Increased Health Threat Reported in Smog, Acid Fog Mix

Evidence is mounting that a chemical mix of smog and acid fog poses a far greater threat to human health than any one pollutant by itself, medical researchers told a state Senate committee Wednesday.

Testifying in El Monte before the state Senate Natural Resources and Wildlife Committee, the researchers said the interactions between ozone--which makes up 95% of what is commonly known as photochemical smog--and acid rain and fog can increase the adverse health impact by as much as six times, based on lab animal studies.

Respiratory problems observed in Canadian children at a summer camp have also been tied to interactions between air pollutants.

Increased Pressure Expected

The emerging medical studies that show the one-two punch of ozone and acid fog can be expected to increase pressure for controls on emissions of oxides of nitrogen from oil refineries, power plants, automobiles and other sources.

Nitrogen oxides play a major role in the formation of both ozone and acid fog.

“The interactions between ozone, nitric acid and fine particles is far more important than the individual components alone, although ozone is very important,” said Michael Kleinman of UC Irvine’s department of community and environmental medicine.

Animal studies have recorded increased damage to the lungs, upper respiratory tract problems and killed cells in areas of nasal passages where nasal cancer most commonly occurs.

Moreover, the South Coast Air Basin--Los Angeles, Orange, Riverside and San Bernardino counties--has an abundant supply of both ozone and acids in the air.

More Acute in California

“In California, I think the problem may be more acute than for many other cities in the country,” Kleinman said. “Not only do we have high levels of ozone but ozone, nitrogen dioxide and very fine particles.”

Dean Sheppard of the UC San Francisco School of Medicine added that sulfuric acid increases the adverse health effects of ozone in rats and that sulfuric acid and ozone together contribute to increased respiratory hospital admissions in southern Ontario province in Canada.

While witnesses said there was less information about nitric acid--which is far more prevalent in the South Coast Basin than the sulfuric acid widely found in the East--there was reason to believe that both forms of acid would basically interact the same with ozone.

Nonetheless, their testimony could step up the drive by clean air activists and others for new controls on oxides of nitrogen.

“I think there’s a considerable body of evidence to suggest that acidity is important for causing many adverse effects caused by air pollution,” Sheppard said.

All the researchers said that there was much that is not known about the interaction of the various pollutants and that more study is needed.

“Ultimately, there are going to have to be some (additional) controls in that area,” Sen. Dan McCorquodale (D-San Jose) said Wednesday. McCorquodale is chairman of the committee and is carrying a bill requiring the state Air Resources Board to set an ambient air quality standard for atmospheric acidity by March 1, 1990.

Major industries have been fighting additional controls on nitric oxide emissions to lower ozone levels. Instead, they have suggested more controls on hydrocarbons, the other component of ozone. Hydrocarbon controls are generally less expensive than controls on oxides of nitrogen.

Larry L. Berg, a USC social scientist and member of the South Coast Air Quality Management District, told the Senate panel that the time has come for a statewide air pollution standard for limiting emissions of chemicals that produce acid rain and fog.