Sunscreen: features of choice and application

Sunlight, in the spectrum of which 10% is ultraviolet rays, has a powerful biological effect. They contribute to the formation of vitamin D, which is necessary for the absorption of calcium, improve blood circulation in the skin, increase immunity, have a bactericidal effect, etc.

However, the effect of solar radiation is twofold. The recommendations of dermatologists and cosmetologists to use sunscreen for the face and body are aimed at reducing the negative effect of sun exposure on the skin and the human body as a whole. It is necessary to understand how to use and which protective agent to choose.

Negative effects of sunlight

Their negative effect is mainly due to exposure to excess ultraviolet radiation. In particular, it leads to the accumulation of free radicals and reactive oxygen species that have a destructive effect on tissues, to the destruction of the water-lipid mantle, damage to elastin and collagen proteins, resulting in dry skin, reduced elasticity and firmness, folds and wrinkles and etc., that is, there is an early tissue.

In addition, taking certain medications, improper use of perfumes, various cosmetics, which include lavender, rose, bergamot and other oils, even some sunscreens, an unfavorable ecological environment - all this greatly increases the degree of damaging effects of solar radiation.

So, as a result of excessive insolation:

photoaging of the skin is accelerated;
weakened general and local immunity;
allergies are provoked and the course of autoimmune diseases is exacerbated;
there are photodermatoses and skin ones, including;
existing dermatological and general somatic diseases are exacerbated.

What is solar radiation and how can one explain the twofold contradictory nature of its effect on the body? A general idea of its types and the mechanism of action of various protective agents helps to understand how to choose a sunscreen so that it not only neutralizes the negative effect of the sun, but also does not cause any complications. This is especially important for problematic facial skin.

The sun's rays consist of electromagnetic waves of different lengths that make up the visible spectrum, infrared and ultraviolet. The most dangerous for the skin in terms of damaging effect is ultraviolet (UV), which, in turn, also consists of waves of various lengths: UVC - 200-280 nm, UV-B (short) - 280-320 nm, UV- A (long) - 320-380 nm. The first, the most dangerous and generally destructive for all living things, are almost completely absorbed by the protective ozone layer of the Earth and almost do not reach its surface.

UV-B radiation mainly affects the surface layers of the epidermis and, in small doses, promotes tanning, stimulates the synthesis of vitamin D in the body, improves blood circulation due to moderate expansion of the capillaries of the dermis. But in higher doses, it leads to sunburn, induces the secretion of EGF (endothelial growth factor), which further provokes the development of melanoma and various other forms of precancerous and malignant neoplasms.

At the same time, UV-A rays are much more aggressive: if UV-B rays are almost 90% delayed by the epidermal layers, then 50-60% of the dose of the former penetrate into the dermis (reticular and papillary layers). In addition, their action is characterized by a cumulative effect. Long-term UV-A exposure to open areas of the skin is the cause of the formation of pigment spots and dystrophic changes in the connective tissue structures. Even more dangerous are the damaging effect of UV-A rays on cell DNA and the processes of mutation in them, leading to the development of melanoma and other tumors.

Composition of sunscreen

It must meet the following basic requirements:

absorb or reflect UV-B and UV-A rays as much as possible;
have a low degree of penetration through the stratum corneum;
must be resistant to light and temperature;
should not irritate the skin;
must be non-toxic and preferably hypoallergenic.

It includes ultraviolet filters, or screens. Depending on the chemical structure and the principle of the protective effect, sunscreens may contain components that combine three groups:

Compounds of mineral origin, or inorganic, which include mainly zinc dioxide, titanium dioxide and iron oxide (only in day colored cosmetic creams and in decorative cosmetics). They, without penetrating into the dermis, function immediately after application and it is on the surface, in the epidermal layer, refracting and reflecting the sun's rays, like a mirror.
Chemical, which are organic compounds. They form a thin film on the surface, penetrate deeper, absorb ultraviolet rays, which are transformed into photoisomers. As a result of the reverse reaction, the energy of the latter is released in the form of harmless long waves. The action does not begin immediately, but 20-30 minutes after the application of the drug. These substances include octoprilene, cinnamates, mexoril, oxybenzone, camphor derivatives, avobenzone, or parsol, benzophenone, and some others.
Antioxidants that are not sunscreen in the truest sense. But they help the body's defense systems of the same name to eliminate the harmful effects of sunlight.

