<Li> Magenta (purple) lights are primarily used by heavy vehicle enforcement / escort officers of the NSW Roads and Maritime Services, Victorian VicRoads and South Australian Transport Safety Inspectors . They are also used in combination with amber lights by some council rangers and the New South Wales Ministry of Transport . In Western Australia magenta is used by the Department Of Environment and Conservation' HAZMAT Response Unit' . Magenta is also used in some Escort Vehicles used whilst escorting large mining equipment to the north of the state . </Li> <Li> White is used on most newer emergency vehicles, both as an extra color on lightbars and in the form of' wig - wag' headlights . </Li> <P> Many police motor vehicles, and less often other emergency services, also fit LED matrix variable message displays to vehicle lightbars . Such message bars used in New South Wales by the police and fire brigade are capable of displaying numerous messages warning motorists of various hazards or dangers . </P> <P> Generally, red is used for emergency vehicles, amber for construction and utility vehicles, and green for volunteer firefighters . Blue is used, along with red, for police, as well as for snow removal vehicles in Ontario (with Amber for Municipal snow removal) and purple is used for a funeral . Police now use both red and blue Canada - wide (except where local laws prohibit), including Ontario (thanks to successful testing in Toronto and Ottawa, and changes in the provincial traffic act), where the color blue was only used for non-emergency work . Blue flashing lights are still permitted on snow removal vehicles in Ontario, as long as they are not used in conjunction with flashing red lights . </P>

When did police lights change from red to blue