Air Is Filled With Toxic ‘Hot Spots,’ Study Shows : Pollution: But it will be years before the effects of 28 million pounds of airborne contaminants will be known.

Automobiles, major industries and other sources poured nearly 28 million pounds of toxic contaminants into San Diego County’s air within a year, according to a new study, but it could be years before the health effects of those emissions are known, Air Pollution Control District officials announced Wednesday.

The first inventory of air toxics “hot spots,” mandated by a 1987 state law, showed that automobiles and other “mobile sources” alone emitted 15 million pounds of toxic chemicals such as toluene, xylene and benzene into the air in 1989, when the assessment was conducted.

“We can conclude (from the study) what we in the profession already know, that there are substantial toxic pollutants in the urban environment,” said Richard Sommerville, the county’s air pollution control officer.

“Much of it is caused by motor vehicles, but there is substantial contamination from industrial sources and natural sources,” he said.

The county’s 107 largest industrial air polluters were responsible for 7.1 million pounds of toxics. Household products, pesticides and natural sources such as wildfires produced an additional 5.6 million pounds, the report showed.

Nevertheless, Sommerville said, the APCD can draw no conclusion on whether the pollution is harming human health until it conducts risk assessments that examine such factors as the toxicity of the compounds and the level of public exposure.

“The data by itself does not imply a health risk,” Sommerville said.

About half of the 107 facilities that produced chemicals such as arsenic, ammonia, gasoline vapors, zinc and other toxic chemicals have been ordered to conduct studies that assess the risk they pose. That information should be available in about a year, Sommerville said.

But because the APCD is still gathering information on pollutants from nearly 1,900 smaller facilities such as gas stations and dry cleaners, it could take three or four years before the agency can predict the overall risk of airborne toxics to the general public, he said.

The report also showed that San Diego industries emitted more than 3.5 million pounds of methyl chloroform and chlorofluorocarbons, two chemical compounds that help deplete the earth’s ozone layer.

Major emitters included Rohr Industries (783,565 pounds of methyl chloroform); Kelco (587,661 pounds of propylene oxide); Signet Armorlite Inc., (853,723 pounds of methylene chloride) and some military facilities.

However, Sommerville held up Kelco, Signet Armorlite and Caspian Inc. as examples of companies that have substantially and voluntarily reduced their production of toxic pollutants.