An estimated 180,000 vehicles would have to be replaced or retrofitted with smog traps, filters or cleaner-burning technology beginning in 2010. The rules adopted Thursday would be phased in through 2020 for fleets of large vehicles and 2025 for smaller equipment.
"We're really breaking new ground here," said Mary Nichols, chairwoman of the California Air Resources Board. "It hasn't been an easy task to come up with a proposal that is both cost-effective and fair."
The clean-air proposal was sought by health advocates but has been the focus of an intense lobbying campaign by industry representatives who said the first-in-the-nation regulation asked too much of contractors and equipment retailers in too little time.
"Our industry has done nothing wrong," said Gordon Downs, owner of Downs Equipment Rental in Bakersfield, who estimated the rule would cost his company $2.1 million in the first year alone. "Why are we being punished by the very state we helped to build?"
Construction industry officials said the cost to companies and government agencies to comply with the rule would be more than $13 billion.
Erik White, a diesel expert at the Air Resources Board, said that estimate assumes that all companies would have to buy new equipment rather than install retrofits on older engines. The air board's economic analysis estimated the total cost to comply with the rule would be $3 billion.
"This is one of the last sectors to get regulated," said Andy Katz of Breathe California, a grass-roots public health organization based in the San Francisco Bay area. "It's time for the construction industry to also come forward and do their part."
The rules adopted Thursday are intended to clean up the state's smoggy skies by targeting nitrogen oxide and air pollutants known as particulate matter that can become embedded in lung tissue and cause respiratory ailments and cardiovascular problems.
Replacing old diesel engines is projected to eliminate 48 tons per day of nitrogen oxide and 5.2 tons per day of particulate matter statewide by 2020.
Gov. Arnold Schwarzenegger said the board's action showed that California is "leading the charge to protect public health."
"This new regulation will prevent thousands of premature deaths every year in the state and save billions in health care costs," he said in a statement.
The new standards are projected to prevent 4,000 premature deaths, 110,000 asthma-related cases, 9,200 cases of acute bronchitis and 680,000 lost work days over 20 years, according to an analysis by the air board.
The requirements will also save up to $26 billion in health care costs by 2030, according to air board projections.
The new standards were approved unanimously by the 11-member Air Resources Board, although two members were absent. They are separate from the first-of-its-kind global warming law California passed last year, which requires a significant reduction of greenhouse gas emissions statewide by 2025.
The new regulations do not apply to snow-removal equipment and other such vehicles that run less than 100 hours per year. Emergency vehicles, agricultural equipment and vehicles that run on less than 25 horsepower also would be exempt.
By Samantha Young