AP-42 Emission Factor Lookup & Calculator
Browse EPA emission factors by source category with built-in annual emissions calculation
Free AP-42 emission factor reference and local arithmetic screen. Select from natural gas combustion, fuel oil, diesel engines, gas turbines, and crushed stone processing prompts. View source pointers and local factor rows, then enter capacity to screen annual emissions in tons per year before current AP-42 row, method, permit, and agency review.
Screen PTE rows after source-factor review
Potential to Emit (PTE) Calculator →Build a facility emissions inventory from your factors
Facility Emissions Inventory →Calculate control device efficiency to reduce uncontrolled rates
Control Device Efficiency Calculator →Screen stack-test data against mass-rate prompts
Stack Flow & Mass Emissions Calculator →How It Works
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Select Source Category
Choose the combustion or process source type that matches your equipment. Categories correspond to specific AP-42 chapters and sections.
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Review Emission Factors
Browse the emission factor table showing each pollutant, factor value, units, EPA quality rating (A through E), and applicable notes.
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Enter Equipment Parameters
Input your equipment capacity and annual operating hours, or enter annual fuel consumption directly. The calculator converts to annual emissions automatically.
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Review Documentation Needs
Use the local rows as a worksheet before permit applications, emission inventories, or compliance reports. Current AP-42 text, factor notes, source data, and agency methods still control regulated use.
Built For
- Consultants organizing source-factor review before permit applications
- Plant engineers estimating emissions from new or existing equipment
- State agency staff reviewing emission inventory submissions
- Students and researchers studying air quality engineering
- Operations staff verifying emission calculations against published factors
Assumptions
- Emission factors reflect uncontrolled emissions unless otherwise noted.
- Equipment operates at steady-state conditions during the reported period.
- Standard fuel compositions are assumed for fuel-specific factors.
Limitations
- Coverage limited to the most commonly used AP-42 chapters (1.3, 1.4, 3.1, 3.3, 3.4, 11.19).
- Does not include process emission factors (kilns, dryers, chemical manufacturing).
- Sulfur-dependent factors use default fuel sulfur values that may not match your fuel.
References
- EPA AP-42, 5th Edition, Volume I: Chapter 1.3 - Fuel Oil Combustion (September 1998)
- EPA AP-42, 5th Edition, Volume I: Chapter 1.4 - Natural Gas Combustion (July 1998)
- EPA AP-42, 5th Edition, Volume I: Chapter 3.1 - Stationary Gas Turbines (April 2000)
- EPA AP-42, 5th Edition, Volume I: Chapter 3.3 - Gasoline and Diesel IC Engines (October 1996)
- EPA AP-42, 5th Edition, Volume I: Chapter 3.4 - Large Stationary Diesel Engines (October 1996)
- EPA AP-42, 5th Edition, Volume I: Chapter 11.19 - Crushed Stone Processing (June 2004)
Frequently Asked Questions
Learn More
Estimating Facility Emissions
AP-42, material balance, CEMS, and stack-test method prompts before source-supported facility emissions review.
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