Ocean Air Provides Relief From Smog Episodes

Ocean air prodded inland by a high-pressure area offshore cleared up most of Southern California’s smog problems Thursday, and the National Weather Service said the air should keep getting cleaner right through the weekend.

High temperature at Los Angeles Civic Center on Thursday reached 77, and forecasters said today should be four or five degrees cooler because of low cloudiness that could linger through the morning and into early afternoon.

Meteorologists explained that there are two high-pressure centers off the California coast that can be counted upon to keep a layer of marine air moving inland through the night hours to provide moisture for the cloud layer.

On the other hand, the South Coast Air Quality Management District predicted a lifting of the inversion layer of atmosphere that confined pollutants close to the ground and produced the Los Angeles Basin’s first-stage smog alerts earlier in the week. Conditions were already improving Thursday; no first stage alerts were called.

District spokesman Ron Ketchum said it was a double-barreled problem based on pollution by nitrogen dioxide as well as ozone. This week’s episodes were the first combined alerts of that type since 1978.

Unlike an ozone alert, which may last no longer than several hours, Ketchum said, eye-stinging nitrogen dioxide can persist for days because its production does not depend on sunlight. That means that even going indoors will not bring much relief to sufferers, Ketchum said.

Each of the pollutants is unhealthful. But there is concern that taken together, ozone and nitrogen dioxide may pose a greater threat.

“They must be synergistic,” Ketchum said. “Unfortunately, the people doing health effects studies have never come out with a Pollution Standards Index that takes a look at those two multiple contaminants. But it makes sense to think that if you are breathing air with two contaminants, it’s going to be more harmful,” he said.

While Thursday’s air was healthy in most places, today’s was supposed to be even better--and the Weather Service said a hot-but-smog-dispersing Santa Ana wind could be blowing in from the deserts by Sunday.

Beaches were expected to stay cool today, with low clouds hanging around most of the day and air temperature hovering in the upper 60s (just a few degrees warmer than the water temperature), while surf was expected to run a moderate two to three feet on most beaches.

Increasing surf and swells were predicted for Saturday and Sunday, however, with air temperatures warming into the mid-70s.

A small-craft advisory was in effect Thursday for northwest winds to 30 knots and combined seas to 12 feet in the outer coastal waters from south of Santa Rosa Island to San Clemente Island.