In Massachusetts, state law (M.G.L. Chapter 90, Section 16A) and DEP regulation (310 CMR 7.11) limit vehicle idling to no more than five minutes in most cases. A vehicle may idle longer only if absolutely necessary. The law includes exceptions for vehicles being serviced, vehicles making deliveries that need to keep their engines running (to power refrigerators, for example), and vehicles that need to run their engines to operate accessories (such as power lifts).

Idling has serious impacts on the public health and hence it is important to minimize wherever possible.  Massachusetts Department of Environmental Protection (DEP) has offered Somerville an educational in kind assistance for public outreach to educate the importance of reducing idling of vehicles.