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It’s possible to install warm colored LEDs with very little blue light output though. You get all those benefits without giving up the more-suitable-for-night s

It’s possible to install warm colored LEDs with very little blue light output though. You get all those benefits without giving up the more-suitable-for-night sodium light spectral benefits.

tqi 2y ago
Agree, but it's more expensive and less energy efficient[1]. Personally, that seems worth it to me [EDIT: "it" being using slightly less efficient lights that are more comfortable for people], but thats a difference in values not in how much I "care" about the problem... [1] https://www.scientificamerican.com/article/streetlights-are-mysteriously-turning-purple-heres-why/#:~:text=The%20other%20is,phosphor%2Dcoating%20combination https://www.scientificamerican.com/article/streetlights-are-....
- nyokodo 2y ago
  > that seems worth it to me How much more energy efficient is it? If it's a tiny efficiency gain vs the negative effects of blue heavy white light then I would suggest it's a bad tradeoff. Some studies have suggested that blue light doesn't affect sleep [1] but the psychological effects of cold vs warm light has been used by lighting designers for decades. Cold light is less comfortable and discourages hanging around, the positive spin is "energizing", it's often used in supermarkets and budget stores that value faster browsing, and impulsive decisions under a greater feeling of urgency. Warm light has a relaxing effect and is used, for example, in luxury stores and restaurants where people are intended to take their time. [2] For outdoor areas where people are intended to enjoy relaxing after dark activities warmer light would be far superior an experience than colder light. 1. https://www.medicalnewstoday.com/articles/blue-light-may-not-affect-sleep-wake-cycle https://www.medicalnewstoday.com/articles/blue-light-may-not... 2. https://www.tcpi.com/how-lights-impacts-psychology-mood-in-retail/ https://www.tcpi.com/how-lights-impacts-psychology-mood-in-r...
- bryanrasmussen 2y ago
  sure - for your house. For lights all over the city that will be lasting years?
_lyxd 2y ago
OK but blinding blue LEDs are most common substitutes, because it's the lazy default, and because people do not care. That's the point of the article.
- teslabox 2y ago
  Blue-white LEDs have become the replacement for High Pressure Sodium [HPS] traffic lights because that's what the LED light companies have to sell. In the early years of the transition to LED streetlights they had to sell blue-white LED streetlights because warmer LEDs were not competitive with HPS on the basis of lumens-per-watt. Most of the people who understood the advantages of blue-free amber HPS light over white metal halide lights retired, and this little tidbit of information didn't get passed to the next generation of city employees. > and because people do not care. People care, but they don't know why they hate the blue-white LED replacement lights. I've complained to the city about their new lights, but have not gotten any responses about why they haven't deployed LED lights with a safe spectrum of color. This comment about unsafe blue-white headlights got a few upvotes: https://news.ycombinator.com/item?id=42444111 https://news.ycombinator.com/item?id=42444111
  - Qwertious 2y ago
    Blue light is safer for cars - it gives slightly faster reaction times, and lower the chance of drivers falling asleep. The problem is that for pedestrians, the reaction-time is irrelevant, they're butt-ugly, and plenty of people go on night walks because they can't sleep but want to. Half of this article is basically about cities being overly car-centric.
    - teslabox 2y ago
      I’m not well-read on the old lighting research, but I’ve come across some explanations for why humans actually do much better with amber outdoor lighting than white. One of these points relates to how our pupils expand and contract with the amount of light available.
    - reddalo 2y ago
matthewdgreen 2y ago
Here in Baltimore the city seems to have purchased a huge batch of defective LEDs that are actually purple. It’s disturbing when you encounter one.
- josephcsible 2y ago
  Nitpick: "are actually purple" makes it sound like they came out of the factory purple, but they're actually changing from white to purple over time as the phosphor coating fails.
  - NikkiA 2y ago
    They'll be near-UV LEDs with a phosphor to produce white, high efficiency, low cost, but garbage long term.
  - matthewdgreen 2y ago
    Just to be clear, these are about 1-3 years old. So yes they probably weren't purple on the day they were installed, but this is a defect and not normal aging. https://www.reddit.com/r/todayilearned/comments/136nz3b/til_since_2020_white_led_streetlights_have_been/ https://www.reddit.com/r/todayilearned/comments/136nz3b/til_...
- 1659447091 2y ago
  The city employee who bought them is probably a massive Ravens fan...
  - gunian 2y ago
    i mean who wouldn't be the way they're playing
- Peanuts99 2y ago
  Might be so that they don't interfere with a certain species of wildlife. We have deep blue ones near me that aren't visible by a protected bat species.
- 2y ago
a_e_k 2y ago
The funny thing is, in my neck of Seattle (the city this post is complaining about), I've seen some of the harsh white LEDs that went in switched over to a warmer color. I remember being quite shocked when I pulled into a city-owned parking lot one night and realized that all of the lights around were all now a warmer color instead of the harsh white. The lights in my neighborhood also seem to have been switched over at some point. I suppose they're the tunable LEDs, but clearly someone here does care.
- lloeki 2y ago
  In my city they started turning off all streetlights at midnight outside of major driving lanes and active center areas. It's weird and somewhat unnerving at first but brilliant. I'd argue road-wise it is possibly even safer because headlights work so much better when it's pitch black by virtue of the human eye having so much dynamic range. Pedestrians can't miss cars as they're blasting light through the dark; cars can't miss bikes because even passive reflectors are blaring in the surrounding darkness; even pedestrians end up being more visible because of the higher contrast, cast shadows, and movement that conspire to make them plainly pop out like cardboard props or Doom 3 flashlight jumpscares. And when you go out of the dark zone into a major axis that's bathed in light that feels warm and safe it's like everything is suddenly muted and flattened as if reality went through a low contrast sepia-tinted desaturation filter. You feel like you see better but everything is muddled together in the sameness of uniform lighting. The experience is highly cognitively dissonant and counterintuitive.
  - jaimebuelta 2y ago
    WTF? What about pedestrians? Are they walking in full darkness? This seems to be totally oriented to cars. I find American cities incredibly dark by night. Walking around feels too dark and unpleasant.
    - quietbritishjim 2y ago
      I'm don't see why this is downvoted, I think it's an honest and legitimate question. What are pedestrians supposed to do when there's no car passing them right this moment? Carry their own torch? Rely on ambient light from the moon and reflected from nearby lit streets? Are we assuming there's such a high volume of cars that there's never a gap? I'm genuinely confused.
Tomte 2y ago
In the netherlands I have seen green street lights with motion sensors. Only on smaller streets and pedestrian paths, though.
- alexandrehtrb 2y ago
  That sounds cool.
maayank 2y ago
Any way to test my light's spectrum? e.g. a cheap home spectrometer
- tmnvdb 2y ago
  Take a photo
  - maayank 2y ago
    Implies no white balance shenanigans
    - NikkiA 2y ago
      A sheet of paper will generally manage ok for white balance calibration. A 3 tone grey card would be better, but a single, simple white will suffice
- neop1x 2y ago
  Use a CD disk - really - it disperses light similarly to a dispersive prism. You can then see and estimate the amount of red, blue and green in a light. It works very well if you just want to check blue light sources at night. And you can even make a DIY spectrometer with it! https://youtu.be/p3MzQ1OF3lk https://youtu.be/p3MzQ1OF3lk
flyinghamster 2y ago
In my town, when they replaced the old mercury arc and high pressure sodium lights, they picked a pleasing neutral white for the side streets that's far better than the bluish-white mercury arcs they replaced, while using 40 watts each instead of 175. Win-win in my book. The main streets have a different LED with a slight yellow cast, but not the ugly orange of high pressure sodium. Yes, we can have nice LED street lighting.

