Human Activities Causing Light Pollution: A Global Concern

Light pollution is a pressing issue that has serious consequences for human health, wildlife, and the environment. It is caused by the inefficient and unnecessary use of artificial light, which spills into the natural world and disrupts the natural rhythms of both humans and animals. This can lead to adverse health effects such as sleep deprivation, fatigue, headaches, stress, and anxiety. Furthermore, it interferes with the life cycles of plants and animals, impacting migration, reproduction, and habitat formation. The excessive use of outdoor lighting in cities and towns contributes to sky glow, making it difficult to observe the stars and constellations that have been significant in cultural traditions throughout history. Addressing light pollution requires a combination of legislative changes, public education, and the adoption of more appropriate lighting technologies that minimize glare and light trespass.

Using outdoor lighting inefficiently or inappropriately

The inefficient or inappropriate use of outdoor lighting is a major cause of light pollution. This can take several forms, including light trespass, over-illumination, glare, light clutter, and skyglow.

Light trespass occurs when unwanted light escapes from one property into adjacent areas. This can be caused by lighting fixtures that are not properly shielded, allowing light to spill into neighbouring properties or areas where it is not wanted. Over-illumination, or the use of excessive light where it is not needed, is another common issue. This can be the result of using high-intensity lighting in areas that only require minimal lighting, such as residential neighbourhoods or areas with low foot traffic.

Glare is a concern for both human health and safety. Intense lighting, particularly blue-rich LED lighting, can cause discomfort and reduce visual acuity, creating a road hazard. Light clutter refers to the redundant clusters of lighting often found in urban centres. This can include excessive lighting on buildings, billboards, and other structures, creating a bright and distracting environment.

Skyglow, one of the most pervasive forms of light pollution, is caused by the collective light pollution found over urban areas. Electric lights from cars, streetlamps, offices, factories, outdoor advertising, and buildings turn night into day, impacting the natural environment and human health. It is important to note that addressing light pollution requires careful consideration of political, social, and economic factors, as it is a complex, human-made phenomenon.

Over-illumination or excessive lighting

Over-illumination occurs when excessive light is used where it is not needed. This can result from inefficient or poorly designed lighting fixtures that produce more light than necessary, such as cobra-head streetlights that project light directly upwards. It can also be caused by the use of certain types of light bulbs, such as blue light light-emitting diodes (LEDs), which have become popular due to their low cost and energy efficiency but can have detrimental effects on human health and the environment.

The adverse effects of over-illumination are extensive. It can cause glare, which reduces visual acuity and can create road hazards. Additionally, it can lead to light trespass, where unwanted light escapes from one property into adjacent areas. This unwanted light can have serious consequences for human health, disrupting internal biological clocks and impairing the production of hormones, such as melatonin, that are governed by the natural day/night cycle. As a result, people may experience sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems.

Furthermore, over-illumination can have detrimental effects on wildlife and ecosystems. It can disrupt the life cycles and behaviours of various species, including migration patterns, wake-sleep habits, and habitat formation. For example, the bright lights of coastal cities can disorient sea turtle hatchlings, causing them to move away from the ocean and towards urban areas, leading to dehydration, predation, and death.

To address over-illumination and reduce its impacts, it is essential to make changes to lighting fixtures and choices of light bulbs. This can include adjusting light fixtures to direct light downwards or using shielded fixtures to reduce glare. Additionally, it is important to use more appropriate light bulbs, such as those that minimize the emission of blue light, which is particularly harmful to human health and star visibility. Educating the public and pushing for legislative change can also help mitigate the effects of over-illumination and light pollution.

Light trespass, where light falls on unwanted areas

Light trespass is a form of light pollution that occurs when unwanted light falls on areas it is not intended for, such as adjacent properties. This can happen when a neighbour installs a new light fixture that is unshielded and casts a bright light onto another property, or when light shines over a fence or into a window of a home. Light trespass can cause sleep deprivation and other health issues, as well as frustration and agony for those affected. It can also impact observations by astronomers when artificial light enters a telescope tube, reducing contrast and making it difficult to adapt to the dark.

Light trespass is a common problem, with many people experiencing it due to streetlights or neighbouring properties. It can be reduced by selecting light fixtures that limit the amount of light emitted above a certain angle, such as 80-90 degrees above the nadir. This can be achieved by using shielded fixtures and dimming light levels to only what is required. Dimming outdoor light fixtures can also reduce glare and save energy.

