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Clean Air Markets

Progress Report

Emission Reductions

The Acid Rain Program (ARP) and Clean Air Interstate Rule (CAIR) programs significantly reduced sulfur dioxide (SO₂), annual nitrogen oxides (NOₓ), and ozone season NOₓ emissions. These reductions occurred while electricity demand (measured as heat input) remained relatively stable, indicating that the emission reductions were not driven by decreased electric generation.

These emission reductions are a result of an overall increase in the environmental efficiency of these sources as power generators installed controls, ran their controls year-round, switched to lower emitting fuels, or otherwise reduced their SO₂ and NOₓ emissions while meeting relatively steady electricity demand. Most of the emission reductions since 2005 are from early reduction incentives and stricter emission cap levels under CAIR.

SO₂ Trends

SO₂ Emission Trends
SO₂ Emissions from CAIR and ARP Sources, 1980–2014
SO₂ State-by-State
State-by-State SO₂ Emissions from CAIR and ARP Sources, 1990–2014
SO₂ Emissions and Heat Input
Comparison of SO₂ Emissions and Heat Input for CAIR and ARP Sources, 2000–2014

Annual NOₓ Trends

NOₓ Annual Program Emission Trends
Annual NOₓ Emissions from CAIR and ARP Sources, 1990–2014
NOₓ Annual Program State-by-State
State-by-State Annual NOₓ Emissions from CAIR and ARP Sources, 1990-2014
NOₓ Annual Program Emissions and Heat Input
Comparison of Annual NOₓ Emissions and Heat Input for CAIR and ARP Sources, 2000–2014

CAIR Ozone Season NOₓ Trends

NOₓ Ozone Season Emission Trends
Ozone Season NOₓ Emissions from CAIR and NBP Sources, 1990-2014
NOₓ Ozone Season State-by-State
State-by-State Ozone Season NOₓ Emissions from CAIR Sources, 2000–2014
NOₓ Ozone Season Emissions and Heat Input
Comparison of Ozone Season NOₓ Emissions and Heat Input for CAIR NOₓ Ozone Season Source, 2000–2014

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