Indoor burning frequently requested information

Burning restrictions apply November-March.
  • Environmental Protection Agency (EPA)-certified Phase II stoves or inserts.
  • Colorado-approved pellet stoves or inserts.
  • Colorado-approved masonry heaters.
For a list of approved devices, see the approved indoor burning devices page.
  • Pollution Action Day restrictions generally apply to seven counties in metro Denver:
    • Denver.
    • Boulder.
    • Broomfield.
    • Douglas.
    • Jefferson.
    • Adams and Arapahoe counties west of Kiowa Creek.
Homes above 7,000 feet in elevation are exempt from the restrictions.
Colorado Regulation 4 prohibits use of uncertified devices on Action Days. Therefore, an uncertified stove, heater or conventional fireplace, regardless of the type of fuel, must not be operated on Action Days.
Check the list of approved pellet stoves to see if yours is exempt:
If you rely on a wood stove as your only source of heat, you should contact your local health department or building department about an exemption from burning restrictions. Most municipalities in the seven-county metro Denver area have their own ordinances and regulations that include provisions for exemptions. 
Individual stoves can’t be tested for emissions. The EPA-approved testing must be conducted at an appropriate laboratory. It’s done for an entire model line and is quite expensive.
Call the 24-hour indoor burning hotline:
If the state has jurisdiction, we’ll contact the suspected violator. If a local municipality has jurisdiction, we’ll pass along the information you report and the local government will follow up on the complaint.
We have enforcement jurisdiction only in areas without local ordinances at least as restrictive as the state regulation. Most of the seven-county metro Denver area falls under the jurisdiction of local ordinances or regulations.
Contact your city or county government to inquire about local enforcement procedures.
Our enforcement procedure
For areas under state regulation:
  1. When we receive a complaint about an alleged violation, we send a letter that describes the indoor burning program and urges compliance.
  2. If the party allegedly responsible still doesn’t comply, we begin an investigation.
  3. If investigators find the responsible party isn’t complying with regulations, we issue a Notice of Violation (NOV). This requires a conference between the responsible party and state regulators.
  4. After the conference, three things can happen:
  • Investigators may determine that the party allegedly responsible didn’t violate regulations.
  • A nonmonetary settlement can be reached by which the responsible party agrees to adhere to all indoor burning regulations.
  • A monetary fine may be assessed.
    • Fines can be up to $15,000 per day.
    • Most likely, any fines assessed will be $100 to $300.
    • Our goal isn’t to fine people; it’s to get people to comply with the regulations. We’ll take every step to bring people into compliance with regulations rather than assess a fine.
Any indoor burning device you buy or install in the seven-county metro Denver area must meet current emissions standards. The 7,000-foot elevation exemption applies only to the use of indoor burning devices, not their sale or installation.
If it can be demonstrated by valid manufacturer testing data that your non-EPA Phase II stove is "cleaner" than EPA Phase II standards, then you can install and use it on Action Days.
To achieve EPA Phase II status, a device must meet the following requirements:
  • Non-catalytic stoves must emit no more than 7.5 grams per hour of particulates.
  • Stoves equipped with a catalytic device must emit no more than 4.1 grams per hour of particulates.
Such devices are still subject to Action Day regulations and ordinances. They’re not certified wood stoves by definition, and only certified wood stoves may be used on Action Days.
You’re not allowed to sell a used, uncertified stove in the seven-county metro Denver area, but you can sell it elsewhere in Colorado.
You can use a conventional masonry fireplace on Action Days only if it's equipped with gas logs, an EPA Phase II insert, an approved pellet insert or an electric device, and if state or local ordinances don’t prohibit it.
Although many pellet stoves burn "cleanly," we approve only those whose manufacturers have performed the required testing and submitted the appropriate paperwork to us certifying that the pellet stove emits less than 4.1 grams per hour of particulates.
We post advisories on our website during the high pollution season. Go to the indoor burning restrictions page to see the latest advisory. For current information during the high pollution season, you can call the 24-hour Air Quality Advisory hotline:
The Air Quality Bulletin hotline carries current advisory information during the high pollution season and other pollution information year-round:
Many local newspapers, radio and television stations provide updates.
Smoke from outdoor wood-fired boilers can be a serious health issue and can violate state regulations. See the wood-fire boilers information page. Wood-fired boilers are located outside in small shed-like structures. The hot water produced by the fire is circulated indoors and used in heating.