I feel the same way about noise pollution. We just take for granted that public space in cities needs to be uncomfortably loud because most people haven't had it otherwise in living memory. It could be so different and everyone would prefer it if it were. Most loud noises on streets are loud because of all the cars on the street, and also the fact that people in the cars can't hear as well as people outside of cars (necessitating louder horns, sirens, etc.)

This is a huge issue in my part of Canada right now. All those Cannabis greenhouse have illuminated the sky. I live north, away from the big cities and used to be able to see the night sky. Now, all I can see is orange and purple glows. Those greenhouses used to grow tomatoes without any issues, it's only since the shift in product that this started.

https://www.cbc.ca/news/technology/cannabis-greenhouses-ligh...

That picture shows a good start. Not directly illuminating the sky when the illumination is being used on the ground is the low-hanging fruit, but additional measures should be considered:

* Use light of lower intensity (candela) to put less illuminance (lux) on what's being illuminated. This is a more precise version of "use a dimmer light", because reducing output (lumens) won't necessarily do that if the light is more focused/directional.

* Illuminate fewer places. Street lighting for traffic safety doesn't need to be everywhere; it needs to be where hazards are.

* Use alternatives to general illumination. Some road hazards can be marked with reflectors or low-intensity marker lights pointed directly at drivers instead of overhead lighting.

* Turn off lights when not in use. Use timers. Use motion sensors. Use buttons pedestrians can press for crosswalks.

* Encourage people to use portable lighting rather than fixed lighting. This becomes more effective when there's less ambient light because less light is required to achieve the same contrast with a faraway background.

What I discovered when pushing locally for less lights is that nobody will tell you, but people are afraid of darkness.

Expect people to push back on lower light intensity, localized lighting and motion sensors with passion. It doesn't even matter if you get a design that improves security (what motion lights usually do), people will go for the less secure one if there is more light.

That's something I have no idea how to solve.

I've noticed that even suggesting it in conversations online. It's not just young children who are scared of the dark.

I'm not sure if it can be used to help solve the problem, but I've seen that when places try reduced lighting, the people who live there love the result long-term and do not want to go back. I have family in Sedona, which places strong limits on almost all fixed outdoor lighting, and Boulder, which has removed street lighting in many areas, and those rules are overwhelmingly popular.

A park near me has painfully bright LED lighting on pedestrian footpaths, in a nasty cold blue colour. It destroys your night vision as well.

I took a lux meter down the footpath, it registered 75 lux holding it in my hand.

I use a ~2500 lumen panel intended for video lighting, pointed at the ceiling as a room light (not in a nasty cold blue color). It produces a similar level of illuminance at my desk. So does a 75W incandescent light bulb from a meter away.

That's ridiculously bright for a footpath.

That “good light” is only all good if you paint the ground with vantablack, otherwise a decent amount if it still bounces back up. So you want to aim all the light downwards, yes, but it’s also important not use more light than necessary.

> So you want to aim all the light downwards, yes, but it’s also important not use more light than necessary.

Note that the little diagram also dims the light source from 500W to 100W. :)

In terms of candela, sure some light will always be reflected upwards but focusing on that really is a case of the perfect is the enemy of the good.

Good point, but I read that as being more that 400W were going into the neighbor's window or up into the sky, and the 100W is intended to keep same light levels as before.

If you don't need those light levels, a 50W floodlight would cut the remaining light pollution from upward reflections in half.

It can make a massive difference. I grew up in village near Portsmouth (UK, metro area population 1.5 million according to Wikipedia), and the night sky was bright orange whenever it was cloudy.

I now live in Berlin (6.1 million metro population), and although it isn’t perfect darkness, it is vastly better even though I’m in a built-up part of the city rather than a rural part of the city equivalent to my childhood area in the UK.

Its even worse when cities use 6000k pure-white LEDs to eke out an extra 2% efficiency. This color temperature shocks the body into thinking it is still daylight, leading to sleep disturbance.