Light Pollution: Impacting Our Health And Environment

Light pollution is the presence of excess artificial light, usually outdoors, and is the result of urbanization and industrialization. It is a pressing issue, with global light pollution increasing by at least 49% from 1992 to 2017, and it affects many aspects of life on Earth. Light pollution has serious implications for the environment, human health, nature, energy efficiency, and astronomy.

The excess artificial light washes out starlight in the night sky, making it harder to see the stars and interfering with astronomical research. It also disrupts ecosystems, with negative impacts on plant and animal physiology, and can confuse the migratory patterns of animals, alter competitive interactions, and change predator-prey relations.

In terms of human health, light pollution can disrupt the body's biological clock, affecting sleeping cycles and the production of melatonin, which can lead to sleep disorders, increased headaches, worker fatigue, stress, and anxiety. It has also been linked to an increased risk of certain types of cancer.

Additionally, light pollution wastes energy and contributes to climate change, as lighting accounts for at least one-fourth of all electricity consumption worldwide.

Addressing light pollution involves reducing the use of light, using shields to direct light towards the ground, employing warm colour lights, and limiting the use of blue wavelength lights.

Human health

Light pollution, caused by the excessive or inappropriate use of outdoor artificial light, is detrimental to human health. The artificial light from sources such as streetlights, buildings, cars, and electronic devices negatively affects the natural day/night cycle, also known as the circadian rhythm, that guides human physiological processes.

The circadian rhythm, or the "body-clock," is linked to internal biology and cues the body to perform various functions, such as releasing certain hormones, getting hungry, or feeling tired. One of the key hormones influenced by this cycle is melatonin, which is released in the absence of light and aids in inducing sleep, boosting the immune system, lowering cholesterol, and regulating the functioning of several glands and organs.

However, artificial light at night suppresses melatonin production, disrupting the natural cycle. Blue light, in particular, found in electronic devices and LED bulbs, has been shown to significantly reduce melatonin levels. This disruption can lead to various health issues, including sleep deprivation, fatigue, headaches, stress, and anxiety.

Furthermore, recent studies have suggested a link between reduced melatonin levels and an increased risk of certain cancers, specifically breast cancer. Additional research has indicated a potential connection between light pollution and Alzheimer's disease, although more studies are needed to fully understand this relationship.

Other health consequences of light pollution include an increased risk of obesity, depression, sleep disorders, and diabetes. The American Medical Association has expressed concern about the impact of blue light from outdoor lighting, recommending the shielding of light fixtures and the use of lower color temperature lighting.

To mitigate the effects of light pollution on human health, individuals can take measures such as using blackout shades, choosing reddish or lower color temperature bulbs for indoor lighting, and utilizing color temperature apps that adjust the lighting on electronic devices according to the time of day.

Astronomy

Light pollution is a growing problem for astronomers, with a significant impact on the observation of the night sky. Light pollution is defined as any adverse consequence or impact of artificial light at night. It is caused by poorly designed or misdirected light fixtures that shine into the sky, where it is scattered by air molecules, moisture and aerosols in the atmosphere. This phenomenon is known as "sky glow" and it creates an orange or yellow halo in the atmosphere, washing out the night sky and interfering with astronomical observations.

The effects of light pollution on astronomy are significant. Light pollution can drown out the light from faint objects such as galaxies, nebulae and stars, making it difficult to observe them. It reduces the contrast between celestial objects and the darkness of the sky, impacting both amateur and professional astronomy. Light pollution also affects astrophotography, as the detailed images of the night sky captured from light-polluted cities cannot compare to those taken under truly dark skies.

To avoid light pollution, astronomers often have to travel to dark-sky locations far from cities, which are the main sources of light and air pollution. The Bortle scale is commonly used to classify the level of light pollution in a particular location, with Class 1 being excellent dark sky viewing and Class 9 being inner-city sky viewing with significant light pollution.

Light pollution is not just an issue for astronomers, it also has negative consequences for the environment, wildlife, and human health. It disrupts ecosystems, wastes energy, and can affect human sleep patterns and melatonin production.

There are efforts to combat light pollution and protect dark skies, such as the work of the International Astronomical Union's Commission B7, which aims to protect existing and potential observatory sites from light pollution. Additionally, organisations like the International Dark-Sky Association advocate for more intelligent lighting solutions that reduce light pollution while also saving energy.

Wildlife and ecosystems

Light pollution has a significant impact on wildlife and ecosystems, disrupting the natural cycles of day and night that govern the behaviours of plants and animals. The introduction of artificial light at night is thought to be one of the most drastic changes humans have made to the environment.

Impact on Nocturnal Animals

Nocturnal animals are active at night and sleep during the day. Light pollution radically alters their environment, turning night into day. Predators use light to hunt, and prey use darkness as cover. For example, bats avoid feeding in illuminated areas as it exposes them to predators. Light shining on or near their roosts can also cause them to delay emerging at dusk, when the insects they eat are most abundant.

