What can LED streetlights do your health. In this article you will read more about what The American Medical Association (AMA) recommend to the city goverments to do with the led streetlights. In short: cool it and dim it.
Many municipalities are replacing existing streetlights with this new and efficient long lasting LED in order to same money on energy and maintenance but they don’t care so much about the effects for peoples health.
The Americam Medical Asssociation recommends that outdoor lighting at night should have a color temperature of no more than 3000K (Kelvin). The color temperature is ameasure of the spectral content of light from a source; how much blue, green, yellow and red there is in it. A higher CT rating generally means greater blue content, and the whiter the light appears.
A white LED at CT 4000K or 5000K contains a high level of short-wavelength blue light; this has been the choice for a number of cities that have recently retrofitted their street lighting such as Seattle and New York.
Can communities have more efficient lighting without causing health and safety problems?
The “old” streetlights have a color temperature of 2400K which means that they contain far less blue and more yellow and red wavelengths. The new LED street lighting which is rapidly being retrofitted in many cities cause two big problems accoreding to the AMA. The first issue is comeing from the high blue content which can cause severe glare resulting in pupillary constriction in the eyes.Blue light scatters more in the human eye than the longer wavelengths of yellow and red, and sufficient levels can damage the retina. This can cause problems seeing clearly for safe driving or walking at night.
The second issue is the impact on human circadian rhythmicity.Color temperature reliably predicts spectral content of light – that is how much of each wavelength is present. It’s designed specifically for light that comes off the tungsten filament of an incandescent bulb.
However, the CT rating does not reliably measure color from fluorescent and LED lights.Another system for measuring light color for these sources is called correlated color temperature (CCT). It adjusts the spectral content of the light source to the color sensitivity of human vision. Using this rating, two different 3000K light sources could have fairly large differences in blue light content. Therefore, the AMA’s recommendation for CCT below 3000K is not quite enough to be sure that blue light is minimized. The actual spectral irradiance of the LED — the relative amounts of each of the colors produced — should be considered, as well.
Why the lighting is so important ?
It’s proven that white LED light is five time more effective at suppressing melatonin at night than the high pressure sodium lamps ( given the same light output) which have been the mainstay of street lighting for decades. Melatonin suppression is a marker of circadian disruption, which includes disrupted sleep. The best for your health is a dark night with natural light from the moon. Bright electric lighting can also affect wildlife by disturbing migratory patterns of birds and someaquatic animals which nest on shore.
Recommendation By AMA
- AMA support proper conversion to community to community based LED which reduces energy consumption and decreases the use of fossil fules.
- AMA encourage minimizing and lowering the level of blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare.
- AMA recommends using of 3000k or lower lighting for outdoor installations such as roadways. All LED lighting should be properly shielded to minimize glare and detrimental human and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.
There is almost never a completely satisfactory solution to a complex problem. We must have lighting at night, not only in our homes and businesses, but also outdoors on our streets. The need for energy efficiency is serious, but so too is minimizing human risk from bad lighting, both due to glare and to circadian disruption. LED technology can optimize both when properly designed.