My local council has replaced the high pressure sodium street lights that bathed the neighbourhood in a warm subtly yellow tinged glow with LED street lights that emit a piercing cool white light.
This is not the first change in street lighting during my lifetime. I'm old enough to remember when the monochromatic yellow low pressure sodium lights were commonplace in side streets and in residential areas before most were replaced by high pressure sodium lights – possibly in order to deter and reduce crime. However, mercury lights that illuminated cities with a weird greenish-white hue were a bit before my time. Where was the last place in Britain that used mercury street lights in large numbers? Was it Hartlepool? Before that were incandescent lights – a dimmer relative (in terms of colour) of the high pressure sodium lights.
The new LED street lights are certainly brighter than the old high pressure sodium lights, but it's a brightness that takes getting used to. The long term consequences of LED street lights remains to be seen. Cool white light has a colour spectrum containing plenty of blue whereas the old high pressure sodium light is shifted more towards the red end of the colour spectrum. I have read that blue light is bad for sleep whereas red light is good for sleep. Could cool white LED street lights end up causing insomnia? Are warm white LEDs a better choice for residential areas?
What do you think?
