Photo pollution, also known as light pollution, is caused by excessive artificial light. It is a result of industrialization and urbanization. It is one of the many forms that pollution can be found on Earth. Others include plastic waste, greenhouse gasses, and sewage.
Light pollution can have serious consequences for our environment and our health. According to The Skyglow Report, street lighting, commercial lights, vehicles, and security light all contribute to the formation of a protective dome of light pollution called skyglow. International Dark-Sky Association.
Skyglow is not the only form of light pollution. Light pollution also includes light trespass, clutter, and glare. Glare refers only to light that can cause visual discomfort. Light Trespass refers only to light that escapes sources such as bedroom windows. Clutter refers to excessively grouped lights.
Other types of pollution like dust and smoke can also contribute to light pollution. These types of pollution can scatter light in different directions and brighten skies even more.
Effects on night vision and astronomy
According to telescope manufacturer, one of the immediate effects of light pollution on the environment is to obscure our view to the true night sky. Celestron. Without artificial light, the night sky would be filled with distant galaxies and constellations. However, if you’re looking up from the belly of a big city, you’d be unable to see many of these night sky objects.
According to the International Observatory for Climate Change, approximately 99% of people in America and Europe live under skies that are almost 10% brighter then they would naturally be. BBC. This also means that a large portion of the population doesn’t use the full potential of their eyes.
The retina of the human eye is able to adjust its light-sensing cell to adapt to very low light conditions. This allows some form of night vision. Duke University. But because of light pollution, 37% of people living in America don’t use their night vision, according to the BBC.
John E. Bortle, an American Astronomer, created the Thermometer to monitor and characterize light pollution. Bortle Dark-Sky ScaleThe brightness of the night sky at different locations is measured by the, The scale measures our ability under skyglow to see celestial objects like planets and stars.
Health risks
The excess use artificial light can have many other implications than just denying us a starry star. It can also throw the body’s natural cycles out of balance.
Circadian rhythms refer to a series of physiological and neurological changes that occur within the body during a 24-hour period. Collectively they’re also known as our body clock and is related to our sleep-wake cycle, according to Harvard University.
Our bodies naturally release melatonin when the Sun is down and we are exposed low light. The brain releases melatonin from the pineal gland. This hormone helps regulate sleep cycles and increases tiredness. Peak production is found in the early morning hours, according to the UK. National Heath Service.
Even at low levels, light pollution has been shown to reduce melatonin production in people. This can disrupt sleep and affect our immune system and stress response. Journal research also suggests that light pollution may be linked to an increased risk of hormone-related cancers like breast or prostate cancer. Environmental Health Perspectives.
The circadian rhythm doesn’t only affect humans, but most other living things. Researchers have discovered that even the lowest light intensities can disrupt the production of melatonin in European perch. journal Environmental Pollution.
Implications for wildlife behavior
Light pollution can also have a negative impact on wildlife behaviours. Light pollution can be particularly harmful to nocturnal predators, such as bats. These flying mammals are well-adapted for hunting at night and actively avoid light pollution.
According to the study, their insect prey is attracted primarily to light sources. This results in bats being unable to hunt in the barren areas. Bat Conservation Trust. It can also prevent bats from leaving their nests and cause them to starve if artificial light sources are placed outside.
Journal reports that researchers found that wallabies born in areas with less pollution, such as near naval bases, had a higher rate of births than those in more rural areas. Proceedings of the Royal Society B.
The study showed that outdoor light-emitting diodes (LEDs) suppress melatonin five to five times better than traditional outdoor lighting.
According to the, artificial lighting can make a difference in the lives of newborn turtles. Sea Turtle Conservancy. Turtle hatchlings are naturally drawn to the sandy beaches where they can swim to the ocean in the moonlight. However, the street lights and commercial lights along the coast can confuse hatchlings and cause them move inland, where they are often eaten by cars or killed by traffic.
Additional resources
Check out “Light Pollution” for more information.The End of Night – Searching for Natural Darkness In An Age of Artificial Light“by Paul Bogard and”Smart Lighting Solutions for Individuals and Communities: Fighting Light Pollution” by The International Dark-Sky Association.
Bibliography
- The International Dark-Sky AssociationLight pollution“, accessed April 2022.
- John E. Bortle.The Bortle Dark-Sky Scale“, accessed April 2022.
- Celestron, “What is light pollution, and how does it affect my view through my telescope?“, February 2022.
- Rebecca Morelle, “Light pollution ‘affects over 80% of the world’s population“, BBC, June 2016.
- Duke UniversityNight vision is natural for the eyes.“, Science Daily September 2018.
- Samantha Tracy,I Can’t Sleep… Can you turn off the lights?“, Harvard University. accessed April 20, 2022.
- NHS, “Melatonin to treat sleep problems“, accessed April 2022.
- Angela Spivey, “LIGHT POLICY: Light at Night and Breast Cancer Risk Worldwide“, Environmental Health Perspective, Vol 12, December 2010.
- Franziska Kupprat, et al, “Can skyglow decrease nocturnal melatonin levels in Eurasian perch“, Environmental Pollution, Volume 262, July 2020.
- Bat Conservation Trust,Lighting“, accessed April 2022.
- Kylie A. Robert, et al, “Artificial light at night desynchronizes strictly seasonal reproduction in wild mammal“, Proceedings of the Royal Society B Volume 282, October 2015.
- Sea Turtle Conservancy,Information about Sea Turtles and Artificial Lighting“, accessed April 2022.