5 Types of Light Pollution and How They Affect Us

Light pollution affects us much more than we think. The first effect that comes to mind if the fact that we can no longer see the night sky – but that seems to be the smallest problem at the moment. Light pollution also radically disrupts ecosystems across the world, as well as contributing to increased CO2 emissions.

Man-made actions have dramatically changed the face of the Earth. The night time before artificial lighting is a concept most of us are not familiar with, since we have been bombarding light towards the sky ever since the industrial revolution.

Before Light Pollution and After

As Jon Henley once wrote in The Guardian, “The pre-industrial night […] was widely regarded with dread and fascination in equal measure.” That has changed significantly, and not for the better.

Before our nights were soaked in light, people relied on simpler strategies to navigate. The practical luminosity of the moon and stars were highly valued, and people learned their neighborhoods and homes by heart. Due to hampered sight, our senses were more finely tuned. It was definitely more dangerous, but, according to Henley, their nighttime also had its charms.

That’s not the case anymore. The western world of today has spread light everywhere. We have so much light that we’re drowning in it. While it’s only logical that we use light to make our lives easier, the current overuse has led to an embarrassing excess.

As the Cornerstone Project explains, “Light pollution wastes money and energy. Billions of dollars are spent on unnecessary lighting every year in the United States alone, with an estimated $1.7 billion going directly into the nighttime sky via unshielded outdoor lights.”

The latest statistics show that U.S. wasted lighting releases around 38 million tons of carbon dioxide into the atmosphere each year. At the same time, unshielded outdoor lights account for 1.2 million tons of carbon dioxide waste.

Moscow Kremlin before and during Earth Hour / Source

Moscow Kremlin before and during Earth Hour / Source

Sources of Light Pollution

Many sources can be blamed for the light pollution we are currently experiencing across the globe. Unsurprisingly, light pollution is mainly caused by man, partly due to powerfully lit electronic sign boards in the cities and on highways.

Lights that come from below end up reflected upwards and towards the night sky. Restaurants, clubs, pubs, and shops in the cities also make use of excessive light to attract customers. Many of the lights are not directed to any particular place, which causes light dispersion.

Urban sky glow – Even though it might sound somewhat poetic, the bright night sky over inhabited areas actually caused the Milky Way and stars to disappear from view. As IYA2009 has pointed out, one needs a full tank and a map to be able to enjoy the beauty of the night sky.

Light trespass – We are all familiar with noise complaints, but what about light complaints? Unwanted light can trespass into private property either from passing headlights, a “bright” neighbor, or street lamps.

Over-illumination – This source of light pollution is often confused with urban sky glow. It occurs when an important building in drenched in excessive light to attract attention. Historic buildings, landmarks, and skyscrapers come to mind.



Glare – The main source of nighttime glare comes from unshielded light. It happens when one source of light spills into the sky and elsewhere, and it can reduce visibility, as well as cause momentary blinding.

Light clutter – It refers to excessive light coming from groups of bright and confusing sources. They can be commonly found in inhabited areas and over-lit cities. The increase of clutter contributes to other sources of light pollution, such as urban sky glow, glare, and trespass.

Effects of Light Pollution

Waste of resources – Public lighting costs a lot of money, especially when it’s used in excess to light homes, public places, commercial and sports places. Apart from the tax payer money, the U.S. also uses millions of tons of coal and oil to produce the power needed to light the night sky.

Loss of cultural and historical value – Astronomers have already expressed their concern regarding the fact that following and reading the sky and outer space has become increasingly difficult. At the same time, we are also gradually losing the wonderful dark sky with its stars. The next generations may have a hard time experiencing this awesome scene if we continue on this path.

Health implications – Excessive light can lead to eye strain, disability glare, and loss of vision. Our eyes can naturally adjust during the night to allow us to see things properly, but too much light can harm the hormones that would normally do the job. Light trespass can also disrupt sleeping patterns.

Wildlife – Besides people, light pollution also affects many mammals, birds, insects, and reptiles. Many aspects of their behavior and physiology are tightly linked to day–night and circadian rhythms. Thousands of deer and other animals become roadkill during the night, because the car lights’ glare blinds them.

Before and after the Northeast Blackout of 2003 / Source

Before and after the Northeast Blackout of 2003 / Source

Reduction of Light Pollution

Simply reducing unnecessary lighting can make a difference. Not only does it save money and energy, but it does it at minimal expense. According to scientists, over-lighting the night does not improve visibility or nighttime safety, utility and security.

Fortunately, reducing light pollution can take place at any level, starting from individuals to corporations and governments. Even a simple decision to turn on the outdoor lights only when necessary can contribute to reducing light pollution. At the same time, you can install shielded light fixtures that direct light downward instead of upward.

How else can you help reduce light pollution? By changing outdoor lighting to LED light bulbs and installing light sensors that minimize their usage. Last but not least, make a habit of closing curtains and shades at night to prevent interior light from spilling out.

Thankfully, darkness is an easily renewable resource. All we have to do is learn to embrace it by turning off some of the lights – and not just on Earth Hour. A little fascination with the night sky might do us some good.

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William E. Eubanks

I'm one of the main writers on the site; mostly dealing with environmental news and ways to live green. My goal is to educate others about this great planet, and the ways we can help to protect it.

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