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Sustainable Energy and Economic Development

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Mercury Protections

Part I.   Regulatory Background:

The Clean Air Act mandates that each and every power plant curb its emissions to reflect levels achievable by the "maximum achievable control technologies" (MACT).

  • In 1990, Congress directed the EPA Administrator to perform a study and report to Congress the hazards to public health reasonably anticipated to occur as a result of emissions by electric utilities. Section 112(n) of the 1990 Clean Air Act Amendments mandates that "EPA shall regulate electric utility...units under this section [112], if the Administrator finds such regulation is appropriate and necessary after considering the results of the study..." 1
  • EPA completed that study and others by 1998, five years after EPA’s deadline under the Act.2 EPA determined that even after other requirements of the Act, such as the Acid Rain program in Title IV, toxic pollution still posed a hazard to public health such that it was "appropriate and necessary" to justify regulating power plants’ emissions of hazardous air pollutants (HAPs). 3 The studies showed that mercury pollution causes severe health threats to fetuses and children by way of maternal consumption of contaminated fish 4; it also found that utilities are the largest domestic source of mercury emissions. 5
  • In November 1998, EPA signed a court-approved settlement establishing a deadline for the Agency to determine, by December 2000, whether the regulation of hazardous air pollutants from power plants under Section 112 was "appropriate and necessary." The settlement was further amended to set a deadline of December 15, 2003 for issuing proposed MACT rules and December 15, 2004 for a final rule.
  • In December 2000, EPA said that mercury is the power plant hazardous air pollutant of greatest concern. The Agency determined that "…regulation of HAP emissions from coal- and oil-fired steam generating units under Section 112 (c) of the CAA is appropriate and necessary." 6 Listing of power plants under 112 (c) triggers regulation under Section 112 (d), requiring that all HAPs emitted by major sources in listed industrial categories be regulated using a "maximum achievable control technologies" standard (MACT). 7

Part II.   EPA’s Undermining of the Clean Air Act:

What the mercury standard should be: In 2001, EPA’s own scientists said that under the Clean Air Act, power plants could achieve 90 percent mercury reductions from power plants by 2008 using existing technologies.

  • In December 2000, EPA said that mercury is the hazardous air pollutant (HAP) of greatest concern and determined that "…regulation of HAP emissions from coal- and oil-fired steam generating units under Section 112 (c) of the CAA is appropriate and necessary." 8 Listing of power plants under 112 (c) triggers regulation under Section 112 (d), which requires that all HAPs from sources listed be regulated using a "maximum achievable control technologies" standard. 9
  • Under a Section 112 (d) "maximum achievable control technologies" (MACT) standard, at minimum, new sources must achieve the same emissions rate as is achieved by the best-controlled similar source in the industry.10 Existing sources’ emissions rates must be set at a level based on the average of the best performing 12 percent of existing sources. 11 This is known as "the regulatory floor." EPA can go "beyond the floor" where greater reductions are achievable – in other words, the Agency is authorized to regulate industrial sources more stringently than the floor, but no less. 12
  • In 2001, EPA estimated that coal-fired power plants can achieve an average of 90 percent mercury reductions under a MACT standard, regardless of the type of power plant or the type of coal burned. Under such a standard, domestic coal-fired power plant mercury emissions would be reduced from 48 tons per year in 2000 to roughly 5 tons per year by 2008.13
  • From 2001 to 2003, a panel of experts convened by EPA met multiple times to consider this and other issues related to the development of a HAPs MACT standard for the electric power industry. That Working Group, as it is known, made recommendations to EPA concerning the MACT standard in the fall of 2002. EPA has all but ignored the panel’s work in putting together the current regulatory proposal.

What EPA is proposing: The Agency has put forward several proposals, none of which provides the degree of public health protections mandated by the Clean Air Act. All of the proposals will allow power plants to emit six to seven times more mercury into our environment compared with what the Act requires and what EPA has determined is achievable using existing technologies.

