How can Light Pollution over the City of Mumbai be Assessed and Reversed?

Light pollution, which adversely affects entire ecosystems, is a lesser-known but completely reversible form of pollution. The financial capital of India, Mumbai has been experiencing a steady rise in light pollution levels. This research article aims to answer the question “How can light pollution over the city of Mumbai be assessed and reversed?” It uses satellite data to map radiance levels over four representative locations in Mumbai over the last decade. To put it into a global perspective, the overall radiance level of Mumbai in 2023 is compared with that of nine other megacities. A graphical analysis of both sets of data reveals that radiance levels over Mumbai have increased in the past decade but in comparison with other global megacities such as New York or Shanghai, they are considerably low. Of particular concern, however, is the sharp increase in radiance level over the biodiversity hotspot within the city: Sanjay Gandhi National Park. The paper further explores five case studies of places from around the world that have successfully identified the emergent problem of light pollution, and introduced policies to mitigate it. Several reports indicate that although awareness about light pollution is generally lacking in India, policies introduced under energy-efficiency programmes have indirectly helped reduce radiance levels and new technological innovations now allow a smart lighting environment. The paper concludes that taking inspiration from global case studies, it is not impossible for cities like Mumbai to implement workable alternatives to conventional lighting practices to curb light pollution.