We all know how dangerous the sun’s rays can be and how important sun protection is. However, are you sure you know what to keep in mind when choosing the right protection? Plus, are you applying it properly?

When choosing a sunscreen, you need to ask the following questions:

  • What is the  SPF of the cream?
  • Does the cream also protect against UVA rays?
  • Is the cream mineral or chemical?
  • Is the cream waterproof?
  • What is in the composition of the cream?

What is the SPF of the cream?

SPF (sunburn protection factor) is a number that indicates how well the product protects our skin from UVB radiation. Thereby:

  • SPF 15: the product blocks 93% of UVB rays
  • SPF 30: the product blocks 97% of UVB rays
  • SPF 50: the product blocks 98% of UVB rays
  • SPF 100: the product blocks 99% of UVB rays

Dermatologists recommend SPF 15 as a minimum, and depending on your skin type, sun exposure and UV intensity, you will need a higher protection factor. SPF 30 is often cited as an ideal factor since the difference between it and SPF 50 is only 1% in blocking air. Any factor above SPF 50 is not significant and there is no product that would block 100% of the sun’s rays. The Food and Drug Administration (FDA) has determined that any product that is declared a sunscreen product and has an SPF below 15 must have a warning on the label that it only protects against sunburn, not cancer or skin aging.

Does the cream also protect against UVA rays?

Two forms of UV radiation reach our skin, and these are UVA and UVB rays. UVB (B as “burns” or “bronzed” skin) rays have  shorter wavelengths and reach the surface layer of the skin. These rays are responsible for getting a tan, but also for sunburn. On the other hand, UVA (A as “aging”) rays have  longer wavelengths and reach deeper into the skin. They are the cause of allergies and permanent skin damage, which we see as skin aging. UVA rays are present throughout the year while UVB rays are strongest in the summer and in the afternoon. As the skin is exposed to the sun’s rays throughout the year, we should more often protect it with broad-spectrum SPF products, i.e., use SPF that protects against both types of UV radiation.

Is the cream mineral or chemical?

Sunscreens can be divided into mineral and chemical. Mineral or physical creams contain inorganic compounds that are active physical blockers. These compounds are most commonly titanium dioxide and zinc oxide. They work on the principle of reflecting the sun’s rays that reach the skin. Nevertheless, most sunscreens are chemical. They contain active ingredients that absorb UV rays, cause a chemical reaction and thus prevent the rays from causing damage. It is also possible to use a combination of both types of ingredients to achieve a synergistic effect in order to produce a non-irritable cream of suitable formulation and high SPF.

Mineral creams are often thicker and whiter than chemical ones so we can clearly see where we applied the cream and whether we missed any area of the skin. It is an advantage for some people, but others see this feature as a disadvantage, so they prefer to choose a chemical cream. Chemical creams often have a more acceptable formulation – they are light, non-sticky, easier to spread on the skin, and do not leave a white mark. On the other hand, a big reason for choosing mineral creams is that they often cause less irritation than chemical ones and are more suitable for more sensitive skin. Concerns have also been expressed over the years about the potential damage from free radicals due to long-term use. However, most modern formulas contain antioxidants that protect the health of your skin, now and in the future.

Is the cream waterproof?

It is important to distinguish between the term waterproof and water-resistant cream. The term waterproof cream was once used on water resistant creams. The FDA banned it because the term waterproof cream would mean that the cream works indefinitely even when we are swimming in the sea or sweating, which is not possible. A water-resistant cream is one that can have a good effect even in the presence of water. Apart from the fact that sunscreen is water-resistant, it should state whether it is water-resistant for 40 or 80 minutes.

What is the composition of the cream?

Oxybenzone. Several studies have been published that warn of the harmful effects of oxybenzone. It has been found to cause endocrine disorders and increase the risk of breast cancer and endometriosis. Because this chemical is harmful to coral reef ecosystems around the world, certain states have banned sunscreens that contain this ingredient.

Octinoxate. Animal studies have shown suspicion of the detrimental hormonal effect of octinoxate on the metabolic system and thyroid hormone production. This ingredient too is banned in some states due to concerns that it has negative effects on the marine ecosystem.

Para-aminobenzoic acid (PABA). In sensitive people, PABA can cause allergic and photosensitivity reactions.

Parabens. Parabens are preservatives found in skincare products, including some sunscreens. Read more about parabens at the link.

Zinc oxide and titanium dioxide. Ingredients of mineral creams that block UVA and UVB rays are known. Both compounds pose a potential hazard if inhaled. Therefore, it is good to avoid products in the form of sprays or powders that contain zinc oxide or titanium dioxide.

The listed ingredients are just some of the possibly problematic ingredients of some sunscreens. In most cases, however, despite the possible negative aspects of certain ingredients, the damage that the sun causes is undeniably more dangerous.

How, when, how much, and where to apply sunscreen?

Even more important than the choice of the cream itself is applying it correctly and quantitatively. It would be advisable to apply the cream 15-30 minutes before going out in the sun. According to FDA recommendations, regardless of the SPF value, it would be advisable to reapply sunscreen every two hours. Improperly applied SPF 50 sunscreen may provide less protection than properly applied lower-factor sunscreen.

The first and main problem is applying too little cream. When developing the cream, the SPF is tested at the applied amount of 2 mg of cream per cm 2 of the body. Often even half the amount is applied. This way, the SPF value of the product is reduced to half its value. To cover the whole face and neck with enough cream, we need about half a teaspoon of cream. To cover the whole body, we usually need an amount of cream that would fit in a hard liquor cup. If you are not sure whether you have applied enough, it’s okay to apply more than needed. We often forget to protect some parts of the body such as the ears, knees, and neck. Also, after swimming or heavy sweating, it is good to reapply the cream.

To make sure that every part of our body is sufficiently protected, dermatologists use the rule that the body is divided into 11 parts. Each part represents approximately 9% of the total area of our body and each part requires an equal amount of sunscreen. These body parts are:

  • head, neck and face
  • left arm
  • right arm
  • upper back
  • lower back
  • chest
  • abdomen
  • upper left leg and thigh
  • upper right leg and thigh
  • lower left leg and foot
  • lower right leg and foot

Sufficient quantity for each of the 11 parts can be determined by the “2 finger rule”. We need as much cream as we can fit when we apply a straight line of cream on the outstretched index finger and middle finger.

Risk factors

There are factors that can make you more vulnerable to sunlight.

if you have fair skin

if you use photosensitive drugs

if you are near water

even in the shade you can burn because the sun’s rays are reflected

Children have  thinner and more sensitive skin and therefore especially need protection

It is important to pay attention to the UV index (UVI). UVI expresses the number of UV rays that reach the Earth’s surface. The higher the value of the index, the more dangerous the radiation and the greater the probability of its negative consequences. It is very important to monitor the values of the UV index because that way we can prepare for higher values that could occur during the day. For example, with UVI 1 we can burn after 60 minutes spent in the sun, while for UVI 8 it occurs after only 15-25 minutes.

Translated by Filip Sakoman


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  2. How to Choose and Use Sunscreen, https://www.rei.com, accessed 5. svibnja 2021.
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  4. Radiation: The ultraviolet (UV) index, 2017, https://www.who.int, accessed 5. svibnja 2021.
  5. The trouble with ingredients in sunscreens, https://www.ewg.org, accessed 5. svibnja 2021.

Photography source

Image by chezbeate from Pixabay