Sunscreen: Choosing SPF and Using It Properly

Sunscreen helps prevent sunburn, skin ageing and skin cancer, but only if you use enough and reapply. Most people apply less than half the amount used in SPF testing.

Imagine using SPF 50 on a beach day and still burning. You put on a thin layer once in the morning and then went swimming. Next trip, you apply a generous amount 20 minutes before going out, reapply every two hours and after swimming, and come home without a burn.

Understanding the labels

• SPF measures protection against UVB rays, which cause sunburn. SPF 30 blocks about 97% of UVB; SPF 50 about 98%.
• UVA protection guards against ageing and contributes to skin cancer. Look for “broad spectrum”, a UVA logo or a high star rating.
• Water resistant doesn’t mean waterproof; reapply after swimming or sweating.

Many dermatology bodies recommend at least SPF 30 with good UVA protection.

How to apply properly

• Use about six to eight teaspoons for the whole body of an adult (roughly a shot glass), and about half a teaspoon for the face and neck
• Apply 15 to 30 minutes before going out
• Reapply at least every two hours and after swimming, sweating or towelling
• Don’t forget ears, neck, feet, scalp partings and the backs of hands
• Check expiry dates

But does darker skin need sunscreen?

Darker skin has more natural protection and burns less easily, but it can still burn and develop skin cancer, which is often diagnosed later in people with darker skin. Sun protection also helps prevent dark patches (hyperpigmentation). Everyone benefits from sensible sun protection.

Beyond sunscreen

Sunscreen is one part of protection. Seek shade when UV is strongest (usually 11am to 3pm), wear a wide-brimmed hat, UV-protective sunglasses and clothing. Babies under six months should be kept out of direct sun.

Sources: World Health Organization (Ultraviolet radiation), American Academy of Dermatology, British Association of Dermatologists, Cancer Council Australia.