4 min readNew DelhiMar 3, 2026 01:00 AM IST
The worsening air quality in major Indian cities has triggered health concerns around sun exposure, which is considered the natural source of Vitamin D. A clinical nutritionist recently shared the “easiest way to get vitamin D naturally”, claiming that the best time to step out in the Sun is when the UV index number is above 3.
In an Instagram Reel, Tanay Mandowara shared the “simplest rule” to find out the best time for sun exposure. He further suggested that his viewers monitor the UV index on their mobile phones. “If it’s above 3, that’s your window. No debates, no fixed timings! Step into the Sun when it truly matters,” Mandowara said.
Dr Aravinda S N, Lead Consultant – Internal Medicine, Aster RV Hospital, Bangalore, shared the time window that works best to boost natural Vitamin D production. “People can naturally obtain Vitamin D through sunlight exposure, which represents their most straightforward and efficient method. Your skin produces Vitamin D when it receives sunlight during the hours from 10 am to 3 pm,” she said.
“People need to show their face, arms, and legs to sunlight for 15 to 30 minutes three to four times per week, which serves as their necessary minimum. People with darker skin need to stay outside for extended periods. The World Health Organization states that people need safe sun exposure because it protects their bone health, immune system, and muscle strength. People can improve their Vitamin D levels by eating fatty fish, egg yolks and fortified milk products,” Dr Aravinda added.
Time window suitable for sun exposure
Explaining why the time window between 10 am and 3 pm is considered safe for sun exposure, she shared that Vitamin D production in the body is at peak efficiency during these hours due to the highest levels of ultraviolet B (UVB) radiation.
“Most people need to expose their arms and legs and face for about 15 to 30 minutes three to four times each week. The body requires direct sunlight exposure during morning and late evening hours to produce Vitamin D,” she noted.
Vitamin D absorption and poor AQI levels
However, growing concerns about poor Air Quality Index (AQI) levels have limited outdoor activities. Citing the World Health Organisation, Dr Aravinda stressed that poor AQI can block sunlight from being absorbed. “The atmosphere contains pollutants, which include particulate matter (PM2.5) and smoke and dust, that create a barrier which stops adequate UVB rays from reaching the Earth’s surface,” she said.
“Your outdoor activities will result in reduced Vitamin D production for your body. The World Health Organisation states that air pollution creates harmful effects on human health because it decreases the sun exposure required for Vitamin D production,” she added.
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Further, Dr Aravinda highlighted the importance of checking the ultraviolet index before stepping out in the sun. “The index shows ultraviolet radiation strength together with its potential to cause skin damage. A moderate UV index (3–5) is usually sufficient for safe Vitamin D production with minimal harm, while high levels (6 and above) increase the risk of sunburn and skin damage,” she explained.
DISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.