  • One proposal, EPA’s preferred, rescinds its prior determination that power plants must be regulated according to MACT levels and instead proposes a far weaker standard. In effect, this approach would regulate power plant mercury emissions as though mercury were a non-hazardous air pollutant.
    • The Clean Air Act requires certain air toxics to be controlled more strictly under Section 112 than conventional air pollutants like soot and smog. Mercury has been one such regulated air toxic since well before 1990; in fact, it was one of only eight air toxic pollutants for which EPA had developed pollutant-based rules prior to the 1990 Clean Air Act Amendments.14
    • Despite the fact that mercury has been a listed pollutant for more than 30 years (since 1971), and despite Congress’s clearly expressed concerns about mercury emissions from power plants,15 EPA is proposing to rescind its year 2000 determination that it is "necessary and appropriate" to regulate power plants as emitters of hazardous pollutants under Section 112.16 In effect, this approach would treat power plant mercury emissions as non-hazardous air pollution.
    • Under EPA’s preferred approach, new sources would be held to a lesser, Section 111 "best demonstrated technology" standard, as is done for conventional pollutants.17 The EPA approach for new and existing sources also would include "cap and trade guidelines." The cap and trade system would establish national and statewide budgets and allow sources to buy and sell allowances; in other words, one plant could emit less than the standard requires and sell credits to another plant in a completely different geographic location. This would exacerbate the problem of mercury "hot spots," or areas where there are documented higher levels of mercury in the local environment near power plants.
    • Under the proposed caps, instead of having to significantly limit mercury emissions by 2008, as is required by the MACT approach of Clean Air Act Section 112, power plants would be allowed to emit 34 tons of mercury per year during the years between 2010 and 2018 – six to seven times the amount of annual mercury emissions required by the Act’s MACT mandate. After 2018, power plant sources would be allowed to emit 15 tons per year, three times more than EPA itself said was achievable in the near term (by 2008) under the MACT standard using existing technologies.18

  • EPA’s other alternative proposal is put forward as a MACT standard, developed under the authority of section 112 of the Act. However, the levels EPA is proposing are far less stringent than is required by the statute’s MACT mandate.
    • EPA’s proposals would allow more than six to seven times (34 tons) more mercury than EPA estimates of what is achievable for the next decade.19
      • One EPA proposed option not only allows more than six to seven times more mercury than what is achievable for the next decade, but also allows emissions trading, increasing the likelihood and severity of mercury hot spots.20

    • In determining the proposed "floor," EPA proposes to subcategorize by type of coal before it determines the MACT.21 This means that especially dirty facilities need only clean up to the levels now achieved by facilities within the same dirty subcategory.
    • EPA employs a series of data manipulations to further weaken the standards and allow more mercury into the air. For example, beyond considering the average performance of the top twelve percent of power plants, EPA proposes to apply a "variability analysis." This raises the emission limits based on the Agency’s uncertainty about how much mercury will actually be captured by control technologies given the various physical properties of the coal that is actually burned. EPA allows the variability factors it has developed to swallow the MACT floors. For example, for existing units that burn a bituminous coal, EPA reports a floor for existing units at a level of 0.118 lb/TBtu. EPA’s variability factors, however, raise this to a 2.0 lb/TBtu standard, an increase by a factor of 17. 22
    • EPA dismissed, out of hand, all technologies and work practices that could achieve beyond-the-floor reductions, 23 even though several studies indicate that existing technologies could affordably achieve great mercury reductions.24

  • In addition, EPA only proposes standards for regulating nickel and mercury,25 even though the Clean Air Act requires EPA to regulate all hazardous emissions from power plants.26 Power plants are the largest source of toxic air chemicals.27


1 42 U.S.C. § 7412 (2000).
2 See e.g., U.S. Environmental Protection Agency, 1997 Mercury Study Report to Congress, EPA-452/R-97-003, December 1997, available at
3 EPA-452/R-97-003, 79830 (Dec. 20, 2000).
4 Id. at 79829.
5 Id.
6 Id. at 79825.
7 42 U.S.C. § 7412 (d)(1); see also National Lime Ass’n v. EPA, 233 F.3d 625, 633 (D.C. Cir. 2000).
8 EPA-452/R-97-003, 79825 (Dec. 20, 2000).
99 42 U.S.C. § 7412 (d).
10 Id.
11 Id.
13 U.S. EPA, December 4, 2001 (supplementary presentation for EEI on mercury), page 6, located at
14 See S. Rep. No. 101-228 (1989) at 131 (noting that mercury is hazardous enough that it was even listed under the air toxics scheme in place between 1970 and 1990; during that period, "EPA has listed only 8 pollutants: mercury, beryllium, asbestos, vinyl chloride, benezene [sic], radionuclides, inorganic arsenic,and coke oven emissions.")
15 Id.
16 69 Fed. Reg. 4652, 4682 (January 30, 2004).
17 Id. at 4689.
18 Id . at 4698.
19 Id. at 4661.
20 Id. at 4661.
21 Id. at 4666.
22 Id. at 4673.
23 Id. at 4679.
24 See e.g., Northeast States for Coordinated Air Use Management, Mercury Emissions From Coal -Fired Power Plants, The Case for Regulatory Action (Oct. 2003), available at
25 Id. at 4660.
26 42 U.S.C. § 7412 (d).
27 Clear The Air, Toxic Neighbors, (October, 2003); see also National Lime Ass’n v. EPA, 233 F.3d 625, 633 (D.C. Cir. 2000).


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