The LED's Challenge to High Pressure Sodium

The youtube channel Technology Connections has a couple of interesting articles about LED (and sodium-vapor lamp) bulbs in street lighting: [VIDEO] (Actually, most if his videos are pretty interesting to explore, especially the ones about early TV)

Warm white LEDs exist, with color quality exceeding that of sodium vapor in every way, but cities often use blueish LEDs because they're cheaper and more efficient. Relevant Technology Connections video: [VIDEO]

Here's a quite good video about the pros and cons of LED vs high/low-pressure sodium street lamps: [VIDEO] . It goes into lamp efficiency, how our eyes see differently at night, response time under different sorts of light, color temperature, circadian rhythm disruption, and light pollution.

It's a good video, but it's also a case study in being 'almost right'. The almost-correct interpretations cascade and result in a faulty conclusion: that blue-white LED streetlights are better than orange-white streetlights. Various comments object to the faulty conclusion ([1], for example). At the end he at least addresses his ignorance: > [18:39] You may have noticed that I didn't talk about the blue light from LEDs, and how this is supposedly ruining our eyes. That's because the "science" behind this is questionable, at best. > [18:55] [discussion of chart with percentage blue light of various light sources] > [19:04] [...] but considering that our eyes can withstand the intensity of sunlight , which is far far greater than any normal artificial light source, and also has a lot of blue light, and ultraviolet, which definitely is harmful, I think the 'blue light' thing is just fear-mongering. If someone can point to some verified, peer-reviewed research supporting this, and not a dodgy website, I'll consider changing my stance. In any case, the high flexibility of LED technology means it can be tuned in pretty much any way we like. The research on the harm of blue light is out there -- For example, one of the comments links to "Effects of blue light on the circadian system and eye physiology" [0]. (only partially read at this point - I don't know if this paper gets into the mechanism of damage done by blue light, as I understand it...) The sun hangs high in the sky and cas

I'm reminded of a Technology Connections video about what happened when his town switched from incandescent to LED stop lights < [LINK] > Of course, while I was looking that up I found out he made a video about sodium vapour lights! < [VIDEO] >