Why Are Some Street Lights Purple? Here's What The Color Change Might Mean

Though they're so common that we don't typically give them much thought, lights are fascinating elements of the modern world. By sending an electrical current through a conductor, extreme amounts of heat are generated, and visible light is created. With that, we can see in the dark, but that's not all. This process can also be used to create lights of different colors, like those generated by the uniquely useful color-changing smart lights, for instance. This technology can liven up a party or make for interesting photography opportunities, but sometimes, the change of hue in lights isn't so intentional.

Some of the most important light systems in use are street lights. They go a long way in keeping drivers safe when the sun goes down, keeping the road visible and hazards illuminated. More often than not, these lights are an off-white, light blue, or light gold color, but there is one strange exception that has become prevalent in some areas. Some motorists have taken notice of street lights giving off a purple glow, and not just one or two here and there, either. It's not unheard of to spot dozens of purple street lights in a similar region, strangely alongside their traditional counterparts. 

As it turns out, this isn't intentional, with the most likely answer pertaining to a manufacturing defect within specific bulbs that cause them to go from white to violet or purple. These defective purple-appearing street lights have made a fair amount of buzz online. Here's what we know about what could be causing this strange phenomena. 

One of the leading hypothesis regarding the reason for street lights turning purple pertains to the newer tech used to illuminate them. Cities have switched from sodium lamps to LEDs due to their comparative energy efficiency, but there's more to it than merely swapping bulbs. LEDs can't give off a white hue, so extra steps need to be taken to make them appear to do so. This process involves adding a phosphor layer to a blue LED, which, when powered on, appears to emit white light by restraining blue and releasing a combination of red and yellow. This is where the mysterious purple coloring could come in.

It's entirely possible that over time, this phosphor layer has peeled away from the blue light, altering the color of the street lights they're housed within. Instead of appearing white to the common driver, they could give off a violet or even full-on purple light. This is nothing compared to the biggest downside of LED lighting, but it's still a noticeable defect. It has been said that this is likely a widespread yet fixable issue with the manufacturing of these bulbs, so these strange purple lights will likely become an anomaly of the past sooner rather than later once they can be replaced with fresh lamps. Before these purple street lights are completely replaced, though, it's worth mentioning the dangers they present for motorists and pedestrians alike.

At first glance, purple street lights might not seem like much of an issue. As it turns out, many have even expressed positive sentiments toward them since they started popping up. Be that as it may, these defective lights are anything but innocuous. They come with some major concerns in terms of driver and pedestrian safety, specifically speaking to how they impact visibility. Due to the nature of the human eye and how it perceives blue-hued light, as objects get closer and come into focus, they become more difficult to see. The longer it takes to visually process a road obstacle, the more likely an accident involving it becomes.

In addition to issues with focusing on objects while under purple light, these defective lamps can give off reduced brightness to their white or yellow counterparts. Naturally, this decreases driver and walker visibility even further. Muddying the waters a bit more, purple light doesn't exactly take well to other colors. They tend to wash most shades out and make colors appear blue, purple, or black. 

This means that everything from street signs to other vehicles can blend in with their surroundings, putting folks in even more danger. You should already keep some key safety tips in mind when driving at night, but doing so around purple street lights calls for another level of caution. Ideally, the remaining purple street lights on the road will be replaced soon enough, eliminating what could be catalysts for potential accidents.