St. Louis, MO Environmental Rules: Vehicle Idling Restrictions (2026)

City ordinance § 11.34.120 bars idling a parked, standing, or stopped vehicle's engine for more than five minutes in any given hour; the limit stretches to ten minutes when the ambient temperature drops below 32°F. Six exceptions apply: emergency vehicles, vehicles transporting disabled or special-needs passengers, vehicles running auxiliary power equipment, vehicles stuck in traffic or bad weather, vehicles undergoing repair or diagnostics, and delivery vehicles loading or unloading goods. St. Louis police and other traffic-enforcement officers write it up as a non-moving violation, and a conviction carries a fine of up to $100.