Accord Near on Hazards of Diesel Exhaust

Ending a bitter fight over diesel exhaust, the California Air Resources Board today is expected to declare diesel soot a cancer-causing pollutant after industry leaders and environmentalists struck a deal that quells nearly a decade of intense opposition.

The agreement is an unusual compromise in a war of words that has endured for nine years--the time that state environmental officials have spent reviewing the dangers that trucks, buses and other diesel engines pose to public health.

Convening this morning, the air board had intended to declare diesel exhaust a toxic air contaminant and begin crafting a strategy to reduce the threat. Instead, under the compromise, the board is expected to identify only a portion of the exhaust--tiny pieces of soot called particulates--as toxic. Diesel particulates are microscopic pieces of carbon that can lodge in the lungs, carrying a host of carcinogenic molecules, and create dark, noxious clouds of smoke.

Once today’s decision is made, the state must review ways to clean up diesel particulates, perhaps by tightening emission standards for future trucks and stepping up efforts to remove old, smoking vehicles from California roads, farms and construction sites.

Engine manufacturers, trucking companies and other businesses say that it would have been unfair and impractical for the air board to indict everything about diesel exhaust as dangerous. The compromise, they say, will allow them to focus instead on finding new technologies and other solutions to reduce the 27,000 tons of particles a year that come from diesel equipment, which includes millions of trucks, buses, trains, ships, tractors and other machinery.

In a statement, a coalition of influential industry groups, led by the California Chamber of Commerce and California Trucking Assn., called it “a fair compromise.”

“It’s time to put past disagreements and public confrontations behind us. With the agreement that has been reached, we can continue to make strides in making diesel fuel safer and cleaner for the future,” the industry leaders said.

Environmentalists are thrilled with the imminent end to the battle with the trucking industry and other business groups, saying that the public will be well-protected if the California air board works to reduce diesel particulates.

“We now have the chance to come out of the box with a strong, focused effort,” said Sierra Club legislative consultant John White. “This is a good thing, because it will give us a chance to get to work and make [air quality] improvements over time. This is going to be a decades-old struggle to clean up diesel exhaust.”

Under Gov. Pete Wilson, the air board is extremely sensitive to opposition from California businesses, and the decision on whether to declare that diesel is toxic prompted vehement dissent and lobbying from every industry group--from oil companies to farmers--as well as Republican legislators.

To quell the protest, Air Resources Board Executive Officer Michael Kenny last month invited negotiations with industry leaders, environmentalists and scientists. White said industry groups agreed to the deal after they failed to persuade the Legislature to prohibit the air board from naming diesel exhaust as toxic.

All major business groups active in the debate signed off on the agreement, including engine manufacturers, unions, oil companies, farmers and manufacturers.

Given the lack of opposition, the air board members will probably adopt the compromise today. Under the proposal, the board’s staff “doesn’t feel they lose any ability to control diesel emissions and it certainly brings a decade-long episode to a close,” said air board spokesman Jerry Martin. “It allows us to move on to the real work of actually reducing emissions.”

The state’s Scientific Review Panel estimated that diesel pollution could eventually kill more than 14,000 Californians by causing 450 lung cancers among every 1 million people exposed to average concentrations for a lifetime. Diesel exhaust ranks sixth in cancer potency among 19 pollutants that the board has already identified as toxic.

Scientists are uncertain what exactly in diesel exhaust causes lung cancer. But they have focused on the particulates, which are easy to inhale deep into the lungs since they measure only a slight fraction of the diameter of a human hair. Dozens of organic compounds linked to cancer also attach to the particles and are carried into the lung.

Daniel Greenbaum, president of the Health Effects Institute, an independent air pollution research group, said Wednesday that it makes sense for regulators to target particulates. Only a small amount of toxic substances are found in diesel gases, as opposed to the particles, he noted, so most of the apparent health danger from diesels can be addressed by reducing them.

Several dozen studies of railroad crews, truckers, miners and other workers have shown they contracted lung cancer at a rate 40% higher than normal.

Particulates have been linked to numerous other serious health problems. In human health studies in dozens of cities around the world, deaths from heart attacks and lung ailments such as asthma increase on days when particulates in the air increase.

Despite the years of controversy, there has been little doubt among air board officials that they would list diesel pollution as a “toxic air contaminant,” which state law defines as a substance that “may pose a present or potential hazard to human health.”

Business groups have argued that the cancer research is flawed and outdated because the people who were studied were exposed to old engines and dirtier fuel that spewed more particles. As part of the new deal, the air board would note that the cancer estimates may not accurately reflect new diesel fuel and engines, which are 90% cleaner than ones manufactured 10 years ago.

Beau Biller, a trucking association spokesman, said declaring just the particles as toxic instead of all exhaust will reduce the threat that trucking companies will be sued by people exposed to fumes. Fear of liability over the cancer threat has been the companies’ overriding concern.