Reducing Toxic Pollution 

from Power Plants

February 8, 2012

Final Mercury and Air Toxics Standards (MATS)

Janet McCabe

Deputy Assistant Administrator

EPA Office of Air and Radiation
Overview of Action

• On December 16, EPA finalized the Mercury and Air Toxics Standards, the first 

national standards to reduce emissions of mercury and other toxic air pollutants from 

new and existing coal- and oil-fired power plants

• Standards will reduce emissions of:

• Metals, including mercury (Hg), arsenic, chromium, and nickel

• Acid gases, including hydrogen chloride (HCl) and hydrogen fluoride (HF)

• Particulate matter

• Air toxic pollutants are linked to cancer, IQ loss, neurological damage, heart disease, 

lung disease and premature death

• Standards create uniform emissions-control requirements based on proven, currently 

in-use technologies and processes

• For more information on these Mercury and Air Toxics Standards: 

http://www.epa.gov/mats

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Power plants are big emitters of 

toxic pollutants

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Sources: Portion of pollution -- NEI Trends Data (2009) and IPM (2010) (SO2, NOX); MATS rule modeling platform, based on inventory used for 

2005 NATA (Hg); Inventory used for 2005 NATA (other toxics). Percent of units: EPA Base Case v. 4.10 PTR 

Portion of US air pollution 

that comes from power plants

• Uncontrolled releases of mercury from power 

plants damage children’s developing nervous 

systems, which can reduce their IQ and impair 

their ability to think and learn 

• Mercury and many of the other toxic pollutants 

also pollute our nation’s lakes and streams, and 

contaminate fish

• Other metals such as arsenic, chromium, and 

nickel can cause cancer 

• Acid gases cause lung damage and contribute to 

asthma, bronchitis and other chronic respiratory 

disease, especially in children and the elderly 

• Particles cause premature death, increased 

numbers of hospital admissions and emergency 

department visits, and development of chronic 

respiratory disease.
Power Plants Are the Largest Remaining 

Source of Mercury Emissions in the U.S.

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Industrial 

Category

1990 

Emissions

tons per 

year (tpy)

2005 

Emissions

(tpy)

%

Reduction

Power 

Plants 59 53 10%

Municipal 

Waste 

Combustors

57 2 96%

Medical 

Waste 

Incinerators

51 <1 >98%

Source: EPA’s 2005 NATA Inventory Modified for the Toxics Rule 2005 Base 

Year (2010) 

• In 1990 three source categories 

made up approximately twothirds of total U.S. mercury 

emissions: municipal waste 

combustors, medical waste 

incinerators, and power plants

• Two of the three are now 

subject to federal emissions 

standards

• So are many other industries, 

such as cement plants and 

steel manufacturers

• Until today, more than 20 years 

after the 1990 CAA 

Amendments passed, there was 

no federal limit for toxic 

emissions – including mercury –

for coal- or oil-fired power plants
MATS covers approximately 1,400 coal- and 

oil-fired units > 25 MW at about 600 power 

plants nationwide

• Includes units that burn coal, coal refuse, oil, or a synthetic gas derived from coal either 

exclusively, in combination together, or in any combination with other supplemental fuels. 

Natural gas power plants are not affected by this rule

• MATS covers emissions of all hazardous air pollutants from power plants

• The rule sets standards for mercury, acid gases, non-mercury metal air toxics, and organic 

air toxics to limit emissions of these pollutants

• Most of these standards are numeric emissions limits; the standard for organic air 

toxics is a work practice standard

• In some cases, these standards are “surrogates” for a number of pollutants. (e.g. 

setting a numeric HCl emissions limit to control all acid gases)

• For many standards, sources can choose to meet the primary standard or an alternate 

standard. (e.g. MATS also sets a numeric SO2 emissions limit as an alternate 

surrogate for acid gases)

• The CAA requires EPA to set the emission standards for existing sources at a level that is 

at least as stringent as the emission reductions achieved by the average of the best 

performing 12% of sources in the category

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Adjustments Since Proposal

• EPA received approximately 900,000 public comments on MATS

• EPA used new information from the public comment process to adjust some 

aspects of the rule; the approach reductions in air toxics remain substantially the 

same

• As a result of additional data, changes include:

• Adjusted some emissions limits, including using filterable PM (instead of total 

PM) as a surrogate for the metal toxics limit

• Clarified the definition of coal subcategories 

• Added subcategories for non-continental oil-fired units and limited use oilfired units

• Simplified and improved monitoring provisions for clarity, consistency, and 

increased flexibility

• Provided an alternative compliance option for sources that plan to comply by 

averaging across multiple units 

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Timing

• EPA expects most facilities will comply with this rule through a range of 

strategies, including the use of existing emission controls, upgrades to existing 

emission controls, installation of new pollution controls, and fuel switching.

