The Denver Municipal Ordinance relevant to “puffing” was enacted to address air quality issues and states:

Sec. 4-43. – Idling restriction.

(a) No person shall allow a vehicle to idle for more than five (5) minutes in any one-hour period unless:

(1) The ambient outside air temperature has been less than twenty (20) degrees Fahrenheit for each hour of the previous twenty-four (24) hour period; or

(2) The latest hourly ambient outside air temperature is less than ten (10) degrees Fahrenheit.

(b) The idling restriction in subsection (a) shall not apply to emergency vehicles; to vehicles engaged in traffic control operations; to vehicles which are being serviced; to vehicles that must idle to operate auxiliary equipment, including but not limited to pumps, compressors or refrigeration units; or to vehicles en route to a destination that are stopped by traffic congestion.

(c) The idling restriction in subsection (a) applies to transportation vehicles, as defined in this subsection, except that the time during which transportation vehicles are actively loading or discharging passengers may not be included in the computation of the five (5) minutes provided for in subsection 4-43(a). A transportation vehicle shall be defined for purposes of this section to mean motor vehicles designed to transport a minimum of sixteen (16) persons.

(Ord. No. 330-90, 6-4-90; Ord. No. 683-08, § 15, 12-8-08)