The SPF (Sun Protection Factor) is an index that measures the ability of a sunscreen product to protect the skin from harmful UVB rays, which are primarily responsible for sunburns and skin damage. The higher the SPF index, the more effective the protection against ultraviolet radiation.
In detail, the protection provided by the most common SPF indices is as follows:
Experts recommend using products with SPF between 30 and 50 for effective daily protection. Although higher indices offer slightly increased protection, the difference is minimal and often creates a false sense of security that may lead to prolonged sun exposure.
It is important to remember that no sunscreen blocks 100% of solar radiation. Consistent and correct use is more effective than relying on a very high SPF.
SPF is also calculated as a multiplier of exposure time. If, for example, your skin burns after 10 minutes without protection, with SPF 15 you can stay in the sun for up to 150 minutes (15 x 10). However, this is theoretical time and is affected by:
Dermatologists recommend reapplying every 2 hours or more frequently in conditions of intense activity.
The chemical (synthetic) filters absorb ultraviolet radiation and convert it into heat. They need about 20 minutes to activate and are absorbed by the skin. They are ideal for daily use as they have a light texture and do not leave white residues.
Conversely, the physical (mineral) filters such as zinc oxide and titanium dioxide, remain on the surface of the skin and reflect UV rays. They offer immediate protection and are suitable for sensitive skin or children.
The action of sunscreens diminishes with exposure to sunlight, water, and sweat. For effective protection:
Using SPF is just one aspect of sun protection. Combine it with practices that reduce exposure to radiation:
The correctly chosen and applied sunscreen can make the difference between healthy, youthful skin and premature aging or skin conditions. Stay informed, protect yourself and enjoy the sun responsibly.
The ultraviolet rays (UV) make up a small percentage of the sunlight that reaches Earth – just 5%. Despite their small quantity, their effect on the skin is extremely powerful. Of these, 95% is UVA and 5% UVB, with long UVA rays covering 75% of the total radiation reaching the surface of the earth.
The UVA rays are present throughout the year, even when the sky is overcast. They penetrate clouds, glass and the upper layers of the skin, reaching deeper cells. They do not cause immediate pain, but they are the main cause of photoaging, as they contribute to the premature aging of the skin.
The UVB rays have higher energy and are less penetrating. Although they are filtered by clouds and glass, they can reach the skin and cause sunburns, allergic reactions and even skin cancer. They are also responsible for tanning.
Solar radiation can provide warmth and well-being, but prolonged exposure without protection has significant negative consequences:
