The Obama administration has announced new fuel and car rules to cut soot, smog and toxic emissions, which it says will reduce asthma and heart attacks.
The so-called Tier 3 rules unveiled by the US Environmental Protection Agency have been under development since President Barack Obama issued a memorandum in 2010 instructing the agency to develop them.
The rules, the third tier in a series of standards, will cut petrol sulphur levels by more than 60 per cent and should also reduce exhaust and evaporative emissions from cars, light and medium-duty trucks and some heavy-duty vehicles.
Health advocates praised the move, while a petroleum refiners' group called the compliance schedule unrealistic and warned of potential supply disruptions.
The rules will be phased in under schedules that vary by vehicle class, generally starting between model years 2017 and 2025, the EPA said.
Once fully in place, the standards will help avoid up to 2,000 premature deaths a year and 50,000 cases of respiratory ailments in children while adding just a fraction of a cent to the cost of a litre of fuel, the agency estimates.
Total health benefits in 2030 are estimated at between US$6.7 billion and US$19 billion a year.
The standards are an attempt to cut the sulphur content of petrol to 10 parts per million from 30 ppm.
The agency said this would boost efficiency for new emission control technologies that automakers would use to help achieve the administration's wider clean car standards.
Every petrol-powered vehicle on the road built before the Tier 3 standards will run cleaner, cutting smog-forming nitrous oxide emissions by 260,000 tonnes in 2018.
"By reducing these pollutants and making our air healthier, we will bring relief to those suffering from asthma, other lung diseases and cardiovascular disease, and to the nation as a whole," said Dr Albert Rizzo, former chairman of the American Lung Association.
Industry groups complained that the new standards were not based on a timetable that was achievable by refiners.
Charles Drevna, president of the American Fuel and Petrochemical Manufacturers, said his group had discussed its concerns about the implementation schedule numerous times with the EPA.
"It chose to ignore our concerns by setting an unrealistic compliance date of January 1, 2017," he said, adding that the schedule could cause supply disruptions.
The EPA said it had considered the feedback of stakeholders, including refiners and carmakers. It said the sulphur rules included a programme to help refiners and importers meet the new standard, and gave smaller refiners more time to comply.
Frank O'Donnell, of the nonprofit Clean Air Watch, said the rule was "the most significant move to protect public health that the EPA will make this year" and that the oil industry's fears.
"Let's remember the oil industry has cried wolf so many times," O'Donnell said, "and it's doing it again here."