Light pollution, also referred to as photo-pollution, is the existence of anthropogenic light at night. Photo pollution is a broad term which refers to all problems caused by the unappealing, unnecessary or inefficient use of artificial light. Light pollution competes with starlight at night, interferes with the astronomical observations, and disrupts the ecosystem. Excessive and misdirected use of light intensifies light pollution. Photo pollution is a side-effect of industrial civilization, and it is more severe in densely populated regions and highly industrialized places.
Types of Light Pollution
1. Light Trespass
Light trespass is a common problem which occurs when an unwanted strong light enters your property and causes sleep deprivation. Numerous cities in the United States developed outdoor lighting standards to protect their citizens against light pollution. The International Dark-sky Association (IDA) developed a series of model lighting rules which protect people and ecology from light pollution.
Excessive light usage causes over-illumination. Over-illumination is responsible for wasting more than two million oil barrels each day in the United States alone. Excessive usage of light stems from numerous causes, like the incorrect choice of light bulbs, daylight lighting, and indirect lighting techniques.
Glare is a public hazard, especially for older individuals. When glare light scatters into your eye, it can cause loss of contrast and even result in unsafe driving conditions. Blinding glare is the effect caused by gazing directly at the sun, which results in a permanent or temporary vision deficiency. Disability glare is the effect caused by being blinded by the lights of the oncoming car. Discomfort glare is very annoying and can be irritating. Overexposure to a discomfort glare can cause fatigue.
4. Light Clutter
Excessive clustering of light causes light clutter. A cluster of lights creates a state of confusion, can distract you from obstacles, and even cause an accident. Light clutter affects people driving on roads with poorly designed street lights.
Skyglow is the diffuse glow noticed over a highly populated region. The light reflected from an illuminated surface and light escaping directly into the sky from an upwards directed light, which is scattered back to the ground by the atmosphere, causes skyglow.
Effects of Light Pollution
Light pollution can disrupt an ecosystem, especially the nocturnal wildlife. Excessive lighting can confuse the migratory patterns of animals, change the predator-prey relationship, alter the competitive interaction between animals, and even cause physiological harm. The natural diurnal patterns of dark and light dictate life in the wild, therefore disrupting this it can affect ecological dynamics.
Lighting is responsible for about 25% of global electricity consumption, and numerous studies confirm that over illuminating constitutes energy wastage, mainly when it is directed upwards at night.
Many species including humans are dependent on the circadian rhythm and melatonin production, which are regulated by the day and night cycles. Therefore, overexposure to light in humans while sleeping can suppress melatonin production, resulting in sleeping disorders and many other health issues including work fatigue, increased headaches, medically defined stress, and increased anxiety.