Greta Jimenez
Light pollution is a pressing issue that affects 80% of the global population. It is caused by the excessive or inappropriate use of outdoor artificial light, impacting human health, wildlife behaviour, and our ability to observe stars and celestial bodies. Light pollution is most severe in highly industrialised, densely populated areas of North America, Europe, and Asia, as well as major cities in the Middle East and North Africa. The problem is expected to worsen without regulatory action, and organisations like DarkSky International and the International Dark-Sky Association are working to address it through education, legislation, and the establishment of dark sky reserves.
| Characteristics | Values |
|---|---|
| Percentage of the world's population living under light-polluted skies | 80-83% |
| Percentage of the world's land area affected by skyglow | 23% |
| Countries with the brightest night skies | Singapore, Kuwait, Qatar |
| Countries least affected by light pollution | Chad, Central African Republic, Madagascar |
| Percentage of Americans who can no longer see the Milky Way | 80% |
| Percentage of Europeans who can no longer see the Milky Way | 60% |
| Percentage of the world's population who can no longer see the Milky Way | 33% |
| Percentage of Americans and Europeans living under sky glow | 99% |
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What You'll Learn
Light pollution affects 80% of the world's population
Light pollution affects a staggering 80% of the world's population, according to a groundbreaking new study. This means that more than four-fifths of people on the planet live under light-polluted skies, with 99% of Europeans and Americans experiencing light pollution. The study, which was published in 2016, used ground measurements and satellite data to create an atlas of the world, illuminated by artificial lights.
The issue of light pollution is a global one, with its sources including building exterior and interior lighting, advertising, outdoor area lighting, offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialised, densely populated areas of North America, Europe, and Asia, as well as major cities in the Middle East and North Africa, such as Tehran and Cairo. Even relatively small amounts of light can have a significant impact, and the problem is only getting worse.
The effects of light pollution are wide-ranging and detrimental, impacting both humans and wildlife. For humans, light pollution can disrupt natural body rhythms and sleep cycles, increase the risk of certain cancers, and hinder astronomy. It can also spoil aesthetic environments, making it difficult for people to appreciate the night sky and observe stars and other celestial objects.
For wildlife, the impact of light pollution can be particularly harmful. Artificial lighting can cause birds to migrate at the wrong time of the year, deter nighttime pollinators like bats, and disrupt underwater ecosystems. These detrimental effects can persist even after the lights have been dimmed or removed.
There is a growing global movement to reduce light pollution, with organisations like DarkSky International and the International Dark-Sky Association (IDA) leading the way. These organisations work to educate the public, certify dark-sky places, and advocate for legislation to control outdoor lighting. Many states and communities have already enacted local laws to reduce light pollution, and manufacturers have designed more efficient light sources that save energy and reduce light pollution.
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Sources of light pollution
Light pollution is a global issue without a single source responsible. Instead, it is a result of the world's increasing reliance on outdoor electrical lights. However, certain factors contribute more significantly to light pollution than others.
One major source of light pollution is outdoor lighting that emits light upwards or sideways. Light escaping upward will scatter throughout the atmosphere, brightening the night sky. Shielded lights, or full cut-off lights, that direct all their light downward can significantly reduce light pollution. Even a single light can disrupt the natural lightscape, causing issues like light trespass, where light extends into unwanted areas, such as a streetlight shining into a bedroom window.
Roadway lighting is a significant contributor to light pollution, accounting for about 35% to 50% of the total light pollution. Many roads use old-fashioned, unshielded lights that emit light upwards, leading to glare and spillover light pollution.
Artificial light from buildings, boats, streetlights, and even fireworks can also pollute the night sky. Light pollution from cities can be observed from remote areas, impacting the natural conditions of protected areas like national parks. It affects human health and physiology by disrupting the circadian rhythm and causing issues like glare, which affects vision and nighttime recreation.
Additionally, light pollution has detrimental effects on wildlife. It confuses migrating birds and sea turtles, leading them astray and often causing their death. Insects, a primary food source for birds and other animals, are attracted to artificial lights and are killed upon contact. Even marine life may be affected by underwater artificial lighting.
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Effects of light pollution
Light pollution, caused by the excessive or inappropriate use of outdoor artificial light, is a global issue. It affects human health, wildlife behaviour, and our ability to observe the night sky. It is a side-effect of industrial civilisation, with light sources including building exterior and interior lighting, advertising, outdoor area lighting, offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialised, densely populated areas of North America, Europe, and Asia, and in major cities in the Middle East and North Africa. However, even relatively small amounts of light can create problems.
The effects of light pollution are magnified at night, and it is estimated that 83% of the world's population lives under light-polluted skies. Only the most remote regions on Earth, such as Siberia, the Sahara, and the Amazon, are in total darkness. Light pollution has detrimental impacts on wildlife, human health, and ecosystem functions and services. Ecosystems suffering from high levels of light pollution deliver 40% less ecological services, and the damage to ecosystems is estimated at 3.36 trillion dollars per year.
