LED street lighting poses potential risks
Here on P.E.I., as in many municipalities in Canada and the U.S., The present high intensity sodium, or old fashioned incandescent bulbs that light our streets, are being replaced with a new form of LED (light intensity diode) lighting which promises to produce more illumination for less energy input, thereby, as most electricity is generated by fossil fuels, reducing production of greenhouse gases that cause global warming.
Although the environmentally friendly impact of use of the new LEDs and attendant cost savings because of reduced energy use, appear attractive; there is concern over the effects of this form of lighting on our health.
In July 2016, the American Medical Association adopted an official policy statement on street lighting: cool it and dim it. It recommends that the colour temperature of the LEDs be no more than 3000 Kelvin, (K). An ordinary incandescent bulb’s temperature is about 2400K. A candle is around 1800K.
On this scale, the higher the temperature, the more the light is emitted at the blue end of the spectrum. Unfortunately, the new street-lighting LEDs are at 4000 to 5000 K. Above 3000K, light suppresses human melatonin production. This can cause sleep problems; such light also scatters more in our eyes, threatening damage to the retina.
It can also be uncomfortably glaring, making walking and driving at night less safe. A September 2016 Toronto Public Health briefing on Health Effects of LED street lighting noted that sleep disruption was “associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer.”
Ottawa and other municipalities, following the AMA warnings, are limiting LED temperatures to 3000K or less. While research continues, it will be sensible to be cautious about replacing street lighting with high temperature (4000 – 5000K) LEDs.