Light pollution, also known as photo pollution, is caused by excessive artificial light and is a byproduct of urbanization and industrialization. It is just one of many types of pollution on the planet, along with plastic waste, greenhouse gases, and sewage.
Light pollution can have serious consequences for our environment as well as our health. According to the International Dark-Sky Association, street lighting, domestic and commercial lighting, vehicles, and security lights, all contribute to the formation of a dome-like shield of light pollution known as skyglow.
Light pollution also includes glare, light trespass, and clutter, in addition to skyglow. Light trespass is light that escapes from sources such as bedroom windows, whereas glare is light that can cause direct visual discomfort. Clutter is defined as the excessive grouping of lights.
Other types of air pollution, such as smoke and dust, can also amplify light pollution. This is due to the fact that these types of pollution can scatter light in all directions, brightening the sky even more.
According to Celestron, one of the immediate effects of light pollution on our environment is that it obscures our view of the true night sky. The night sky is awash with celestial bodies, distant galaxies, and constellations when there is no artificial light present. Many of these night sky objects, however, would be invisible if viewed from the heart of a major city.
According to Duke University, the retina of the human eye can naturally adjust its light-sensing cells to acclimate to very low-light conditions, allowing some sort of night vision.
The Bortle Dark-Sky Scale was developed by American astronomer John E. Bortle to monitor and characterize light pollution. It measures the brightness of the night sky at various locations. The scale assesses our ability to see celestial objects like planets and stars through the interference of skyglow.
Consequences of Light Pollution:
Aside from depriving us of a starry sky, excessive use of artificial light has many other consequences, such as disrupting the human body's natural cycle.
Circadian rhythms are a set of physiological and neurological changes that occur in the body over the course of a 24-hour period. According to Harvard University, they are collectively known as our body clock and are related to our sleep-wake cycle.
When the sun goes down and we are exposed to low light, our bodies naturally release a hormone known as melatonin. According to the UK's National Sleep Foundation, melatonin is released from the pineal gland in the brain and helps to increase tiredness and regulate sleep cycles, with peak production occurring in the early hours of the morning.
Light pollution, on the other hand, has been shown to suppress melatonin production in humans, even at low levels. This can cause sleep disruption, as well as a negative impact on our immune system and stress responses.
According to the journal Environmental Health Perspectives, it has also been suggested that melatonin disruption caused by light pollution is linked to an increased risk of hormone-related cancers such as breast or prostate cancer.
The circadian rhythm affects all living things, not just humans. According to the journal Environmental Pollution, researchers discovered that even the lowest light intensities disrupted melatonin production within the European perch.
Along with health concerns, light pollution can have an impact on wildlife behaviour. Light pollution has the greatest impact on nocturnal predators such as bats. These flying mammals are well adapted to hunting at night and actively avoid areas that are illuminated.
