Board Declares Diesel Soot a Cancer-Causing Pollutant

Diesel soot--the culprit behind the smoke from trucks and buses that annoys many Californians--is a toxic, cancer-causing danger to the public, the state’s air quality board declared in a unanimous vote Thursday.

The decision, which set in place an unusual compromise between industry and environmentalists, ended nearly 10 years of political debate and scientific analysis by state officials and a panel of scientists.

Now, the real work begins for the state Air Resources Board. In a process likely to take years, the agency must evaluate strategies to protect Californians from the fine carbon particles emitted by diesel engines, including those in trucks, tractors and trains.

Air board Chairman John Dunlap assured business leaders that banning diesel engines or fuel is not an option.

Instead, the air board voted to create a working group of health experts, industry leaders and environmentalists who will help devise a plan that is likely to focus on tightening emission standards for future vehicles and finding ways to get rid of old, smoking trucks.

Ending years of confrontation, environmentalists and industry groups Thursday endorsed the move to list diesel particulates as a toxic air contaminant.

“This is a really important step and we’re very pleased,” said Linda Waade of the environmental group Coalition for Clean Air. “After nine years, I absolutely believe that it starts the clock ticking and we’ll see some really good [policy] out of this. There will be no new regulation immediately, but it starts this very important risk-evaluation process.”

Earlier this week, industry groups, from trucking companies to oil giants, agreed to end their years of intense opposition to air board action on diesel so long as the board identified only diesel particulates--not diesel exhaust as a whole--as a toxic pollutant.

The main difference, business leaders say, is that the board is giving them something specific to focus on--finding new technologies to reduce the particles created by diesel engines.

Particulates are microscopic pieces of soot that contain molecules of various toxic compounds and can penetrate deep into lungs. The particles are believed to cause serious respiratory problems.

California Chamber of Commerce President Allan Zaremberg called it a “win-win situation” and a “fair compromise.”

Board member Joseph Calhoun, a former General Motors engineer, said he had “lost some sleep” over the prospect of voting to identify diesel exhaust as toxic. But he found it more reasonable to act only on diesel particulates--the ingredient that health studies, engineers and regulators have focused on.

Already, under existing emission standards, a new diesel truck or bus emits 90% fewer particles than one manufactured a decade ago. Many trucks on the road, though, are still putting out large amounts of smoke because the engines are older models.

Despite the years-long delay brought by industry opposition, Dunlap said California is now ahead of the curve. The U.S. Environmental Protection Agency is evaluating diesel exhaust and is likely to declare it a carcinogen.

Since 1989, debate has centered on how much of a cancer risk diesel poses to people driving on freeways, riding on buses, living near trucking centers or simply breathing urban air.

A state-appointed panel of scientists concluded that diesel pollution could be causing 14,000 cases of lung cancer in California. But that cancer estimate is highly controversial and uncertain because it is extrapolated to the general population from studies that found a high cancer rate among railroad crews, truckers and other workers who encounter high doses of exhaust.