(WHTM) — Emergency vehicles have a multitude of ways to get our attention, including flashing lights, horns and sirens.
But why do police cars use red and blue lights? Why not red and purple, or any other combination?
Red and blue lights are used on U.S. police cars for many reasons, but the main one is that they are highly visible and easily distinguishable from one another.
According to LEDequipped.com, it also has to do with color association, among other factors. When most people see the color red, they usually associate it with danger or the inclination to stop and look. But this could create an issue when emergency lights are only red, as they can be confused with brake lights.
That is where the color blue comes in.
Blue normally has a calming effect on many people and is considered a fairly unique color in some respects. LEDequipped mentioned that in one study, blue is only seen in about 15% of our natural habitats. So, this can make the color eye-catching as well.
Another reason why the red and blue lights work well together is contrast. From a distance, you can easily recognize a police car with its lights on. According to research cited by LEDequipped, people can see the difference between red and blue lights up to a mile away.
Blue and red lights also stand out regardless of the time of day. Because blue is a fairly unique color to see in our natural world (besides a blue sky), it stands out in the daytime. Unlike yellow and green, which are colors we always see in our surroundings, blue can be easier to spot during daylight hours.
Additionally, LEDequipped.com said that people with color blindness can usually see either red or blue, but missing both colors is rare. That makes the color combination “more inclusive for people who may have trouble distinguishing certain colors,” the publication states.
It should be noted, according to SpeedTech Lights, a provider of emergency lighting products, that it is illegal in some places to install red and blue lights on your personal vehicle since those light colors are usually reserved for emergency use.
