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Smog Study Points to Local Cancer Risk

Pollution: The 9-year-old report indicates urban areas missing Clean Air Act goals. But reliability of data is questioned.


Despite decades of smog cleanup, toxic air pollution poses an excessive cancer risk to people in the region that includes Ventura County, according to a federal government study released Wednesday by an environmental group.

The 9-year-old study, the first to attempt to show the threat that airborne toxins pose to every community in the nation, indicates urban areas continue to miss by a wide margin the goals set by the Clean Air Act.

Throughout Ventura County, the study shows, air contained enough chemicals to boost the risk of contracting cancer 310 times above federal objectives. The county ranked 18th in the nation for toxic air pollution exposure, according to the Environmental Defense Fund, a clean-air advocacy group.

The estimates are derived from 1990 pollution and population data compiled by the U.S. Environmental Protection Agency. The EPA, however, is updating the information and cautions the numbers released by the environmental group are out of date and may be unreliable because they come from an early computer simulation of ambient air.

But David Roe, senior attorney for the Environmental Defense Fund, said the findings are significant because they considered 148 substances in smog--more than in previous studies--to derive estimates for all communities in the continental 48 states. The numbers were based on an ongoing EPA program to more fully assess the health effects from breathing multiple toxic pollutants over a lifetime.

Terri Thomas, air toxics supervisor for the Ventura County Air Pollution Control District, said the findings serve as a reminder that despite blue skies and coastal breezes, urban pollution remains a health threat in the county.

"It's something to be concerned about," Thomas said.

The results from the EPA's computer model correspond with actual measurements taken at the county's only toxic air pollution monitoring station in Simi Valley. Based on measurements from that station, 303 people in 1 million could be expected to contract cancer over a lifetime from chemicals in the air in east Ventura County. Regulations aim to keep the cancer risk below one in 1 million. In contrast, Americans have a 1-in-5 chance of contracting cancer from all causes.

In Los Angeles County, air contains enough chemicals to boost the risk of contracting cancer 660 times over the federal objective. In Orange County, the added cancer risk was 590 times greater. In California, San Francisco topped the list as the most at-risk city for cancer-causing emissions; Los Angeles was second, according to the Environmental Defense Fund.

Ventura County is the nation's sixth-smoggiest urban area. Swirling within a haze of microscopic particles and ozone, the main ingredients in smog, are numerous substances capable of causing cancer, birth defects and neurological harm.

While businesses from metal platers to factories to dry cleaners get blamed for most of the toxic air pollution, the study shows vehicles produce 80% of the cancer-causing contaminants. Smaller sources, including dry cleaners, gas stations and other small businesses, comprise about 17% of the emissions in Southern California, Roe said.

"Up to now, lack of information has meant lack of attention to some of the biggest causes of toxic air," Roe said.

Using computer models, the EPA examined traffic, fuel consumption, location of industries and wind patterns to estimate toxic pollutants in the community. Such models are commonly used in air quality planning.

EPA spokesman Al Zemsky said the agency is not entirely confident in its findings because smog levels today are lower than they were a decade ago, when the toxic air study began. Further, the computer model has undergone several refinements since 1990.

"This data does not represent the real world," Zemsky said. "It is not timely and is not the most reliable data."

The EPA prepared the study between 1990 and 1994 but never released it. It was obtained by the Environmental Defense Fund through a Freedom of Information Act request.

The EPA is completing a study using 1996 data, which Zemsky says will take into account new air standards and lower pollution levels. Results of that work are expected later this year.

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