Speaking about the influence of the sun on the human body, it is impossible to accurately determine the harm or benefit it brings. The sun's rays are like kilocalories from food.. Their deficiency leads to malnutrition, and in excess they cause obesity. So it is in this situation. In moderate amounts, solar radiation has a beneficial effect on the body, while an excess of ultraviolet radiation provokes burns and the development of numerous diseases. Let's take a closer look.

Solar radiation: general effect on the body

Solar radiation is a combination of ultraviolet and infrared waves.. Each of these components affects the body in its own way.

Influence of infrared radiation:

1. The main feature of infrared rays is the thermal effect they create. Warming up the body contributes to the expansion of blood vessels and the normalization of blood circulation.
2. Warming up has a relaxing effect on the muscles, providing a slight anti-inflammatory and analgesic effect.
3. Under the influence of heat, metabolism increases, the processes of assimilation of biologically active components are normalized.
4. Infrared radiation from the sun stimulates the brain and visual apparatus.
5. Thanks to solar radiation, the biological rhythms of the body are synchronized, sleep and wakefulness modes are launched.
6. Treatment with solar heat improves the condition of the skin, relieving acne.
7. Warm light uplifts the mood and improves the emotional background of a person.
8. And according to recent studies, it also improves the quality of sperm in men.

Despite all the debate about the negative effects of ultraviolet radiation on the body, its lack can lead to serious health problems. It is one of the vital factors of existence. And in conditions of ultraviolet deficiency in the body, the following changes begin to occur:

1. First of all, immunity weakens. This is caused by a violation of the absorption of vitamins and minerals, a malfunction in metabolism at the cellular level.
2. There is a tendency to develop new or exacerbate chronic diseases, most often occurring with complications.
3. Lethargy, chronic fatigue syndrome are noted, the level of working capacity decreases.
4. The lack of ultraviolet light for children interferes with the production of vitamin D and provokes a decrease in growth.

However, you need to understand that excessive solar activity will not benefit the body!

Sunbathing contraindications

Despite all the benefits of sunlight for the body, not everyone can afford to enjoy the warm rays. Contraindications include:

• acute inflammatory processes;
• tumors, regardless of their location;
• progressive tuberculosis;
• angina pectoris, ischemic disease;
• endocrine pathologies;
• damage to the nervous system;
• dysfunction of the thyroid and adrenal glands;
• diabetes;
• mastopathy;
• uterine fibroids;
• pregnancy;
• recovery period after surgery.

In all cases, active radiation will aggravate the course of the disease, provoking the development of new complications..

Do not get involved in the sun and the elderly, infants. For these categories of the population, treatment with sunlight in the shade is indicated. The necessary dose of safe heat will be enough there.

Stories from our readers

Vladimir
61 years old

The negative influence of the sun

The time of exposure to infrared and ultraviolet waves must be strictly limited. In excess solar radiation:

• can provoke a deterioration in the general condition of the body (the so-called heat stroke due to overheating);
• negatively affects the skin, causing permanent changes;
• impairs vision;
• provokes hormonal disruptions in the body;
• can provoke the development of allergic reactions.

So that hours of lying on the beach during periods of maximum solar activity cause enormous damage to the body.

To get the necessary portion of light, a twenty-minute walk on a sunny day is enough.

The effect of the sun on the skin

Excessive solar radiation leads to serious skin problems. In the short term, you risk getting a burn or dermatitis. This is the smallest problem you can face when you get carried away with a tan on a hot day. If such a situation is repeated with enviable regularity, the radiation of the sun will be the impetus for the formation of malignant formations on the skin, melanoma.

In addition, UV exposure dries out the skin, making it thinner and more sensitive. And constant exposure to direct rays accelerates the aging process, provoking the appearance of early wrinkles.

