The American Medical Association (AMA) has recently responded to the rise of new LED street lights by adopting an official policy statement concerning the brightness and negative impact they may be having on both human health and the environment. The guidelines, presented by an AMA committee, address how communities can benefit from LED streetlights correctly.
The reason municipalities are replacing their existing streetlights with “efficient and long-lasting” LEDs is in an effort to save money on energy and maintenance. The LED streetlights are indeed achieving these outcomes; however, the AMA’s recent guideline adoptions stress the importance of properly designing new technologies. With that, the AMA emphasizes the research concerning light’s impact on human health.
Specifically, the AMA has recommendations concerning the color temperature of outdoor lighting at night. The color temperature is a measure of how much blue, green, yellow and red there is in a light source. The higher the color temperature the higher the concentration of the color blue that is present, which coincides with a whiter appearance of the light. The AMA’s statement recommends that all outdoor lighting at night should have a color temperature of no greater than 3000 Kelvin.
To put it into perspective, an incandescent light bulb has a color temperature of 2400 kelvins, meaning it contains much less blue and a considerably greater amount of yellow and red wavelengths in comparison to the new LED lights.
The AMA expresses two major concerns with the new LED street lights. First off, the high concentration of blue can cause severe glaring, which can cause extreme discomfort because of the constricting effect on the pupils. At sufficient levels, blue light can cause damage to the retina of the eye. As a driver or walker at night, this can cause problems with visual clarity and increase the risk of accidents.
The second issue raised by the AMA addresses the impact LED lighting has on the human circadian rhythmicity. Specifically, LED lighting is estimated to be five times more effective at suppressing melatonin at night in comparison to the high pressure sodium lamps that have been the general street lighting for decades. When melatonin is suppressed, our circadian rhythms are disrupted, which in turn disrupts sleep.
Various cities such as Seattle and New York have chosen white LEDs with a color temperature of 4000k or 5000k. Many complaints have arisen in response to these recent installations across the nation concerning the harshness of the new lights. For example, residents from the city of Davis, California, have demanded a complete replacement of the new street lights.
All in all, three recommendations have been put forth by the AMA in its new policy statement: