California grossly miscalculated pollution levels in a scientific analysis used to toughen the state's clean-air standards, and scientists have spent the past several months revising data and planning a significant weakening of the landmark regulation, The Chronicle has found.
The pollution estimate in question was too high - by 340 percent, according to the California Air Resources Board, the state agency charged with researching and adopting air quality standards. The estimate was a key part in the creation of a regulation adopted by the Air Resources Board in 2007, a rule that forces businesses to cut diesel emissions by replacing or making costly upgrades to heavy-duty, diesel-fueled off-road vehicles used in construction and other industries.
The reasons for the error are not clear, with some suggesting the economic slump, and others pleading ignorance:
Mary Nichols, chairwoman of the California Air Resources Board, offered no explanation when The Chronicle questioned her about the diesel emissions miscalculation. She was recently asked why the air board estimate of a nitrous oxide source was off by at least a factor of two - air board scientists have since revised their numbers, and data show the estimate was off by 340 percent. Nichols' response: "I can't answer that for you."
Nichols was emphatic, though, when asked whether she has concerns about other scientific calculations made by air board scientists.
"No, no, no, no, no, no, no and no," she said.
Members of Nichols' board don't have an answer for the overestimate either, said Ron Roberts, an air board member who is a Republican supervisor in San Diego County and who voted in favor of the diesel regulation.
"One of the hardest things about being on the board is separating fact from political fancy," Roberts said.
And of course, no story would be complete without the specter of climate change politics lurking in the background. Have a look at the article for the details.