The American Medical Association (AMA) has issued a warning about the human health and environmental impacts of LEDs that emit excessive blue light. A new AMA-approved report backs six-year-old findings of the International Dark-Sky Association (IDA) about the negative consequences of the global movement to LEDs as the preferred outdoor lighting technology.
Blue-rich LED streetlights not only brighten the night sky, as this map shows, but also cause health and environmental problems. Image credit: F. Falchi et al., Science Advances 2016
Travis Longcore, an architect and biologist at the University of Southern California, said in an IDA statement about the AMA's warning, “Policy makers, government officials, and the American public now have the science and the imprimatur of the AMA to insist that LED installations be designed to reduce impacts on wildlife and human health.”
The AMA report details scientific evidence that nighttime exposure to blue-rich white light leads to increased risk for cancer, diabetes, and cardiovascular disease. Blue-rich LED streetlights are five times as disruptive to the human sleep cycle as conventional lighting, according to two large surveys cited in the report. Recent surveys have also found that brighter residential nighttime lighting is associated with reduced sleep duration, impaired daytime functioning, and elevated rates of obesity, the report says. Some of the detrimental effects apply to other animal species as well.
The report recommends that when converting to LED fixtures, engineers should pay attention to design features such as proper shielding and adaptive controls that can dim or extinguish light. The correlated color temperature (CCT), a measure of the spectral content of light, should be limited to 3000 K or lower, the report says; higher CCT indicates a greater amount of blue light. The IDA issued an identical CCT guideline in 2014.
“Electric light has great attributes, but we now realize, when poorly used and abused, there are also many problems,” said University of Connecticut epidemiologist Richard Stevens in the IDA statement. The AMA has previously endorsed the use of shielding for minimizing glare from streetlights and has warned about the detrimental human health effects of nighttime lighting in general.
The recently released IDA New World Atlas of Artificial Night Sky Brightness warned that street and outdoor lighting retrofits that use 4000 K lamps could cause a 2.5-fold increase in light pollution.
