White LED streetlights impacts on health and safety
LED Streetlights has become the preferred choice by municipalities due to more energy saving, better reliability, and advanced control options, but white led streetlights impacts on health and safety should be taken in consideration.
When we compare an LED vs HPS, we can see that LEDs actually really do pay for themselves for many reasons:
- The LED much better than high pressure sodium or even metal halide which can allow municipalities to save up to 60% of lighting electricity bill.
- A high pressure sodium lamp can work for up to 20000h but good quality LED street lighting can last for 50000 h; which also help to save maintenance cost over the lifetime
- Lumen depreciation is the process in which the lumen output of a light source diminishes over time; LEDs depreciate more slowly than many traditional light sources such as HPS and Metal Halide.
Some of lighting manufacturers promoting led street lighting with a color temperature greater than 3000K to increase their product efficacy .
The major issue that lighting people or lighting manufacturers may not understand is that lighting that emits a greater component of blue light may look more efficient; But it is not.
The human eye is very sensitive to blue light, at high levels of Blue light it washes the visual purple out of the eye, reduces dark adaption as well as closing the pupil of the eye. In other words, the missing component in their calculations is the human eye itself.
Research’s showed that 4000K LED street light the city emits out twice as much spectral distribution in the blue then the 3000 K LED street light; and this percentage will increase more with 5000K, 5700K and with some chinese street lighting models it can be 6500K.
American Medical Association Gives Warning About LED Street lighting
During the annual meeting of AMA (the American Medical Association) to show the importance of declaring the effects of white led streetlights on health and safety; a guidance for communities have been released on how to reduce the harmful human and environmental effects of high-intensity [LED] street lighting.
The Guidance focused on LED lighting with High CT, which emits a large amount of blue light and appears white to the naked eye
The guidance declared that “Despite the energy efficiency benefits, some LED lights are harmful when used as street lighting.” as emitting a greater component of blue light; and has five times greater impact on circadian sleep rhythms than conventional street lamps.
this in turn, may lead to problems with sleep and related conditions. They cited “recent large surveys” that found brighter nighttime light in communities is linked with Reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, Impaired daytime functioning, obesity.
Which color Temperature is the best for street lighting ?
LED still one of the best options for street lighting nowadays; but to eliminate risks some precautions should be taken in consideration such as:
- 3000 K street lighting could be the best solution as it has half the spectral output distribution below 500 nanometers, and it’s the closest option to the HPS.
- It should be properly shielded to minimize glare and detrimental human health and environmental effects