RCW 46.37.185: Green light on firefighters' private cars.

Firefighters, when approved by the chief of their respective service, shall be authorized to use a green light on the front of their private cars when on emergency duty only. Such green light shall be visible for a distance of two hundred feet under normal atmospheric conditions and shall be of a type and mounting approved by the Washington state patrol. The use of the green light shall only be for the purpose of identification and the operator of a vehicle so equipped shall not be entitled to any of the privileges provided in RCW 46.61.035 for the operators of authorized emergency vehicles.