Light Pollution: Environmental, Biological, and Societal Challenges

• Light pollution refers to the excessive, misdirected, or obtrusive use of artificial outdoor light. 
• It is a growing environmental concern that negatively impacts human health, wildlife, ecosystems, and astronomical observations.

Types of Light Pollution

• Skyglow
  • Brightening of the night sky over populated areas.
  • Makes it difficult to see stars and celestial bodies.
• Glare:
  • Excessive brightness that causes visual discomfort, especially for drivers.
• Light Trespass:
  • Unwanted or intrusive light entering someone’s property or home.
• Clutter:
  • Bright, confusing, and excessive groupings of light sources, especially in urban areas.

Impact on Human Health

• Disruption of Circadian Rhythm
  • The human body has a natural biological clock (circadian rhythm), regulated by the light-dark cycle.
  • Exposure to artificial light at night inhibits melatonin production a hormone essential for sleep and brain health.
• Link to Alzheimer's disease (AD)
  • A recent study highlighted that exposure to night-time light pollution increases the risk of Alzheimer's disease.

Mechanism:

• Disrupted sleep cycles → poor memory consolidation.
• Chronic melatonin suppression → increased amyloid-beta accumulation in the brain—a hallmark of Alzheimer’s.

Other Health Effects

• Insomnia and poor sleep quality.
• Depression, mood disorders.
• Obesity, diabetes, and cardiovascular diseases due to hormonal imbalances.
• Breast and prostate cancer risks due to long-term melatonin suppression.

Impact on Biodiversity and Ecosystems

Birds and Animals

• Migratory birds rely on stars for navigation. Skyglow and bright city lights confuse their paths, leading to fatal building collisions.
• Artificial light increases visibility of prey, making them vulnerable to predators.
• Disruption in the reproductive cycles of nocturnal animals like frogs, bats, and turtles.

Insects and Pollination

• Artificial lights attract insects, leading to exhaustion and death.
• Pollinator insects like moths are drawn away from flowers, reducing pollination and affecting plant reproduction.

Ecosystem Imbalance

• Change in predator-prey dynamics.
• Alters nocturnal foraging behaviour, habitat selection, and species distribution.

Impact on Astronomy

• Skyglow hampers visibility of celestial objects.
• Makes scientific observations difficult from ground-based observatories.
• Loss of cultural and scientific connection with the night sky.

Impact on Energy and Climate

• Wasted lighting consumes energy, often produced via fossil fuels.
• Increases carbon footprint and contributes to climate change.

Economic Cost

• Billions are spent annually on inefficient or unnecessary lighting.
• Energy wastage adds to urban expenses and electricity load.

Measures to Mitigate Light Pollution

Use of Fully Shielded Fixtures:

• Ensures light is directed downward and not upward into the sky.

Smart Lighting Technologies:

• Motion-sensor lights, time-controlled street lights.
• Reduced Luminosity and Warm Lighting:
• Use of low-intensity, warm colour temperature LEDs.

Legislation and Urban Planning:

• Light pollution regulations in cities and towns.
• Dark Sky" reserves like in Ladakh (India's first).

Public Awareness Campaigns:

• Encourage responsible lighting in homes and businesses.
• Environmental Impact Assessments (EIA):
• Mandatory EIA for major lighting projects near wildlife habitats.

Legal and Policy Aspects

• India does not yet have a dedicated national policy on light pollution.
• However, guidelines are being considered under the Environment Protection Act.
• The International Dark-Sky Association (IDA) promotes dark-sky-friendly lighting globally.