CARB has been working for years to implement new regulations to cut diesel emissions from different sources. The air board took action to approve new regulations increasing restrictions on diesel emissions from off-road construction equipment in 2007, and on-road trucks in 2008. The new rules imposed significant costs on businesses, requiring many to make expensive modifications to engines, or even buy new vehicles, in order to meet the new standards over a period of several years.

A controversy arose in 2009, as the air board faced criticism when it was revealed one researcher involved in work studying diesel emission-related health effects had lied about his education, prompting CARB to order the study he’d been involved with redone. The off-road construction equipment rule next became subject to scrutiny after the release of an independent report in 2009 by two environmental scientists at UC Berkeley, Dev Millstein, a doctoral student, and Robert Harley, professor of environmental engineering. Their study showed the air board had relied upon flawed methods of estimating emissions from off-road construction equipment, contributing to emissions estimates that were found ultimately to have been over three times too high. The air board scrambled to review its data, and also found problems with its emissions estimates for trucks, which were exaggerated primarily because the collapse in the economy had reduced trucking activity, according to Tony Brasil, chief of CARB’s Heavy Duty Diesel Implementation Branch.

“It was based on the best information at the time,” Brasil said. “The older information was not as accurate as we’d like.”

The mix-up forced the board to amend the truck and construction equipment regulations, for example, extending the implementation timelines for both.

Harley said the error in CARB’s methodology was longstanding, not the result of rushing the process, but the miscalculation resulted in criticism that the air board was putting in place ambitious environmental rules without adequate review. Harley said the mistake could have been costly to businesses.

“(Industry’s complaint was), why should they replace or retrofit this off-road equipment at great expense if the emissions were much lower than originally understood? The air quality benefits would not be as large as anticipated,” Harley said in an email response.

An emissions rule that would impact farm equipment won’t be proposed until 2013, while the air board works to accurately gauge how much is operating in the state.

Problems with the science behind some environmental regulations don’t only unnecessarily burden businesses – as noted by Boren, the issue also impedes the ability of rules to effectively combat environmental problems as well. One such example occurred several years back in the San Joaquin Valley area.

Michael Marsh, president of Western United Dairymen, an organization representing some 60 percent of dairy farmers in California, said in 2004 the San Joaquin Valley Air Pollution Control District - the regional air quality agency - was considering requiring that dairy farmers employ costly strategies to control the creation of Volatile Organic Compounds. VOCs are chemicals involved in the formation of smog. The air district believed they were coming from cow manure on dairies, and as a result, expensive solutions being considered included requiring that some new dairies install methane digesters, according to Sheraz Gill, Senior Air Quality Engineer for the district. Methane digesters are machines costing upwards of $1 million that are used to convert cow manure into methane gas that can be burned off, which the air board believed would eliminate VOCs.