E.7. Light Pollution
Light pollution refers to the overuse, improper direction, or intrusive presence of artificial lighting, especially in outdoor environments. This excessive illumination diminishes the visibility of stars in the night sky, hinders astronomical observations, interferes with natural ecosystems, affects human health, and leads to significant energy waste.
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Causes
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- Most visible light sources, excluding lasers, radiate light in multiple directions, which can lead to atmospheric scattering. In cities, nearly every surface reflects light—so even illumination aimed downward often gets reflected upward, intensifying light pollution during the night.
- Recent research indicates that artificial light not of natural origin has been annually increasing the overall brightness of the night sky (skyglow) by approximately 9.2-10%.
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Light pollution in India
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- India, according to recent studies, has the lowest percentage among G20 nations, with approximately 19.5% of its population residing in areas where skyglow obscures the view of the Milky Way and prevents human eyes from adapting to darkness.
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Effects
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- Stimulates cone cells in human eyes that activate in well-lit environments or during the day.
- Light pollution can disrupt circadian rhythms and melatonin production, potentially leading to sleep disorders and health issues, including an increased risk of breast cancer.
- Poses a serious threat to nocturnal animals, migrating creatures, and cross-light hatchery animals and their physiology.
- Skyglow disrupts insect behavior, extending hunting time for insect predators. Artificial nighttime light exposure results in the failure of clownfish eggs to hatch, leading to offspring death. Guidelines adopted by the Convention on Migratory Species parties in 2020 aim to address this issue.
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Control measures
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- Use light only when and where necessary.
- Use only the necessary amount of light.
- Use energy-efficient bulbs.
- Use bulbs with the right spectral power distributions.
- The “Outdoor Lighting Code” in the United Kingdom aims to reduce light pollution by encouraging the use of lighting that is only as bright and as long as necessary for the task.
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