Choose a sunscreen that’s right for you

Read the label

A lot of the information you need is right on the bottle, if you know what to look for and understand what it means:

Sunscreen versus sunblock: Sunscreen contains chemicals that absorb or reflect the sun's rays to prevent them from reaching the deeper layers of the skin. In contrast, sunblock has ingredients (usually titanium oxide and zinc oxide) that physically block light, causing it to reflect or scatter. Sunblocks are thought to keep the skin cooler because they reflect rather than absorb rays, and may therefore be better for conditions like rosacea.

Broad Spectrum: Make sure the product protects against both UVA and UVB. UVA rays coverage may not be included, but these rays penetrate deeper into the skin and are mainly responsible for damage and signs of aging. The Environment Protection Agency's The Burning Facts (pdf) has a list of federally-approved ingredients and their effectiveness at blocking UVA or UVB rays.

SPF (Sun Protection Factor): SPF indicates how many times longer protected skin can stay in the sun before redness occurs versus unprotected skin. For example, if unprotected skin burns in 20 minutes, then an SPF 15 extends this time to 300 minutes (20 x 15). Experts recommend at least SPF 15, or higher if your skin burns easily or you plan to be outdoors for long periods of time.

But don't be fooled by the numbers: they aren't proportionate to strength. A sunscreen with SPF 15 blocks 93 per cent of UVB rays, while SPF 30 blocks 97 per cent. There is currently no standard measure for protection against UVA rays.