Annual emissions reporting applicability and exemptions
Overview
The Colorado Air Quality Control Commission Regulations 3 and 7 require certain facilities to report emissions annually. This applies to both toxic air contaminants (TACs) and criteria pollutants. Use this page to determine if your facility is subject to annual emissions reporting and which sources or activities are exempt.
Sources subject to annual emissions reporting must still comply with APEN and permit requirements, including the 5-year APEN renewal requirements. View the list of the APEN and air permitting exemptions.
Oil and gas facilities
If your equipment or activities are required to report under Colorado’s Oil and Natural Gas Annual Emission Inventory Reporting (ONGAEIR), visit CDPHE’s ONGAEIR website. Review Regulation 7, Part B, Section V for information on which equipment or activities are subject to reporting.
Exemptions for ONGAEIR reporting are separate from the annual emissions reporting exemptions in Regulation 3 that are detailed below.
Non-road engines must report annual volatile organic compound (VOC), nitrogen oxides (NOx), carbon monoxide (CO), and greenhouse gas emissions to ONGAEIR. Non-road engines are exempt from reporting emissions of toxic air contaminants (TAC), particulate matter (PM), and sulfur dioxide (SO2).
Facilities required to report emissions annually
All emissions at the facility should be included unless equipment or activities meet the Regulation 3 IX.A.2. exemptions below.
Use the following criteria to determine if your facility is subject to annual emissions reporting. If your facility is subject to annual emissions reporting, review the exemptions list on this page to see if any specific equipment or activities can be excluded from your report.
- Facilities that are required to have Title V operating permits.
- Synthetic minor source facilities.
- All other facilities with industrial processes that use or emit the following TACs above their respective minimum reporting thresholds: cadmium (≥0.088 lbs/yr), nickel (≥0.16 lbs/yr), or hexavalent chromium (≥0.013 lbs/yr).
- Industrial processes that commonly emit these metals include: electroplating, plating, polishing, anodizing, coloring, thermal spraying, welding, plasma cutting, and metal heat treating.
- All facilities that emit ethylene oxide above the minimum reporting threshold (≥0.032 lbs/yr).
- All facilities that report emissions to the EPA Toxic Release Inventory (TRI).
Source Applicability Under Regulation 3, Part A, Section IX.A.1.
For facilities subject to annual reporting, visit the air toxics emissions reporting web page.
Equipment and activity exemptions for facilities required to report emissions annually
The following exemptions apply only to annual emissions reporting under Regulation 3, Part A, Section IX.
If an annual emissions reporting exemption below applies, activities or equipment may still be subject to APEN and/or air permitting requirements, unless an APEN and/or air permitting exemption also applies to the equipment or activity. Exemptions marked with an asterisk (*) next to the exemption reference apply to both annual emissions reporting and APEN reporting.
Regulation 3 Appendix C reporting thresholds are based on the source-wide annual actual TAC emissions from the previous calendar year for each individual TAC, after considering any controls that may be installed. Emissions from any exemptions listed below do not need to be included in this source-wide total.
The following activities and equipment are exempt from annual emissions reporting requirements under Regulation 3, Part A, Section IX. *
Note: Certain sources are required to report their TAC emissions annually for calendar year 2023 without any exemptions. Until rule changes are fully implemented, beginning with calendar year 2026, the division will allow sources to use the exemptions in Regulations 3 Part A, Section IX.A.2, as summarized below, should the facility determine this is more streamlined for reporting their annual emissions.
TAC Reporting Exemptions Under Regulation 3, Part A, Section IX.A.2.
- Emissions from building or altering residential homes and heating systems. Regulation 3 IX.A.2.b.(vi)*
- Land development under 25 acres and less than 6 months long. This doesn’t apply to mining or digging up contaminated soil. Regulation 3 IX.A.2.b.(viii)*
- Welding, brazing, soldering, or laser cutting — unless you're in NAICS codes 325, 331, 332, 333, 335, or 811. And all short-term maintenance welding is always exempt. Regulation 3 IX.A.2.b.(xiv)
- Sawing that supports facility operations but is not production. Regulation 3 IX.A.2.b.(xviii)*
- Use of lubricants (e.g., WD-40), sealants, adhesives, and small-use paints—when used for minor, unscheduled repairs on industrial and process equipment. Regulation 3 IX.A.2.b.(xxi)
- Caulking operations that are not part of a production process. Regulation 3 IX.A.2.b.(xxiii)*
- Plastic pipe welding. Regulation 3 IX.A.2.b.(xxix)*
