The sweeping regulation, which are aimed at smog caused by power plants and factories across the country, particularly in the Midwest, is the latest in a series of Environmental Protection Agency controls on air pollution that wafts from smokestacks and tailpipes. Such regulations, released under the authority of the Clean Air Act, have become a hallmark of President Obama’s administration.
Environmentalists and public health advocates have praised the E.P.A. rules as a powerful environmental legacy. Republicans, manufacturers and the fossil fuel industry have sharply criticized them as an example of costly government overreach. The National Association of Manufacturers has called the proposal “the most expensive regulation ever.”
The proposed regulation would lower the current threshold for ozone pollution to a range of 65 to 70 parts per billion, from 75 parts per billion. That range is less stringent than the standard of 60 parts per billion sought by environmental groups, but the E.P.A. proposal would also seek public comment on a 60 parts-per-billion plan, keeping open the possibility that the final rule could be stricter.
The agency estimates that the new regulation would by 2025 prevent from 320,000 to 960,000 asthma attacks in children, and from 330,000 to 1 million missed school days. It also estimates that by 2025 the rule would prevent 750 to 4,300 premature deaths, 1,400 to 4,300 asthma-related emergency room visits and 65,000 to 180,000 missed workdays.
The regulation would come with a high cost to industry, which the E.P.A. estimates would be $3.9 billion in 2025, using a standard of 70 parts per billion. The cost would be $15 billion in 2025 at a standard of 65 parts per billion. (The E.P.A. chose 2025 as an example because that is when the agency expects the regulation to be fully in force.)
The agency estimates that the economic benefits of the rule – measured in avoided asthma attacks, heart attacks, missed school and work days and premature deaths – would significantly outweigh the costs. It calculates the benefits at $6.4 billion to $13 billion annually in 2025 for a standard of 70 parts per billion and $19 billion to $38 billion annually in 2025 for a standard of 65 parts per billion.
“Bringing ozone pollution standards in line with the latest science will clean up our air, improve access to crucial air quality information, and protect those most at-risk,’’ the E.P.A. administrator, Gina McCarthy, said in a statement. “It empowers the American people with updated air quality information to protect our loved ones — because whether we work or play outdoors – we deserve to know the air we breathe is safe.”
Public health groups have lobbied the government for years to rein in ozone emissions and said the regulation was one of the most important health decisions Mr. Obama could make in his second term.
But industry groups say that the regulation would impose unwieldy burdens on the economy, with little public health benefit.
“Air quality has improved dramatically over the past decades, and air quality will continue to improve under the existing standards,” said Howard Feldman, director of regulatory affairs for the American Petroleum Institute, which lobbies for the oil industry. “The current review of health studies has not identified compelling evidence for more stringent standards, and current standards are protective of public health.”
The proposed ozone rule comes as the longstanding battle over Mr. Obama’s use of the Clean Air Act to push his environmental agenda is erupting in Congress and the courts. The ozone rules are expected to force the owners of power plants and factories to install expensive technology to clean the pollutants from their smokestacks.
Next year, the E.P.A. is expected to make final two more historic Clean Air Act rules aimed at cutting planet-warming greenhouse gas emissions from coal-fired power plants. Those rules, which are intended to curb pollutants that contribute to climate change, could lead to the shutdown of hundreds of power plants and freeze construction of future coal plants.
The Republican-majority Congress, to be led by Senator Mitch McConnell of Kentucky, the incoming majority leader, has vowed to block or overturn the entire group of rules. In a separate development, the Supreme Court on Tuesday agreed to take up a challenge led by industry groups against another E.P.A. rule intended to curb emissions of mercury from coal plants.
“We’re facing a series of regulations, and the cumulative cost of compliance and the burden of permitting is significant,” said Cal Dooley, president of the American Chemistry Council, a group which has lobbied aggressively against the rules. “An industry such as ours is poised to make significant investments in growth, but these regulations make that harder.”
The standard for ozone was last set in 2008 by the Bush administration at a level of 75 parts per billion, above the range of 60 to 70 parts per billion recommended by the E.P.A.’s scientific advisory panel at the time, although never enacted. Environmental and public health groups challenged the Bush standard in court, saying it would endanger human health and had been tainted by political interference. Smog levels have declined sharply over the last 40 years, but each incremental improvement comes at a significant cost to business and government.
The E.P.A. had planned to release the new ozone rule in August of 2011, but as Republicans and powerful industry groups prepared to go on attack against the plan, Mr. Obama decided to delay its release, fearing that opposition to the regulation would hurt his re-election chances in 2012.
At the time, Mr. Obama said the regulation would impose too severe a burden on industry and local governments at a time of economic distress.
Environmental advocates, who took the delay as a setback, then sued the Obama administration, and earlier this year a federal judge ordered the E.P.A. to release the rule by Dec. 1.