Despite fierce opposition from the construction industry, the California Air Resources Board late Thursday afternoon voted to adopt a sweeping regulation to reduce emissions from more than 180,000 off-road vehicles used in construction, mining and other industrial activities.

The regulation requires diesel equipment operators to reduce diesel emissions 74 percent from current levels and nitrogen oxide emissions by 32 percent by 2020. According to Air Resources Board staff, these reductions would prevent 4,000 premature deaths statewide and save at least $18 billion in health costs.

But to achieve the cuts, construction firms and other equipment operators will have to spend billions of dollars to replace existing engines or install pollution control equipment a whole range of vehicles, from bulldozers and skiploaders to forklifts. The air board put the compliance figure at $3.5 billion over the next 12 years; the industry puts the figure closer to $20 billion.

During a daylong hearing Thursday, industry representatives said many fleet operators would opt to cut back their equipment fleets instead of making the cuts, resulting in extensive job losses and delays in completing various construction projects.

The 11-member board did make some concessions to industry, including extending the compliance deadlines for operators of small fleets. However, an ad hoc industry group remained dissapointed with the outcome.

“Unfortunately the rule adopted today will do nothing but move California’s economy backward. Jobs will be lost. Businesses will cease to exist. And the state’s infrastructure rebuilding efforts will suffer,” said Mike Lewis, executive vice president of the Construction Industry Air Quality Coalition, in a prepared statement.

The vote served as a test for new board chair Mary Nichols, who accepted the post earlier this month after the ouster of previous chair Robert Sawyer and the resignation of the board’s executive director after claims of interference in agency decisions from Gov. Arnold Schwarzenegger’s Administration.

Responding to the board’s vote, Schwarzenegger said, “With this first in the nation, landmark measure to improve air quality, California is again leading the charge to protect public health by adopting balanced and well-crafted regulations aimed at reducing toxic and cancer-causing diesel emissions.”

The board’s action sets the stage for an even more controversial regulation to be unveiled next year to reduce emissions for several hundred thousand diesel trucks.