March 15, 2005
The Clean Air Mercury Rule
- On March 15, 2005, EPA issued the first-ever federal rule to
permanently cap and reduce mercury emissions from coal-fired power plants.
This rule makes the United States the first country in the world to regulate
mercury emissions from coal-fired power plants.
- The Clean Air Mercury Rule will build on EPA’s Clean
Air Interstate Rule (CAIR) to significantly reduce emissions from coal-fired
power plants -- the largest remaining sources of mercury emissions in
the country. When fully implemented, these rules will reduce utility
emissions of mercury from 48 tons a year to 15 tons, a reduction of nearly
- CAIR and the Clean Air Mercury Rule are important components
of the Bush Administration’s plan to improve air quality. The Administration
remains committed to working with Congress to help advance the President’s
Clear Skies legislation in order to achieve greater certainty and nationwide
emission reductions, but believes the U.S. needs regulations in place
- EPA believes it makes sense to address mercury, SO2 and NOx
emissions simultaneously through CAIR and the Clean Air Mercury
Rule. These rules will protect public health and the environment without
with the steady flow of affordable energy for American consumers
- The Clean Air Mercury Rule establishes “standards of
performance” limiting mercury emissions from new and existing coal-fired
power plants and creates a market-based cap-and-trade program that will
reduce nationwide utility emissions of mercury in two distinct phases.
The first phase cap is 38 tons and emissions will be reduced by taking
advantage of “co-benefit” reductions – that is, mercury
reductions achieved by reducing sulfur dioxide (SO2) and nitrogen oxides
(NOx) emissions under CAIR. In the second phase, due in 2018, coal-fired
power plants will be subject to a second cap, which will reduce emissions
to 15 tons upon full implementation.
- New coal-fired power plants (“new” means construction
starting on or after Jan. 30, 2004) will have to meet stringent new source
performance standards in addition to being subject to the caps.
- Mercury is a toxic, persistent pollutant that accumulates
in the food chain. Mercury in the air is a global problem. While
fossil fuel-fired power plants are the largest remaining source of human-generated
mercury emissions in the United States, they contribute only
amount (about 1 percent) of total annual mercury emissions worldwide.
- EPA’s modeling shows that CAIR will significantly reduce
the majority of the coal-fired power plant mercury emissions that deposit
in the United States, and those reductions will occur in areas where
mercury deposition is currently the highest. The Clean Air Mercury Rule
is expected to make additional reductions in emissions that are transported
regionally and deposited domestically, and it will reduce emissions that
contribute to atmospheric mercury worldwide.
Mercury Emissions: A Global Problem
- Mercury emitted from coal-fired power plants comes
from mercury in coal, which is released when the coal is burned.
While coal-fired power plants are the largest remaining source
of human-generated mercury emissions in the United States, they
contribute very little to the global mercury pool. Recent estimates
of annual total global mercury emissions from all sources -- both
natural and human-generated -- range from roughly 4,400 to 7,500
tons per year. Human-caused U.S. mercury emissions are estimated
to account for roughly 3 percent of the global total, and U.S.
coal-fired power plants are estimated to account for only about
- EPA has conducted extensive analyses on mercury emissions
from coal-fired power plants and subsequent regional patterns of deposition
to U.S. waters. Those analyses conclude that regional transport of mercury
emission from coal-fired power plants in the U.S. is responsible for
very little of the mercury in U.S. waters. That small contribution will
be significantly reduced after EPA’s Clean Air Interstate Rule
and Clean Air Mercury Rule are implemented.
- U.S. coal-fired power plants emit mercury in three different forms:
oxidized mercury (likely to deposit within the U.S.); elemental mercury,
which travels hundreds and thousands of miles before depositing to land and
water; and mercury that is in particulate form.
- Because mercury can be transported thousands of miles
in the atmosphere, and because many types of fish are caught and sold
globally, effective exposure reduction will require reductions in global
- The United States is leading an effort within the United
Nations Environment Programme to create a program that would establish
partnerships designed to help developing countries reduce mercury emissions.
