Light Pollution

Subject – Environment

Context – light pollution disorients ecosystems.

Concept –

Light pollution is an unwanted consequence of outdoor lighting and usually occurs due to excessive and inappropriate artificial light.
There are five overlapping components of light pollution: Urban sky glow, light trespass, glare, uplight and clutter.
- Urban sky glow refers to the brightening of the night sky over urban inhabited areas.
- The falling of light in an area where it is not intended or needed is called light trespass.
- Glare is the excessive brightness of light, causing visual discomfort and disability.
- An uplight is directed toward the open sky, causing a very strong, localised form of light pollution.
- Clutter refers to an excessive grouping of lights, commonly found in over-lit areas.
Poor placement of signage and streetlights, excessive and inappropriate use of light, high population density and a higher road density and traffic density contribute significantly to light pollution.
At times, certain environmental conditions such as smog, fog and high levels of suspended particles also increase the intensity of light pollution.

Impact of light pollution on plants, animals and human beings

Plants are affected by three characteristics of light: Quantity, quality and duration.
- Quantity of light refers to the total concentration or intensity of the light.
- Light quality indicates the wavelength of the light and duration refers to the total period for which light is present.
light pollution affects plants by interfering with photoperiodism.
Many plant species (such as night-blooming cacti, for example, Queen of the Night Epiphyllum Oxypetalum) bloom only at night and depend on nocturnal pollinators for pollination. Increasing lighting can prevent flowering and pollination in such plants and hamper reproduction.
Similarly, animals are also affected by light pollution. Crepuscular (active only at dusk and dawn) and nocturnal (active only during the night) animals depend on the duration of day (light) length to start / stop their daily activities.
Artificial light at night is one of the prominent causes of global decline of insects.