Several natural ingredients are usually introduced into sunscreens, containing plant bioflavonoids, vitamins “E”, “C”, “K”, minerals selenium, zinc.

The natural sunscreen includes filters only of the first and third groups, as they are neutral and do not enter into chemical reactions. How to replace them, especially in the presence of problematic facial skin? Recently, some companies have been producing preparations with natural vegetable oils that have an average and high degree of protection from the sun - sunflower, carangi, avocado, olive oils. You can use your own products instead of factory-made preparations - sunflower, olive, sesame, soybean oils. But the degree of their protection against ultraviolet rays, especially from UV-A, is rather low.

How to use

The effectiveness of any protective agent lasts no more than 1.5 - 2 hours, after which it must be applied again. It should be applied to dry skin, preferably half an hour before going outside.

Chemical filters can cause allergic reactions and skin irritation, contribute to the formation of free radicals, and reduce the antitumor protection of tissues. Effective creams should include at least two photoprotective components. People with allergic reactions and diseases, dermatitis of any origin should use only natural preparations.

In what form is it better to use such creams?

For oily or combination skin, gels, light texture emulsions or lotions with matting effects are more suitable;
for dry, especially in the presence of a different nature of dermatoses - products in the form of milk or a moisturizer containing hyaluronic acid and antioxidants or natural vegetable oils. The facial products additionally include other ingredients that protect the skin from aging, for example, some substances from age spots, light-reflecting, moisturizing ingredients, coenzyme Q 10, yarrow and chamomile oil, etc.

Which is better - sunscreen or spray?

The spray is very easy to use, evenly applied and distributed over the surface of the skin, does not stick to it, does not pollute the hands. Its main disadvantage is the lack of resistance to water. There are also waterproof sprays. But due to the high consumption, they are uneconomical, in addition, they contain mainly chemical filters, sometimes alcohols and can cause an allergic reaction, a feeling of dryness or irritation in case of problem skin.

How to choose sunscreen

It is desirable that it has a broad spectrum of activity and protects against UV-B and UV-A. It is imperative to pay attention to the expiration date of the drug and, in order to avoid negative skin reactions, do not use an expired product.

In order to decide which cream is better, in addition to individual characteristics, it is also necessary to take into account its compliance with your skin phototype through the index on the package. For phototype:

I corresponds to a cream with an SPF index of 50 units;
II - SPF 20 or 30 units;
III - SPF 15-20 units;
IV-VI - enough SPF 4 units.

The SPF index, or sun protection factor, is a rating that indicates the degree of protection against exposure to only short UV-B rays. The index number is the result of the ratio of the time of first redness on sun-protected skin to the time of first redness on unprotected skin.

That is, this index is an indicator of the increase in the time of possible exposure to the sun. Despite the large numerical difference, the difference between them in the absorption or reflection of rays is not so significant, for example, a cream with an index of 15 protects against 93% of UV-B rays, 30 - 97%, 50 and 50+ - 98-99%. For the face and other most sensitive areas of the body, it is recommended to use a cream with spf 50, especially for the nose, auricles, eyelids, thighs, décolleté zone, as well as in the first days of tanning.

A cream only labeled SPF can protect against burns, but not against the penetration of UV-A rays. To limit the latter, there are brands of sunscreen with ppd - permanent pigmentation darkening factor, or delayed secondary pigmentation. The number with this abbreviation means how many times less rays of this type will penetrate the skin.

The best option is to use sunscreens with both protection factors, the ratio of which is: SPF / PPD = 2/3. Creams with this ratio of factors provide the most effective protection against the harmful effects of ultraviolet rays.

Currently, sunscreens are not only a necessary part of the treatment of dermatoses, their prevention and malignant neoplasms, as well as reducing the degree of premature skin aging, but, if used correctly, these products are an important component of cosmetic daily care for healthy skin. Is it possible to tan while using them? Yes, more than that, they provide a gradual uniform beautiful tan.