Sunscreens: what sunscreen should have to protect us
Posted by Xanit Internacional Xanit Internacional | Posted in dermatology | Posted on 30-07-2019
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Dr María Victoria de Gálvez and Dr Norberto López, members of the Dermatology Team at Vithas Xanit International Hospital, led by Dr Enrique Herrera Acosta, talk to us today about the characteristics and properties that sunscreen must have to really protect us. They also explain how to apply sunscreen.
To begin with, we need to know that there are three types of ultraviolet radiation, A, B and C, but only UVA and UVB rays reach Earth because UVC rays are filtered out by the ozone layer. UVA rays are active all year round and affect skin ageing and solar allergies. UVB rays reach the Earth’s surface in less quantity but are more energetic and are active especially in summer. They are primarily responsible for sunburn.
What really makes a cream protect us from solar radiation?
- Physical and chemical filters: Sunscreens have physical filters and chemical filters. Physical filters contain particles that act as blockage of solar radiation. Chemical filters contain substances capable of absorbing solar radiation in the UV strip.
- SPF: SPF is the ability of a sunscreen to decrease erythema caused by exposure to the sun. It is a number that indicates how long we can expose our skin without getting sunburned with UV rays.
What factors should we consider when choosing a sunscreen?
As a basic rule, it is necessary to take into account the SPF enclosed on the packaging, photoprotection against UV rays and water resistance, especially at children’s age. It should be borne in mind that in patients with pathologies such as photodermatosis or skin cancer, it is necessary to ensure a very high photoprotection.
Tips for properly using sunscreen
- The most important thing is that we should never expose ourselves to the sun without any protection because even when it seems to us that there is no evident danger from the sun, ultraviolet rays always reach our skin.
- We must avoid direct exposure to the sun, mainly during midday and especially in summer.
- The sun cream blocks UV from the moment it is applied and stabilises after 5-10 minutes. So the general recommendation would be to apply it 5-10 minutes before exposure to the sun and repeat it at least every two hours, or more often if we have been swimming or had the sunscreen absorbed with our clothes.
- Sunscreens have their expiration day and should be changed every year, as they lose properties and we may not be really protected and may suffer from sunburns or skin allergies.
Children, elderly and pregnant women are recommended to limit exposure to the sun. In the case of children and the elderly, the skin is more sensitive. In the case of pregnant women, hormonal changes cause them to be at greater risk of sunburns.