On Tuesday, the Environmental Protection Agency disclosed its plan to reduce the emission of mercury, a highly toxic chemical. The plan was criticized by some environmental groups.

"This rule fails the most elementary test of sound public policy of protecting the public’s health by allowing toxic pollution to affect another generation rather than calling for meaningful cuts now," said Vickie Patton, a senior attorney for Environmental Defense in Colorado.

The EPA plans to reduce the annual tonnage of mercury by 10 tons by 2010, to 38 tons a year from last year’s 48 tons, and cut mercury’s emission to 15 tons a year in 2018.

"This rule marks the first time the United States has regulated mercury emissions from power plants. In doing so, we become the first nation in the world to address this remaining source of air pollution," said Steve Johnson, EPA’s administrator.

Mercury cuts are expected to protect the health of pregnant women and children, officials from the EPA say.