LED street lighting may pose health risks

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The American Medical Association issued guidelines on June 14 on how communities can choose LED streetlights to “minimize potential harmful human health and environmental effects.”

Converting conventional street light to energy efficient LED lighting leads to cost and energy savings, and lowers reliance on fossil fuels. But some LED lights can pose health risks.

The American Medical Association recommends that outdoor lighting at night, particularly street lighting, should have a color temperature of no greater than 3000 Kelvin.

According to the American Medical Association, LED street lighting has two problems.

LED streetlights that appear white to the naked eye emit a large amount of blue wavelength light, which is estimated to be five times more effective at suppressing melatonin at night than the high pressure sodium lamps that have been the mainstay of street lighting for decades. Melatonin suppression is a marker of circadian disruption, which includes disrupted sleep.

Blue light also scatters more in the human eye than the longer wavelengths of yellow and red. Sufficient levels of blue light can damage the retina. And LED light is concentrated, which can cause severe glare, resulting in pupillary constriction.

RUNDOWN SHOWS:
1. Street lights conversion
2. How it works: incandescent bulb
3. How it works: LED bulb
4. LED at 3,000K
5. Color dispersion
6. Color Temperature: white light
7. Color Temperature: incandescent
8. Color Temperature: candle
9. Blue light frequency
10. Blue light in eye
11. Circadian rhythm
12. Circadian rhythm disruption

VOICEOVER (in English):

“Converting conventional street light to energy efficient LED lighting leads to cost and energy savings, and a lower reliance on fossil-based fuels as well.”

“With incandescent bulbs, an electric current is passed through a wire filament until it becomes hot enough to emit light. Incandescent bulbs therefore waste a lot of energy as heat.”

“An LED bulb produces light when positive and negative electrons move around within its semiconductor structure. But not all LEDs are good for you, depending on their color temperature.”

“The American Medical Association recommends that outdoor lighting at night, particularly street lighting, should have a color temperature of no greater than 3000 Kelvin.”

“Color temperature is a measure of spectral content: how much blue, green, yellow and red is in a light.”

“A higher color temperature generally means more blue content, which in the case of street lights causes them to appear white to the naked eye.”

“An incandescent bulb has a color temperature of 2400 Kelvin, containing far less blue and far more yellow and red wavelengths.”

“A flame from wood or a candle burning has a color temperature of about 1800 Kelvin, mostly yellow and red with almost no blue.”

“Blue-rich LED street lighting can cause discomfort and glare. This is because blue light scatters more in the human eye than yellow and red.”

“Sufficient levels of blue light can damage the retina. And LED light is concentrated, which can cause severe glare, resulting in strained eyes.”

“The American Medical Association also warns that blue-rich LED light can have a negative impact on human circadian rhythmicity.”

“Blue-rich LED light is estimated to be five times more effective at suppressing melatonin at night than the sodium lamps previously used for street lighting, causing sleeplessness.”

SOURCES: CNN, American Medical Association, How Stuff Works
http://edition.cnn.com/2016/06/21/health/led-streetlights-ama/index.html
http://www.ama-assn.org/ama/pub/news/news/2016/2016-06-14-community-guidance-street-lighting.page
http://science.howstuffworks.com/environmental/green-tech/sustainable/led-light-bulb.htm