Sunscreen Q & A

What is SPF?

A sunscreen's SPF, or Sun Protection Factor, measures how long a sunscreen will protect your skin from ultraviolet B (UVB) rays before burning, compared with how long it takes to burn unprotected skin. For example, if used correctly, sunscreen with an SPF of 15 will prevent sunburn 15 times longer than if the product wasn't used. So, according to the Skin Cancer Foundation, if it takes 20 minutes for your unprotected skin to start going red, applying a sunscreen with an SPF of 15 theoretically delays this for 15 times longer - about five hours. Furthermore sunscreen with an SPF of 15 effectively filters out about 93% of all incoming UVB rays, while SPF 30 keeps out 97% and SPF 50, 98%.

What type of sunscreen should I choose?

A high SPF alone isn't enough: SPF measures protection against UVB, but not against the sun's long-wave, ultraviolet A (UVA) rays, and new research shows that UVA penetrates the skin more deeply than UVB, causing as much or even more damage. UVA is also the main cause of sun-induced skin aging. Look for products that offer "broad spectrum" or "UVA/ UVB" protection, and make sure your sunscreen has one or more of these UVA-filtering ingredients: titanium dioxide, zinc oxide, stabilised avobenzone (Butyl Methoxydibenzoylmethane).

Do I only need sunscreen on a sunny day?

You need to use sunscreen every day, all year-round, in every kind of weather, even if you have dark skin. Here's why:

• Sunlight reflects off roads, sand and water, intensifying ultra violet radiation effects by up to 80%. So even in winter when it's cold but bright, ensure that your hands, neck, and as much as possible of your face are covered
• On overcast days, up to 80% of UV radiation penetrates clouds, mist and fog. Water reflects an additional 5% of the sun's rays back on you. Even dry surfaces reflect the sun's rays, for example, concrete reflects 10% to 12% of the sun's rays.

What about vitamin D?

You get more than enough exposure to the sun for adequate vitamin D production when spending short times outdoors. Remember that the 'sun safe' time (amount of time you can safely be exposed to the sun with bare skin) in South Africa is 10 minutes!

Are fair-skinned people the only ones who need to cover up?

Even though darker skins seldom get melanoma, it's more often fatal when they do. Melanomas in darker skins most often occur on non-exposed skin with less pigment, with up to 60-75% of lesions arising on the palms, soles of the feet, mucous membranes and under toe nails (as in the case of Bob Marley). CANSA advises using SPF20 for darker skins. Remember to always notify your dermatologist about any suspicious marks that develop on your skin or changes to moles on your body.

How much sunscreen is enough?

Sunscreen only works to the indicated SPF if you're putting on enough, which most of us don't do. Leading dermatologists advise using a minimum of 30ml or two tablespoons on the average body. After two hours in the sun, even if you're not swimming, sunscreen loses its effectiveness, so it's vital to reapply. If you are swimming or exercising, reapply immediately afterwards to keep the original level of protection, otherwise top up every two hours.