Proposed last Jan. 30, the first-ever rule to substantially curb mercury emissions from coal-fired power plants would cut mercury emissions by nearly 70 percent when fully implemented. On Feb. 24, the agency released a supplement that provides language for a model cap-and-trade approach.

The rule, also known as the Clean Air Mercury Rule, derives from a settlement agreement reached during the Clinton Administration in which the agency faced a deadline of last Dec. 15 to finalize a regulation. The plaintiff in the action has agreed to extend the deadline to allow time for additional comment. See www.epa.gov/air/mercuryrule/rule.htm