When you look up at the night sky, what do you see? If you’re reading this post from a city, chances are you don’t see very much. Though lighting cities has economic and social benefits, poorly designed lighting comes at a cost. In addition to tainting our view of the milky way, light pollution has a negative impact on wildlife, affecting the migration of birds and the breeding patterns of nocturnal animals and insects. There are more downsides for us humans too. Light pollution is increasing globally, with an estimated 80% of the world’s population currently living under a “lit sky” - a figure closer to 99% in Europe and North America. The amount of artificial light on the Earth’s surface is increasing by at least 2% annually, while the use of artificial light at night is substantially increasing all over the world.
What easy things can we do?
If a tree falls in the forest and there’s no one around to hear it, does it… ok, let’s not go there. But when there’s no one in the street, do we need street lighting? Motion sensitive street lighting is a pretty self explanatory idea.
Good street lighting should feature a bulb which is encased above and to the sides. This channels light downwards - where it is needed – and reduces the amount of wasted light. Known as ‘cutting off light at the horizontal’, this ensures that light is used to illuminate the ground, not the sky.
Switching to low watt bulbs is a straightforward way of reducing light pollution, albeit one that could not be deployed across every piece of outdoor lighting in a city. Moving away from bluish-white lighting could be a bigger contributor to reduced light pollution on an urban scale. LED outdoor lighting, whilst energy-efficient, often emits a blue light which creates more light pollution. This can be avoided with warm-white lighting.