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 goal of the second phase is to reduce emissions by over 2 million tons per year beginning in the year 2000. The Clean Air Act requires states to reduce ground-level ozone. EPA issued a rule in 1998 that requires 22 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 1.2 million tons in the affected states by 2007.