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 Earth?
The stars and darkness have been replaced by artificial lights, and this has proven to be harmful to human health.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). 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.