The agency predicted the rule would prevent about 14,000 to 36,000 premature deaths a year.
The rule would overturn and toughen rules issued during the administration of President George W. Bush.
More than a dozen states, along with environmental groups, sued the EPA several years ago, contending that the Bush administration ignored science and its own specialists when it decided in 2006 not to lower the nearly decade-old soot standard.
A federal judge threw out the Bush rule in 2008, but an appeals court later reinstated it, while ordering the EPA to make changes that better explain how the rule protects public health.
Lisa Jackson, EPA administrator, said the rule signed yesterday should improve air quality and public health in a broad swath of states, from New England down to Florida, over to Texas, and up to Minnesota.
“We’re working to limit pollution at its source, rather than waiting for it to move across the country,’’ Jackson said in a statement.
The proposed reductions should save more than $120 billion a year in avoided health costs and sick days and save thousands of lives each year, Jackson said.
Those benefits would far outweigh the estimated $2.8 billion annual cost of compliance, she said.
Environmental groups hailed the tougher rules as a step toward taming pollution from coal-fired power plants and solving the problem of one state’s emissions harming residents in other states.
But industry groups said it will boost power prices and force many older coal-fired power plants to be closed.
Senator Tom Carper, a Democrat from Delaware, said the new rules will clean the air in Delaware and other Eastern states.
“As those of us who live in Delaware and other so-called tail pipe states on the East Coast know all too well, air pollution knows no boundaries,’’ Carper said.
Even as Delaware has worked to clean its air, “pollution from neighboring states has adversely affected the health of Delawareans for too long just by virtue of our location,’’ he said.
