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Emissions Applicability Thresholds

Potential to emit (PTE) is used for determining new source review and operating permit requirements, unless there are requirements based on industry source category.

The tables below contain the PTE thresholds used for determining the applicable operating permitting level. For example, the Registration Thresholds Table shows that a registration may be required for carbon monoxide emissions between 25 and 100 tons per year. A source with PTE less than the minimum Registration Thresholds is typically exempt from permit regulations.

As shown in the Title V Thresholds Table for Major Sources, there are lower thresholds for certain nonattainment areas so a source’s location may be a factor.

Applicants should refer to rules for permitting purposes, and contact IDEM for permitting assistance.

Note: PTE is calculated for use in permit determinations. PTE is different than actual emissions, which are based on the actual operating schedule and production levels and take into account air pollution controls that may be in place. Actual emissions are used for reporting purposes and evaluating compliance.

Registration Thresholds Table
Type of PollutantMinimum Threshold (PTE Equal to or Greater Than) in Tons Per YearMaximum Threshold (but Less Than) in Tons Per Year
Volatile organic compounds (VOCs) for sources not required to use air pollution control equipment to comply with the VOC emission rules1025
VOCs for sources that are required to use air pollution control equipment to comply with the VOC emission rules525
Nitrogen dioxide and oxides of nitrogen (NOX)1025
Carbon monoxide (CO)25100
Sulfur dioxide (SO2)1025
Particulate matter (PM)525
Particulate matter smaller than 10 microns (PM10)525
Particulate matter smaller than 2.5 microns (PM2.5)525
Lead0.2 (400 pounds per year)5
Fluorides525
Hydrogen sulfide525
Total reduced sulfur525
Reduced sulfur compounds525
Title V Thresholds for Major Sources
Type of PollutantPTE threshold in tons per year
VOCs (related to ozone formation)100 TPY in attainment areas
100 TPY in marginal nonattainment areas
100 TPY in moderate nonattainment areas
50 TPY in serious nonattainment areas
25 TPY in severe nonattainment areas
10 TPY in extreme nonattainment areas
NOX (related to ozone formation)100 TPY in attainment areas
100 TPY in marginal nonattainment areas
100 TPY in moderate nonattainment areas
50 TPY in serious nonattainment areas
25 TPY in severe nonattainment areas
10 TPY in extreme nonattainment areas
SO2100 TPY
CO100 TPY
PM10100 TPY
PM2.5100 TPY
Lead10 TPY
A single hazardous air pollutant (HAP)10 TPY
A combination of HAPs25 TPY
Any other air pollutant subject to regulation100 TPY

Note: Secondary lead smelters are required to have a Title V permit by 40 CFR 63 Subpart X.

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