Massachusetts last week adopted the nation’s most stringent controls on mercury emissions from coal-fired power plants. Under the two-phase regulation, the state’s four coal-fired power plants must capture at least 85% of their mercury releases by 2008 and 95% by 2012. Because the plants already capture some mercury in pollution control equipment for sulfur dioxide and nitrogen oxides, the net effect of the regulation will be to cut their mercury emissions by 50% as of 2008 and 85% by 2012, says the Massachusetts Department of Environmental Protection. The regulation ultimately will reduce mercury emissions in the state by about 155 lb per year. The Massachusetts regulation is far more ambitious than a national mercury standard for power plants recently proposed by the Bush Administration. That EPA proposal, which state environmental officials say is too weak, would cut mercury emissions from coal-fired power plants either 29% by 2007 or 69% by 2018 (C&EN, May 3, page 7).