Right around the time of the pandemic, people across America began noticing something unusual: Streetlights were turning purple. In at least 30 states, people started taking photos like these, typically posting them to social media with questions.
In this photo you can see that the effect isn’t consistent across neighboring streetlamps.
Scientific American got to the bottom of what was happening. All of the streetlamps that turned purple were LED “upgrades” from sodium lamps. LEDs cannot produce truly white light, just red, green or blue. To compensate, manufacturers use blue LEDs coated with phosphor. This phosphor layer distorts the blue wavelengths to produce a light that appears white.
The phosphor layers in the affected lamps have been delaminating, yielding purple. In short, it’s a manufacturing defect. American Electric Lighting, an Atlanta-based manufacturer that has federal contracts and makes (or at least assembles) their lights in America, is one of the suppliers that has acknowledged the malfunction. Other manufacturers have not been named.
AEL, for their part, has been stepping up and replacing the affected lamps.