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US Streetlights Are Turning Purple

scientificamerican.com

11–20 of 122 posts

Re: US Streetlights Are Turning Purple

#11
> people driving at night may notice a moving object in their peripheral vision more quickly under bluish-white light than under yellowish-white light, [...] Gaining improved peripheral vision under blue-tinged light comes with a trade-off, however: once the moving object comes into focus, it becomes harder to see.

If we were switching away from LED to sodium vapor lamps instead of the other way around, they would have written the exact same article but in reverse, still claiming the change makes us less safe.

Re: US Streetlights Are Turning Purple

#12

A Trader Joe's in Phoenix has had these for so long (years?), the parking lot is bathed in almost completely blue light. They don't seem to care. It really throws off your vision and things look "fuzzy".

Maybe it's just me but the actual color of the light never bothered me. The first time I saw it I figured out it was a form of LED failure. It's so common here that I don't think about it anymore

monochromatic light as emitted by LEDs is quite disorienting.

Re: US Streetlights Are Turning Purple

#13
post #12

Earlier quoted context omitted.

Maybe it's just me but the actual color of the light never bothered me. The first time I saw it I figured out it was a form of LED failure. It's so common here that I don't think about it anymore

monochromatic light as emitted by LEDs is quite disorienting.

I grew up in the generation where every manufacturer decided blinding bright blue LEDs were standard features of all consumer electronics. Maybe I am just desensitized to it?

Re: US Streetlights Are Turning Purple

#14
> And yet some streetlights have suddenly turned a jarring shade of purple. It is hard to determine the exact cause without dissecting one of the defective lights, but scientists have a hypothesis: bright purple light suggests the phosphor layer around the lights has been “delaminated”—peeled off—exposing the blue LED light underneath, Brgoch says.

What an annoying/bad article. "Here are our guesses of this when we could have actually figured it out". It's not like these are in space and hard to get to, they are on the freaking street. Get a crew out there and figure it out.

Then they go on to do a _bunch_ of handwavy "science" about blue light while not really making any point (IMHO).

> One thing that Bullough suggests pedestrians and drivers do to stay safe under purple streetlights—or any lights, for that matter—is to remove sunglasses and blue-light-filtering glasses when walking or driving at night.

Ahh yes, for all the people that wear their sunglasses at night, I'll make sure to let Corey Hart know.

This just seems like an incredibly low-effort article with zero definite facts and enough hand waving to sprain your wrist.

Re: US Streetlights Are Turning Purple

#15
post #9

Better article with lots of pictures and diagrams, links to conference talks, etc: https://inside.lighting/news/24-05/heres-why-led-streetlight...

Thank you, this has been happening near me for years now and I've seen countless news articles on it, but this is the first time someone's actually linked what looks like an authoritative source (or at least anything that goes into more detail than "the phosphor is falling off... or something").

Re: US Streetlights Are Turning Purple

#16

“ producing light that is comparable or better in quality.” They don’t support this claim about led’s, and many groups are concerned about harsh cool light interrupting circadian rhythms. They’re also hideous.

It depends strongly on implementation. LEDs can produce white light at any color temperature and CRIs ranging from terrible to great. Quality LEDs are quite nice indeed (when they're not turning purple). Most LED streetlights replaced sodium vapor lights, though, which produce the sickliest, most horrible orange color known to humanity. Just about any LED is an improvement over those.

Sodium lights aren’t even orange in the normal sense of the word. They only emit one wavelength.

Re: US Streetlights Are Turning Purple

#18
post #10

TL;DR - coating is wearing off.

Sure, white LEDs are blue LEDs with a phosphorus layer. The Blue LED invention led to the 2014 Nobel Prize for Physics.

I (and my 6-year-old) really enjoyed this video from Veritasium about the invention of the blue LED. https://www.youtube.com/watch?v=AF8d72mA41M

Re: US Streetlights Are Turning Purple

#20

> And yet some streetlights have suddenly turned a jarring shade of purple. It is hard to determine the exact cause without dissecting one of the defective lights, but scientists have a hypothesis: bright purple light suggests the phosphor layer around the lights has been “delaminated”—peeled off—exposing the blue LED light underneath, Brgoch says. What an annoying/bad article. "Here are our guesses of this when we c…

FWIW I do wear sunglasses for long highway drives at night.

Without them halogen headlights in my side mirrors give me a migraine after a while.

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