Light Pollution: The City That Never Sleeps

Light pollution, a growing concern for human health and the environment, is caused by the excessive use of artificial lighting at night. It has detrimental effects on wildlife, human health, and ecosystem functions. While many cities are known for their bright lights and vibrant nightlife, some contribute more to light pollution than others. This paragraph aims to introduce the topic of light pollution and set the context for exploring the question: Which city causes the most light pollution?

Impact on human health

Light pollution is a pressing issue that has a wide range of negative effects on human health. It is caused by the human-made alteration of outdoor light levels from those occurring naturally. Light pollution is particularly prevalent in highly populated urban areas, with more than 80% of people living under light-polluted skies.

One of the primary ways light pollution impacts human health is by disrupting the body's natural circadian rhythms. Circadian rhythms, also known as the 24-hour day/night cycle, affect various physiological processes in humans, including brain wave patterns, hormone production, cell regulation, and other biological activities. Artificial light at night, especially the short-wavelength blue light, interferes with the production of melatonin, a hormone that regulates daily cycles and is released by darkness and inhibited by light. Disruption of these rhythms can lead to insomnia, depression, and an increased risk of obesity, cardiovascular disease, and cancer.

The impact of light pollution on sleep quality is well-documented. It can cause sleep deprivation and sleep disorders, leading to reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, and impaired daytime functioning. The American Medical Association has recognized light at night as a carcinogen and health risk, and it is estimated that white LED lamps have five times the impact on circadian sleep rhythms compared to conventional street lamps.

Additionally, light pollution can contribute to mental health issues such as depression. It can also cause disability glare, a condition where the intense light causes us to avert our eyes, temporarily impairing our vision.

The health consequences of light pollution are significant, and ongoing research continues to explore the complex relationship between artificial light exposure and various health conditions, including Alzheimer's disease. The World Health Organization has recognized the potential dangers, listing "shift work that involves circadian disruption" as a probable carcinogen.

While some cities have developed standards for outdoor lighting to protect their citizens, light pollution remains a pervasive environmental issue that requires further attention and action.

Impact on wildlife

Light pollution, caused by the excessive or inappropriate use of outdoor artificial light, has a detrimental impact on wildlife, human health, and ecosystem functions. It disrupts the biological rhythms of wildlife, interfering with the behaviour of nocturnal animals and birds.

Light pollution has a significant impact on wildlife, particularly on nocturnal animals and birds. The introduction of artificial light at night is likely the most drastic change humans have made to the environment for nocturnal animals. Predators use light to hunt, and prey species use darkness as cover. Light pollution can make prey species more visible to predators, altering food webs in unanticipated ways. It can also disrupt the nocturnal activities of amphibians such as frogs and toads, interfering with their breeding rituals and reducing their populations.

Light pollution can also cause birds to become disoriented, leading to millions of bird deaths each year as they collide with illuminated buildings and towers. It can cause them to migrate too early or too late, missing ideal climate conditions for nesting, foraging, and other behaviours. A study of blackbirds in Germany found that artificial night lighting caused birds in the city to become active up to five hours earlier than those in natural areas.

Artificial lighting can also affect marine animals, with fewer filter-feeding animals making their homes near lighted panels. This suggests that light from oil rigs, ships, and harbours may be altering marine ecosystems. Light pollution also endangers sea turtles, as hatchlings are attracted to lights and crawl away from the sea, making them more vulnerable to predators.

Additionally, insects are drawn to artificial lights, and declining insect populations can negatively impact all species that rely on them for food or pollination. Light pollution can also impact plants, as it affects the production of hormones that regulate growth and development.

Overall, light pollution disrupts the natural rhythm of day and night that all life on Earth has relied on for billions of years, encoded in the DNA of plants and animals. It can interfere with migration patterns, wake-sleep habits, and habitat formation, threatening biodiversity and ecosystem functions.

