Progress Report
Emission Reductions
The Acid Rain Program (ARP) and Cross-State Air Pollution Rule (CSAPR) programs significantly reduced sulfur dioxide (SO₂), annual nitrogen oxides (NOₓ), and ozone season NOₓ emissions from power plants. Most of the emission reductions since 2005 occurred in response to the Clean Air Interstate Rule (CAIR), which was replaced by the CSAPR in 2015. The Mercury and Air Toxics Standards (MATS) set limits on the emissions of hazardous air pollutants from coal- and oil-fired electric utility steam generating units (EGUs) and have been one of the reasons for reductions in those emissions since 2010. This section covers changes in emissions at units affected by CSAPR, ARP, and MATS between 2018 and previous years.
Sulfur Dioxide (SO₂) Figures
![SO₂ Emissions from CSAPR and ARP Sources, 1980–2018](img/emissions_reductions_so2_f1_small.png)
![State-by-State SO₂ Emissions from CSAPR and ARP Sources, 1990–2018](img/emissions_reductions_so2_f2_small.png)
![Comparison of SO₂ Emissions and Generation for CSAPR and ARP Sources, 2000–2018](img/emissions_reductions_so2_f3_small.png)
Annual Nitrogen Oxides Figures
![Annual NOₓ Emissions from CSAPR and ARP Sources, 1990–2018](img/emissions_reductions_nox_f1_small.png)
![State-by-State Annual NOₓ Emissions from CSAPR and ARP Sources, 1990–2018](img/emissions_reductions_nox_f2_small.png)
![Comparison of Annual NOₓ Emissions and Generation for CSAPR and ARP Sources, 2000–2018](img/emissions_reductions_nox_f3_small.png)
Ozone Season Nitrogen Oxides Figures
![Ozone Season NOₓ Emissions from CSAPR Sources, 2005–2018](img/emissions_reductions_ozone_f1_small.png)
![State-by-State Ozone Season NOₓ Emissions from CSAPR Sources, 2000–2018](img/emissions_reductions_ozone_f2_small.png)
![Comparison of Ozone Season NOₓ Emissions and Generation for CSAPR Sources, 2000–2018](img/emissions_reductions_ozone_f3_small.png)
Mercury and Air Toxics Figures
![Mercury Emissions from MATS Sources, 2010–2018](img/emissions_reductions_mats_f1_small.png)
![State-by-State Mercury Emissions from MATS Sources, 2018](img/emissions_reductions_mats_f2_small.png)