Summer is back. And stepping out without putting on a sunscreen means you are likely to do a lot of damage to your skin. Every sunscreen contains SPF (Sun Protection Factor), a number that lets you know how long you can stay out in the sun without burning your skin. For instance, if your skin starts turning red after 10 minutes in the sun, an SPF of 15 allows you to stay out for 150 minutes without burning.

How much SPF do you need?
A sunscreen with SPF 15 blocks close to 95 per cent of UVB radiation, while an SPF 30 will block around 97 per cent of UVB. Skin experts recommend that everyone should use at least SPF 15 before they step out in the sun. “If you are going to spend a lot of time out in the sun, use SPF 30 or higher,” says Dr S K Bose, dermatology, Indraprastha Apollo Hospitals, New Delhi. Whichever SPF value that you use, be sure to reapply the sunscreen every two hours, else its effect wears off. Even if the sunscreen is waterproof, you need to apply it every two hours as it comes off because of water and sweat.

Mixing products with SPF does not necessarily add up to higher protection. For instance, using an SPF 15 moisturiser with an SPF 15 sunscreen does not result in SPF 30 protection.
SPF has its limitations though. It only measures the protection you get from UVB, which are the sun’s rays that cause burning. An SPF does not tell you how much protection, if any, you are getting from the sun’s UVA rays which are responsible for tanning, and premature ageing of the skin. To ensure that you are protected against UVA as well as UVB, make sure that your sunscreen contains avobenzone (also known as Parsol® 1789), titanium dioxide, or zinc oxide. Sunscreens that protect against both UVB and UVA rays are often called broad-spectrum sunscreens.

... contd.