest since 1968, when daily measurements of smog began in Ventura County, according to county Air Pollution Control District officials.

They warn a blast of hot, stagnant weather may still be lurking out there to besmirch the pretty picture before Halloween, when the smog season that began May 1 officially ends. A bad stretch often occurs in late August and early September.

Yet the pollution forecast for the remainder of the year in Southern California suggests conditions conducive to clean air will continue.

“If we continue without any [ozone violations], this would be the best year on record,� said Dick Baldwin, executive officer at the air district. “Things are so much better this year. People are breathing much cleaner air today than ever before in recorded time, and we expect it to become cleaner still.�

So far, days of heavy ozone, when concentrations of the pollutant violate federal standards, have been absent across the county, according to the district. If that continues, it would mark the first year the county has attained that important benchmark.

Ventura County must meet that goal under the Clean Air Act by 2005 or face sanctions for noncompliance. Five violations of that limit occurred last year, two the year before and 17 in 1996.

What little ozone there is this year is largely concentrated in Simi Valley, the county’s air-pollution hot spot. Ocean breezes act like a conveyor belt to dump pollution there, and the bowl-shaped valley sometimes gets a pulse of emissions blown in from Los Angeles.

So far, ozone exceeded California standards, which are 25% more stringent than the federal limits, in Simi Valley 16 days this year, compared with 15 by this time last year and 27 at the same point in 1997. Thousand Oaks has had five such violations as of Friday, compared with six this time last year; Ojai has had three, compared with four last year. Many of those violations were clustered around June 21, the summer solstice, when maximum sunshine was available to help produce smog.

Ozone, an invisible gas, is formed when carbon-based chemicals mix with other emissions and abundant sunshine. It oxidizes plastic and stone; causes headaches and shortness of breath; and scars lung tissue, which can lead to long-term loss of respiratory function.

Airborne haze, which people commonly associate with air pollution, is down this year, too. Concentrations of microscopic dust and soot have not exceeded federal limits and have only surpassed more stringent state standards twice in Simi Valley and once in Piru this year, according to the air district. The sky may still look smoggy at times, but that is because it takes just a dash of extremely small particles, in amounts below health-based limits, to smudge visibility and leave tell-tale haze.

The improvements are particularly impressive because they occur during a period of rapid population growth and a resurgent California economy. Ventura County has gained 86,160 people in the last decade, roughly equivalent to adding a city nearly the size of Ventura.

Weather hostile to smog is the chief reason for improved air quality.

Ordinarily, Southern California is a perfect smog factory. Thousands of tons of emissions are released along the coast every day. Sunlight and chemistry cook them into a noxious broth of pollutants scientists have yet to fully comprehend. Winds push it to inland valleys. Tall mountains trap it. Warm-air layers called inversions descend from above to lock smog atop cities like a Tupperware lid.

But that is not how things have worked this year. A procession of weird weather phenomena, from La Nina to monsoons, has clobbered smog across Southern California.

“We are reducing emissions and that is part of the progress, but the air quality appears really good because the weather is so favorable,� the air district’s Baldwin said.

During La Nina, a slug of cooler-than-normal water spreads across the Pacific along the equator. For Southern California, that means more sea breezes, more clouds, a stubborn marine layer and cooler temperatures. The result: spring-like conditions lasted longer and summer smog season is shortened, said Joe Cassmassi, senior meteorologist for the South Coast Air Quality Management District, the agency charged with cleanup of Los Angeles-area smog.

For example, Ventura County air temperatures were well below normal early in the year. In Oxnard, temperatures were an average of 3 degrees cooler than normal in March and April, and it was probably much cooler in the county’s inland areas, said Jonathan Slemmer, meteorologist for the National Weather Service.

By the time May and June rolled around, a low-pressure system over the eastern Pacific had forced the jet stream out of the Northwest and over Southern California. That kept a steady flow of onshore breezes that swept away smog and blasted the lid off any threatening inversions, Cassmassi said.

Heat began to bear down in the second week of July, and ozone levels shot up in Simi Valley and Ojai. But that was short-lived. Powerful monsoon thunderstorms roared over mountains and deserts through much of July, bringing more unstable air that allowed smog to ventilate.

“Our weather patterns are different this year. It has not been conducive to making ozone,� said Kent Field, meteorologist at the air district.

Air-quality officials hope their good fortune continues. Three months remain in the smog season of 1999, and a sudden return to hot, stagnant weather could send smog levels soaring. A crucial period is late August and early September, historically a period of high air pollution after onshore breezes diminish but before Santa Ana winds roar, Baldwin explained.

“Air quality has been good so far this year. It would be nice if it continues, but we just don’t know,� Field said.

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Clearing the Air

Ventura County skies are remarkably free of air pollution so far this year. As smog season reaches the midway mark today, no violations of the federal ozone standard have occurred and there are fewer violations of the more stringent California limit. The county is on a pace for a record clean year.

Federal Ozone Violations

The federal ozone standard prohibits more than .12 parts of ozone per million parts of air in any one-hour period.

State Ozone Violations

The state ozone standard prohibits more than .09 parts per million of ozone in the air in any one-hour period.