We’re familiar with various forms of pollution, but are we aware of light pollution? You might wonder if light can indeed spread pollution. Let’s get acquainted with light pollution. To understand light pollution, we must first realize that the light we use today is not natural. At the dawn of civilization, we had no means of artificial lighting. The environment would light up with sunrise each morning and darken after sunset each evening. However, this wasn’t always consistent. Heavy rain could darken the skies during the day, and at night, the moon’s faint light would slightly diminish the darkness. In summer, the sun would light up the day for longer, and in winter, darkness would prevail for extended periods. But with the advancement of civilization, we started using artificial light, which has been increasing over time. For example, nighttime maps of the United States from the 1950s to predictions around 2025 show a significant increase in artificial lighting.
Artificial lighting isn’t natural, and its various impacts on the Earth are not surprising. Researchers have begun studying this excess of light and found it affects physical and mental health, the environment, astronomical research, and more, leading to global crises. This excessive application of light is termed light pollution.
Researchers have documented several characteristics of light pollution, including the disruption of habitats for light-dependent organisms, interference with natural light in outdoor environments, excessive use of light indoors harming human health, and the indirect effects of artificial lighting on the environment. Light pollution is inherently human-made and occurs in populated areas, raising concerns as it represents a significant waste of electricity. This electricity production is also tied to environmental pollution as power plants contribute to environmental degradation. In today’s competitive market, dazzling lights are used in advertising, decorations, retail spaces, sports fields, offices, and factories to attract attention, which could be significantly reduced with awareness. The excessive use of bright lights results in the burning of forty to fifty million barrels of fuel oil daily in the United States alone. Improvements in energy-efficient lighting and enhanced safety measures have also led to much brighter lighting in streets and public places than before.
The issue of concern is the lack of awareness about light pollution. It has only recently been recognized as a form of pollution. The science of vision is rarely considered in the design of lighting in buildings or elsewhere. Most places lack sensors or timers to ensure lights are only on when needed. Carelessness in selecting light bulbs results in light being cast far beyond necessary areas, with a significant portion of this light dissipating into the sky, serving no purpose.
The effects of light pollution and its causes have been discussed. Now, let’s examine its impacts, starting with the environment. According to the International Dark-Sky Association (IDA), unnecessary and excessive artificial lighting releases an additional 12 million tons of carbon dioxide into the atmosphere each year, contributing to global warming. This amount of carbon dioxide would require 700 million trees to offset, illustrating the indirect effects of light pollution. Directly, light pollution contaminates the environment. The National Oceanic and Atmospheric Association reports that light pollution disrupts the formation of nighttime nitrates in the atmosphere. These nitrates help mitigate the harmful emissions from vehicles and factories, reducing smog, ozone pollution, and the impact of other harmful particles. This process occurs only at night, as sunlight breaks down nitrates during the day. Light pollution disrupts this natural air purification process at night.
Nighttime brightness adversely affects the feeding habits, sleep, reproduction, and migration cycles of wildlife. Excessive artificial lighting disrupts wildlife’s time perception, interfering with their daily routines. Nighttime feeding of mammals like bats, raccoons, coyotes, and deer is hindered. Their reproduction decreases, and their nighttime vision is impaired. Nocturnal birds face similar issues. Migratory birds become disoriented by the lights, losing their way, sometimes drowning, or becoming prey to other animals. In North America, approximately 100 million birds die annually from collisions with illuminated buildings or towers. Amphibians, reptiles, and insects also suffer from the effects of light pollution.
The impact of light pollution in astronomy is direct and severe. Astronomers are likely the biggest victims of light pollution compared to any other community. Light pollution changes the natural night sky, making it impossible to identify distant, faint objects. To understand the impact of light pollution on astronomy, consider the following images.
The two images are from before and after a power outage in 2003. The first image shows no stars, while the second clearly shows the Milky Way. Those of us living in cities know that nowadays, apart from a few bright objects, no stars are visible at night. Observing stars at night brings mental peace and helps reduce stress. Light pollution also affects physical health. The human body and mind are regulated by a day-night cycle, known as the circadian clock, which controls various physiological activities such as brain function, hormone secretion, and sleep cycles. Current nighttime brightness disrupts this cycle, leading to sleep imbalance, anxiety, depression, diabetes, cancer (especially breast and prostate cancer), heart disease, and obesity. Bright light also impacts vision.
The magnitude of the effects of light pollution is vast. This introduction only scratches the surface. Like air pollution, noise pollution, and water pollution, combating light pollution is essential. International organizations have been established to fight light pollution globally, working to raise awareness.
