Why are police lights red and blue?

A viewer named Kim asked, "Why are police lights red and blue?"

Flashing red lights on law enforcement vehicles date back to the early 1900s. Red was always used to signal some type of warning or caution.

Over the past century two things happened leading up to the red and blue combo.

Studies conducted show that during daylight hours, flashing red is easier to see. They also concluded that the flashing of just a red light at night was not sufficient and a blue light could be seen easier and from a distance. However, blue is also difficult to see during the daytime, ultimately leading to the combination.

Also, over time, medical studies revealed that some people were color-blind and could not see red or blue.

In 2004, the Florida Highway Patrol conducted a study on this very topic. This study resulted in a new type of light bar for Florida Highway Patrol vehicles that would show one color more significantly than the other, depending on the time of day and the amount of light.

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