April 11, 2022 \u2013 The Emmett Environmental Law & Policy Clinic submitted comments today on behalf of a group of leading scientists supporting the Environmental Protection Agency\u2019s (EPA) proposal to reaffirm earlier findings underlying the agency\u2019s regulation of mercury and other toxic air pollutant emissions from coal-fired power plants.<\/p>\n
The Clinic filed the comments on behalf of Elsie Sunderland, Charles Driscoll, Jr., Joel Blum, and Celia Chen\u2014leading experts in the atmospheric transport, aquatic fate, bioaccumulation, human exposures, and health outcomes associated with mercury contamination of the environment.\u00a0 Emmett Clinic Acting Director Shaun Goho wrote the comments in collaboration with Clinical Fellow Tommy Landers.<\/p>\n
EPA regulates emissions of toxic air pollutants such as mercury under section 112 of the Clean Air Act.\u00a0 When Congress amended the Act in 1990, it directed EPA to set emissions standards for all major sources of 189 toxic air pollutants under a strict timeline.\u00a0 The one exception was emissions from coal-fired power plants.\u00a0 In those same 1990 amendments, Congress had created the acid rain cap-and-trade program\u2014which applied only to coal-fired power plants\u2014and Congress anticipated that the controls installed by power plants to reduce sulfur dioxide emissions might also reduce emissions of mercury and other air toxics.\u00a0 Therefore, Congress instructed EPA to determine whether it was \u201cappropriate and necessary\u201d to regulate power plant emissions under section 112 after taking into account the effect of the acid rain program.<\/p>\n
In the end, power plants largely complied with the acid rain program by switching to low-sulfur coal, and coal-fired power plants remained the leading source of mercury emissions in the United States.\u00a0 EPA therefore determined in 2000 that it was appropriate and necessary to regulate toxic air pollutant emissions from power plants.\u00a0 It confirmed this finding in 2012 and imposed emissions standards at that time.\u00a0 All coal-fired power plants have been in compliance with those standards since 2019.<\/p>\n
Nevertheless, in 2019, EPA proposed to reverse its prior findings and conclude that it was not \u201cappropriate\u201d to regulate these emissions.\u00a0 On behalf of several scientists (including the signatories of the comments filed today), the Clinic filed comments opposing the 2019 proposal for several reasons.\u00a0 Overall, the Clinic argued that EPA based its proposal on (i)\u00a0outdated and very incomplete data on benefits and (ii) an over-emphasis on previously predicted compliance costs, even though the actual costs were about one tenth of the predicted costs.\u00a0 In 2020, EPA finalized its finding that the mercury and air toxics standards were no longer \u201cappropriate.\u201d<\/p>\n
Earlier this year, EPA proposed to revoke that 2020 decision and reaffirm that regulating mercury and air toxics is \u201cappropriate and necessary.\u201d\u00a0 The Clinic\u2019s comments filed today stated strong support for the latest proposal.\u00a0 While the comments also identify areas for improvement in the scientific analysis and benefits quantification \u2013 including using a state-of-the-science assessment of mercury deposition attributable to power plants, and considering how power plants\u2019 emissions affect individuals\u2019 cumulative exposure to mercury \u2013 any such improvements would only strengthen the \u201cappropriate and necessary\u201d finding.<\/p>\n