PSD / NSR Modification Calculator
Local federal emissions-increase prompts before state, permit, and qualified air-review decisions
Free source-aware PSD/NSR modification screen for environmental managers, engineers, and consultants who need transparent arithmetic before formal air-permitting review. Enter user-reviewed baseline and projected emissions for NOx, SO2, VOC, CO, PM, PM10, PM2.5, and Lead. The screen compares each row against local federal significant-emission-rate prompts and keeps the unresolved PSD, NNSR, netting, source-category, state SIP, and permit-review gaps visible.
Screen source-level PTE before major-source and permit review
Potential to Emit (PTE) Calculator →Aggregate reviewed source rows before facility inventory review
Facility Emissions Inventory Calculator →Review AP-42 source pointers before choosing emission factors
AP-42 Source Pointer →Compare local control-efficiency prompts before vendor and permit review
Control Device Efficiency Calculator →How It Works
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Enter Baseline Prompts
Input source-supported baseline emissions in tons per year for each pollutant. The app does not determine baseline actual emissions, lookback periods, demand-growth exclusions, or accepted methods.
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Enter Projected Prompts
Input source-supported projected emissions after the project. Keep capacity, fuel, control, operating, and emission-method assumptions documented outside the calculator.
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Set Review Context
Select the major/minor source prompt and ozone attainment context. These choices do not determine major-source status, area classification, state SIP treatment, or NNSR requirements.
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Review Source Boundaries
Use the local review prompts, source pointers, and residual data gaps to prepare for qualified environmental, legal, state, local, or EPA review.
Built For
- Environmental managers organizing source-supported project emissions before permit strategy review
- Consultants checking arithmetic in baseline versus projected emissions worksheets
- Plant engineers documenting unresolved data gaps before capital-project gate reviews
- Operations staff comparing reviewed fuel, equipment, or control-change scenarios before environmental signoff
Assumptions
- Emission increases are calculated as projected emissions minus baseline emissions for each pollutant.
- Federal PSD significant-emission-rate prompts are local source-aware values from the cited eCFR source pointers.
- Serious, severe, and extreme ozone nonattainment prompts apply only to local NOx/VOC major-source context in this screen.
- State, tribal, local, permit, and agency rules may differ from the local federal prompts.
Limitations
- Does not calculate emissions from raw activity data or choose emission factors.
- Does not determine baseline actual emissions, projected actual emissions, actual-to-potential, hybrid tests, demand-growth treatment, or project aggregation.
- Does not perform contemporaneous netting, offsets, PAL, synthetic-minor, BACT, LAER, modeling, public-notice, or permit-completeness review.
- Does not determine state SIP acceptance, minor NSR applicability, construction authorization, or agency acceptance.
References
- 40 CFR 51.166 - Prevention of Significant Deterioration of Air Quality
- 40 CFR 51.165 - Permit Requirements
- 40 CFR 52.21 - Prevention of Significant Deterioration of Air Quality
- EPA New Source Review Laws and Statutes