California clean air regulators have unanimously approved the world's most stringent rules to reduce vehicle emissions. The regulations are expected to cut exhaust from cars and light trucks by 25 per cent and in larger trucks and SUVs by 18 per cent.
The motor industry will have until 2009 to begin introducing cleaner technology, and will have until 2016 to meet the new emission requirements.
The move by the state's air resources board came despite vigorous opposition from US motor industry officials, who argued that the board did not have the authority to adopt such sweeping regulations and that they could not be met by current technology. The industry has threatened to challenge the regulations in court. Governor Arnold Schwarzenegger has expressed support for the proposals and has pledged to fight any such lawsuits.
Heat-trapping greenhouse gases such as carbon dioxide are believed by many scientists to contribute to global warming. Car makers will be required to reduce emissions by way of such innovations as better air conditioners, more efficient transmissions and smaller engines.
The industry argued that the regulations would raise new vehicle costs as much as $1,700. But the agency's staff said that the car makers had exaggerated and that the cost increases would top out at around $500 per vehicle by 2016.
The new standards could have coast-to-coast effect - California represents 10 per cent of the US car market, sso the industry often overhauls all of its cars to meet Californian standards.
Also, other states sometimes follow California's lead when it comes to adopting clean-air standards. New York has already said it would adopt the new regulations, and several other north-eastern states and Canada are expected to do the same.