What is the meaning of the sun protection factor (SPF) values in sunscreens and the differences between them?
Sunscreens are used to block ultraviolet radiation emitted by the sun. To calculate the SPF, you first need to know the so-called erythema dose. The erythema dose is the amount of ultraviolet radiation needed to cause a sunburn. A person with SPF 15 sunscreen needs to be exposed to 15 times more radiation to cause the same sunburn as a person without sunscreen. A person with SPF 30, thirty times more radiation, and so on.
The problem is that these values are calculated under laboratory conditions, that is, constant radiation doses and with amounts of sunscreen applied to the skin that are unfortunately much higher than what we normally apply. Therefore, we recommend that the sunscreen always has an SPF 50+ to try to compensate for the lower amount of cream applied.
After applying sunscreen, how long should we wait before going into the water?
You can bathe immediately after applying sunscreen. There is no problem. However, only 20 to 30% of the sun we get during the year is at the beach. The vast majority of solar radiation we are exposed to is received on the street, while we live our daily lives. Therefore, it is important that sunscreen is not only applied at the beach. It should be applied at home, and we should have the habit of applying sunscreen daily, in summer and winter. Sunscreen protects against solar radiation, which is the main cause of many skin cancers. In addition, it is the best anti-wrinkle product that exists.
On the other hand, if we are at the beach or pool, we should use a water-resistant sunscreen, and even if it is water-resistant, it should be reapplied after bathing.
How often should sunscreen be reapplied?
Ideally, every 2 hours while we are exposed to the sun. However, there are circumstances that alter this rule. For example, sunscreen should be reapplied after bathing.
What are the areas that people usually forget to apply sunscreen?
Without a doubt, the ears. No one ever applies sunscreen to their ears, and it is one of the most frequent places for actinic keratoses and skin cancer. The most important thing is to apply sunscreen to all the skin that is exposed to the sun, which varies greatly depending on what you are wearing.
What is a sunburn?
Basically, the skin received so much radiation that the cells start to die. All this produces an inflammatory reaction that makes the skin red, hot, and starts to hurt. It is exactly the same inflammatory response as a burn from fire. Finally, the skin regenerates and ends up peeling.
However, there is another consequence of sunburn, which we could call “chronic sunburn.” In this case, the skin receives ultraviolet radiation, but this radiation is not enough to make the cells die. However, this radiation is absorbed by our DNA and causes mutations. These mutations are generally repaired, but over time they accumulate and end up causing skin cancer. On the other hand, the radiation is not only absorbed by the DNA but also by the collagen and other proteins in the skin, making the skin more aged. That is why sunscreen not only protects against skin cancer but also against aging.
After a sunburn, how should I take care of my skin?
Ideally, you should not get sunburned. We should use SPF 50+ sunscreen, appropriate clothing, and stay in the shade under an umbrella and avoid the hottest hours.
When the damage is done, the most important thing is not to repeat the mistake the next day.
A lot of moisturizer, which may or may not be aftersun, can help relieve the symptoms of the burn slightly.
If there are blisters or a lot of pain, you need to see a dermatologist or family doctor.
What are the consequences of sunburn?
In addition to the pain and a couple of sleepless nights, which are obvious, a sunburn can leave spots on the skin, called actinic lentigines. On the other hand, one of the chronic effects of radiation on the skin is that it makes the skin thinner and more aged, sometimes so much that the capillaries can be seen through it – the so-called poikiloderma of Civatte. However, the most important effect is that the DNA of our skin cells accumulates mutations that over the years can end up in skin cancer.
How and should tanning cream be applied?
Most tanning creams and spray tanning booths work with a substance called dihydroxyacetone. This substance reacts with the skin and gives a brown tone. To date, there are no scientific studies on the long-term effects of dihydroxyacetone. However, we know two things – the first is that, despite the tanned tone, the protection factor it provides is 3. This low protection factor and the brown skin give a false sense of security, and people who use these tanners tend to expose themselves more to radiation without protection.
The second thing we know is that those who use this type of product are those who want to be tanned and, as such, expose themselves more to the sun and tanning booths and the like. And that is the mistake. We need to change our ideals of beauty. Beauty is a consequence of health. We find those people who are generally healthier more beautiful (and as such ideal partners for having children). Beauty that comes from unhealthy habits is not beauty.
What are the most common skin diseases that can arise due to the sun?
The most common and most relevant are undoubtedly skin cancers. Skin cancer is the most common type of cancer in humans, more than colon, lung, or breast cancer. There are two major groups of skin cancer, melanomas, which everyone knows, and another group – non-melanoma skin cancer.
Melanomas are similar to moles. If you or someone in your family has a mole with more than three colors (usually shades of brown), irregular borders, asymmetrical or most importantly, that is changing – that mole needs to be seen by a doctor, ideally a dermatologist.
Non-melanoma skin cancer is much more common than melanomas and usually manifests as a wound that does not heal despite adequate treatment or that heals and reappears in the same place. Once again, if you or someone in your family has a lesion of this type, you should see a doctor, ideally a dermatologist.
