Smog Level Stays in Ozone Despite Winds of Change

Ah, summer. Long, sunny days at the beach, evening barbecues--and air that looks as if you could cut it with a knife.

The smog season has blown into town, bringing with it some good news and bad.

The good news: Levels of ozone, the lung-irritating gas that is the main component of smog, have been dropping gradually over the last 10 years in most of Greater Los Angeles--including the San Fernando and Santa Clarita valleys and eastern Ventura County.

The bad news: The area still has the worst ozone pollution in the country, and is not close to meeting the federal government’s minimum air quality standard.

Air-monitoring records show that the frequency and intensity of violations during the May through October smog season have been reduced by controls on cars and industry.

But, based on this data, it is also safe to predict that the federal health standard for ozone this summer probably will be exceeded at least every other day in the San Fernando and Santa Clarita valleys, with less frequent excesses in eastern Ventura County.

In a recent issue of its newsletter, the South Coast Air Quality Management District, which regulates air quality in Los Angeles, Orange, Riverside and San Bernardino counties, reported a 33% drop over the last 10 years in the number of more serious Stage 1 ozone episodes, when pollution levels are so high that even healthy people should avoid strenuous outdoor activity.

Despite this progress, Stage 1 episodes are almost certain to occur at least a few days this summer in the San Fernando and Santa Clarita valleys, judging from data collected in recent years.

Los Angeles’ severe ozone problem stems from excessive polluting emissions and a summer weather pattern that is highly unfavorable for air quality.

Ozone is formed when hydrocarbons from auto exhaust and industries mix with oxides of nitrogen, another type of polluting gas, in strong sunlight. The long hours of intense sunshine promote this chemical reaction, while weak summer winds and temperature inversions reduce the mixing of air.

Ozone irritates the respiratory system and, at high levels, can cause coughing, wheezing and shortness of breath. It aggravates breathing ailments such as asthma and bronchitis.

Ron Ketcham, a spokesman for the air quality district who coaches youth soccer in his spare time, said he has observed the harmful effect of smog on young athletes even on moderately polluted days.

“It gives them headaches” and they complain “of their lungs hurting,” Ketcham said. “These kids suffer, and this is at levels below Stage 1 episodes.”

The chronic effects of ozone exposure are not as well understood and are the subject of continuing research.

An as-yet unpublished study suggests that Los Angeles children, on the average, have somewhat poorer lung function than do children in Houston, where smog levels are considerably lower.

Dr. Kaye Kilburn, a USC professor of medicine who worked on the study, said researchers compared 12 groups of Los Angeles youngsters with 12 groups from Houston, matching the children by grade in school, sex and ethnic background.

Kilburn said 11 of the Houston groups tested better in lung function tests than did their Los Angeles counterparts.

“These are not big differences. They’re of the order of 5% to 10%,” Kilburn said. “But one wonders what that means for the future of these people--whether their lungs are going to grow to the same extent.”

Recent experiments on mice by UCLA researchers have suggested a link between chronic exposure to ozone and lung cancer.

Nature of Study Told

In the study, reported last fall in the Journal of the National Cancer Institute, 40 mice were exposed to clean air for six months, while 40 others, during the six months, were exposed for five days every other week to air with an ozone concentration of .31 parts per million--a level reached or exceeded at least a few days each summer in the South Coast Air Quality Management District.

Autopsies performed on the mice revealed that more of the ozone-exposed mice developed non-malignant lung tumors, and more developed multiple tumors than did those in the clean-air group.

Dr. Mohammad G. Mustafa, a UCLA professor of public health who co-authored the study, said the findings do not prove that ozone exposure causes cancer in humans, which could only be proved or discounted by exhaustive epidemiological studies.

“We could say that it does bring a concern,” Mustafa said.

The federal health standard for ozone limits hourly average concentrations to .12 parts of the pollutant per million parts of air. The standard is exceeded more than 120 days a year in some parts of the South Coast basin, and, in the San Fernando and Santa Clarita valleys, about 70 to 90 times annually.

