Lawmakers voted 229 to 199 to approve the Ozone Standards Implementation Act of 2017. The measure delays by eight more years the implementation of 2015 air pollution standards issued by the Environmental Protection Agency under the prior administration.
The bill also makes key technical changes that environmentalists say will weaken the Clean Air Act, including switching the EPA's mandated review of air quality standards from every five years to every 10. Ground-level ozone can cause breathing problems among sensitive groups, causing thousands of premature deaths each year.
More than a dozen major health organisations opposed the bill, including the National Medical Association, the American Academy of Pediatrics and the American Public Health Association.
The head of the American Lung Association called the industry-backed bill a "direct assault" on the right of Americans to breathe healthy air, and urged senators from both parties to reject it.
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"The bill would delay lifesaving protections against ozone pollution, exposing Americans to unnecessary pollution levels that will lead to asthma attacks and premature deaths that could have been prevented," said Harold P. Wimmer, the group's national president and CEO.
It is part of a larger push by the Trump administration and congressional Republicans to weaken, block or delay stricter pollution and public health standards approved under President Barack Obama, a Democrat.
Primary sponsor Rep Pete Olson, R-Texas, praised the progress made in cleaning up the nation's air since the 1970s, when choking blankets of smog regularly blanketed US cities.
But he said the stricter standards approved by Obama's EPA would force American companies to invest billions in new pollution reduction measures.
Democrats countered that the GOP bill, which they derided as the "Smoggy Skies Act," would cost lives through increased rates of asthma and lung disease while endangering decades of hard-won progress in cleaning up the environment.
"This is a blueprint to Make America Sick Again," said Rep. Gerald Connolly, D-Va., mocking the Trump campaign slogan.
Ground-level ozone is created when common pollutants emitted by cars, power plants, oil refineries, chemical plants and other sources react in the atmosphere to sunlight. The National Ambient Air Quality Standards adopted by EPA in 2015 reduced the allowed amount of ground-level ozone from 75 parts per billion to 70 parts per billion.