• Existing sources generally will have up to 4 years if they need it to comply with 

MATS.

• This includes the 3 years provided to all sources by the Clean Air Act. EPA’s 

analysis continues to demonstrate that this will be sufficient time for most, if 

not all, sources to comply. 

• Under the Clean Air Act, state permitting authorities can also grant an 

additional year as needed for technology installation. EPA expects this 

option to be broadly available.

• EPA is also providing a clear pathway for reliability critical units to obtain a 

schedule with up to an additional year to achieve compliance. This pathway is 

described in a separate enforcement policy document. The EPA believes there 

will be few, if any situations, in which this pathway will be needed.

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Any effect on future electricity costs will be 

small and within normal historical fluctuations

• The graph shows the effect 

MATS may have on future 

electricity prices. 

• The blue line shows 

historical electricity rates and 

what projected electricity 

rates would be without MATS 

(both from EIA). The green

line shows how cleaning up 

power plants under MATS 

may lead to a slight increase 

in these prices in the future. 

• However, the effect is small 

and keeps costs well within 

the normal historical 

fluctuation of electricity prices. 

• In fact, even with MATS, 

electricity rates are projected 

to stay below historical highs.

Sources: EIA Historical (Annual Energy Review – October 2011); EIA Projected (Annual Energy Outlook 2011 ); EPA 

modeling of projected price increases using the Integrated Planning Model.
Benefits of MATS Are Significant

• The final rule will: prevent 90 percent of the mercury in coal burned in power plants from 

being emitted to the air; reduce 88 percent of acid gas emissions from power plants; and cut 

41 percent of sulfur dioxide emissions from power plants beyond the reductions expected 

from the Cross State Air Pollution Rule

• Reduces mercury exposure from power plants for pregnant women and children, reducing the 

risk of damage to children’s developing nervous systems that can impair their ability to think 

and learn 

• Protects Americans from cancer and other health risks from exposure to metals such as 

arsenic, chromium, and nickel

• Prevents thousands of premature deaths each year by reducing the amount of dangerous 

fine particles in the air across the country 

• This includes neighborhoods near power plants and neighborhoods hundreds of miles 

away from the nearest power plant 

• Protects thousands of lakes and streams – and the fish that live there and the mammals and 

birds that eat them – by reducing mercury and acid rain pollution

• Provides employment for thousands of American workers building, installing, and operating 

the equipment to reduce emissions of mercury, acid gases, and other toxic air pollutants

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MATS Health Benefits in Detail

• The value of the improvements to health alone total $37 billion to $90 billion each year 

• The estimated annual costs of this final rule are $9.6 billion, about a billion dollars less 

than the proposed standards. This means that for every dollar spent to reduce this 

pollution, we will get $3-$9 in health benefits

• Each year the rule is fully implemented, the rule will prevent serious health effects, 

including:

• 4,200 – 11,000 premature deaths

• 4,700 heart attacks

• 130,000 asthma attacks

• 540,000 missed work or “sick” days

• Avoiding “sick days” saves companies and families money. It is particularly important for 

the millions of Americans whose jobs do not provide paid sick leave and who risk losing 

their jobs if they miss work too often

• The rule is also projected to annually prevent 5,700 hospital admissions and emergency 

room visits; 2,800 cases of chronic bronchitis; and 3.2 million days when people must 

restrict their activities each year

10 Source: EPA Regulatory Impact Analysis
MATS and Navajo Generating Station

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• EPA has committed to working with NGS to help MATS implementation go smoothly

• From the final MATS rule text:

“...EPA is sensitive to the commenters’ concerns and particularly recognizes the 

significance of Navajo Generating Station to the Central Arizona Project and the 

water delivery to tribes. As a result, EPA has been consulting with affected Indian 

tribes and working closely with other federal agencies, including the Department of 

the Interior, on these issues and intends to work with tribal and other authorities to 

ensure a smooth transition and address specific issues as they arise.”
MATS Implementation at NGS

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• EPA will continue to work with the Department of Interior, Salt River Project, and other 

plant owners as well as the Tribes that are affected by the plant operations to determine a 

reasonable path forward.

• EPA has had two conference calls with SRP since MATS was finalized to answer 

their questions about MATS implementation; we will continue to work with them as 

needed

• Gina McCarthy, Assistant Administrator for EPA Office of Air and Radiation, recently 

visited NGS