The latest comparison of the Nighttime Light Pollution Index across major cities provides a picture of the intensity of artificial illumination in urban skies. The higher a city's score, the greater the level of artificial lighting, intrusive illumination, and nighttime light pollution. According to the published data, Tehran scored 75.2, placing it 38th globally. Among the 40 cities surveyed, it ranks as one of those experiencing significant light pollution.
Tokyo tops the list with a score of 100, making it the world's most light-polluted city at night. It is followed by New York (98), Seoul (96), Beijing (95), and Los Angeles (94). The dominance of these major metropolitan areas suggests that population density, urban expansion, high-rise buildings, digital advertising, extensive street lighting, and vibrant nighttime activity are among the primary drivers of light pollution.
Further down the rankings are London (92), Paris (91), Singapore (88), Moscow (86), Istanbul (86.5), Dubai (85.5), and Madrid (84.5). Karachi, Pakistan, with a score of 76, ranks only slightly above Tehran.
According to the data, Tehran's score of 75.2 places it 38th, indicating a higher level of light pollution than cities such as Riyadh (74.8), Doha (74), Cairo (73.2), Zurich (70.4), Vancouver (64.4), Muscat (55.7), and Helsinki (55.4).
The rankings indicate that Tehran is not far behind some other cities in the region. Nevertheless, its position underscores the need for improved urban lighting management, greater use of standardized lighting equipment, and the reduction of unnecessary nighttime illumination. Environmental experts emphasize that light pollution is not merely an aesthetic concern but one with direct and indirect consequences for human health, wildlife, and energy consumption.
One of the most significant effects of light pollution is the loss of the night sky and the visibility of stars. In brightly illuminated cities, artificial skyglow reduces visibility of celestial objects and limits astronomical observation. In addition, prolonged exposure to intense artificial light at night can disrupt the body's circadian rhythm, reduce sleep quality, and negatively affect the production of the hormone melatonin.
Light pollution also affects a wide range of animal species. Migratory birds, insects, bats, and many nocturnal animals rely on natural darkness for navigation, feeding, and reproduction. Increased artificial lighting can disrupt migration routes, natural behaviors, and even the survival of certain species.
Non-standard lighting also leads to higher electricity consumption and increased energy costs. The use of energy-efficient lighting, well-designed street illumination, reducing unnecessary decorative lighting, and directing light downward toward the ground are among the key measures that many cities around the world have adopted to reduce light pollution.
The rankings show that, alongside urban development, light pollution has become a major environmental challenge. While adequate lighting is essential for public safety and urban activity, striking a balance between the needs of cities and preserving the natural darkness of the night sky is crucial. Achieving that balance can benefit both public health and environmental protection.
NOURNEWS