The rule clarifies when facilities must keep records and report emissions when a 'reasonable possibility' test shows that projected emissions increases could equal or exceed 50 percent of the Clean Air Act's NSR significant levels for any pollutant. This rule does not change permitting requirements.
The 'reasonable possibility' test examines the difference between a project's baseline emissions and the sum of emissions projected to result from the project and emissions attributable to independent factors such as growth in market demand.
NSR significant levels are pollutant-specific emission rates (in tons per year) that are used to determine when a project is subject to NSR permitting requirements. Today's rule will help EPA and state and tribal permitting authorities track projects, using information on emissions that could exceed significant levels.