Have you ever looked up at the night sky and felt that nights were getting brighter? Where have all the stars disappeared? What if we told you your view of the universe had been adversely impaired? Bizarre as it may sound, the distinction between night and day is gradually disappearing on Earth.
The inappropriate and excessive use of artificial light does not only affect energy consumption. It is the reason the Earth is in danger of losing its night light – also known as light pollution.
Just like land, water and air, light pollution has environmental consequences for us, animals and our climate.
Between 2012 and 2016, artificially lit areas at night across India increased by 33%.
This was recorded using data from the first-ever calibrated satellite radiometer, which is designed especially for night lights.
An international study led by Christopher Kyba from the GFZ German Research Centre for Geoscience has shown that in the past four years, the artificially lit surface of the planet at night increased in radiance and extent by 2.2% per year.
What’s more, there is only a part of the light increase that we can see. Sometimes the instrument may record dimming of a city when it hasn’t occurred, or the city may have even gotten brighter. This is because the sensor cannot detect light at wavelengths below 500 nanometres (nm). This happens when orange lamps are replaced with white LED lights that emit radiation below 500 nm.
The use of LED lights has been encouraged the world over, as they are known to reduce energy consumption and light pollution. However, this has encouraged people to light up more areas than ever, and the transition from high-pressure orange sodium lamps to white LED lights for street lights has become counter-productive.
There are four components of light pollution. First is ‘glare’, which is the excessive brightness that causes visual discomfort. Second is ‘skyglow’, which is the brightening of the night sky over inhabited areas. The third is ‘light trespass’, which is when light falls where it is not intended or needed.
And the fourth is clutter, which is bright, confusing and excessive groupings of light sources.
A real-life example of this happened recently in Mumbai. Residents living around Wilson Gymkhana in Marine Lines, Mumbai, approached environmentalists after being disturbed by the high-intensity floodlights used there. They complained that they had to use thick curtains due to the lights at night, but that prevented the cool breeze from entering the house. Officials have issued notices to the management to shut the use of any lights after 10 pm.
There is work being done to combat this as well. The Awaaz Foundation has spoken about the need for stringent norms and is in the process of creating a case study that will help the government impose limits on time and intensity of light. So far, there are no such guidelines.
So, what can we do at our end to reduce light pollution?
The first step is to be informed. How it is caused, how it affects our health and what we can do about it.
We could start by minimising the use of lights in the house. Switching off lights when not in use is the most cost-effective solution to the problem.
Reducing the use of decorative lights and using environment-friendly candles during festivals instead will also help. Street lights should have covered bulbs facing downwards so that the light reflecting into the sky is eliminated. Plus they shouldn’t be turned on during the day.
You should also make sure your outdoor lights aren’t too bright and don’t trespass into other houses. This creates discomfort for others living around you and is completely unethical.
Using glare-free bulbs, or low hanging bulbs with lights facing downwards can also go a long way in reducing pollution.
Coloured lights are anti-glare and can well serve the purpose of lighting. You should also look into using glare-free lighting for vehicles at night when there is sufficient light around.