On: Dutch town installs bat-friendly red LED street lights (2018)

[mlyle]

The dynamic range of the eye is confusing for aspects like this.

The amount of blue light you're exposed to from the night sky is trivial. Outdoors on a moonless night is 0.002 lux (of which, my understanding, about half is airglow and fairly blueish).

Compare to a not-too-bright single blue LED in your bedroom, emitting 0.5 lumens. You could spread that over 2000 square feet of surfaces and still have more blue light around than comes from the night sky.

[TylerE → mlyle]

Lux != lumen. Lux is lumen per unit area.

[mlyle → TylerE]

> Lux != lumen. Lux is lumen per unit area.

Yes... that is why I divided by area.

It's kind of sad how many of us end up so impatient over common mistakes that we screw up just as badly in our eagerness to snap at people.

Obviously it's fudged a bit. The LED is not an isotropic emitter, and it's not at the center of a spherical room with perfectly reflective walls.

In practice, I suspect the amount of blue illumination from one dim blue LED in a large bedroom and the night sky are pretty much equal.

[BenjiWiebe → TylerE]

Isn't that what they are saying? 0.5 lumen spread out over 2000 sq feet is still more lux than the night sky?