HealthyCal.org

By Daniel Weintraub

More than 9,000 Californians are dying prematurely every year because of the health effects of the kind of pollution emitted by diesel trucks and heavy equipment, according to a new study by the Air Resources Board, the state’s air quality regulator.

The study is the first released by the state to claim that the microscopic particles emitted by engines burning diesel fuel actually cause early deaths, rather than simply being correlated with them.

The new analysis uses the same methodology as a recent report from the US Environmental Protection Agency, which relied extensively on a study of a half million people in 116 cities across the country.

“The EPA concluded that there was a causal relationship between (diesel pollution) and premature death,” Bart Croes, chief of research for the Air Resources Board, said in an interview. “It’s not just some random statistical association.”

The study doesn’t say how much longer the victims would have lived, on average, if they had not been exposed to diesel pollution. But the people dying early are thought to have been suffering already from heart disease, emphysema and other disorders that left them vulnerable to the effects of the particles, which are about 1/30th the diameter of the average human hair.

Both the EPA and air board studies used epidemiology – the study of disease trends – to conclude that fine particles were causing premature deaths. Researchers examined death rates from all causes and found that they were correlated with increases in detected levels of diesel pollution. They then used statistical modeling to try to account for other potential causes of death, from smoking to diet and job hazards.

They were left with numbers which, they concluded, showed about a 5 percent increase in deaths above the expected rate in places with a heightened exposure to PM 2.5, the kind of particulate matter generated when engines burn diesel fuel and send their exhaust into the air.

Although toxicologists have not established exactly how these fine particles cause disease and death, they are believed to lodge in the lungs or other tissue and lead to illness.

The latest air board study replaces one released two years ago that estimated the number of early deaths at about 18,000 per year. That study was controversial in part because its lead author, Hien Tran, had falsified his credentials.

Although the ARB disciplined and demoted Tran, the agency stood by his study, saying it had been reviewed and found to be sound. But the latest study used different methods, a different data base and had the benefit of the latest EPA numbers.

While its estimate of premature deaths is only half as large as the Tran study concluded, the new report has a smaller error range – plus or minus about 2,000 deaths – and is considered by the board’s staff to be a tighter estimate.

The research also concluded that about 2,700 deaths per year could be avoided by implementation of the air board’s rules forcing trucking companies and construction firms to reduce the pollution from their trucks and equipment.

But James Enstrom, a UCLA researcher and frequent critic of the air board’s work, said in an interview that he doubts the accuracy of the new report. He said his own research and that of several other scientists has shown that there is essentially no measurable risk of premature death from fine particles in California.

“There’s no relationship between total mortality and PM 2.5 in the state of California,” Enstrom, an epidemiologist, said in an interview. “I am saying I think the effect is not present in California.”

ARB researchers, however, point out that Enstrom’s own research found an effect similar to the one they have established. His work focused on people who were part of a group followed for decades as part of a research project originally aimed at tracking the effects of tobacco.

When that group was younger, Enstrom’s data show, there appeared to be an increase in early mortality that was similar to what the most recent ARB study found. Numbers for the older members of the research database did not show the same effect, however, and those are the figures that Enstrom says are more reliable.

But the ARB says the effect declined as the research subjects aged because those who were most vulnerable to the harmful effects of the pollution died early. Those whose bodies were more equipped to weather the pollution lived longer, making it less likely that researchers would see an effect on them in their later years, said Croes, the chief of research.

Updated at 9:40 am March 10.

Diesel emissions from off-road construction equipment like this would be regulated by a rule the Air Resources Board is being pressured to roll back.

California’s Air Resources Board is coming under increasing pressure from construction industry contractors seeking to roll back regulations adopted three years ago to sharply reduce the amount of diesel pollution from big off-road tractors, scrapers and earth-movers.

The air board adopted the new rules in 2007 to eliminate thousands of tons of emissions annually from construction vehicles by 2025. The regulations required truck owners to retire old engines and retrofit other machines with filters to trap the particulates before they could reach the air.

At the time, the board said the regulation would prevent 4,000 premature deaths in California by 2025, when the rules were to be fully implemented.

The construction industry opposed the regulations, arguing that the benefits were unproven and the costs would be enormous, placing a huge financial burden on companies forced to dump or retrofit old equipment. And the industry has been fighting the rules ever since.

