Relating to engine emissions; prescribing an effective date.

Requires certain public improvement contracts to meet certain requirements related to use of diesel engines in course of performing public improvement contract. Requires Environmental Quality Commission to adopt indirect source review program by rule. Requires certain nonroad diesel engines to be registered with Department of Environmental Quality. Authorizes commission to adopt rules and registration fees. Directs commission to adopt by rule diesel engine emission standards for medium-duty trucks, heavy-duty trucks and nonroad diesel engines. Requires commission to phase in implementation of certain standards. Makes certain provisions operative January 1, 2019. Authorizes additional uses of moneys received by state pursuant to Volkswagen Environmental Mitigation Trust Agreement. Repeals state preemption of local regulation of idling by primary engines in commercial vehicles. Takes effect July 1, 2018.