There’s a fine line between sun-kissed and sun-singed. And so, whatever the weather – rain or shine – SPF is a non-negotiable in any skincare routine. You can spend a fortune on moisturiser, but it won’t make a real difference if you don’t use it alongside an effective SPF, every single day.

While studies show that natural sunlight can improve serotonin levels, lower blood pressure and help strengthen bones, there is no such thing as a ‘safe’ tan. Even though we know that our skin needs protection, it’s easy to get befuddled by the array of factors, acronyms and star-ratings attributed to sunscreens. If you need a little help getting to grips with this, as well as when to use SPF, how much to use and how often, scroll on.

Both UVA and UVB rays harm the skin but, as the effects they have are a little different, it’s important that you’re protected against both (hence ‘broad-spectrum’ sunscreen). Think of UVA as the ageing rays and UVB as the burning ones.

UVA are the deepest penetrating and most ageing ultraviolet rays. Due to their shorter wavelengths, UVB rays aren’t able to penetrate the skin as deeply, but they do more damage to the surface layers and are the cause of most skin cancers.

The sun protection factor (SPF) is the measure of how many times longer a sunscreen will protect you from UVB (and only UVB) rays compared to if you weren’t wearing any at all.

However, it's important to note that a sunscreen with an SPF of 30 is not twice as effective as one with an SPF of 15. In fact, SPF 15 filters about 93 per cent of UVB rays, SPF 30 filters 97 per cent and SPF 50 filters 98 per cent. Even if you were to layer all of these factors on top of each other, you would never achieve 100-per-cent coverage.

No. All skin types burn and all need a broad-spectrum, high-SPF sunscreen.

Physical sunscreens (or UV reflectors) block the sun’s rays on the surface of the skin, while chemical sunscreens (or UV absorbers) absorb into the skin, where they convert the sun’s rays into heat and then release them.

Don’t get too bogged down in the word ‘chemical’, as all sunscreens – even ‘chemical-free’ or physical sunscreens, which contain titanium dioxides and zinc oxides – feature some form of chemicals in their formula.

In general, chemical sunscreens tend to be best for tanning, while physical sunscreens benefit those with sensitive skin and rosacea as they deflect heat from the sun’s energy away from the skin.

For the face SPF is the final layer in your skincare routine – apply two fingers’ worth (enough for face, neck, décolletage and hands) and wait 60 seconds for it to fix before doing your makeup. 

For the body you’ll need about one teaspoon of SPF for each of your arms, two for your legs and two for your torso (front and back). 

Apply 30 minutes before sun exposure and reapply every two hours.

Did you know that UV rays reflect off sand and sea foam, making them more potent? Try to limit sun exposure between 11am and 4pm, and add some antioxidant insurance in the form of a vitamin C serum, which can be layered under your SPF to help neutralise damaging UV rays.

The final sunscreen rule? Reapply, reapply, reapply! Every two hours as standard, and also immediately after swimming.