Why are America's streetlights turning PURPLE? [10:46]

[aeronmelon@lemmy.world]

Hundreds of local news stories. Tens of thousands of social media reports. All asking the same thing: why the heck are our streetlights turning purple? The answer is… a lot dumber than you think.

If you're over the age of 25, you probably remember that all streetlights used to be sodium vapor lamps, which give off a comforting yellow/orange light that was easy on the eyes and cut through fog best. But they also generate a ton of heat, and when you're trying to make light, heat is just wasted energy.

But as lighting technology evolved, LEDs entered the picture. The 2010s saw the first big push by local, state, and federal governments to switch out the old lamps for LED streetlights, which are a lot more efficient. They also produce a much harsher, colder, blueish white light that a lot of people can't stand.

So why are they turning purple now? The thing is, white LEDs don't exist. To make one, manufacturers use a blue LED that shines through a special filter that turns it into white(ish) light. And it turns out that in the mad rush to convert everything to LEDs, no one realized that the filter layer would break down a lot quicker than anyone expected, which causes the lights to turn purple. Or blue, depending on how complete the failure is.

So like with many things in life, that's the answer: bad quality control, and good old fashioned government contracting.

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