At a time when temperatures continue to rise and much of the planet experiences extreme heat waves, people are increasingly turning to sunscreen. We know they help the skin against dangerous UV rays, but how exactly do they do it? And how do these creams prevent us from tanning?
How do we protect ourselves from ultraviolet radiation?
We already know quite well what the negative effects of sun exposure are: burns, skin cancers and premature skin aging are among them.
But our ability to combat them by using sun protection creams has also increased. However, we are probably not that familiar with the scientific explanations behind this “shield”.
Sunscreens work by protecting the skin from ultraviolet (UV) rays. By doing this, we can extend the time we spend in the sun before we burn.
Sunburn or solar erythema occurs when UV rays damage the cells of the epidermis, the first layer of our skin. The immune system responds by increasing blood flow to the affected areas, causing the skin to become red and hot to the touch. White blood cells work to replace the damaged cells, causing the skin to itch and peel.
To prevent this, sunscreens stop UV rays from causing the problem in the first place, either by absorbing them, as with chemical-based creams, or by reflecting them, as with physical sunscreens.
How effective are sunscreens?
Chemical creams usually include oxybenzone, avobenzone, octisalate, or octocrylene that convert UV to heat before it spreads through the body. In the other type of protective creams the main ingredients are titanium dioxide and zinc oxide which create a barrier, removing UV rays from the skin.
There are two types of UV radiation: UVA and UVB. According to the Centers for Disease Control and Prevention (CDC), almost all radiation reaching the Earth is UVA, which penetrates deep into the skin.
Because of this, they are responsible for skin aging, while stronger UVBs are responsible for sunburn. The broad protection spectrum of the creams protects against the action of both types.
The fact that we tan is due to UV action increasing the production of melanin – a pigment that also gives our eyes and hair color – as our skin tries to prevent damage from this radiation.
“There is no such thing as a safe tan. Increased melanin production is a response to epidermal damage and is associated with an increased risk of skin cancers,” explained the US Food and Drug Administration.
If the tanning is caused by UV rays, the use of sun protection creams prevents this to some extent.
“Tanning is mostly caused by UVA rays, and if we use broad-spectrum products—both UVA and UVB—most people will stop tanning,” dermatologist Loretta Ciraldo told Byrdie.
“Exceptions can be made by people who already have, naturally, a very accentuated pigment. In their case, even a minimal amount of UVA that can pass the protection of creams can tan the skin”
However, it should be known that no sunscreen cream completely blocks the action of ultraviolet rays, so it is good to use other methods to protect yourself from their action.