Don’t Back Off on Diesel Issue
Diesel-powered vehicles make up just a tiny part of the cars and trucks on California’s roads, but they spew one-third of the nitrogen oxides, elements in the brown brew called smog, and nearly two-thirds of particle emissions.
There is no question that the air is polluted by diesel exhaust, emitted by many trucks, buses, trains, ships and construction and farm machines. But can the exhaust also cause cancer in humans? That issue is now before the state Air Resources Board, which on July 30 is scheduled to consider an April report of a state-funded advisory panel that concludes diesel exhaust poses a serious cancer danger.
The report followed nine years of study and rancorous debate. The air board should formally endorse it and declare diesel a toxic air contaminant under state law. But if politics, not science, carries the day, the board probably will put off that important decision, and cleaning up our air will be further delayed.
Diesel exhaust contains many compounds. State and federal regulations control some of those, like benzene and arsenic. Others, like phenol, napthalene and styrene, are controlled in factories but not in vehicle exhaust.
A 1983 state law requires the air board to identify toxic air contaminants and then devise a strategy to protect Californians from them. Benzene was the first of the 19 compounds so far labeled as toxic air contaminants under this unique law. Adding diesel fumes to that list seems warranted. In addition to the April report from the air board’s science advisors, the U.S. Environmental Protection Agency, in a March draft report, identified diesel as a probable human carcinogen, as has the International Agency for Research on Cancer.
These findings, along with the fact that, as one air board official said, diesel exhaust is “everywhere and affects everyone,†add urgency to the board’s deliberations. Yet the ubiquitous nature of diesel and the extent to which our economy depends on the diesel-fueled transport of goods and services make this a tough call politically. The trucking industry wants a delay pending further analysis and has support from many state legislators. Industry leaders fear litigation and burdensome regulation if the fuel is labeled a potential killer, and they challenge the validity of studies linking diesel and cancer.
State law is clear. It requires frank disclosure by the air board on public health risks--and that’s what the board should do. But the currently available fixes are expensive and the law sets no timetable for action. Bipartisan measures (AB 1368 and SB 1857) now before the Legislature would be a good start. They would provide grants to retrofit existing diesel vehicles and heavy-duty equipment and the funds to purchase some low-emission vehicles.
The state needs to be honest about public health risks while thinking creatively about their solution. State officials should also be reasonable in setting the pace for required changes and provide incentives where possible to encourage retrofitting and the use of alternative fuels.