To address light trespass, it is important to work together with neighbours and the community to create an atmosphere that benefits everyone. Writing a letter or having a conversation about the issue can be a good first step. It is also important to remember that conclusive evidence does not suggest that more and brighter lighting improves safety; in fact, glare from unshielded lights can make it difficult to see into shadowed areas, creating potential safety hazards.

Light trespass is a serious issue that can have negative impacts on the health and well-being of those affected. By taking steps to reduce light trespass, such as adjusting light fixtures and using appropriate light bulbs, it is possible to improve the situation and create a more comfortable and safe environment for all.

Light clutter from redundant clusters of lighting

Light clutter, caused by redundant clusters of lighting, is one of the most common forms of light pollution. It refers to the excessive use of lighting in urban centres, often resulting from poorly designed light fixtures that allow artificial light to shine outward and upward into the sky. This not only wastes energy and resources but also contributes to air pollution, as coal-fueled power plants are typically used to generate the electricity needed for lighting.

The redundant clusters of lighting can be attributed to several factors, including outdated lighting technologies, inadequate urban planning, and a lack of awareness about the impacts of light pollution. In many cases, lighting fixtures produce more light than is necessary, leading to over-illumination and light trespass, where unwanted light escapes into adjacent properties or areas.

The effects of light clutter are far-reaching. On a local scale, it can cause glare and light trespass issues, impacting the comfort and safety of residents. It can also disrupt the natural cycles of wildlife, such as migration, reproduction, hunting, and feeding. For example, sea turtle hatchlings instinctively move towards the brightest source of light, which should be the starlight reflecting off the ocean. However, with bright coastal city lights, they become disoriented and fall prey to dehydration and predators, never reaching the safety of the ocean.

Additionally, light clutter contributes to sky glow, the brightening of the night sky over urban areas. This phenomenon turns night into day for people who work or play outdoors, disrupting their natural day-night cycles and affecting their health. Studies have shown that artificial light at night can negatively impact human health, increasing the risks of obesity, depression, sleep disorders, diabetes, and even certain types of cancer.

To address the issue of light clutter, it is essential to implement measures that reduce light pollution. This includes using shielded fixtures, dimming lights to appropriate levels, and establishing quality requirements for outdoor lighting. By taking these steps, we can mitigate the negative impacts of light clutter on both the environment and human well-being.

Artificial satellites and sky glow

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It is caused by the excessive or inappropriate use of outdoor artificial light. Billions of people around the world experience light pollution in the form of skyglow, an ever-present "haze" of light over cities at night. Skyglow is the brightening of the night sky, mostly over urban areas, due to electric lights from cars, streetlamps, offices, factories, and buildings. It is a result of bad lighting design, which allows artificial light to shine outward and upward into the sky.

The light projected directly upwards from a cobra-head streetlight is about 30% of the total light it emits. The average desk lamp uses 40 watts of electricity, while to generate the electricity required for streetlights, predominantly coal-fueled power plants expel around 15 million tons of carbon dioxide pollution into the atmosphere each year. Some of the light emitted by streetlights escapes into space, where it is observed by satellites.

Earth-orbiting satellites intercept some of the light that escapes into space, and their cameras provide valuable evidence of where artificial light is used in the world and how it's changing. The earliest artificial satellites, launched in the 1960s to monitor weather patterns, could see the nighttime lights of Earth, but their cameras weren't powerful enough to make scientific observations. Today, NASA's Earth-observing satellites are helping to address light pollution and its effects on the planet.

The effects of light pollution are felt by both humans and wildlife. Nocturnal light interrupts sleep and confuses the natural circadian rhythm, affecting the production of melatonin, which is released when it is dark and inhibited when there is light. Research has linked reduced melatonin levels to sleep deprivation, fatigue, headaches, stress, anxiety, and even cancer. Light pollution also affects animal behaviours, such as migration patterns, wake-sleep habits, and habitat formation. For example, sea turtle hatchlings instinctively head toward the brightest source of light, which used to be starlight reflecting off the ocean. Now, with coastal cities flooding the night with bright lights, the hatchlings become disoriented and fall prey to dehydration and predators.

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