Light pollution is a problem with planetary consequences. Unlike other forms of environmental contamination, this phenomenon has serious adverse impacts on wildlife, economies and human health. Developing a more widespread societal understanding of these issues is ultimately critical to improving people's quality of life.

What Is Light Pollution?

Light pollution is a basic concept, but many humans remain unaware of how it occurs. In the natural world, light emanates from a limited number of sources, such as the sun and moon. Furthermore, these sources adhere to routine schedules where they only shine down on the landscape at certain times. Even uncommon forms of natural light, like brush fires, historically stuck to set seasonal timetables.

The modern developed world is markedly different. People create illumination as it suits them. Although there are certainly useful reasons to brighten up their surroundings, humans aren’t always careful about where and how they use light.

Light pollution, which is the unintentional, misdirected or unwanted use of artificial illumination, is commonplace around inhabited areas all over the world. In other words, it has a global impact that researchers and observers have thoroughly documented for decades.[1]

Different Kinds of Light Pollution

Although all forms of light pollution, or photopollution, involve artificial illumination, they aren't all the same:

  • Over-illumination occurs when people use lighting in excess, such as in big-box stores, offices and other commercial settings that don't employ smart occupancy-sensing light switches.
  • Light clutter involves poor spacing or unbalanced groupings of individual lights, like those along certain highways, where they may cause air travel dangers or increase the risk of vehicle accidents.
  • Glare is the potentially blinding light that emanates from fixtures that aren't positioned or angled correctly, such as a neighbor's floodlights shining into someone else's home at night.
  • Light trespass takes place when properties are lit inaccurately so that direct illumination goes beyond their boundaries to cause a nuisance to those in the vicinity.
  • Skyglow is a phenomenon observed over populated areas at nighttime. The night skies of most cities aren't as dark as they should be. Instead, they’re bright due to upward light trespass and the reflected rays that travel from light sources and bounce off of relatively high-albedo surfaces. For instance, sidewalks and certain pavements are designed to mitigate urban heat island effects by being reflective.[2]

Why Is Light Pollution a Problem?

One of the issues with light pollution is that many people remain unaware of its ill effects. The negative ramifications aren't widely publicized. Also, readily available lighting is usually regarded as a positive aspect of modern life. It may be difficult for some individuals to understand how lighting might do harm when it's misused.

The Gravity of the Dilemma

Although brilliant city lights may have once been a local problem, photopollution has long since become a worldwide issue. One study reported by the BBC in 2016 revealed that 83 percent of the world's population lives in an area where the sky is at least 10 percent brighter than it would normally be without human lighting.[3]

The same study’s authors found that the issue is severe enough that almost one out of every seven humans don't even need to use their nighttime vision the way they normally would. Instead, their eyes rely on their color receptors, which are generally poorly adapted to low-light conditions. In the U.S. and Europe, those who live under abnormally bright night skies account for 99 percent of the population.

Measuring Light Pollution

The prevalence of light pollution has many negative impacts on people's well-being and that of the environment. It also makes it nigh-on impossible to see the normal night sky from the ground, which is why the issue is of particular interest to astronomers.

The Bortle Dark Sky Scale describes how well stargazers can view distinct celestial bodies at night in the presence of different levels of light pollution. The photopollution in most urban areas makes it impossible to observe many of the details of the stellar constellations, and cameras also have difficulty imaging objects clearly.[4]

Skies with high Bortle Dark Sky Scale numbers, such as the level-9 conditions observed in many inner cities, are hundreds of times brighter than they naturally should be.[5] These skies are characterized by significantly bright nocturnal glows, and some even make it possible to read a book while standing outdoors at night.

Forbes reports that since the 1950s, dark skies in the U.S. have grown increasingly polluted. By 2025, many of the country's regions will have skies so bright that fewer than 100 stars remain visible with the naked eye.

A Burden on the Environment

People may create unwanted light, but as with many human inventions, its effects are problematic for other species. Although the animal kingdom is broad, it seems that few creatures are immune to light pollution.

Trees Dying Sooner

Peter Wohlleben, a well-known German forester, said that city streetlights might be contributing to the early deaths of nearby trees.[6] Normally, these plants would rely on light to know when they need to perform certain biological processes in time with the changing seasons. Being exposed to constant illumination deprives them of this ability, however, and according to a Journal of Ecology study, artificial light can disrupt their natural cycles.[6]

Such problems aren’t the only challenges that city trees face. These plants lack the root-level connections and robust canopies that they'd usually enjoy with other trees in denser forest settings that would help them combat animal predation and intense weather. This could make their improper day-night cycles even more detrimental.

