Why are police lights red and blue?

Why are police lights red and blue?

PROF WAQAR HUSSAIN

             Until the late-50s, all of the police lights were red. Then, OW Wilson the Chief of Police in Chicago changed police lights to blue with a purpose to distinguish between the police and the fire fighting vehicles. Other departments get confused on this changeas some emergency vehicles started using red on left and blue on right. This lack of uniformity created confusion. Afterward all started using red and blue. Red indicates danger and blue emergency. In order to restore certainty and surety; they shifted to both blue and red. This is how red and blue lights came in vogue.

                Red being a slower, less energetic and longer wavelength of light and do not ‘sink in’ during the day and shows up the best and gains attention. Meanwhile at night, blue being faster, more energetic and shorter wavelengths of light are easier to be seen and travels farther and brings attention. 

              
             





The combination of red and blue; one is longer in wavelength and other is shorter; one has lowest energy and the 

other has highest; one is  present on one terminal of the visible spectrum while other is almost present on the other side. So these contrasting qualities gain sudden and shocking attention. Thus, Red and Blue can be seen by the human eye better than other colours. So if you want to be seen from a distance, use red or blue.