The U.S. Environmental Protection Agency has set more stringent new air-quality standards for sulfur dioxide (SO₂). In a final regulation announced on June 3, EPA is jettisoning the current standard, which is 140 parts per billion over 24 hours, in favor of a one-hour, 75-ppb level.

The estimated cost to fully implement the new standard by 2020 is $1.5 billion, EPA says.

The agency says the new one-hour standard will protect public health by reducing exposure to high short-term concentrations of SO₂, which is commonly emitted from powerplants and industrial facilities.

EPA also is revising ambient-air monitoring requirements for SO?. States will be required to have monitors in place that meet the network design regulations for the new one-hour standard by Jan. 1, 2013.

Sen. Tom Carper (D-Del.), chairman of the Subcommittee on Clean Air and Nuclear Safety, praised the EPA SO₂ announcement but said that new legislation addressing powerplant emissions also is needed.