The partnerships will leverage resources, technical expertise, technology
transfer, and information exchanges to provide immediate effective
action that will result in tangible reductions of mercury use and emissions.
It accelerates the work of the UNEP Mercury program, originally proposed
by the U.S. at the 2003 UNEP Governing Council meeting.
Mercury and Fish
- Concentrations of mercury in the air are usually low. However,
atmospheric mercury falls to Earth through rain, snow and dry deposition
and enters lakes, rivers and estuaries. Once there, it can transform
into, methylmercury, and can build up in fish tissue.
- Americans are exposed to methylmercury primarily by eating
contaminated fish. Because the developing fetus is the most sensitive
to the toxic effects of methylmercury, women of childbearing age are
regarded as the population of greatest concern. Children who exposed
to methylmercury before birth may be at increased risk of poor performance
on neurobehavioral tasks, such as those measuring attention, fine motor
function, language skills, visual-spatial abilities and verbal memory.
Revision of December 2000 Finding
- Also on March 15, 2005, in a separate but related action,
EPA revised and reversed its December 2000 finding that it was “appropriate
and necessary” to regulate coal- and oil-fired coal-fired power
plants under section 112 of the Clean Air Act. We are taking this action
because we now believe that the December 2000 finding lacked foundation
and because recent information demonstrates that it is not appropriate
or necessary to regulate coal- and oil-fired utility units under section
- EPA nevertheless believes it is important to regulate mercury
emissions from coal-fired power plants. For that reason EPA has signed
two complementary rules – CAIR and the Clean Air Mercury Rule,
issued under sections 110(a)(2)(D) and 111 of the law, respectively.
These rules will allow us to more effectively limit mercury emissions
from these plants.
Cap and Trade Basics
- Today’s rule establishes a cap-and-trade system
for mercury that is based on EPA’s proven Acid Rain Program.
The Acid Rain Program has produced remarkable and demonstrable results,
reducing SO2 emissions faster and at far lower costs than anticipated,
and resulting in wide-ranging environmental improvements.
- In the Clean Air Mercury Rule, EPA has assigned each state and two
tribes an emissions “budget” for mercury, and each state
must submit a State Plan revision detailing how it will meet its budget
for reducing mercury from coal-fired power plants. Two tribes that have
coal-fired power plants that will be affected by this rule also have
been assigned a mercury emissions budget.
- Today’s rule includes a model cap-and-trade program that states
can adopt to achieve and maintain their mercury emissions budgets. States
may join the trading program by adopting the model trading rule in state
regulations, or they may adopt regulations that mirror the necessary
components of the model trading rule.
- Although states and tribes are not required to adopt the EPA-administered
cap-and-trade program, the Agency believes most will do so. The state
and tribal emission budgets are permanent, regardless of growth in the
- The mandatory declining emissions caps in the Clean Air Mercury
Rule, coupled with significant penalties for noncompliance, will ensure
that the rule’s mercury reduction requirements are achieved and
sustained. At the same time, stringent emission monitoring and reporting
requirements ensure that monitored data are accurate, that reporting
is consistent among sources – and that the emission reductions
occur. The flexibility of allowance trading creates financial incentives
for coal-fired power plants to look for new and low-cost ways to reduce
emissions and improve the effectiveness of pollution control equipment.
The Benefits of Cap-and-Trade Regulation over MACT
- For both a cap-and-trade system and a MACT, emissions limits
are established and must be achieved.
- However, under a cap-and-trade system reductions and caps
emissions are capped permanently and nationwide emissions can only
go down. The ability to bank unused allowances for future use can lead
early reductions of mercury. A trading approach is forward-looking
in its assessment of technology because it provides a continuous incentive
for technology innovation.
- A traditional Section 112(d) MACT approach sets standards
based on technology performance. Each plant subject to a MACT must
meet a specific emissions limit. However, benefits of MACT are not always
permanent: With shifts in coal use and with economic growth, nationwide
emission reductions could erode over time. In addition, a MACT
would not create as much continuous incentive for the development
of new mercury control technology.
For More Information
- More information about mercury, EPA’s efforts to
reduce mercury emissions, and today’s rule is available at www.epa.gov/mercury.