Light has revolutionized human activities and has changed the environment we live in. Indeed, when it comes to light, we usually think about all the positive effects it creates. However, what about its negative repercussions? What are we losing because of lighting technologies? What about light pollution?
Light takes on different shapes, colors and forms. Would you have guessed that pollution is one of the forms it can take? We have come to realize that light pollution occurs for many reasons and that it impacts numerous fields of study such as ecology, economics, and astrology.
What Causes Light Pollution?
Light pollution, or excessive artificial light, is particularly prominent at night. It is mainly caused by misdirected, excessive, inefficient and unnecessary lighting systems. In urban areas where artificial light sources (e.g. street lights) are abundant, the phenomenon is common. When light shines upward, downward, or is reflected upward, it is dispersed by layers in the atmosphere, which results in a glow that reduces the darkness of night sky. Today, over 95% of stars that are usually seen with the naked eye are invisible. What is next for our future generations? New energy-efficient and cost-efficient light sources such as LED will only aggravate light pollution.
How Does Light Pollution Affect Humans?
The stars and darkness have been replaced by artificial lights, and this has proven to be harmful to human health. Researchers have observed that the production of melatonin is delayed when our circadian rhythm is exposed to excessive artificial light. Hence, this means that it takes longer to fall asleep at night and causes an unsatisfactory night of sleep. White LED light, commonly used in outdoor lighting, not only disrupts sleeping patterns, particularly if it emerges through window blinds, but it also affects eyesight.
Although researchers have proven LED lamps to affect human health, they do not provide evidence for health hazards to the eyes or skin associated with LEDs when total exposure is below the international agreed-upon exposure limits (ICNIRP).
How Does Light Pollution Affect Animals?
Light pollution has also been proven to have significant effects on animal behavior and when they perform certain activities. Indeed, some animals rely on the darkness of night to hunt, mate, migrate and hibernate. Studies show that some nocturnal animals mistake man-made lights for moonlight while others are disoriented by them. For example, birds that use darkness to orient themselves fail to migrate due to high-intensity light in urban areas. Researchers have also observed that artificial lights affect the way in which animals scavenge for food at night. Light pollution extends day into the night, which reduces time and limits the surface area in which nocturnal animals forage or scavenge. Moreover, artificial lights favor diurnal species, which directly conflicts with nocturnal ones. Thus, predation problems arise. For example, animals that have evolved to hide in the darkness are exposed to light and become vulnerable, and therefore more likely to be hunted.
On a broader level, excessive and unnecessary lighting can have serious repercussions on an entire ecosystem. In lakes, for example, when natural night light is reduced, zooplankton stop feeding on algae. Eventually, the excessive growth of algae leads to an increase in bacterial activity. This results in oxygen depletion in the lake, thus asphyxiating organisms that live there.
Economic Point of View
Excessive and unnecessary lighting result in a waste of energy that is costly to individuals and to industries. In Québec, the cost of lighting our businesses and residences amounts to an annual estimate of 50 million dollars.
Astronomical Point of View
Light pollution creates important and critical issues in astronomy. As previously mentioned, over 95% of stars that used to be visible to the naked eye are now invisible. Artificial lights make the collection of data more difficult for astronomers. When the glow from the sky is too bright, pictures of dim objects in the sky become foggy and unclear. Astronomers often attempt to takes spectra of objects and fail to do so. Spectrographs split the light of fluorescent objects from the telescope into colors and number lines, which allow astronomers to study their chemical composition, temperatures and speed at which they move. The spectroscope is one of the most valuable tools in astronomy; however, light pollution wreaks havoc on spectrographs. More and more observatories are forced to move to isolated regions.
On a broader level, excessive and unnecessary lighting has decreased people’s curiosity and awe about the Universe. People are less and less interested in the science and profession of astronomy as they are unable to see the wonders of the night sky.
Rethinking The Way We Light
Often, combating light pollution is interpreted as a need to completely stop lighting our surroundings, when it should be interpreted as a need for smarter lighting. We need to rethink the way we light our environment.
You can help reduce light pollution and protect natural night light by following these 3 rules of thumb:
- Choose lamps with low light intensity or dimming features to adjust brightness. Ensure visibility and safety without damaging eyesight.
- Choose dark sky compliant lighting. These lights are fully shielded (pointing downward) to minimize sky glow, dazzling glare and light trespass caused by lighting fixtures that are oriented toward the sky or towards the horizon. Consult IDA’s page on Outdoor Lighting Basics to learn more about dark sky compliant lighting fixtures.
- Use only what is necessary. Turn off lights when not needed; light only areas that need it; install a light timer or motion sensor light.