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EPA's Efforts to Reduce NOx

Nitrogen Oxides

The U.S. Environmental Protection Agency (EPA), states, and local governments work as partners to reduce emissions of NOx. Reducing emissions of NOx is a crucial component of EPA's strategy for cleaner air.

Emissions standards for motor vehicles

Since the 1970s, EPA has required motor vehicle manufacturers to reduce millions of tons of NOx from their products, resulting in significant improvements to public health. As a result of the Tier 2 program, all cars, SUVs, pickups, and vans will be 77-95 percent cleaner by 2009. The requirements are phased in, starting in 2004. The program will also result in cleaner-burning gasoline that contains 90 percent less sulfur. Through its clean diesel truck and buses program, EPA reduced the level of sulfur in highway diesel fuel by 97 percent starting in 2006, and will reduce NOx emissions by over 90%. The Clean Air Nonroad Diesel Rule will cut nonroad diesel vehicle exhaust emissions by more than 90 percent and fuel sulfur levels by 99 percent, beginning in 2007.

Emission standards for electric utilities

To help reduce acid rain, EPA devised a two-phased strategy to cut NOx emissions from coal-fired power plants. The first phase, finalized in a rulemaking in 1995, aimed to reduce NOx emissions by over 400,000 tons per year between 1996 and 1999. The second phase began in 2000, and aimed to reduce NOx emissions by over 2 million tons per year. The second phase reduction goal has been surpassed, in part due to additional state-initiated NOx reductions in the Northeast.

NOx Transport rule for 21 States

The Clean Air Act requires states to reduce ground-level ozone. Since NOx and ozone can be transported long distances, the Act also requires "upwind" states to implement programs that will help "downwind" states meet the ozone standards. EPA issued a rule in 1998 that requires 21 states and the District of Columbia to revise their Implementation Plans to further reduce NOx emissions by taking advantage of newer, cleaner control strategies.

The rule does not mandate how the reductions are to be achieved, but gives each affected state a NOx emission target. States have flexibility in determining how to reduce emissions. The goal of this rule is to reduce total emissions of NOx by 1 million tons in the affected states by 2007. Reductions in most states were required to begin in 2004.

 

NOx and ozone are transported great distances by wind. Generally, they follow transport wind directions.


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