It’s possible to install warm colored LEDs with very little blue light output though. You get all those benefits without giving up the more-suitable-for-night sodium light spectral benefits.

tqi 2y ago

Agree, but it's more expensive and less energy efficient[1]. Personally, that seems worth it to me [EDIT: "it" being using slightly less efficient lights that are more comfortable for people], but thats a difference in values not in how much I "care" about the problem... [1] https://www.scientificamerican.com/article/streetlights-are-mysteriously-turning-purple-heres-why/#:~:text=The%20other%20is,phosphor%2Dcoating%20combination https://www.scientificamerican.com/article/streetlights-are-....

nyokodo 2y ago
> that seems worth it to me How much more energy efficient is it? If it's a tiny efficiency gain vs the negative effects of blue heavy white light then I would suggest it's a bad tradeoff. Some studies have suggested that blue light doesn't affect sleep [1] but the psychological effects of cold vs warm light has been used by lighting designers for decades. Cold light is less comfortable and discourages hanging around, the positive spin is "energizing", it's often used in supermarkets and budget stores that value faster browsing, and impulsive decisions under a greater feeling of urgency. Warm light has a relaxing effect and is used, for example, in luxury stores and restaurants where people are intended to take their time. [2] For outdoor areas where people are intended to enjoy relaxing after dark activities warmer light would be far superior an experience than colder light. 1. https://www.medicalnewstoday.com/articles/blue-light-may-not-affect-sleep-wake-cycle https://www.medicalnewstoday.com/articles/blue-light-may-not... 2. https://www.tcpi.com/how-lights-impacts-psychology-mood-in-retail/ https://www.tcpi.com/how-lights-impacts-psychology-mood-in-r...
bryanrasmussen 2y ago
sure - for your house. For lights all over the city that will be lasting years?

