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Ground-level Ozone Pollution

Required SIP Elements by Nonattainment Classification

NOTE: Transportation and General Conformity apply in all ozone nonattainment areas.

Marginal (3 years to attain):

  • Baseline emission inventory (EI), followed by periodic EI updates
  • New source review (NSR) program
    • NSR offset ratio 1.1:1
  • Major source emission statements
    • Major source threshold 100 tons per year (tpy)

Moderate (6 years to attain):

  • All requirements for Marginal classification, with
    • Major source threshold 100 tpy
    • NSR offset ratio 1.15:1
  • Major source volatile organic compounds/nitrogen oxides (VOC/NOx) reasonably available control technology (RACT)
  • Attainment demonstration
  • 15% reasonable further progress (RFP) over 6 years
  • Basic emissions inspection and maintenance (I/M) program
  • Contingency measures for failure to attain
  • Stage II gasoline vapor recovery

Serious (9 years to attain):

  • All requirements above, with
    • Major source threshold 50 tpy
    • NSR offset ratio 1.2:1
  • 18% RFP over 6 years
  • Enhanced monitoring plan
  • Modeled demo of attainment
  • Milestone contingency measures for RFP
  • Enhanced I/M
  • Clean fuels program (if applicable)
  • NSR requirements for existing source MODS
  • Vehicle miles traveled (VMT) demonstration, and transportation control measures if needed

Severe (15 or 17 years to attain)

  • All requirements above, with
    • Major source threshold 25 tpy
    • NSR offset ratio 1.3:1
  • VMT growth offset
  • Low VOC reformulated gas
  • Penalty fee program for major sources

Extreme (20 years to attain)

  • All requirements above, with
    • Major source threshold 10 tpy
    • NSR offset ratio 1.5:1
  • Clean fuels requirement for boilers
  • Transportation congestion controls