Feeling a little blue? You might be standing under a bad streetlight

Streetlights give a blue glow along a city street
LED street lights that've changed hue from white to blue, due to a manufacturer's defect, are seen near the corner of Prior and Carroll avenues in St. Paul on Jan. 2.
Tim Nelson | MPR News

These short days of midwinter have a lot of Minnesotans out and about in the dark — and increasingly driving and walking through pools of weird street lighting.

They’re now a common sight in St. Paul, where the bulbs in scores of LED fixtures have been slowly changing hue from daylight white to stunningly blue.

It’s not on purpose. The city’s public works department says it’s a “a manufacturer's defect and failure of the LED bulb installed in many of the city's ‘cobra style’ street lights.” (They’re called cobra-style because the bulbous fixture on the end of a support arm looks like a cobra snake’s head.)

A Business Insider interview in November with an executive from Acuity, the company that supplies many cities with lights, explained the issue: The light-emitting diodes in the bulbs are built blue, then wrapped in a fixture that includes phosphorous, filtering the light and turning it white.

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The executive with Acuity called the problem “phosphor displacement.” The article further explained the “wrapping” around the bulbs is failing, or delaminating. That leaves the blue, or some say Prince-esque purple light, shining alone from the affected street lights. 

The defective bulbs also have been reported in Apple Valley, as well as cities in Arizona, New Mexico, Wisconsin, Maryland, Kentucky, North Carolina and Florida, to name a few. They apparently involve LED light sources made from 2017 to 2019. 

St. Paul officials say they’re replacing the bulbs as they fail. The lights are under warranty, and the manufacturer is providing replacements as they fail, according to public works spokesperson Lisa Hiebert.  

The city says if you see the tell-tale blue tinge in a street light, call in the location to the city’s lighting division, at (651) 266-9777.