Air permits

Any business in Colorado that emits air pollution may be required to report its emissions and apply for a Construction Permit to Emit. The type of permit needed is determined by the volume and type of emissions. For more information:
Select sources that emit less than certain thresholds may not need an Air Pollutant Emission Notice (APEN) or air permit. Applicable APEN- or permit-exempt form letters are available for these sources. This is a pilot project designed to eliminate the need for an engineer to review an application and issue an APEN- or permit-exempt letter for certain source categories.
Air pollution permits specifically for the oil and gas industry
General Permits offer a streamlined approach to air emissions permitting and are currently available for land development activities, natural gas and diesel engines, and for certain oil and gas operations.
Air pollution construction permits and forms for all other businesses and industries
If you completed a construction permit and are over the emissions limit, you'll be issued an operating permit.
Permits for the emission of greenhouse gas and information about greenhouse gas regulations
Fees and frequently requested information 
To certify compliance with permit requirements after permit is issued
Form for visual determination of the opacity of emissions from stationary sources
See the status of your permit
Guidance for completing the requirements for modeling of estimated impacts from air pollution sources
Current permit public notices