Do we always need to use sunscreen?

When is sunscreen necessary?

Check the local UV index in your weather app. The UV index measures radiation rather than temperature, so the weather has more than one number worth reading. At 3 or above, protect your skin with sunscreen, clothing and shade. At 8 or above, avoid being outside around midday as well. At 0 to 2, sun protection is generally unnecessary under normal circumstances. Applying sunscreen whenever you go outdoors is a simple routine; checking the index helps explain when protection is especially needed.3

Being indoors changes the answer, but sitting beside a sunny window is not the same as being away from sunlight. UVA rays pass through window glass and contribute to wrinkles and age spots; glass blocks UVB rays, the main cause of sunburn. As general guidance, consider protection for exposed skin during prolonged time beside a sunny window, rather than treating every indoor day as identical.4

Why do we need sunscreen?

Ultraviolet radiation, or UV, can damage skin cells, and too much exposure causes most skin cancers. Sunscreen helps prevent sunburn and reduces the risk of skin cancer and premature skin ageing. Protection matters for every skin tone. Naturally brown or black skin has some protection against UV, but people of all skin tones can get skin cancer. A tan is not a safe substitute for sun protection.256

What sunscreen should I use?

Choose broad spectrum SPF 30 or higher, with water resistance. Broad spectrum means protection against both UVA and UVB; SPF mainly describes UVB protection. A higher SPF does not last longer or remove the need to reapply. For sensitive skin, a mineral sunscreen containing zinc oxide or titanium dioxide is an option. Keep sunscreen containers out of excessive heat and direct sunlight, and replace expired products.145

How should I apply sunscreen?

1. 1Apply sunscreen before going outside. Follow the product's directions; general application advice is to apply it 15 minutes before sun exposure.
2. 2Cover all exposed skin generously, including ears, neck, hands, feet and exposed scalp. Avoid the eyes and mouth, and use an SPF lip balm on your lips.
3. 3Use about one ounce for an adult's exposed skin, with more needed depending on body size. For the face, use at least one teaspoon.
4. 4Reapply about every two hours while outdoors, and after swimming, sweating or towel drying. Follow the label's water resistance and reapplication directions.

Sun protection includes clothing and shade as well as sunscreen, so the bottle does not get the entire job description. Wear a wide brimmed hat and sunglasses that block UVA and UVB. Water, sand and snow reflect UV and increase exposure. Shade reduces exposure, but sunscreen and protective clothing still belong in the plan.27

Who needs extra care?

Take extra care if you burn easily, have many moles, have a family history of skin cancer or spend a lot of time outdoors. Some medicines, including certain antibiotics, and some topical products can increase sensitivity to UV. Keep babies under six months out of direct sunlight and ask a doctor before applying sunscreen. If sunburn causes severe swelling, blisters or feeling unwell, seek medical help.567