Light clutter

Light pollution, in general, has been growing since the invention of the incandescent lightbulb and has serious effects on human well-being, safety, the environment, and culture. More than 80% of people live under light-polluted skies, and one-third of the world's population can no longer see the Milky Way. Light pollution can cause sleep deprivation, increase the risk of depression and diabetes, and kill 300 million to 1 billion birds each year. It also wastes billions of dollars' worth of energy annually.

Light trespass

To address light trespass, several measures can be taken. Firstly, it is important to educate people about the issue and promote the use of appropriate light bulbs and fixtures, such as those that limit the amount of light emitted above 80 degrees. This can include using light shields or flocking the telescope tube to reduce reflection. Additionally, individuals can encourage their neighbours to reduce light trespass by adopting principles that minimise glare and light trespass into their domain. Dark Sky International provides guidance on how to approach neighbours about their lighting without creating conflict.

Some cities in the U.S. have developed standards for outdoor lighting to protect citizens against light trespass, with the support of organisations like the International Dark-Sky Association. These standards aim to reduce light pollution and preserve the visibility of stars. U.S. federal agencies also play a role in enforcing standards and processing complaints related to light trespass. For example, the Federal Communications Commission maintains a database for citizens to identify offending structures and process inquiries.

While light trespass is a concern, it is important to note that other forms of light pollution, such as skyglow, light clutter, and over-illumination, also contribute to the overall problem. Reducing light pollution requires a comprehensive approach that addresses multiple factors, including the efficient use of light sources and the adoption of measures to protect biodiversity and dark-sky areas.

Global initiatives to reduce light pollution

Light pollution is a global issue, with 99% of Americans and Europeans living under sky glow. It is caused by artificial light, which can have detrimental effects on the health of people and animals, as well as the environment.

There is a global movement to reduce light pollution, with various initiatives and organisations working to address this issue. DarkSky International, for example, is a world-leading authority on light pollution that works with communities, professionals, and governments to establish codes and statutes that reduce light pollution. They also certify lighting products, designs, and installations that minimize light pollution.

Legislation and Regulations

• The Korean Ministry of the Environment passed the Act on the Prevention of Light Pollution Due to Artificial Lighting in 2012. This regulation introduced limits on the average luminance and maximum vertical plane illuminance of flashing screen videos based on four environmental zones and the time of application.
• The Environment Bureau of the Government of the Hong Kong Special Administrative Region established a voluntary initiative called the Charter on External Lighting. This scheme requires participating businesses to switch off all external lighting for decoration, promotion, or advertising, as well as rooftop signs, from 11 pm to 7 am.
• Dark Sky International's International Dark Sky Places program works with communities, parks, municipalities, and the public to certify and protect dark places for humans and wildlife.
• Dark Sky International also has a DarkSky Approved program that works with various stakeholders to evaluate and certify dark sky-friendly outdoor lighting equipment and projects.

Public Awareness and Education

• Dark Sky International informs the public about how excessive artificial light can harm humans, wildlife, and the climate. They also provide education and advocacy efforts to reduce light pollution.
• The World Economic Forum's Global Plastic Action Partnership brings together governments, businesses, and civil society to create a more sustainable world by eradicating plastic pollution.
• The World Economic Forum's 2030 Water Resources Group has facilitated almost $1 billion to finance water-related programs, operating in 14 countries/states.
• The World Economic Forum's SCALE 360 initiative reduces the environmental impacts of value chains within the fashion, food, plastics, and electronics industries, positively impacting over 100,000 people in 60 circular economy interventions globally.

Lighting Design and Technology

• Using covered bulbs that direct light downward can reduce sky glow and light trespass, minimizing light pollution.
• LEDs and compact fluorescents (CFLs) can reduce energy use and protect the environment, but warm-colored bulbs are recommended to minimize blue light emission, which is particularly disruptive.
• Dimmers, motion sensors, and timers can help reduce average illumination levels and save energy.
• Using environmentally friendly candles during festivities and celebrations instead of excessive decorative lighting can help reduce light pollution and conserve energy.
• Automated timers and systems can turn off street and highway lights when natural lighting is sufficient, such as during the daytime or when the moon is bright.

Frequently asked questions