Light pollution

What is light pollution

The inappropriate or excessive use of artificial light is known as light pollution. The components of light pollution include:

• Glare – excessive brightness that causes visual discomfort. Glare is often the result of excessive contrast between bright and dark areas in the field of view. For example, glare can be associated with directly viewing the filament of an unshielded or badly shielded light. Light shining into the eyes of pedestrians and drivers can obscure night vision for up to an hour after exposure.
• Skyglow – brightening of the night sky over inhabited areas. It is the combination of all light reflected from what it has illuminated escaping up into the sky and from all of the badly directed light in that area that also escapes into the sky, being scattered (redirected) by the atmosphere back toward the ground.
• Light trespass – Light trespass occurs when unwanted light enters one's property, for instance, by shining over a neighbor's fence. A common light trespass problem occurs when a strong light enters the window of one's home from outside, causing problems such as sleep deprivation or the blocking of an evening view.
• Clutter – Clutter refers to excessive groupings of lights. Groupings of lights may generate confusion, distract from obstacles (including those that they may be intended to illuminate), and potentially cause accidents. Clutter is particularly noticeable on roads where the street lights are badly designed, or where brightly lit advertising surrounds the roadways.
• Over illumination - Over-illumination is the excessive use of light.

Sources of light pollution

Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. The fact is that much outdoor lighting used at night is inefficient, overly bright, poorly targeted, improperly shielded, and, in many cases, completely unnecessary. This light, and the electricity used to create it, is being wasted by spilling it into the sky, rather than focusing it on to the actual objects and areas that people want illuminated.

Effects of light pollution

• With much of the Earth’s population living under light-polluted skies, over lighting is an international concern. If you live in an urban or suburban area all you have to do to see this type of pollution is go outside at night and look up at the sky. According to the 2016 groundbreaking “World Atlas of Artificial Night Sky Brightness,” 80 percent of the world’s population lives under skyglow.
• Artificial lights overpower the darkness and our cities glow at night, disrupting the natural day-night pattern and shifting the delicate balance of our environment.

• A most notable impact of light pollution is wastage of electricity or energy. 
• Excessive lighting in outdoor areas can cause a lot of glare and can thus impact visibility of drivers and pedestrians.
• Light pollution causes disruption to ecosystems and is not good for various flora and fauna.
• Excessive lighting can also cause sleep disorders and other health issues such as increasing risks for obesity, depression, diabetes, breast cancer and more.

Tips to avoid light pollution

• Installing quality outdoor lighting could cut energy use by 60–70 percent, saves money and cuts carbon emissions.
• To minimize the harmful effects of light pollution, lighting should

• Only be on when needed
• Only light the area that needs it
• Be no brighter than necessary
• Minimize blue light emissions
• Be fully shielded (pointing downward)

• Outdoor lighting should be fully shielded and direct light down where it is needed, not into the sky. Fully shielded fixtures can provide the same level of illumination on the ground as unshielded ones, but with less energy and cost.
• Unnecessary indoor lighting – particularly in empty office buildings at night – should be turned off.
• LEDs and compact fluorescents (CFLs) can help reduce energy use and protect the environment, but only warm-white bulbs should be used.
• Quality lighting design reduces energy use and therefore energy dependence.
• Use low color temperature light sources for interior and exterior light. Their light is less harsh and less harmful to human health and the environment. Look for warm white sources with a color temperature of 3500K or lower.

Source : International Dark Sky Association; Light Pollution and Impact of Light Pollution