As state air pollution officials step up inspections of diesel exhaust from big rigs, some of their best allies are truckers themselves.
They are pushing the Air Resources Board to enforce pollution rules more aggressively for trucks in advance of a Jan. 1 deadline.
Truckers are also the No.1 tipsters, placing anonymous calls and sending emails to finger competitors they say are gaining an unfair advantage by not upgrading their engines or installing expensive filters that capture harmful diesel particulates before they are released into the air.
Diesel exhaust is the worst remaining pollution source on roadways. It contains smog-forming nitrogen oxides and fine particles — soot — that lodge deep in the lungs and are linked to lung and heart disease, asthma and cancer. Diesel soot was classified as a toxic air contaminant by the state in 1998.
Air quality officials say it accounts for 85% of Southern California's cancer risk from air pollution.
The regulations being phased in over the next decade are the nation's toughest and target the nearly 1 million diesel trucks that operate in the state.
By Jan. 1, about 50,000 more heavy diesel trucks — including those of the smallest fleets, owner-operators and independent drivers that make up the bulk of the industry — will have to install diesel particulate filters or upgrade to newer, cleaner engines.
The industry says the rules are not being enforced strongly enough.
"Companies have invested millions of dollars only to be undercut by carriers that are choosing not to comply because they figure they won't get caught," said Michael Shaw, a spokesman for the California Trucking Assn. "Without additional investment in enforcement ... there's little chance the Air Resources Board is going to do more than scratch the surface."
The agency sends about 20 enforcement staffers a day to conduct field inspections of trucks around the state. They target truck fleets and major transportation corridors, including the Los Angeles and Long Beach ports, the Central Valley and the U.S.-Mexico border. Fines range from few hundred to thousands of dollars.
"Resources are limited, and for a lot of this we expect the deterrent effect," said Paul Jacobs, chief of diesel enforcement for the Air Resources Board. "We'll have an enforcement presence, but we're not going to get everyone."
Most trucks pass the inspections. In the first six months of 2013, the agency conducted 3,098 inspections for the diesel truck rules and issued 378 citations, for a compliance rate of 88%.
That could dip once new requirements take effect.
"At the end of this year, there are going to be a lot of people clambering to try to get into compliance," said Matt Schrap, president of California Fleet Solutions, a company that helps trucking firms meet air quality regulations. "Some guys are probably just going to turn in the keys or keep operating until the ARB catches them."
California's rules, approved in 2008, faced stiff opposition from truckers and were relaxed two years later to give the industry more time to comply. But the rules put the state on track to slash emissions from diesel trucks 90% over the next decade and avoid 3,500 premature deaths, according to the Air Resources Board.
State officials estimate that trucking companies will pay $2.2 billion to comply with the rules through 2023. The industry says it is spending much more, about $1 billion a year, to replace trucks and install particulate filters, which can cost more than $10,000 per truck.
Environmental groups laud air quality officials for boosting the number of inspectors in recent years and helping truckers access grants and loans to upgrade their rigs. As the rules kick in, they hope to see air quality improve and rates of respiratory illness ease in neighborhoods near heavy truck traffic.
"Millions of people are exposed in these hot-spot areas and need the relief," said Diane Bailey, senior scientist at the Natural Resources Defense Council.
Likely to see some of the sharpest drops in exposure to diesel pollution are truckers, she added. "They will gain the most in terms of public health protections."
That's perhaps one reason scrap truck driver Carlos Resendiz was not particularly upset when he was stopped at a roadside inspection at the Port of Los Angeles last month. Inspectors wrote out a ticket for a missing engine label, which carries a $300 minimum fine for the company that owns the vehicle.
"The idea is not to pollute the air," Resendiz said in Spanish, "so I'm OK with it."