LED Streetlights Are Giving Neighborhoods the Blues

LED Streetlights Are Giving Neighborhoods the Blues - IEEE Spectrum
"Early adopters of LED street lighting are struggling with glare and light pollution
You may have noticed them going up in your town’s streets and parking lots: a new generation of pole-mounted lights that pour down a cool torrent of lumens from an array of light-emitting diodes. Like me, you might have welcomed this development. LEDs are, after all, the most energy-efficient lighting option on the market.
They can last twice as long as ordinary sodium-vapor streetlights, and their prices have dropped to within range of the competition.
If the switch to LEDs had needed any more support, it came from growing evidence about climate change.
In the United States, street lighting accounts for a whopping 30 percent [PDF] of all the energy used to generate electricity for outdoor lighting.
...Armed with statistics like these, and a mandate to cut energy use wherever they can, municipalities across the United States have installed more than 5.7 million outdoor LED street and area lights.
...For some, those first LED lights have been a fiasco.
The harsh glare of certain blue-rich designs is now thought to disrupt people’s sleep patterns and harm nocturnal animals.
And these concerns have been heaped on the complaints of astronomers, who as far back as 2009 have criticized the new lights.
...The episode invites a few questions: How did an energy-saving technology that looked so promising wind up irritating so many people...? 
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