Impact on Migration

Light pollution can cause migratory birds to wander off course and towards dangerous, illuminated landscapes. It is estimated that millions of birds die each year from colliding with needlessly lit buildings and towers. Migratory birds depend on cues from properly timed seasonal schedules, and artificial light can cause them to migrate too early or too late, causing them to miss ideal conditions for nesting and foraging.

Impact on Reproduction

Artificial light can interfere with the reproductive behaviours of many creatures, including amphibians, birds, and insects. For example, the nocturnal activity of frogs and toads, whose croaking is part of their breeding ritual, is disrupted by artificial light.

Impact on Orientation

Light pollution can also impact the ability of some animals to orient themselves. For example, sea turtles live in the ocean but hatch on beaches at night. Hatchlings find their way to the sea by detecting the bright horizon over the ocean, but artificial lights can draw them away from the ocean, leading to their demise.

Impact on Plants

Plants also depend on the daily cycle of light and dark. While there is limited research on the effects of light pollution on plants, one study found that artificial light cues can disrupt the migration route of monarch butterflies.

Impact on Food Webs

Light pollution can also impact food webs. Insects are drawn to light, and declining insect populations can negatively impact all species that rely on them for food or pollination.

Solutions

Unlike other forms of pollution, light pollution can be eliminated immediately by turning off lights. Other solutions include installing motion sensors, adding dimmers, using LED bulbs with yellow-tinted filters, and shielding lights to concentrate the light downwards.

Energy and climate change

Light pollution has a significant impact on energy consumption and climate change. Lighting accounts for almost one-fifth of the world's electricity use, and a considerable amount of this energy is wasted. In the United States, outdoor lighting consumes approximately 380 terawatt-hours of energy per year, enough to power 35 million homes. This wasted light contributes to global greenhouse gas emissions, with the energy used to generate light that escapes into space estimated at a minimum of 1% of global emissions.

The economic and environmental consequences of this waste are significant. In the US, it is estimated that at least $3.3 billion is spent on wasted outdoor lighting, resulting in the release of 21 million tons of carbon dioxide annually. This waste could be reduced by installing quality, shielded outdoor lighting that directs light downwards, reducing energy consumption and carbon emissions.

The use of new lighting technologies, such as LEDs, can also help to reduce energy consumption and protect the environment. However, the increased use of lighting, particularly with the transition to cheaper and more efficient options, may result in a "rebound effect", leading to even higher energy consumption.

To address these issues, organizations like DarkSky International promote responsible outdoor lighting practices through education and advocacy. They work with communities to establish codes and statutes that reduce light pollution, and they certify lighting products, designs, and installations that minimize light pollution while still providing functional and aesthetically pleasing lighting solutions.

By implementing measures to reduce light pollution, we can not only improve energy efficiency and reduce our carbon footprint but also minimize the negative impacts of artificial light on human health, wildlife, and our ability to observe the night sky.

Human culture and inspiration

Light pollution has a significant impact on human culture and inspiration, robbing us of the wonders of the night sky that have captivated artists, writers, and scientists for centuries. From ancient mythology to modern science fiction, the night sky has been a constant source of inspiration for cultures worldwide. However, light pollution obscures our view of the stars and the Milky Way, diminishing our sense of wonder and curiosity about the universe.

The night sky has inspired artists such as Van Gogh, whose painting "Starry Night" captures the beauty of a starry sky. Literature is also filled with references to the night sky, from Shakespeare's use of astronomy in "Julius Caesar" to the poetry of Samuel Taylor Coleridge and Lord Byron, who wrote, "Ye stars! Which are the poetry of heaven!".

The night sky has also played a significant role in science and exploration. Astronomers and scientists have studied the stars for centuries, uncovering the secrets of the universe and expanding our knowledge. However, light pollution hinders their ability to observe celestial objects, limiting their research and our understanding of the cosmos.

Light pollution affects more than just our view of the stars. It also impacts our health and well-being. Research suggests that artificial light at night can disrupt our circadian rhythm and melatonin production, leading to increased risks of obesity, depression, sleep disorders, diabetes, and even breast cancer.

Additionally, light pollution has economic implications. The International Dark-Sky Association estimates that one-third of all lighting is wasted, costing $2.2 billion annually. Reducing light pollution can save energy and costs while also improving our health and connection to the natural world.

In conclusion, light pollution has far-reaching effects on human culture and inspiration. By obscuring our view of the night sky, it diminishes our sense of wonder and inspiration, impacting art, literature, and science. It also affects our health and well-being, highlighting the importance of finding ways to reduce light pollution and preserve the natural darkness of the night sky.

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