Local Ordinances
Idling ordinances provide a public education opportunity, strengthen community anti-idling campaigns at schools or in neighborhoods, and if there is a significant penalty, anti-idling ordinances can deter first time or subsequent idling infractions.
Colorado State Idling Law
Colorado's state idling law (§ 42-14-105) prohibits only commercial diesel vehicles with a gross vehicle weight limit of 14,000 lbs or more from idling for more than 5 minutes in any one-hour period. The state law formerly preempted local municipalities from creating stronger ordinances, but as of 2024, local governments are now able to pass idling laws that are more stringent than the state law - as long as certain exemptions for health and safety are included (see below). Local governments have always been able to regulate passenger vehicle idling.​
Exemptions to be included in Colorado idling ordinances (a) When it remains motionless because of highway traffic, an official traffic control device or signal, or at the direction of a law enforcement officer; (b) When the driver is operating defrosters, heaters, or air conditioners or is installing equipment only to prevent a safety or health emergency, and not for rest periods; (c) In the case of a law enforcement, emergency, public safety, or military vehicle, or any other vehicle used to respond to an emergency, when it is responding to an emergency or being used for training for an emergency, and not for the convenience of the vehicle operator; (d) When necessary for required maintenance, servicing, or repair of the vehicle; (e) During a local, state, or federal inspection verifying that the equipment is in good working order if required for the inspection; (f) During the operation of power take-off equipment if necessary for operating work-related mechanical or electrical equipment; (g) In the case of an armored vehicle, when a person is inside the vehicle to guard its contents or during the loading or unloading of the vehicle; (h) In the case of a passenger bus, when idling for up to five minutes in any sixty-minute period to maintain passenger comfort while nondriver passengers are on board; (i) When used to heat or cool a sleeper berth compartment during a rest or sleep period at a location where the vehicle is legally permitted to park and that is at least one thousand feet from residential housing, a school, a daycare facility, a hospital, a senior citizen center, or a medical outpatient facility providing primary, specialty, or respiratory care; or (k) When idling for up to twenty minutes in any sixty-minute period if the ambient temperature is less then ten degrees; or (l) for a critical service or a utility provider, when performing the functions of the provider's duties.
Model anti-idling ordinance
Every minute that a vehicle idles, 150 balloons worth of emissions are released, containing pollutants harmful to human health. For that reason, we recommend that idling ordinances prohibit passenger and commercial vehicles from idling for longer than one minute. Because it is difficult to enforce idling laws, we recommend applying a fine structure high enough to deter idling violations.​ Download our sample anti-idling ordinance to read more, or view several of the ordinances adopted by Colorado municipalities.
Basalt
Limits vehicle idling to no more than two consecutive minutes.
Denver
Limits vehicle idling to five minutes in any one-hour period and the vehicle must be attended to at all times.
Telluride
Limits vehicle idling to 30 seconds and vehicle must be attended by a driver. Idling time permitted is extended to three minutes for starting an engine in cold weather.