In order to protect yourself from the negative effects of solar radiation, it is enough to follow simple safety measures:

1. Be sure to use sunscreen in the summer? Apply it to all exposed areas of the body, including the face, arms, legs and décolleté. The SPF badge on the packaging is the same UV protection. And its degree will depend on the number indicated near the abbreviation. For going to the store, cosmetics with an SPF 15 or SPF 20 level are suitable. If you plan to spend time on the beach, use special products with higher rates. For children's skin, a cream with a maximum protection of SPF 50 is suitable.
2. If you need to be outdoors for a long time at maximum intensity of sunlight, wear clothes made of light fabrics with long sleeves. Be sure to wear a wide-brimmed hat to hide the delicate skin of your face.
3. Control the duration of sunbathing. The recommended time is 15-20 minutes. If you are outside for a longer time, try to get some shade from the direct sunlight.

And remember that in the summer, solar radiation affects the skin at any time of the day, with the exception of night hours. You may not feel the obvious warmth from infrared waves, but the ultraviolet remains high in activity, both in the morning and in the afternoon.

Negative effect on vision

The influence of sunlight on the visual apparatus is enormous. After all, thanks to light rays, we receive information about the world around us. Artificial lighting to some extent can become an alternative to natural light, but in conditions of reading and writing with a lamp, eye strain increases.

Speaking about the negative impact on a person and vision of sunlight, it means damage to the eyes during prolonged exposure to the sun without sunglasses.

Of the unpleasant sensations that you may encounter, one can single out cutting pains in the eyes, their redness, photophobia. The most serious lesion is a retinal burn.. It is also possible dry skin of the eyelids, the formation of small wrinkles.

1. Wear sunglasses. When buying, first of all, pay attention to the degree of protection. Image models often slightly obscure the light, but do not prevent the penetration of ultraviolet radiation. Therefore, it is recommended to put aside a bright frame and opt for quality lenses.
2. Make sure that direct rays do not fall on your face. Stay in the shade, wear a hat, cap or other headgear with a visor.
3. Don't look at the sun. If you do not experience discomfort, this does not indicate the safety of this undertaking. Even the winter sun has enough activity to provide vision problems.

Is there a safe time of year

The use of solar radiation as a health treatment is a common practice. That ultraviolet, that heat belongs to the category of strong irritants. And abuse of these benefits can earn serious problems.

Sunburn is the production of melanin. And to be more precise, the protective reaction of the skin to an irritant.

Is the radiation of the sun so dangerous at any time of the year? It is difficult to give a definite answer to this question. Everything will depend not so much on the season as on the geographical location. So, in the middle latitudes, the activity of solar radiation increases by 25-35% in the summer. Therefore, the recommendations regarding staying outside on a clear day apply only to the hot season. In winter, residents of these regions are not threatened by ultraviolet radiation.

But the inhabitants of the equator face direct sunlight all year round. Therefore, the likelihood of a negative impact on the body is present both in summer and in winter. The inhabitants of the northern latitudes in this regard were more fortunate. After all, with distance from the equator, the angle of incidence of the sun's rays on the earth changes, and with it the radiation activity. The length of the thermal wave increases, and at the same time the amount of heat decreases (energy loss). Hence the winter all year round, as the surface of the earth does not have enough heat to warm up.

Solar radiation is a friend of our body. But do not abuse this friendship. Otherwise, the consequences can be the most serious. Just enjoy the warmth without forgetting the precautions.

The benefits and harms of ultraviolet rays of sunlight on the human body and skin: how to provide protection when tanning

The sun's ultraviolet rays give life to all life on our planet. If at one moment the ultraviolet rays of sunlight disappear, then all the processes of photosynthesis will immediately stop, a terrible cold will come, the light will disappear. The real "end of the world" will come.

And all this importance, scientists are constantly questioning the positive biological effect of ultraviolet rays, theories are being built that this is harmful radiation. Indeed, some facts suggest that the action of ultraviolet rays on the body leads to the development of pathological processes. But basically, if you follow the recommendations of dermatologists, even a tan is a useful procedure. After all, only under the influence of ultraviolet rays in the human body is produced irreplaceable vitamin D. Without it, bone destruction begins and the process of calcium absorption is impossible.

