Chapter 1: The Phenomenon of Purple Streetlights

In recent years, an unusual occurrence has captured attention across the United States: streetlights emitting a purple hue. You might have noticed them in your neighborhood or elsewhere, but this color change is not by design.

Since 2020, reports of purple streetlights have surfaced from various states, including Texas, North Carolina, New Mexico, Iowa, Kentucky, Kansas, Florida, California, and Wisconsin, among others. This phenomenon has even reached locations beyond the U.S., appearing in Ireland and Canada. So, if these purple lights weren't intentionally installed, what caused this shift?

Typically, streetlights emit a white glow from LED technology or an orange hue from sodium vapor lights. The orange light is produced when electricity vaporizes sodium, which is a common method used in streetlighting. However, cities have been transitioning to LED lights for their energy efficiency, cost-effectiveness, and longevity—lasting nearly ten years.

The mystery lies in the fact that these purple lights are LED fixtures, but they possess a significant defect. Although sightings of these purple streetlights began around 2020, the issue originated during the manufacturing phase between 2017 and 2019.

The primary manufacturer of these lights is Acuity Brands, a leading player in the LED market. Reports indicate that the purple lights seen in various cities originated from a specific Acuity brand known as American Electric Lighting.

These streetlights utilize a blue LED covered by a ceramic and glass lens infused with a yellow phosphor. This cheaper design, which relies solely on blue LEDs combined with yellow phosphor, aims to create white light without incorporating red and green LEDs. However, the problem arose when the phosphor coating began to delaminate. As this process occurred, the once-white light shifted to purple. Factors such as heat fluctuations and potential issues in manufacturing were believed to contribute to this defect. Notably, Acuity outsources its LED production to vendors in Asia, where lower production costs can sometimes compromise quality.

The prevalence of these purple streetlights across various regions is linked to Acuity Brands as the common source. Duke Power estimates that about 1% of the LED streetlights exhibit this color issue, which translates to approximately 5,000 affected lights. Although not an insignificant number, Acuity has assured the public that it will replace all defective streetlights under warranty.

So, the next time you encounter a purple streetlight while driving, you can rest assured knowing that it's not an innovative lighting solution but rather a significant manufacturing flaw that will require time to remedy.

In the video titled "Why are Phoenix street lights turning purple?", the phenomenon is explored further, shedding light on the various factors contributing to this perplexing issue.

Another insightful video, "Why are our Streetlights Turning Purple?!!?", delves into the implications of these purple lights and their impact on communities.

Chapter 2: Understanding the Causes and Solutions

By unraveling the complexities behind the purple streetlights, we can better comprehend the challenges faced by cities and manufacturers alike.