The California Air Resources Board last week announced they would scale back impending regulations regarding off-road diesel vehicles after a study found that data used as the basis for the regulations overestimated the levels of air pollution created by the vehicles by 340 percent.
The regulations were originally adopted in July 2007 and called for engine upgrades and/or the installation of retrofit pollution-control devices on hundreds of thousand of construction and other off-road diesel vehicles starting this year.
In anticipation of the regulations' first-phase deadlines this year, the construction industry is estimated to have spent $10 billion to $12 billion to upgrade their vehicles to the new standards.
On Thursday, CARB officials announced revisions to the original calculations and said that enforcement of the regulations would now be delayed until at least 2014. There will also be a widening of the number of vehicles eligible for exemptions, the agency said.
CARB, which researches and sets air quality standards statewide, said that the overestimate was due to the board calculations of future off-road vehicle pollution generation prior to the economic downturn. Since the global financial meltdown and the resulting collapse in the California construction industry, many of the state's 150,000 such vehicles have wound up sitting idle.
Independent researchers from the University of California, Berkeley and the Lawrence Berkeley National Laboratory first discovered the overestimate and found that the CARB error was not due to the economic downturn but mainly to faulty methods of calculation. The researchers found that even prior to the downturn, CARB's estimates were too high by 310 percent to 450 percent.
The CARB estimates were originally based on the calculation that off-road vehicles and machinery would burn about 1 billion gallons of fuel a year. A revised estimate calculates the amount of fuel to be used at about 228 million gallons- 340 percent lower.
It is the second time in as many months that CARB has had to backtrack on pollution-related estimates.
In late August, CARB officials announced that a CARB researcher had falsified his academic credentials, throwing into doubt his work on developing estimates of statewide premature deaths due to air pollution. A subsequent investigation found the researcher's estimates of 18,000 premature deaths a year due to air pollution were grossly overestimated, with the real calculation being nearly 50 percent less. The statistics were eventually used as the basis for the adoption of some CARB regulations.