• Anna Solana, science journalist

    The ABC of a good tan

    It is not just a matter of lying down and smearing the skin with any product promising a safe and lasting tan. Sunscreens are not what they were. But how should we use the creams? Are they all safe? How much does clothing protect us? Here are some tips to make the most of our skin care.


    According to the American Academy of Dermatology (AAD), we should use a broad-spectrum shield, which protects against the UVA rays responsible for skin ageing and against the UVB rays that cause sunburn. It is best to use a high sun protection factor (SPF) of at least 30. This is even more important for people with fair skin (phototype I and II), children, pregnant women and people doing water or mountain sports who spend long hours under a blazing sun. For the first sun exposure, the SPF should never be under 15. We need not go to the other extreme, however, as an SPF of more than 50 does not afford more protection.


    We also need to remember that there is no such thing as a full sun block. In other words, there is no cream on the market that can guarantee complete protection against the sun’s radiation. Finally, the label should indicate that the product is resistant to water and perspiration.


    In fact, according to the latest US Food and Drug Administration (FDA) indications, manufacturers are required to state on the label how many minutes a product will last after a swim (40 or 80 minutes).


    Does it matter whether it’s a lotion, gel or spray?

    This is a matter of taste, but it also varies depending on the body part to protect. But bear in mind that creams are best for the face and dry skin, that gels are more practical for areas with hair (such as the head and chest in men) and that sprays are easier to apply to children. Tthe FDA continues to evaluate safety for sprays, however, recommending that the body be covered with sufficient product and, above all, that the spray is not inhaled.


    When and how to apply sunscreen?

    It has been said time and again, but tends to be forgotten. Sunscreen should be applied 15 to 30 minutes before sun exposure. That means before you leave home, to all exposed body parts – including fingers and toes, hands and feet, ears and nose and even the head when bald – and always in sufficient quantities.


    The AAD, which states that most people only apply 25% to 50% of the cream they need, recommends at least one ounce (30 mL or the equivalent of 6 teaspoons) of product every two hours.


    Does clothing protect us from the sun?

    Yes and no. Ultraviolet protection provided by clothing depends on the type of fabric, its colour and porosity and on whether or not it is wet. For example, a white cotton t-shirt has an ultraviolet protection factor (UPF) of 5 to 7, but this value drops to 3 when the garment is wet.


    The belief that light colours protect more than dark colours is werroneous. A green t-shirt, for instance, protects almost 50% more than a white t-shirt; even so, the UPF for the green t-shirt is just 10.


    To enhance these values, the textile industry has developed anti-solar fabrics with a minimum SPF of 30, which protect the skin when dry or wet.


    What precautions should be taken with babies and children?

    The best protection for babies is to keep them in the shade, dressed and wearing a hat. The AAD confirms that the skin of babies under 6 months is not capable of absorbing the chemicals in sunscreens, so it is best not to apply these products.


    For older children, use special children’s creams that contain zinc oxide or titanium dioxide as a protection against unnecessary irritation.