While numerous studies have found economic value of switching to LED-based streetlights, the American Medical Association says that some LED streetlights are harmful to human health and the environmental. The AMA has officially taken a stand against light pollution and promoted the public awareness of the pervasive nighttime lighting adverse health and environmental effects, especially from blue-rich LED lighting.
“Despite the energy efficiency benefits, some LED lights are harmful when used as street lighting,” stated AMA Board Member Maya A. Babu, M.D., M.B.A. “The new AMA guidance encourages proper attention to optimal design and engineering features when converting to LED lighting that minimize detrimental health and environmental effects.”
LED streetlights create a blue-rich light that appears white to the naked eye. The AMA asserts that this blue-rich light of conventional LEDs worsens nighttime glare compared to traditional street lighting. According to the AMA, disability glare is caused by light scattered in the eye, especially blue light. The scattered light in the eye creates a luminous veil over the retinal image, which has the effect of reducing retinal contrast. The AMA asserts that the discomfort and disability from intense, blue-rich LED lighting can decrease visual acuity and safety, and potentially create a road hazard.
Blue-rich LED streetlights operate at a wavelength that most adversely suppresses melatonin during night. For this reason, the AMA says that LED street lights had five times greater impact on circadian sleep rhythms than conventional street lamps.
The AMA pointed to some recent large surveys that found that brighter residential nighttime lighting is associated with reduced sleep times, dissatisfaction with the quality of sleep, excessive sleepiness, impaired daytime functioning, and even obesity.
The adverse effects of high-intensity LED lighting are not limited to humans. Excessive outdoor lighting can disrupt the dark environment that many species need. For example, poorly designed LED lighting can disorient some bird, insect, turtle and fish species. The U.S. national parks have adopted optimal lighting designs and practices that minimize the effects of light pollution on the environment.
The AMA advocates the use of LED lighting with the lowest emission of blue light possible to reduce glare. The AMA recommends that LED lighting should have an intensity threshold that minimizes blue-rich light. The AMA also suggests that all LED lighting should be properly shielded to minimize glare and other detrimental human health and environmental effects. Also, dimming during off-peak time periods should be considered when looking into LED street lighting.
Mario Motto M.D. created a comprehensive presentation about the impact of lighting on human health and the environment that is the basis for these AMA recommendations.
Motto, Mario M.D. (2015). Glare and Human Eye Physiology, Human and environmental effects of Poorly Designed Night Lighting. [PDF File of PowerPoint Slides] Retrieved from http:// artificiallightatnight.weebly.com/uploads/3/7/0/5/37053463/motta-mario.pdf