SACRAMENTO, CA – California air quality regulators were considering what would be the United States’ toughest emission standards for diesel-powered vehicles such as bulldozers and airport baggage trucks, according to the Web site www.iht.com.

If adopted, the rules would force the oldest and most polluting pieces of equipment out of service and require construction firms and other companies to spend billions of dollars on new vehicles or engine retrofits.

The standards before the California Air Resources Board would require emissions from backhoes, forklifts, and other forms of diesel equipment to be cleaned up gradually beginning in 2010. The rules would be phased in through 2020 for fleets of large vehicles and 2,025 for smaller equipment. An estimated 180,000 vehicles would have to be retrofitted with cleaner-burning technology or replaced.

The rules are separate from the global warming law California passed last year, which requires a significant reduction of greenhouse gas emissions statewide by 2025.

The pollutants targeted in the rule — particulate matter and nitrogen oxide — are blamed for premature deaths, respiratory ailments, and cardiovascular problems, according to www.iht.com. The standards under consideration are projected to prevent 4,000 premature deaths, 110,000 asthma-related cases, and 9,200 cases of acute bronchitis over 20 years. The requirements also would save up to $26 billion in healthcare costs by 2030, according to air board projections.

Construction industry officials said the cost to companies and government agencies would be more than $13 billion. Construction companies operate about half the vehicles that would be regulated. They asked the air board for an additional five years, until 2025, to have fleets of large vehicles comply with the new pollution standards.