- Non-asbestos demolition. Regulation 3 IX.A.2.b.(liv)*
- Battery recharging areas. Regulation 3 IX.A.2.b.(xvi)*
- Electric drying or curing ovens (but not what’s being dried). Regulation 3 IX.A.2.b.(xxxix)*
- Electric motors driving equipment at non-commercial machining shops. Regulation 3 IX.A.2.b.(xlix)*
- Seal and lubricating oil systems for steam turbine electric generators. Regulation 3 IX.A.2.b.(lix)*
- Fuel burning equipment, that uses gaseous fuel, that has a design rate less than or equal to ten (10) million British thermal units (Btu) per hour, that is used solely for heating buildings for personal comfort, unless the aggregate annual fuel usage is greater than 75 million standard cubic feet, or 77,000 million British thermal units (Btu) per year. (See definition of fuel burning equipment, Common Provisions Regulation). Regulation 3 IX.A.2.b.(ix)
- Fuel burning equipment, other than smokehouse generators and internal combustion engines, that uses gaseous fuel, that has a design rate less than or equal to five (5) million British thermal units (Btu) per hour, unless the aggregate annual fuel usage is greater than 75 million standard cubic feet, or 77,000 million British thermal units (Btu) per year. (See definition of fuel burning equipment, Common Provisions Regulation). Regulation 3 IX.A.2.b.(x)
- Internal combustion engines powering portable drilling rigs. Regulation 3 IX.A.2.b.(xi)*
- Combustion of residual, distillate, or diesel oil, Tier 4 or higher diesel engines: 100 gallons of fuel combusted per year, or 5 hours per year of non-emergency operation. Tier zero through tier 3 diesel Engines: 30 gallons of fuel combusted per year, or 5 hours per year of non-emergency operation. Combustion devices other than compression ignition engines: 100 gallons of fuel combusted per year. Regulation 3 IX.A.2.b.(lxiv)
- Non-road engines are not subject to annual emissions reporting. This is due to the definition of "stationary source" in Regulation 3 IX.A.1., which excludes non-road engines and mobile sources. Regulation 3 I.KKK., Non-road engine definition in Regulation 3 I.B.36
- Fires and equipment used for noncommercial cooking or cooking commercial food service establishments, except for char broilers and wood fired equipment in PM10 nonattainment areas. Regulation 3 IX.A.2.b.(iii)*
- Safety flares used to indicate danger to the public. Regulation IX.A.2.b.(iv)*
- Open burning activities, except that all reporting and permitting requirements that apply to such operations must be followed (see Regulation Number 9). Regulation 3 IX.A.2.b.(xiii)*
- Fire training activities. Regulation 3 IX.A.2.b.(xxii)*
- Emergency events such as accidental fires. Regulation 3 IX.A.2.b.(xxvii)*
- Landscaping and site housekeeping devices equal to or less than ten (10) horsepower in size (lawnmowers, trimmers, snow blowers, etc.). Regulation 3 IX.A.2.b.(xxiv)*
- Fugitive emissions from landscaping activities (e.g., weeding, sweeping). Regulation 3 IX.A.2.b.(xxv)*
- Landscaping use of pesticides, fumigants, and herbicides. Regulation 3 IX.A.2.b.(xxvi)*
- Grounds keeping activities and products. Regulation 3 IX.A.2.b.(xxxv)*
- Blast cleaning equipment using a suspension of abrasive in water and any exhaust system or collector serving them exclusively. Regulation 3 IX.A.2.b.(xli)*
- Air conditioning or ventilating systems not designed to remove air pollutants generated by or released from other processes or equipment. Regulation 3 IX.A.2.b.(i)*
- Fireplaces used for recreational purposes, inside or outside. Regulation 3 IX.A.2.b.(ii)*
- Aerosol can usage. Regulation 3 IX.A.2.b.(xvii)*
- Vacuum cleaning systems used exclusively for industrial, commercial, or residential housekeeping purposes. Regulation 3 IX.A.2.b.(xxx)*
- Janitorial activities and products. Regulation 3 IX.A.2.b.(xxxiv)*
- Office emissions, including cleaning, copying, and restrooms. Regulation 3 IX.A.2.b.(xxxviii)*
- Equipment used exclusively for portable steam cleaning. Regulation 3 IX.A.2.b.(xl)*
- Bench scale laboratory equipment and laboratory equipment used exclusively for chemical and physical analysis, including associated vacuum producing devices. Regulation 3 IX.A.2.b.(vii)
- Wet screening operations notwithstanding the applicability of the New Source Performance Standards included in the Code of Federal Regulations, Title 40, Part 60, Subpart OOO. Regulation 3 IX.A.2.b.(lxiii)*
- Fugitive emissions of hazardous air pollutants that are natural constituents of native soils and rock (not added or concentrated by chemical or mechanical processes) NOT associated with underground mines or surface mines, unless the source of such emissions is a major source of hazardous air pollutants under Part C of Regulation Number 3. Regulation 3 IX.A.2.b.(lxvi)
- In other words, sources generally do not need to report fugitive TAC emissions from natural, unprocessed soil and rock, unless those emissions come from a mine that's a major source of HAPs under Regulation 3, Part C.
