In literature promoting his re-election campaign as county supervisor, Ron Roberts touts his longtime participation on the state’s Air Resources Board, which oversees air quality research and regulation.

Today, the San Francisco Chronicle reported the latest in a series of statistical gaffes from the agency’s past research, which framed landmark policies in 2007 to cut pollution. The Chronicle found that the agency’s research methodology actually exaggerated the amount of pollution attributed to off-road diesel machinery by 340 percent.

The Chronicle quoted Roberts calling the string of research errors “a major black eye” for the board, which now plans to soften air quality restrictions and put them in line with new research findings. Here’s a longer excerpt from the story with Roberts’ response:

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.

Roberts has been on the board for 15 years and said the agency has built a solid scientific reputation, but he said the board can’t afford another mistake and he still does not know what really happened.

“I think somehow some very poor decisions have been made and politics have entered the picture too much,” he said. “There are plenty of excuses but no explanations.”

To read the Chronicle’s full story, click here.

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