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We’re facing different kinds of pollution in the 21st century and we have to constantly look for new ways to take action against them. To have clean air to breathe and clean water to drink. But how can light be a pollutant? Does it have any effects on our lives or is it just a problem for astronomers?
The inappropriate or excessive use of artificial light is known as light pollution. It all began around 100 years ago and now has become a global environmental problem.
Nowadays more than 80 percent of the world's population, including 99 percent of Americans and Europeans, live under light-polluted skies. In other words, 80 percent of people can never see a natural dark sky from their hometown.
Losing the starry nights is the obvious result of light pollution and you might think it’s just an issue for astronomers and stargazers. Energy waste is another obvious effect of bad lightning. But there are many more things that create much more serious concerns.
Several scientific studies have shown us that light pollution has negative effects on wildlife, ecosystems and even human health.
Life on Earth relied on Earth’s predictable rhythm of day and night for billions of years. But in the past century, artificial lights disrupted this cycle for many species. Many nocturnal animals need the natural darkness at night for their activities and in many places in the world we’ve already lost that.
For instance, fireflies need darkness for some of their most important activities. They communicate by the language of light, in a process called Bioluminescence. By emitting light, they send signals for mating and also for protecting their territory. In many places around the world, we’re facing declines in fireflies populations because of light pollution.
Beside that, some animals use moonlight or starlight for navigation. That leads us to one of the most famous examples of light pollution's effect on wildlife which is the sad story of baby sea turtles. Hatchlings find the sea by detecting the bright horizon over the ocean. But now, in many coastal areas, the other side is much brighter due to artificial lights of cities and villages and many of the newborns choose the wrong way and never reach the sea.
Light pollution has devastating effects on migratory birds as well. Migratory birds use starlight or moonlight for navigation. But now, artificial light can cause them to wander off course and toward the dangerous nighttime landscapes of cities.
Because of this problem, millions of birds die due to colliding with needlessly illuminated buildings and towers.
Another negative effect of light pollution on ecosystems is related to insects. Many insects are drawn to light, but this attraction can be fatal for them. As insect populations can affect many species in food chains, this can be a very concerning issue that may not be obvious at first, but may have destructive consequences for the ecosystems.
Like most forms of life on Earth, the predictable rhythm of day and night is encoded in our DNA and sets our biological clock. Artificial light can disrupt this cycle and in some cases suppresses melatonin production. A hormone that induces sleep, boosts the immune system and lowers cholesterol.
Exposure to white-blue light at night is particularly harmful and disrupts melatonin production. The LEDs used in all kinds of screens (from smartphones to TVs) emit abundant blue light. The American Medical Association expressed concerns about exposure to blue light at nights in 2016 and recommended using lighting with 3000K color temperature or lower at night.
In this info-graphic by International Dark-Sky Association, you can see effective ways to protect yourself from bad lightning and take a step toward controlling light pollution. Fortunately, the solutions to solve the light pollution issue are clear and not too expensive and in many cases, we just need public and government awareness about the issue.
You can visit the International Dark-Sky Association for more information and take more action in protecting the natural darkness of the night.
So, let’s begin!
Cover photo: Faint Milky Way in the light polluted sky of Pasargadae, a UNESCO world heritage site near Shiraz, Iran. Credit: Amirreza Kamkar
