The science of sunscreen & why you need to apply it EVEN in winters according to an expert

Updated on Nov 17, 2021 01:49 PM IST  |  124.5K
The science of sunscreen & why you need to apply it EVEN in winters according to an expert
The science of sunscreen & why you need to apply it EVEN in winters according to an expert

If there's one thing that has to be a staple in everybody's skincare or a basic morning routine, it is Sunscreen. It helps you protect yourself from the harmful UV rays & all the skin concerns that come with it. These radiations are undetectable by the human eye and are responsible for a lot of skin concerns such as sunburn, pigmentation, suntan, loss of skin elasticity, early signs of ageing, & skin cancer.

UV rays are a form of electromagnetic radiation that naturally comes from the sun. On the electromagnetic spectrum, UV light has a shorter wavelength than visible light, so our eyes can't see them. There are three types of UV rays; UVA (315-400 nm), UVB (280-315 nm), UVC (100-280 nm), and each one of them has its own effects on the skin.

By the grace of our Ozone layer, the UVC rays (which are the most harmful kind of UV rays) get absorbed in the atmosphere itself, so it doesn't reach the earth's surface.

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UVB is responsible for sunburns, tanning & skin cancer. UVB directly interferes with the skin's DNA, which triggers solar erythema & induces melanogenesis. Hence, long exposure to UVB radiation can result in excessive melanin production & residual inflammation.

UVA, on the other hand, makes up 95% of the most harmful UV rays reaching earth & penetrates deeper into the skin than UVB. They form free radicals in the skin, which react with the skin's DNA, protein & lipids. This oxidative stress in the skin results in loss of elasticity, degrading collagen, skin cancer & early signs of ageing. While UVB levels are highest at between 10 AM - 4 PM (highest in summers); UVA is constant throughout the year. What makes them even more dangerous is their strong penetration power. UVA rays can easily penetrate through glass windows and clouds.

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There's a tool initiated by the World Health Organization, known as UV Index that helps us understand the number of UV rays reaching the earth surface. This tool tells how strong the sun's UV rays will be; the greater the strength, the higher UV index value and the more damage it can do to your skin. Just like the weather forecast, UV index varies throughout the world depending on the time of the day, season, the amount of cloud coverage and ozone protection. It is measured on a scale of 0 to 11+, where 0-1 denotes low-level UV, while 10-12+ denotes an extremely high amount of UV rays.

India, being a tropical country, always falls under the higher scale of UV index. The average UV score ranges from 5 and goes up to 12 in some states of India, during the peak hours and summer season. Even though the UV index value is highest in the month of summer, it is still under the 'High Spectrum' of UV index in the months of winters. The average UV index score for October in 4 metro cities of India is 7.5, which is still high and requires proper sun protection. This score varies depending on the time of day and location (south, being close to the equator, has much higher UV index as compared to north).

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All this data shows why it is extremely important to wear broad-spectrum sunscreen even when you're indoors, on overcast days and in winters.

About the author: Mohit Yadav, Co-Founder and CEO at Minimalist

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