Above the .12 ppm limit, air is considered unhealthful for sensitive people.

By the reckoning of the California Air Resources Board, this pollution-sensitive group makes up about half the population--including the elderly and people with breathing or cardiac ailments; children, whose lungs are developing and respiration rate is greater, and athletes, who breathe deeply and rapidly during exercise.

In fact, California has adopted an ozone standard of .10 ppm on the premise that the federal standard is not protective enough. But, for the Los Angeles area, the difference is academic because officials concede that air quality won’t even approach the weaker federal limit without substantial pollution controls beyond those now on the books.

At an ozone level of .20 ppm, a Stage 1 episode is declared and air is considered unhealthful for everyone.

Stage 1 Efforts Described

When a Stage 1 episode is forecast, electric utilities in the South Coast district are required to switch from oil generation to cleaner-burning natural gas if it is available. Large employers are asked to take voluntary steps to reduce polluting emissions and encourage car pooling.

The elderly and people with cardiac or respiratory conditions are advised to stay indoors and reduce activity. Even healthy people should avoid strenuous outdoor activity, confining vigorous play or exercise to the home or gym. Congested traffic areas and cigarette smoke should be avoided.

A Stage 2 alert is declared when the ozone level reaches .35 parts per million. When Stage 2 levels are predicted, large employers are required to implement contingency plans to reduce the use of fleet vehicles and increase car pooling by workers, and major polluting industries are required to scale back operations.

During a Stage 2 episode, all people are advised to remain indoors, close doors and windows, and reduce activity. Stage 2 episodes happened seven days last year in the South Coast basin, mainly in the eastern San Gabriel Valley. There have been no Stage 2 episodes in the San Fernando or Santa Clarita valleys since 1980.

As part of its four-county surveillance network, the South Coast district operates air-monitoring stations in Burbank, Reseda and Newhall. The Ventura County Air Pollution Control District has three stations in the eastern part of the county, in Simi Valley, Thousand Oaks and Piru.

Of these six area stations, Newhall claims the dubious honor of most frequent ozone violations, with Burbank a close second, followed by Reseda, Simi Valley, Piru and Thousand Oaks.

From 1976 through 1985, the federal ozone standard was exceeded an average of 109 days a year at the monitoring station on San Fernando Road in Newhall. The last three years have seen some improvement, with violation days dropping to an average of 88 a year, or a 19% reduction.

Over the last decade, the Newhall station also recorded an average of 36 Stage 1 episodes a year. From 1983 through 1985, an average of 17 episodes occurred a year, less than half the 10-year average.

At the eastern San Fernando Valley station, in the 200 block of West Palm Avenue in Burbank, violations of the federal ozone standard occurred an average of 92 days a year from 1976 through 1985. The standard was exceeded an average of 85 days during the last three years.

Modest Stage 1 Drop

There has also been a modest drop in the more serious Stage 1 episodes, from an average of 23 a year in the last 10 years, to 19 a year in the last three.

At the western San Fernando Valley station in the 18300 block of Gault Street in Reseda, the federal ozone standard was exceeded an average of 90 times a year from 1976 through 1985. From 1983 through 1985, the standard was violated an average of 73 days annually, or 19% less.

Episode levels were recorded at Reseda an average of 19 days a year from 1976 through 1985, but only eight days on average from 1983 through 1985.

At the Simi Valley station, the federal ozone standard was violated an average of 52 days a year from 1976 through 1985. The average was 39 days, or 25% fewer, in the last three years.

The average of Stage 1 episodes in Simi Valley was two a year over the last decade, but there have been no ozone episodes there since 1983.

The most dramatic improvement has been at Piru, where there were 34 violation days on the average over the last 10 years but only nine a year from 1983 through 1985. There have been no Stage 1 episodes at Piru since 1981.

At the Thousand Oaks station, ozone levels exceeded the federal standard an average of 20 days a year during the last decade, but only nine days a year from 1983 through 1985. The last ozone episode there was in 1981.