Now the board, after insisting for years that its original analysis would stand the test of time, is giving ground. The board’s staff is preparing a report that will likely suggest
changes to the off-road rule and, possibly, a similar rule involving heavy-duty on-road trucks and buses.

“There will probably be at least some changes to the off-road regulation,” said Kim Heroy-Rogalski, a staff air pollution specialist for the board.

The regulators have conceded that they did not fully anticipate the toll the economic recession would take on the construction industry.

“We definitely under-estimated the worst recession since the Great Depression,” Heroy-Rogalski said. “People are operating their off-road vehicles less than we would have anticipated.”

Aside from the effects of the recession, however, industry representatives also believe that there were serious flaws in a computer model the air board used in 2007 to estimate the level of diesel emissions statewide. The air board is studying some of those claims and plans a response soon.

“We’re currently undertaking a comprehensive review to look at what we think the current off-road emissions are versus what we thought they’d be,” Heroy-Rogalski said. “We’re looking at every source out there, every rule we have, how the recession has affected it, how new information plays into it, where do we really think we are and what
flexibility we have where we can bend on some of these things.”

The challenge comes at a sensitive time for the air board. A little over a year ago, the board was forced to admit that a staff scientist who led a study of the health effects of diesel exhaust had falsified his resume, and the board relied on his work anyway. And the board’s conclusions about the economic benefits of the state’s landmark greenhouse gas law have been harshly criticized in peer reviews and, this week, questioned by the non-partisan legislative analyst.

A board acknowledgment that its computer modeling produced inflated estimates of diesel emissions from the off-road vehicles would be more fodder for critics who argue that the once widely respected ARB is now driven more by ideology than by science.

The Legislature and the governor already have forced some changes in the off-road rule. As part of one of last year’s budget agreements, lawmakers voted to postpone enforcement of the rule for companies that could demonstrate that the recession had forced them to shrink or idle their fleets.

Then, last month, the board postponed enforcement altogether at least until California could gain a regulatory waiver from the US Environmental Protection Agency as part of the state’s effort to meet federal clean air standards.

But the contractors say that’s not enough. They want the rule repealed, or at least suspended for several years.

“There is no need to implement this rule at this point,” said Brian Turmail, a spokesman for the Associated General Contractors of America, a group that has led opposition to the regulation from the start. “To do so despite data showing it’s not necessary will have a very serious and negative impact on the state’s already beleaguered construction industry.”

The contractors say that because of the recession, nitrogen oxide emissions from off-road diesel equipment will be 58,000 tons below the state’s target levels in 2010 and will remain below the target every year through 2025. They believe the emission of diesel particulate matter will be 2,500 tons below the target this year and will stay below the state’s goals at least through 2013.

The air board has not accepted those numbers. Heroy-Rogalski said they are based on what she believes is an incomplete count of the off-road machines in use in the state. And she says the industry’s projections also assume that the deep cuts in the size of company fleets caused by the recession will never be recouped – an assumption she described as “disingenuous.”

“If you have a huge recession, at some point you’re going to have a huge recovery,” she said.

Environmentalists who follow the air board’s rule-making are also concerned that the recession not be used as an excuse to accomplish with the industry has been arguing for all along.

“There are some legitimate reasons for adjustment, but it’s also the same old agenda on behalf of the contractors and others,” said Bill Magavern, executive director of Sierra Club California. “We want to make sure that the importance of public health is weighed, including the economic impact of sickness due to air pollution, along with the industry’s arguments.”

Magavern said the two diesel rules are “two of the most important ways to improve air quality in California and protect our longs and our health.”

But Heroy-Rogalski acknowledged that the board will probably adjust its numbers at some point and is looking for ways to accommodate the industry without forfeiting the public health goals behind the regulation.

“I suspect it will come out that because the recession is so severe, there is some emission cushion we can look at,” she said. “Our goal is not to impose pain. It is to clean up the air.”

The board’s executive officer has scheduled a hearing for Thursday at which he will listen to the industry’s complaints. The staff will then take those views into account as it considers adjusting what is known as the emissions “inventory” – an estimate of the amount of pollution caused by the vehicles in a given year.

A report on the issue is scheduled to go to the board in April, and could also incorporate proposed changes in a similar rule adopted for on-road trucks and buses. Heroy-Rogalski said she expects the board to study the issue for several months and adopt any changes in August or September.

–Daniel Weintraub

Photo by threecee.