Light Pollution: Just How Can Light Be Harmful To Anyone?

When we think of pollution, we often imagine barrels of nuclear waste, factories puffing smoke into the air, car exhaust, and aerosol cans, but the concept of pollution is a bit broader than that. In fact, even though we need light to accomplish thousands of things in our lives, there is a particular type of pollution (you guessed it, “Light pollution”) caused by misdirected, inappropriately used, or excessive artificial light in a given area.

A small example of light pollution (Photo Credit: chungking / Fotolia)

A small example of light pollution (Photo Credit: chungking / Fotolia)

You’ve probably heard the term “light pollution” before, but you probably haven’t considered all the ramifications that it can have for people, the environment and society as a whole.

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The Many Faces of Light Pollution

In its most basic form, light pollution is simply the presence of artificial light in a space where light would not naturally be, or where some do not want it to be. Depending on the source of the light pollution or the affected person/area, most types of light pollution can be broken down into one of five types.


  1. City Glow: You see this type of light pollution when looking at a city from a distance. There is a strange dome of light that hovers in the clouds and sky above major metropolitan areas. Much of that is due to light particles being shot or reflected straight up and bouncing around in the atmosphere. This can affect animals and humans in various ways, from mixed-up migratory patterns to creating dangerous conditions for pilots.
  2. Glare: When powerful light is reflected off of a surface, it results in glare, which can be a painful or uncomfortably bright “gleam” that can make normal sight of that particular area very difficult.
  3. Over-illumination: This is a rather self-explanatory one. If lights don’t need to be turned on, but they are, then the space is being artificially lit for no reason. Streetlights turning on too early, or offices in a building not turning off their lights at night, are both forms of light pollution.
  4. Light Clutter: The poor placement and design of artificial lighting systems or installments can create light clutter, where pockets of light are concentrated and distracting for people and animals. The stark contrast between light and dark can impact night vision and be dangerous for drivers.
  5. Light Trespass: This may be the most annoying form of light pollution, because it means that light is invading your personal space. Perhaps your neighbors left their upstairs lights on for two weeks straight while they were out of town, or there is a new neon sign across the street from your bedroom window. The invasion of light into your home and personal space is annoying, and in many places, actually illegal!

What’s the Problem With Light Pollution?

Quite simply, light pollution has only been an issue for the past century or so, considering that light bulbs weren’t even invented until the 1870s, but in that short span of time, human beings have certainly made their mark on the planet. Filling our sprawling cities with powerful electric lights to illuminate the darkness makes sense for a global culture that operates during the night and day, but there are so many other aspects to consider.

Photo Credit: Sergey Nivens / Fotolia)

Photo Credit: Sergey Nivens / Fotolia)

For thousands of generations, human beings used to operate by natural light sources like the Sun, moon and stars (and the occasional fire, of course). Human beings evolved with those natural light sources guiding our Circadian rhythms, sleep patterns, and natural behaviors. In the past ten generations, however, all of that has changed, and we can effectively ignore the visual clues that used to guide our behaviors. Also, human beings have adapted to have eyes that operate in the day and night, but constant light pollution is not a good thing. Excessive amounts of sensory light input can speed up vision loss and eyestrain, simply because we’re never giving our eyes a break!


Culturally speaking, the inability for many city-dwellers to escape the glow of city lights can be a psychological struggle at times. The amount of light that we experience has a direct affect on our minds and attitudes; for example, Seasonal Affective Disorder is theorized to stem from a lack of light during the winter months. However, what does the dull glow of artificial light twelve months a year do to the body and mind? Being unable to peer up into the majesty of space and count the stars is also a major downside to light pollution, and as cities continue to sprawl, people need to go further and further away to experience the raw beauty of nature in proper darkness. And who doesn’t like stargazing?

Light Pollution vs. Nature

We’re not the only animals who can suffer from the effects of light pollution. Animals have relied on the natural light of the sun, moon, and stars for millions of years to establish migratory patterns, sleep habits, mating rituals, and hunting techniques. With a drastic increase in artificial light and the glow of major cities, animals across the world are affected.

Thousands of species and animals rely on these natural cues of light and dark to survive, and when those light cycles are disturbed by excessive manmade light, the results can be disastrous. Thousands of deer are struck every year on highways for “freezing” in the glow of headlights, sea turtles crawl towards hotel resort lights instead of moonlight over the ocean, millions of birds fatally fly into lit-up buildings every year… the list goes on and on.

Reptiles, birds, mammals, humans…. it doesn’t matter. Light pollution affects all of us, and can even damage the planet itself. When artificial light is reflected up into the atmosphere, it actually interrupts the natural flow of light rays coming down to the planet. These UV rays are essential for growth patterns and the earth’s natural seasonal shifts, which have adapted based on changing amounts and intensities of sunlight over the course of hundreds of millions of years.

City Lights Over Europe (Photo Credit: 1xpert / Fotolia)

City Lights Over Europe (Photo Credit: 1xpert / Fotolia)

Despite the obvious problems that light pollution poses for our planet and all its inhabitants, cities continue to grow and the problem of light pollution shows no sign of stopping. Do your part by turning off lights when you’re not using them, and occasionally take the time to get away from artificial lights and soak up the rare, true darkness of the natural world.

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About the Author

John Staughton is a traveling writer, editor, publisher and photographer who earned his English and Integrative Biology degrees from the University of Illinois. He is the co-founder of a literary journal, Sheriff Nottingham, and the Content Director for Stain’d Arts, an arts nonprofit based in Denver. On a perpetual journey towards the idea of home, he uses words to educate, inspire, uplift and evolve.

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