Air pollution can travel hundreds of miles and cause multiple health and environmental problems on regional or national scales, EPA noted in a presentation on the proposed rule. This proposal reduces emissions contributing to fine particle (PM_2.5) and ozone nonattainment that often travel across state lines.

The transport rule would reduce power plant emissions of sulfur dioxide (SO₂) and nitrogen oxides (N_Ox) to meet state-by-state emission reductions. By 2014, the rule and other state and EPA actions would reduce SO₂ emissions by 71% over 2005 levels. NO_x emissions would drop by 52%.

SO₂ and NO_x react in the atmosphere to form fine particle pollution and ground-level ozone (smog), which are linked to widespread illnesses and premature deaths. These pollutants are carried on the wind to other states, contributing to health problems for their residents and interfering with states’ ability to meet air quality standards.

The rule proposes a procedure for determining each upwind state’s control responsibility that EPA can apply to any revised air quality standard. Each time air pollution standards (NAAQS) are changed, if interstate pollution transport contributes to the air quality problem, EPA will evaluate whether new emission reductions will be required from upwind states.

The Clean Air Act requires states to submit plans to eliminate significant interstate pollution transport before they submit plans to meet ambient air quality standards. By determining the amount of emissions that upwind states must eliminate in advance of the time that state pollution transport plans are due, EPA says it will promote timely reductions in pollution transport. When downwind states design their plans to meet the air quality standards, they will know how much upwind state control is required.

Key elements of the proposal include:

• Twenty-eight states would be required to reduce both annual SO₂ and NO_x emissions. By reducing the emissions from the upwind states, the proposal would help downwind states attain air quality standards, specifically the 24-hour PM_2.5 standards established in 2006 and the 1997 annual PM_2.5 standards.

• Twenty-six states would be required to reduce NO_x emissions during the hot summer months of the ozone season because they contribute to downwind states’ ozone pollution. By reducing the emissions from the upwind states, the proposal would help downwind states’ attain air quality standards, specifically the 1997 ground-level ozone standard.

EPA is proposing one approach for reducing SO₂ and NO_x emissions in states covered by this rule and taking comment on two alternatives:

• In EPA’s preferred approach, EPA is proposing to set a pollution limit (or budget) for each of the 31 states and the District of Columbia. This approach allows limited interstate trading among power plants but assures that each state will meet its pollution control obligations.

• In the first alternative, EPA is proposing to set a pollution limit or budget for each state. This option allows trading only among power plants within a state.

• In the second alternative, EPA is proposing to set a pollution limit for each state and to specify the allowable emission limit for each power plant and allow some averaging.

To meet this proposed rule, EPA anticipates power plants will:

• Operate already installed control equipment more frequently;
• Use lower sulfur coal; or
• Install pollution control equipment such as low NO_x burners, Selective Catalytic Reduction, or scrubbers (Flue Gas Desulfurization).

EPA estimates the annual cost of compliance with the proposed rule at $2.8 billion in 2014. The cost is far outweighed by the estimated $120 billion in annual health benefits in 2014, including avoiding an estimated 14,000 to 36,000 premature deaths, 23,000 nonfatal heart attacks, 21,000 cases of acute bronchitis, 240,000 cases of aggravated asthma, and 1.9 million days when people miss school or work due to ozone- and particle pollution-related symptoms, according to EPA.

The transport rule also would help improve visibility in state and national parks and would increase protection for ecosystems that are sensitive to pollution, including streams in the Appalachians, lakes in the Adirondacks, estuaries and coastal waters, and red maple forests.

The proposal would replace and improve upon the 2005 Clean Air Interstate Rule (CAIR), which the US Court of Appeals for the DC Circuit ordered EPA to revise in 2008. The court allowed CAIR to remain in place temporarily while EPA works to finalize the replacement rule proposed today.

EPA will take public comment on the proposal for 60 days after the rule is published in the Federal Register. The agency also will hold public hearings. Dates and locations for the hearings will be announced shortly. The final rule is expected in Spring 2011.

Resources

• Proposed Transport Rule