SLUMGULLION PASS — Silent stars sparkle across the night sky and reflect off alpine snowfields like scattered diamonds, a treasure southwestern Colorado towns are mobilizing to protect as never before by declaring dark zones.
Celestial views from remote spots
Celestial views from remote spots, such as this pass at 11,530 feet in the San Juan Mountains, measure almost totally free of the artificial light that increasingly blots out starry skies in cities worldwide.
At the opposite extreme, metro Denver measures 100 times brighter than natural darkness and, since 2006, the brightness increased by a factor of at least 16, according to sky quality records kept by local astronomers.
The push in Colorado to designate largescale dark-sky preserves, and reduce urban light pollution, is widening and gaining momentum amid greater pandemic-driven focus on a long-neglected part of the natural environment. Night skies never gained the federal legal protection Congress established in the 1970s to limit human degradation of the air, land and water.
Excessive artificial light causes biological harm
But scientists since then have determined that excessive artificial light causes biological harm, impairing basic functioning of wildlife, plants and people. The American Medical Association warned in 2016 that blue LED light, in particular, disrupts sleep rhythms and may raise risks of cancer and cardiovascular disease.
For decades, population growth and development in the Rocky Mountain West has brought steadily more blinding glare, sky glow and other forms of light pollution — as in Denver, where utility crews are installing 44,000 high-intensity Intelligent LED Street Light and video billboards flash at drivers downtown and en route to Denver International Airport.