For the most part, streetlights are a bright, vibrant white or orange hue. No one is putting color-changing bulbs in these lights and turning them rainbow shades. But then why are streetlights turning purple?
While it might sound wild, some streetlights across the United States are purple, but it’s not because someone popped in a purple lightbulb.
Nowadays, most streetlights use LED bulbs that last nearly a decade and are more energy efficient. It’s those LED lights that have been turning purple due to a manufacturing issue. Between 2017-2019, LED lights were manufactured by placing a blue LED under a lens made of ceramic and glass. It’s then impregnated with a yellow phosphor. The blue LED combined with the yellow phosphor is why we get white light. But that creation method is a bit of a shortcut.
Typically, a white LED light is created by using red, green, and blue LEDs to create the hue. When the yellow phosphor was used alone (typically in bulbs made between 2017-2019), the coating began to delaminate and degrade. When that happened, the light took on a purple hue—not a white one.
But what caused the degradation? Heat and temperature. But, there could have been an issue during manufacturing. However, this hasn’t been confirmed. As for what’s being done about the purple hue, the believed manufacturer has pledged to replace bulbs that are still under warranty.
If you’re planning a road trip for the summer and see a purple streetlight, it’s not a city’s fancy way of setting itself apart. That purple glow is just an oopsie.