Bush, a former Texas oilman, was expected to nominate New Jersey Gov. Christine Todd Whitman for the post of EPA administrator. Green groups praised the rules as a key step in cleaning up the air for those with asthma, bronchitis and other breathing ailments. Diesel engines have been blamed for spewing out 100 times more sooty particles than comparable gasoline engines. But environmentalists questioned whether the new Bush administration would support the new pollution rules. The World Health Organization and the California state environmental protection agency have determined diesel exhaust and particulates may cause cancer.
Scientists say the nitrogen oxide emissions also contribute to smog and acid rain.
Children with asthma will be able to spend more time outdoors. The elderly and people with respiratory problems will be able to breathe easier. The new rules are the latest in a series of tougher air pollution measures spearheaded by EPA Administrator Carol Browner during her eight years as head of the agency.