Animal Behavioral Issues

Researchers have also shown that light pollution harms many different animal species. For instance, the Florida Fish and Wildlife Conservation Commission notes that excessive lighting impacts both diurnal animals, or those that are primarily active during the day, and nocturnal species, which would usually be awake at night.[7]

Animals that should avoid bright lights to keep themselves hidden from predators, such as sea turtles, moths and amphibians, may find themselves attracted to dangerous conditions by the presence of continuous lighting. Other creatures that use the sun to decide when to sleep may end up failing to get proper rest and hinder their ability to heal or reproduce. In some cases, animals that dislike light will abandon otherwise viable habitats, which can have dramatic negative impacts on entire species and locales.

Coastal Food Chain Disruption

In 2017, the Plymouth Marine Library and the University of Exeter conducted controlled laboratory experiments to determine the effect that light pollution had on dog whelks. These predatory sea snails act as critical links in the food chain and coastal communities of the East Atlantic Ocean.

Individual dog whelks that received test exposure to artificial lighting failed to seek shelter as often as they should, which meant that they were also vulnerable to predators for longer periods.[8] The researchers said that such phenomena induce critical changes in at-risk coastal ecosystems. Unfortunately, they also noted that these problems might receive far less attention than they merit.

Economic and Indirect Environmental Losses

Although the impacts that light pollution has on the natural environment are far-ranging and difficult to quantify, it's possible to get an idea of exactly what it's doing to the global economy. The light that gets misused at night must originate somewhere, and the energy that powers it costs money.

According to James Madison University, the amount of electricity that goes to waste at night accounts for one-third of all lighting use. In financial terms, this amounts to around $2.2 billion in annual losses.[9] To create the electricity that keeps these lights shining, coal-fired plants around the world release some 15 million tons of atmospheric pollution, which exceeds the emissions produced by 9 million cars each year.

Human Health Issues

The air pollution, ecosystem losses and energy waste associated with light pollution are all undoubtedly negative side effects for humanity. People are also at risk, however, from the direct impacts of living in areas where there are always lights on nearby.

Like other animals, humans exhibit circadian rhythms. These are biological processes that occur in time with approximate 24-hour cycles. For instance, the cycles that determine when people sleep or wake up and control the way their bodies release certain hormones are examples of circadian rhythms. Even though timing is an important determiner of these patterns, light also plays a huge role by influencing when people produce melatonin, which is a critical hormone for sleeping.[10]

As nighttime lighting disrupts people's circadian rhythms, they may suffer a greater incidence of diseases and physiological issues.[11] These problems might be temporary or chronically persistent. For instance, some scientists suggest that photopollution can contribute to ailments like

  • Mood and anxiety disorders,
  • Cancers,
  • Diabetes,
  • Medically significant stress,
  • Dangerous worker fatigue,
  • Headaches,
  • Certain kinds of obesity related to lack of sleep, and
  • Sleeping disorders.

How Can Modern Societies Fight Light Pollution?

If the light pollution problem has any positive aspect, it's that it may be one of the easiest environmental challenges for humanity to overcome. Unlike the air, ocean and groundwater pollution that the planet suffers from, light pollution is non-persistent. Merely re-engineering the way people use lighting on a daily basis could be a critical step in the quest for a healthier planet.

For instance, many light fixtures that allow light trespass can be replaced with options that are better-shielded. This is a relatively easy solution that doesn't require massive modifications or a contractor's assistance.

Those who own lighting that typically shines all night long might benefit from outfitting such fixtures with timers or motion sensors. In addition to cutting down on light pollution, these devices help property owners save money and reduce their carbon emissions.

In some cases, a simple change of bulbs might be sufficient. Lighting that produces a different range of light spectra can still satisfy the same visibility-oriented functions, but it may be less harmful to humans and their wild acquaintances.

The Future Outlook

Although light pollution is a major problem, the situation may not be as bleak as some of the other challenges of modern life. As science examines the issue with increased scrutiny and the general public gains heightened awareness of how it works, more consumers, businesses and lighting producers are taking steps to use lighting more responsibly.

Lamps Expo is dedicated to promoting technologies and measures that help the planet solve the predicaments of light pollution. In addition to providing a range of energy-efficient fixtures and lighting elements that minimize unintentional illumination, the company is committed to educating consumers about the nature of these problems and how to implement potential solutions. To learn more, visit