High AQI In Delhi-NCR Reduces Sunlight, Increasing Vitamin D Deficiency Risk

Delhi's worsening air pollution crisis, with the Air Quality Index (AQI) reaching 325 in the 'severe' category on Wednesday, has triggered an overlooked public health issue: a sharp rise in vitamin D deficiency among residents. Thick smog layers have drastically reduced sunlight penetration across the National Capital Region (NCR), impairing the body's natural synthesis of the "sunshine vitamin", which is critical for bone health, immune response, and calcium-phosphorus regulation. Medical experts are now recommending supplements and indoor UVB exposure alternatives to counter the deficit, as at least ten monitoring stations recorded 'very poor' air quality, with PM2.5 concentrations spiking to 350 micrograms per cubic meter—over 30 times the World Health Organization's safe threshold.

Vitamin D is primarily produced when skin is exposed to ultraviolet B (UVB) rays from sunlight, a process increasingly disrupted in Delhi during the winter months when smog, crop burning in neighbouring states, and vehicular emissions combine to form a persistent haze. Studies from the All India Institute of Medical Sciences (AIIMS) indicate that over 80 percent of urban Indians already exhibit suboptimal vitamin D levels year-round, a figure exacerbated in polluted metros like Delhi, where residents receive less than 30 minutes of effective midday sun exposure daily. The current smog blanket, visible in satellite imagery and ground-level photographs, blocks up to 90 percent of UVB radiation, according to environmental scientists tracking solar irradiance data.

Health professionals warn that prolonged deficiency heightens risks of osteoporosis, autoimmune disorders, respiratory infections, and even cardiovascular complications—conditions that compound the lung damage already inflicted by toxic air. Paediatricians report a surge in rickets cases among children confined indoors, while rheumatologists note increased joint pain and muscle weakness in adults. The Delhi government, alongside the Central Pollution Control Board, has imposed emergency measures, including construction bans and odd-even vehicle schemes, but these focus on particulate reduction rather than solar access. Fortified foods and over-the-counter supplements have seen a 40 per cent sales uptick in pharmacies across NCR, reflecting growing public awareness.

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As the crisis persists, experts advocate integrated solutions: short-term supplementation protocols endorsed by the Indian Council of Medical Research, alongside long-term urban planning for green corridors and smog towers to restore sunlight reach. Community health camps are distributing free vitamin D tests, revealing deficiency in nine out of ten screened individuals in high-AQI zones like Anand Vihar and Punjabi Bagh. With winter inversion likely to sustain hazardous conditions through January, addressing this dual threat of respiratory and nutritional impairment has become imperative for Delhi's 20 million residents.

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