Nearly twelve years ago Davis, California set the bar for LED streetlight conversion backlash. Residents rejected excessively bright and glaring 4000K streetlights, and the city responded by putting the conversion on hold, changing course, and switching to 2700K streetlights at lower lumens. (The Smart Outdoor Lighting Alliance provides this case study.) 

Unfortunately, word did not spread to the people calling the shots, and cities continued to repeat the same mistake. But it looks like the tide is turning.  In 2023 Boulder, Colorado took the temperature on Color Correlated Temperature, providing a public survey with a full of range of options.

An example of streetlight temperature options for residential roadways. 55% of respondents favored option C (2700K) while 29% favored option D (2200K).

The verdict? Residents overwhelmingly preferred "warm" 2700K and 2200K streetlights. Read more here: Streetlight Color Our Community Cares About. 

More recently, Pittsburgh--which already had made light pollution headlines by being the first city of its size to pass a DarkSky blessed ordinance--opted for 2700K streetlights with part-night dimming. That common sense approach is so worthy of emulation that the New York Times selected it for its "50 States, 50 Fixes" feature: Why This Pennsylvania Town Put Its Streetlights on a Dimmer

Back in 2010, DarkSky International (then the International Dark-Sky Association) published a white paper warning of the harms of high blue content solid state lighting, particularly because of increased sky glow from the more expansive scattering of short wavelength light in the atmosphere. Glare and physiological impacts to humans and animals, with cascading degradation to ecosystems, added to the evidence in favor of warmer lighting.  Is the rest of the world finally catching up?