In Coming Utility MACT, EPA Has Clean Air Act Authority to Make Big Strides in Protecting Americans from Mercury Pollution

By Wednesday of next week, EPA is due to publish its long-anticipated rule controlling mercury emissions from coal-fired utilities.  This is how we ought to judge the rule: does it follow the mandate of the Clean Air Act (CAA)? For too long, utilities have managed by various means to fend off regulation required by the CAA. Assuming EPA’s rule at long last complies with Congress’s directives, Americans may look forward to a day when they can again eat fish without serving their families a side of methylmercury. 

The mercury that coal-fired utilities emit is highly toxic to humans. Exposure to even small amounts of methylmercury can lead to irreversible neurological damage. Methylmercury's neurodevelopmental effects place the developing fetus, children, and adults up to age 20 at particular risk. The most recent data also suggest adverse effects on the cardiovascular systems of adults. Mercury emitted to the air from coal plants and other sources gets deposited to surrounding land and waters; it makes its way into fish tissue in the form of methylmercury. The primary route of human exposure to methylmercury is through consumption of fish. 

The saga of federal regulation of mercury emissions from coal-fired utilities is long and lamentable. Although the CAA Amendments of 1990 seemed to portend more determined efforts to reduce emissions of this potent neurodevelopmental toxin, utilities have successfully forestalled any federal requirements that they reduce their mercury pollution. The Bush Administration even attempted to remove utilities from the list of sources whose toxics emissions are to be regulated under section 112 of the CAA – an attempt the D.C. Circuit threw out in 2008. Utilities remain the single largest unregulated source of mercury emissions in the United States today; they contribute some 40% of U.S. mercury emissions. 

While two decades came and went, mercury emissions continued.

What's at Stake

With widespread mercury contamination in the nation’s lakes and rivers, agencies have issued increasing numbers of fish consumption advisories. By the most recent tally, all 50 states, one U.S. Territory, the District of Columbia, and several tribes have issued advisories placing some or all of their waters off limits for those who would eat the fish they catch. As of 2008, 43 percent of lake acres and 39 percent of total river miles within the United States’ borders are under advisories for mercury. In addition, 100 percent of Lakes Superior, Michigan, Huron, and Erie and significant stretches of coastal waters are under advisories. The number and extent of advisories have increased steadily for the past 15 years. 

Human bodies, too, became increasingly burdened – though not equally so. According to a recent study, one in ten women of childbearing age in the United States has a blood mercury level that would put a developing fetus at risk. This figure nearly triples for women who designated their ethnicity as “other” (i.e., who are Native American, Asian American, or from the Pacific or Caribbean Islands) – fully 27.4 percent of women of childbearing age in this group have blood mercury concentrations above levels determined by the EPA to pose a risk to those exposed in utero.

The States Step in, and an Industry Innovates

While the mercury saga was playing out at the federal level, however, states and tribes tired of its sorry plot – a story line that threatened the health and capabilities of their children; that undermined tribal fishing rights; and that needlessly contaminated an available and inexpensive source of food in trying economic times. And more than one-third of the states enacted their own mercury regulations. The specifics vary from state to state, but in every case, they required substantial emissions reductions, and quickly. New Jersey required 90% reductions by 2007. Massachusetts mandated 85% reductions by 2008 and then 95% reductions by 2012. Illinois required 90% reductions by 2009. 

Now, EPA is required under the terms of a consent decree to issue a proposed National Emission Standard for Hazardous Air Pollutants (NESHAP) regulating mercury and other hazardous air pollutants by March 16, 2011, and to issue the final rule by November 16, 2011. Under section 112 of the CAA, EPA is to apply a technology-based standard to require emissions reductions at a level keyed to the best performing sources in a source category – commonly referred to as “maximum achievable control technology” or “MACT” standards. Specifically, the process of setting a MACT standard for a given source category requires two steps: a “MACT floor,” determination and a “beyond-the-floor” analysis. In setting the MACT floor, EPA is required to determine the level of emissions reductions for existing sources that “shall not be less stringent than the average emission limitation achieved by the best performing 12 percent of the existing sources” and for new sources that “shall not be less stringent than the emission control that is achieved in practice by the best controlled similar source.” This floor thus establishes the minimum degree of stringency for the emissions standards; the EPA then considers whether control is appropriate beyond this minimum. In undertaking the beyond-the-floor analysis, EPA is directed to “take into consideration” costs, non-air quality health and environmental impacts, and energy requirements. Notably, costs are to be taken into account only in the second step, i.e., the beyond-the-floor analysis – costs don’t enter directly into a determination of the MACT floor at all.

One consequence of the various regulations at the state level is that mercury emissions control technologies such as Activated Carbon Injection (ACI) have been successfully implemented by a number of utilities across the nation. And, according to a 2009 study by the Government Accountability Office (GAO), these control technologies are enabling sources to obtain mercury emissions reductions as high as 99%. Moreover, reductions on the order of 90% have been achieved by plants firing different types of coal (i.e., bituminous, sub-bituminous, lignite) and employing a variety of configurations.  Indeed, according to data supplied by utilities as part of EPA’s Information Collection Request for the rule, plants firing each of the different types of coal have in fact opted to apply ACI to control their mercury emissions (see the convenient table of this data from page 8 of the American Lung Association's recent report). As I have argued here before, this degree of control should have been facilitated under the CAA long ago. Putting the larger lessons to the side for the moment, this evidence also has implications for EPA’s immediate task.

What to Expect from EPA’s MACT

With a congressional directive that the MACT floor be keyed to the best performers, and with those performers able to achieve considerable mercury emissions reductions, EPA’s task is fairly straightforward. EPA should do now what it should have done years ago: issue a MACT standard that complies with the CAA.

This doesn’t mean that the utilities won’t have pushed EPA for still further concessions and won’t continue to do so after next week's announcement.

First, there is the matter of subcategorization. Under the CAA, EPA has the authority to divide categories of sources, such as utilities, into subcategories. This authority is meant to allow EPA to account for differences among sources within a category that would render a single standard unworkable. Industry generally favors subcategorization, given that a category of sources can be sliced and diced in ways that mean that the worst performers don’t end up grouped along with the best performers. By this device, Congress’ intention that the laggards be prodded to catch up, at least to the level of emissions reduction that the best of their peers are managing, is flouted. Yet the evidence amassed by the GAO suggests that significant reductions in mercury emissions are achievable across coal-fired sources using even differed types of coal. EPA should be judicious in its use of its authority to subcategorize.

Second, there is the possibility of extensions or other delay tactics. Under the CAA, sources are required to comply with a MACT standard within three years. But the EPA (or other permitting authority) is also authorized to grant a one-year extension. Any delay, of course, would simply prolong the harms that have been accruing as the months and years are ticked off, with no federal regulation of this major source of mercury pollution (see CPR's white paper from 2009 on the human costs of delay in this and other protracted rulemakings). Here too, EPA ought to hold the line, say “enough is enough,” and use the authority granted it by Congress to stem the injuries to Americans’ health.

If EPA takes seriously its statutory duties, the rule it proposes for utilities will make a real difference – it will help make it safe for Americans to put fish on their tables.