One of the most inspiring sights is standing under a dark sky with the night sky ablaze with stars. Today, this inspiration is diminished by ever-increasing light pollution. Energy efficient LED street lights, being installed by cities across Canada, can make things worse. Further, as Halifax and other cities have discovered: the residents often hate LED street lights.
An episode of The Current on CBC radio documents a complaint from a resident of Halifax who said the whiteness of the light keeps her whole family up at night – even her cat, Coco. Other cities have faced similar complaints and more: LED street lights have been blamed for stealing the romance of Rome, ruining nighttime film production in Los Angeles, and disorienting salmon in the Sacramento River.
The American Medical Association’s (AMA) research concludes that LED street lights that are too blue or white can suppress melatonin, affect our sleep, and lead to obesity. Other studies indicate an increased risk for certain cancers.
LED lighting is an amazing technology, and while LED street lights are costly to install, the new lights promise to last for decades, be maintenance-free, and cost considerably less to operate.
Colour is a major obstacle for LED lighting. The most cost-effective LEDs emit a much bluer light than the sodium vapour lamps that are traditionally used. Blue-rich LED lights increases the amount of glare sensed by the human eye and also the amount of visible light pollution. This occurs because blue light scatters more through the atmosphere than red light.
The colour for lighting is measured by a unit of temperature known as kelvins. The higher the kelvins the whiter the light. Light with a temperature between 2,000 and 3,000 kelvins is a warm white that’s comfortable, like the older lights. Light from LEDs with a temperature over 5,000 is extremely harsh: they’ve been called “zombie lamps” in Seattle and “prison lamps” in Oceanside, California.
Hopefully, cities in Canada and elsewhere will follow the AMA’s guidance on LED street lighting that includes several recommendations to help reduce light pollution.
- The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light (less than 3000 kelvins).
- The AMA also recommends all LED lighting should be properly shielded to minimize glare.
- Consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.
For more information:
- Visit our table on light pollution that is part of Science Rendezvous and Astronomy Day on May 13th, 2017 at Simon Fraser University.
- The International Dark Sky Association has additional information including 5 Popular Myths About LED Streetlights.
- Read the material in the Light Pollution section of our website.