_lyxd 2y ago

OK but blinding blue LEDs are most common substitutes, because it's the lazy default, and because people do not care. That's the point of the article.

teslabox 2y ago
Blue-white LEDs have become the replacement for High Pressure Sodium [HPS] traffic lights because that's what the LED light companies have to sell. In the early years of the transition to LED streetlights they had to sell blue-white LED streetlights because warmer LEDs were not competitive with HPS on the basis of lumens-per-watt. Most of the people who understood the advantages of blue-free amber HPS light over white metal halide lights retired, and this little tidbit of information didn't get passed to the next generation of city employees. > and because people do not care. People care, but they don't know why they hate the blue-white LED replacement lights. I've complained to the city about their new lights, but have not gotten any responses about why they haven't deployed LED lights with a safe spectrum of color. This comment about unsafe blue-white headlights got a few upvotes: https://news.ycombinator.com/item?id=42444111 https://news.ycombinator.com/item?id=42444111
- Qwertious 2y ago
  Blue light is safer for cars - it gives slightly faster reaction times, and lower the chance of drivers falling asleep. The problem is that for pedestrians, the reaction-time is irrelevant, they're butt-ugly, and plenty of people go on night walks because they can't sleep but want to. Half of this article is basically about cities being overly car-centric.
  - teslabox 2y ago
    I’m not well-read on the old lighting research, but I’ve come across some explanations for why humans actually do much better with amber outdoor lighting than white. One of these points relates to how our pupils expand and contract with the amount of light available.
  - reddalo 2y ago

matthewdgreen 2y ago

Here in Baltimore the city seems to have purchased a huge batch of defective LEDs that are actually purple. It’s disturbing when you encounter one.

josephcsible 2y ago
Nitpick: "are actually purple" makes it sound like they came out of the factory purple, but they're actually changing from white to purple over time as the phosphor coating fails.
- NikkiA 2y ago
  They'll be near-UV LEDs with a phosphor to produce white, high efficiency, low cost, but garbage long term.
- matthewdgreen 2y ago
  Just to be clear, these are about 1-3 years old. So yes they probably weren't purple on the day they were installed, but this is a defect and not normal aging. https://www.reddit.com/r/todayilearned/comments/136nz3b/til_since_2020_white_led_streetlights_have_been/ https://www.reddit.com/r/todayilearned/comments/136nz3b/til_...
1659447091 2y ago
The city employee who bought them is probably a massive Ravens fan...
- gunian 2y ago
  i mean who wouldn't be the way they're playing
Peanuts99 2y ago
Might be so that they don't interfere with a certain species of wildlife. We have deep blue ones near me that aren't visible by a protected bat species.
2y ago

a_e_k 2y ago

The funny thing is, in my neck of Seattle (the city this post is complaining about), I've seen some of the harsh white LEDs that went in switched over to a warmer color. I remember being quite shocked when I pulled into a city-owned parking lot one night and realized that all of the lights around were all now a warmer color instead of the harsh white. The lights in my neighborhood also seem to have been switched over at some point. I suppose they're the tunable LEDs, but clearly someone here does care.

lloeki 2y ago
In my city they started turning off all streetlights at midnight outside of major driving lanes and active center areas. It's weird and somewhat unnerving at first but brilliant. I'd argue road-wise it is possibly even safer because headlights work so much better when it's pitch black by virtue of the human eye having so much dynamic range. Pedestrians can't miss cars as they're blasting light through the dark; cars can't miss bikes because even passive reflectors are blaring in the surrounding darkness; even pedestrians end up being more visible because of the higher contrast, cast shadows, and movement that conspire to make them plainly pop out like cardboard props or Doom 3 flashlight jumpscares. And when you go out of the dark zone into a major axis that's bathed in light that feels warm and safe it's like everything is suddenly muted and flattened as if reality went through a low contrast sepia-tinted desaturation filter. You feel like you see better but everything is muddled together in the sameness of uniform lighting. The experience is highly cognitively dissonant and counterintuitive.
- jaimebuelta 2y ago
  WTF? What about pedestrians? Are they walking in full darkness? This seems to be totally oriented to cars. I find American cities incredibly dark by night. Walking around feels too dark and unpleasant.
  - quietbritishjim 2y ago
    I'm don't see why this is downvoted, I think it's an honest and legitimate question. What are pedestrians supposed to do when there's no car passing them right this moment? Carry their own torch? Rely on ambient light from the moon and reflected from nearby lit streets? Are we assuming there's such a high volume of cars that there's never a gap? I'm genuinely confused.

Tomte 2y ago

In the netherlands I have seen green street lights with motion sensors. Only on smaller streets and pedestrian paths, though.

alexandrehtrb 2y ago
That sounds cool.

maayank 2y ago

Any way to test my light's spectrum? e.g. a cheap home spectrometer

tmnvdb 2y ago
Take a photo
- maayank 2y ago
  Implies no white balance shenanigans
  - NikkiA 2y ago
    A sheet of paper will generally manage ok for white balance calibration. A 3 tone grey card would be better, but a single, simple white will suffice
neop1x 2y ago
Use a CD disk - really - it disperses light similarly to a dispersive prism. You can then see and estimate the amount of red, blue and green in a light. It works very well if you just want to check blue light sources at night. And you can even make a DIY spectrometer with it! https://youtu.be/p3MzQ1OF3lk https://youtu.be/p3MzQ1OF3lk

flyinghamster 2y ago

In my town, when they replaced the old mercury arc and high pressure sodium lights, they picked a pleasing neutral white for the side streets that's far better than the bluish-white mercury arcs they replaced, while using 40 watts each instead of 175. Win-win in my book. The main streets have a different LED with a slight yellow cast, but not the ugly orange of high pressure sodium. Yes, we can have nice LED street lighting.