Light pollution can negatively affect human health, increasing the risks of obesity, depression, sleep disorders, diabetes, breast cancer, and more. Artificial light at night can disrupt the natural body rhythms of both humans and animals, interrupting sleep and confusing the internal twenty-four-hour circadian rhythm that guides day and night activities and affects physiological processes. One of these processes is the production of the hormone melatonin, which is released in the dark but inhibited in the presence of light. Lowered melatonin production due to increased light at night can result in sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems. Studies have also shown a link between reduced melatonin levels and cancer.
Light pollution also has significant effects on wildlife and their behaviour. Wherever human light spills into the natural world, some aspect of animal life is affected, including migration, reproduction, hunting, and feeding. For example, sea turtle hatchlings instinctively head toward the brightest source of light, which for hundreds of years was the starlight reflecting off the ocean. But with coastal cities illuminating the night, the hatchlings become disoriented and head towards the cities instead of the sea, falling prey to dehydration and predators. Bird migration is also impacted by light pollution, with birds guided by moonlight becoming confused and losing their way. Many cities have adopted a ""Lights Out" program to turn off building lights during bird migration. Insects, a primary food source for birds and other animals, are drawn to artificial lights and are killed upon contact with light sources.
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Organisations working to reduce light pollution
A recent study has revealed that more than 80% of the world's population lives under light-polluted skies. This form of pollution is a side effect of industrial civilization and is caused by artificial lighting from buildings, offices, factories, streetlights, and illuminated sporting venues, among other sources. Light pollution has been detrimental to the health of people and animals in affected areas, and disrupts ecosystems and spoils aesthetic environments.
Various organizations are working to reduce light pollution and its harmful effects. Here are some of them:
International Dark Sky Association (IDA)
The International Dark-Sky Association (IDA) is a U.S.-based organization formed in 1988 with the mission to preserve the natural night sky. IDA educates the public about the harmful effects of light pollution and certifies parks and other places that have successfully reduced their light emissions.
DarkSky International
DarkSky International is a world-leading authority on light pollution that works to restore the nighttime environment and protect communities and wildlife from light pollution. They have over 70 chapters worldwide that serve as local organizing centers for the dark sky movement. DarkSky International certifies lighting products, designs, and installations that reduce light pollution, and works with communities to establish codes and statutes that minimize light pollution.
National Park Service Natural Sounds and Night Skies Division
The National Park Service Natural Sounds and Night Skies Division in the United States is dedicated to preserving and monitoring night sky quality in national park units across the country. They have measured the range of sky quality, from pristine conditions in some parks to severely degraded conditions in others.
In addition to these organizations, many states have adopted legislation to control outdoor lighting, and manufacturers have developed high-efficiency light sources that save energy and reduce light pollution. Individuals are also encouraged to use outdoor lighting only when necessary, ensure that lights are properly shielded to direct illumination downward, and close window coverings at night to keep light from escaping outdoors. These collective efforts demonstrate a growing awareness of the importance of reducing light pollution to protect the environment, human health, and natural rhythms.
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Methods to reduce light pollution
Light pollution, a side effect of industrial civilization, affects more than 80% of the world's population. It is caused by unwanted, inappropriate, or excessive artificial lighting, which can have harmful effects on human health, wildlife, and the climate.
Switch to Warmer Lights
LED lights, while energy-efficient, often emit a blue light that creates more light pollution. Moving away from bluish-white lighting and switching to warm-white lighting can help reduce light pollution. LEDs and compact fluorescents (CFLs) can also be used, but only with warm-colored bulbs.
Use Dimmers, Motion Sensors, and Timers
Dimmers, motion sensors, and timers can help reduce average illumination levels and save energy. Motion-sensitive street lighting, for example, can illuminate an area only when people or moving objects approach, reducing the amount of wasted light emitted.
Shield Light Sources
Outdoor lighting fixtures that shield the light source can minimize glare and light trespass, helping to prevent light pollution. Lights that are shielded or can dim or turn off when not in use can also help reduce light pollution and save energy.
Reduce Screen Time and Use Night Modes
With the widespread use of devices such as computers, laptops, phones, etc., screen light can contribute significantly to light pollution. Reducing screen time, especially after dark, and using night modes or dimmer settings can help reduce light pollution and benefit eye health.
Use Window Shades and Curtains
Using window shades or curtains can help keep room lights from escaping and contributing to light pollution outdoors. This also enhances privacy, especially in close quarters such as apartment buildings.
Advocate for Local Legislation
Citizens can band together to enact local legislation and advocate for reducing light pollution. Organizations like DarkSky work with communities to establish codes and statutes that reduce light pollution and educate the public about its harmful effects.
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Frequently asked questions
Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. It is a side effect of industrial civilization, with sources including building exterior and interior lighting, advertising, outdoor area lighting, offices, factories, streetlights, illuminated sporting venues, and fireworks.
According to various studies and sources, it is estimated that more than 80% of the world's population lives under light-polluted skies. A 2023 study analyzing data from 26 sites across Europe found average annual increases in night sky brightness of 1.7% in rural areas, 1.8% in urban areas, and 3.7% in intermediate areas.
Light pollution has been found to have detrimental effects on both humans and wildlife. It can disrupt sleep cycles and increase the risk of certain cancers in humans by decreasing melatonin production. In wildlife, it can cause birds to migrate at the wrong time of the season, deter nighttime pollinators like bats, and disrupt underwater ecosystems. It also hinders astronomy and our ability to observe the stars and Milky Way.
