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National NOx Emission Reductions and NOx Budget Program Cap and Trade Results

Cap and Trade

NOx emissions from power plants have decreased by 4 million tons from 1995 levels(more than 65 percent). Other efforts, such as the NOx Budget Trading Program (NBP) and Clean Air Interstate Rule (CAIR) in the eastern United States, also contributed to this reduction.

To date, EPA's cap and trade programs have delivered significant environmental results. The interactive map below demonstrates the success of these programs.

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(Clicking on the Play button in the bottom left corner of the map sets the map in motion.)

Note the reductions in NOx emissions over time (orange dots in the map above) beginning in 1995 with the advent of the Acid Rain Program (ARP), and subsequent reductions in the East due to the NBP.

The colored background is an isopleth map showing the change in nitrate concentrations as measured by the CASTNET rural air quality monitoring network, leading to significant improvements in air quality and human health. Since the inception of the ARP, total nitrate concentrations have declined by almost 40 percent in the eastern United States.

The ARP was created under Title IV of the 1990 Clean Air Act (CAA) Amendments to reduce the adverse effects of acid deposition through reductions in annual emissions of SO2 and NOx, primarily from fossil fuel-burning electricity generation. The ARP employs two policies: a cap and trade program for SO2 and a rate-based reduction program for NOx, the goal of which is to limit NOx emission levels from affected coal-fired boilers so that emissions are at least 2 million tons less than the projected level for 2000 without the program. NOx contributes to acid deposition, as well as the formation of ground-level ozone, a pervasive air pollution problem—also known as "smog"—in many areas in the East.

* Note that there are no available facility level data for NOx emissions prior to 1995. National power plant emissions for 1990 are based on estimates; in 1995, continuous emissions monitoring systems (CEMS) were required of all program sources.

These animations are based on data and interactive mapping applications at EPA's Airmarkets website. For complete ARP and NBP data overlay files, as well as air quality and deposition data for interactive mapping applications (i.e., Google Earth), go to the Airmarkets Interactive Mapping page.

Additional Resources

Air Quality and Deposition Data and Maps

Emissions Monitoring Data


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