Is LED blue light hazard really that serious?
If people in Seattle suffer from insomnia, heartbreak may only be part of the reason.
According to a report by The Washington Post on September 25, the American Medical Association issued a warning in June that high-intensity LED street lights in Seattle, Los Angeles, New York and other places release invisible blue light that disrupts sleep rhythms. It may also increase the risk of cancer and cardiovascular disease. The medical association also reminded that LED affects drivers' night driving vision. The American Medical Association urged states and cities to reassess the intensity of existing LED lights.
The US Department of Energy reported last year that about 13% of areas or roads use LED lighting. LEDs save at least 50% more energy than yellow high-pressure sodium lamps and can last 15 to 20 years. Unlike high-pressure sodium lamps, LED light is uniform.
Blue light from electronic products interferes with sleep
City managers consider the evidence for these health concerns to be insufficient. Yet it is a fact that the first generation of LED lights has benefited the entire city. New York responded to residents' complaints, promising to replace high-intensity LED bulbs. Medical associations consider low-intensity white LED bulbs to be safe.
Scott Thompson, Seattle's city lighting spokesperson responsible for Seattle's outdoor lighting, refuted claims that high-brightness, white LED lights affect health, and pointed out that street lights emit fewer blue light waves than computers and televisions.
After a year and a half of discussions and sampling, Lake Worth, Florida, replaced its sodium street lights with 4,150 amber LED lights. "We have found color to be of great importance to the city, and we are proud to have made this choice," said city manager Michael Born.
Mark Hartman, Phoenix's chief sustainability officer, said that the city's intersections and stadiums require dense, bright lighting, while residential areas have relatively soft lighting. He said the city would consider residents' health concerns. "Although blue light affects sleep, no one stops watching TV or using computers after 9 p.m. because of it," he said.
Should LED lights be approved?
As soon as outdoor LED lights were put into use, the federal government encouraged states and municipalities to use them, claiming that LED lights are highly efficient and energy-saving, and can be used as traffic signals and evacuation indicator lights. However, critics say the federal authorities' endorsement of LED lights was too hasty.
"The U.S. Department of Energy and the Environmental Protection Agency are aggressively promoting OLED," said Michael Siminovitch, director of the California Lighting Technology Center at UC Davis. "I think it is too hasty."
Siminovitch said that early LED lights did indeed have adverse effects on human physical health.
Light is measured by color temperature, usually expressed in "Kelvin" or "K". "The initial LED street lights had temperatures of at least 4000K, with bright white light accompanied by invisible high-intensity blue light. Now, LEDs do not emit harmful blue light; instead, they produce a soft amber color."
Reactions to the installation of 4000K and 5000K LEDs have varied. Police, traffic safety officials, and drivers prefer the bright lights because they make the road easier to see. However, in New York and Seattle, residents have complained that streetlights are too glaring and terrifying, damaging the city's image.
Even before the medical association issued its warning, researchers had raised health concerns. Some have pointed out that blue-rich LED outdoor lights may reduce the body's secretion of the hormone melatonin. Melatonin secretion at night helps balance reproductive, thyroid, and adrenal hormones, regulating the body's physiological rhythms.
Smitsevich said, "Humans need to rest at night and do not need lighting."
The medical association cited the melatonin issue, noting that research indicates LEDs reduce sleep duration, lower sleep quality, and affect daytime performance. Evidence suggests that prolonged exposure to strong light may increase the risk of cancer, diabetes, cardiovascular disease, and obesity.
Finally, the American Medical Association has warned about the impact of intense LEDs on wildlife, especially nocturnal animals, birds, and insects. "These lights are not only harmful to us — LEDs are equally detrimental to the environment," said Mario Motta, one of the authors of the American Medical Association report. The medical association praised LEDs for their energy efficiency and lighting effectiveness, but urged cities to minimize blue light on streets as much as possible, recommending the use of light-emitting diodes with a color temperature below 3000K.
Just use LED lights with caution
The Lighting Research Center at Rensselaer Polytechnic Institute in Troy, New York, believes that the dangers posed by lighting are far less severe. The research center points out that the report by the American Medical Association is based on the premise that prolonged exposure to high-intensity LED lights is dangerous, as blue-rich LEDs can be harmful. However, for the vast majority of people, the normal use of lighting equipment poses no issues at all.