Dallas recently began enforcing its new anti-idling ordinance, an initiative intended to improve air quality in the city by fining truckers found to be idling excessively.

The City Council passed the law last spring, which prohibits trucks weighing more than 14,000 pounds from sitting still with their engines running for more than five minutes within the city limits.

The ordinance will be enforced during the state’s ozone season, April 1 to Oct. 31.  The Class C misdemeanor carries a $350 fine.