Item — HN Reader

> Also good is using more LED street lamps that focus the light where we need it,

Focusing light where needed is good. Using LEDs, as we do now, has downsides though. LED lighting in cities is making astronomy and astrophotography and even animal life worse in some cases.[1]

Traditional sodium vapour lights pollute around a wavelength of 589 nm.[2] That's the yellow/orange sky you used to see in the sky around cities. In theory, if you filtered out that wavelength 10 years ago, you'd be able to eliminate a lot of light pollution. But today, with more LED lighting, the pollution tends toward white/blue. This is "nicer" in some objective and subjective ways. e.g. colour accuracy. But it's a bitch to filter out, without also removing all the white and broad spectrum we want to see in the features of the night sky.

Animals are also sensitive to white and blue light emitted by modern LEDs, and the NatGeo link and others go into why this can be a bad thing, compared to "old fashioned" lighting methods, inefficient as they are.

[1] https://www.nationalgeographic.com/news/2017/11/light-pollut...

[2] https://www.peterzelinka.com/blog/2019/8/light-pollution-fil...

We made LED lighting white because we wanted it. We can make yellow LED lighting as well. This should be suggested to city councils, if changing the wavelength would be beneficial to insects with no downsides.

I'd be so stoked for red street lights. They don't mess up your vision at night.

Indeed. Nor does red light mess as much with animal (incl. human) physiology and behaviour and waking cued by white/blue/daylight.

Potential small (safety?) downside: red light illumination does greatly reduce colour discrimination at night versus white light.

Belgium uses yellow light. And, unlike its neighbors, it has lights all along its interstates. Quite eerie to see when you’re not used to it.