Direct Final Fine Particle Pollution De Minimis Emission Threshold Rates for General Conformity Applicability

June 5, 2006 - Through the Federal rulemaking process, the EPA amended its regulations implemented in accordance with Clean Air Act (CAA) section 176(c)(4)(A). Under CAA section 176(c)(1), the EPA requires Federal agencies to ensure emissions caused by their Federal activities to conform to the purpose of the State, Tribal or Federal air quality implementation plan applicable within the nonattainment or maintenance areas affected by such activities. This amendment added annual de minimis emission rates that now apply to directly emitted fine particle matter that has an aerodynamic diameter equal to or less than 2.5 micrometers (PM_2.5) and also apply to the precursors of secondary formation of PM_2.5, specifically, SO₂, VOC, and NOx. Both the proposal and the "direct to final" rule were published on April 5, 2006, and the final was effective on June 5, 2006. 

• PM2.5 De Minimis Emission Levels for General Conformity Applicability. Direct Final Rule, amendments (pdf) (84.02 KB, April 5, 2006, 40CFR Pts 51 and 93) 71 FR 17003, Apr. 5, 2006
• PM2.5 De Minimis Emission Levels for General Conformity Applicability, Proposed Rule (pdf) (77.17 KB, April 5, 2006) 71 FR 17047, Apr. 5, 2006
• Fact Sheet: Direct Final Fine Particle Pollution De Minimis Emission Levels for General Conformity Applicability (pdf) (29.18 KB, March 2006)
• Interim Policy for General Conformity Applicability in PM2.5 Nonattainment Areas (pdf) (63.7 KB, April 2006)