- Furnace/kiln brickwork (not operation). Regulation 3 IX.A.2.b.(xix)*
- Sources of odorous emissions that do not utilize emission control equipment for control of odorous emissions. This exemption applies to the odor emissions only. All other emissions are subject to other exemptions set forth in this regulation. This exemption does not exempt any source from the requirements of Regulation Number 2. Regulation 3 IX.A.2.b.(xxxvi)*
- Venting of compressed natural gas, butane or propane gas cylinders, with a capacity of one gallon or less. Regulation 3 IX.A.2.b.(xlv)*
- Indirect sources are exempt until a permit regulation specific to indirect sources is promulgated by the Commission. Regulation 3 IX.A.2.b.(xlvi)*
- Recreational swimming pools. Regulation 3 IX.A.2.b.(l)*
- Forklifts. Regulation 3 IX.A.2.b.(li)*
- Handling equipment and associated activities for glass that is destined for recycling. Regulation 3 IX.A.2.b.(lii)*
- Ventilation of emissions from mobile sources operating within a tunnel, garage, or building that are not operating for transportation purposes and are subject to stationary source requirements. Regulation 3 IX.A.2.b.(liii)*
- Sandblast equipment when the blast media is recycled and the blasted material is collected, including small sandblast glove booths. Regulation 3 IX.A.2.b.(lv)*
- Venting of natural gas lines for safety purposes. This exemption does not apply to routine or predictable emissions at or associated with a stationary source. Regulation 3 IX.A.2.b.(lx)*
- Sanding of streets and roads to abate traffic hazards caused by ice and snow. Regulation 3 IX.A.2.b.(xii)*
- Street and parking lot striping. Regulation 3 IX.A.2.b.(xv)*
- Road paving (but not asphalt or cement batch plants unless exempt elsewhere). Regulation 3 IX.A.2.b.(xx)*
- Dust from unpaved roads (unless TACs come from industrial processes, such as mining operations). Regulation 3 IX.A.2.b.(Ixv)
- Agricultural operations such as farming, cultivating, harvesting, seasonal crop drying, grain handling operations that are below NSPS de minimis levels. This exemption does not apply to an agricultural operation that:
- (1) is a major source;
- (2) meets or exceeds the storage capacity thresholds of NSPS; or
- (3) participates in the early reduction program of the Federal Act, Section 112. Ancillary operations such as fueling stations located at farms or ranches are not exempt from Air Pollutant Emission Notice and permit requirements unless otherwise below de minimis emission levels. Regulation 3 IX.A.2.b.(v)*
- Smoking rooms and areas. Regulation 3 IX.A.2.b.(xxviii)*
- Beauty salons. Regulation 3 IX.A.2.b.(xxxi)*
- Pharmacies. Regulation 3 IX.A.2.b.(xxxii)*
- Truck and car wash units. Regulation 3 IX.A.2.b.(xxxvii)*
- Commercial laundries (except dry cleaners) that do not burn liquid or solid fuel. Regulation 3 IX.A.2.b.(xlii)*
- Chemical storage areas where chemicals are stored in closed containers, and total storage capacity is ≤5,000 gallons.
- This exemption applies solely to storage of such chemicals and not the transfer of chemicals from, to, or between such containers. Regulation 3 IX.A.2.b.(xxxiii)*
- Storage of butane, propane, or liquefied petroleum gas in a vessel with a capacity of less than sixty thousand <60,000 gallons, provided the requirements of Regulation Number 7, Section IV. are met, where applicable. Regulation 3 IX.A.2.b.(xliii)*
- Storage tanks of capacity less than forty thousand <40,000 gallons of lubricating oils or used lubricating oils. Regulation 3 IX.A.2.b.(xliv)*
- Storage tanks meeting all of the following Criteria:
- Annual throughput is less than four hundred thousand <4000,000 gallons; and Regulation 3 IX.A.2.b.(xlvii)(A)*
- The liquid stored is one of the following:
- (1) Diesel fuels 1 D, 2 D, or 4 6;
- (2) Fuel oils #1 through #6;
- (3) Gas turbine fuels 1 GT through 4 GT;
- (4) Oil/water mixtures with a vapor pressure equal to or lower than that of diesel fuel (Reid Vapor Pressure of 0.025 pounds per square inch absolute). Regulation 3 IX.A.2.b.(xlvii)(B)(1-4)*
- Natural gas vehicle fleet fueling facilities. Regulation 3 IX.A.2.b.(xlviii)*
- Sodium hydroxide storage tanks. Regulation 3 IX.A.2.b.(lxi)*
- Containers, reservoirs, or tanks used exclusively for dipping operations that contain no organic solvents for coating objects with oils, waxes, greases, or natural or synthetic resins. Regulation 3 IX.A.2.b.(lxii)*
- Surface water storage impoundment of non-potable water and storm water evaporation ponds, with the exceptions of oil and gas production wastewater impoundments (including produced water tanks) and commercial facilities that accept oil and gas production wastewater for processing. Regulation 3 IX.A.2.b.(lvi)*
- Non-potable water pipeline vents. Regulation 3 IX.A.2.b.(lvii)*
- Steam vents and safety release valves. Regulation 3 IX.A.2.b.(lviii)*
- The collection and transmission processes at wastewater collection systems by floor drains, manholes, siphons, and lift stations. Regulation 3 IX.A.2.b.(lxvii)
Note: All exemptions with an asterisk * after Regulation 3 references are also APEN exemptions.