Reader's View: Preserve the ambience of Duluth’s nighttime sky

The Nov. 21 story, “In search of the right light: Duluth’s LED streetlight conversion rankles some residents,” seemed to mistake LED color temperature for brightness.
Two LED lights of different color temperature can put out the same brightness (lumens). The issue with higher color temperature, like 4000K or higher, is that they put out more light in the blue part of the visible spectrum. It is the blue wavelengths of light that are the problem. The sky is blue because our atmosphere scatters blue light. Blue light has more energy (nothing to do with brightness) and can more quickly break down body-made chemicals like Rhodopsin in our eyes, which is created to give us better night vision.
When driving at night, which vehicle headlights cause less glare in your eyes, the bluish ones or the white ones?
Another issue about lighting is the fixture being used? To prevent glare, a shielded fixture, one that prevents light from going upward or off to the sides, is needed. We want the light on the ground to illuminate things, not shining into the sky to cause light pollution or in our eyes to cause glare.
As a native Duluthian, I hope the city’s engineers preserve the skies and the ambience of Duluth. It is a truly remarkable city.
Gregory Furtman
Webster, Wis.