Why some LED street lights turn purple?

Do you know why some long neglected LED street lights suddenly turned purple one day?

This phenomenon might seem weird but innocuous. After all, what harm could purple streetlights possibly do other than scare nearby residents as Christmas approaches? 

How do white LED street lights work?

LEDs (light-emitting diodes) are one of the most energy-efficient lighting technologies that currently exist. They also tend to be more durable and longer-lasting than other types of lighting while producing light that is comparable or better in quality.

These diodes can emit light at a variety of wavelengths—but one color they do not produce naturally is white. So when you see white LEDs, such as those in streetlights, they are actually emitting some mixture of the RGB(red, green and blue) colors, which together produce the appearance of white. 

There are two popular ways to create this white light. One is to combine tiny LED lights that each emit red, green or blue into a single big device. The other is to use only blue LEDs but coat them with a type of fluorescent substance called phosphor. When the blue light from the LED goes through this layer, the phosphor absorbs some of the blue wavelengths and spits out red and yellow ones. This results in a mixture of colors that, once again, appears white. The second method gained popularity because it's more energy-efficient and lower costly than the first. 

Why some LED street lights turn purple?

Now we can roughly guess the reason for the purple color. The phosphor coating around the LED has been delaminated (or peeled off, failed) exposing the blue LED light underneath. So the mixture light turn purple or indigo blue.

What are the hazards of purple street lighting?

Purple streetlight isn't good for driver or pedestrian safety. Blue- and violet-saturated light can worsen people's ability to see details because of the lack of blue-sensitive cones in the center of the retina. The blue-purple light makes it very difficult to distinguish between different colors, everything becomes a shade of blue or black. 

So, the municipal government should immediately replace these purple street lights, although some people still prefer this kind of ambient lighting. If these lighting fixtures have already passed the warranty period, then this will be a significant expense. Realshine company's LED street lights come with a 5-10 years warranty, which is your best choice. Free you from the trouble of replacing purple damaged streetlights.