Needless to say, how we all aspire to the beach in summer to enjoy swimming and sunbathing? In recent years, scientists have greatly expanded their understanding of the effects of sunlight on the skin. And the more information about this appears, the louder they urge us to be careful. Abuse of sunbathing is fraught with serious consequences. Regular intensive tanning leads to premature aging: the appearance of wrinkles, unhealthy skin color, burns, irritation, and the most dangerous - an increase in the risk of skin cancer. So why not prevent negative consequences in a timely manner?

Types, types and proven properties of ultraviolet rays

It is widely known that there are several types of ultraviolet rays. UVA and UVB radiation are two different types of solar radiation. UVA types of ultraviolet rays penetrate deep into the skin, reducing its elasticity and firmness, causing premature aging of the skin, which is expressed in the accelerated formation of wrinkles, age spots and freckles, especially in fair-haired and light-eyed people. These rays can also cause skin cancer.

UVB rays are much more energetic than UVA rays. They cause sunburn and are one of the most common causes of skin cancer. It should be remembered that UVA and UVB rays have a harmful effect on the skin even in cloudy weather! Various creams protect against UVB, and nutritional supplements increase internal resistance to UVA radiation. The scientifically proven properties of ultraviolet rays have both beneficial and harmful effects on the human body.

Of course, you noted that older people, who are used to protecting themselves from the sun with umbrellas and wide-brimmed hats, have much smoother and softer skin than their peers - sailors, gardeners and representatives of other professions whose work involves being outdoors in any weather. and at any time of the year.

But do not consider the sun as your enemy! In moderate doses, it prevents rickets and seasonal depression, helps fight psoriasis and, according to anecdotal evidence, breast and colon cancer.

Thanks to the sun's rays, our body produces vitamin D, which is necessary for strengthening the skeleton, and hormones of good mood. Among other things, the sun's rays are an excellent natural pain reliever.

However, do not forget that the possibilities of sunlight- a double-edged sword. Did you know that sunburn is not just ugly and painful? This is a real burn with a deep skin lesion, which requires no less treatment than household one.

7 bad news about the dangers of the sun

The benefits and harms of ultraviolet rays have not yet been thoroughly studied, so scientists are building hypotheses. Currently, there are 7 bad news for a modern person about the dangers of the sun:

To ensure effective protection against ultraviolet rays, doctors have developed special recommendations. They are listed further down the page.

1. Did you get sunburn? Take 500mg rose nutmeg oil capsules 3 times daily for 20 days.
2. "How many times have they told the world": protect yourself from the sun's rays! And all the same, adults and children sunbathe on the beach for hours in the heat! A classic example of frivolity and irresponsibility!
3. Careless exposure to the sun will inevitably affect the state of health. Deep wrinkles, redness, cataracts, degenerative spots, skin cancer - this is not a complete list of possible consequences. Not to mention that the sun's rays are the most powerful factor accelerating aging. UVB rays destroy the skin, and penetrating UVA rays damage the cells that make up the skin. Don't forget: sunscreens/sunscreens only protect against UVB rays!
4. The best means of protecting the body from the influence of ultraviolet rays on the body is a shadow, and it doesn’t matter what exactly helps in this - the wall of the house, an umbrella, a beach fungus, a wide-brimmed hat or sunglasses ... A T-shirt, windbreaker or pareo will become indispensable helpers. And, of course, a protective cream that needs to be lubricated on all exposed surfaces, including ears and toes.
5. A balanced diet is another remedy for ultraviolet rays and a faithful assistant. Proper nutrition cannot protect against sunburn, but it will help strengthen the body's defenses. Eat more olive oil, exotic fruits and apricots, vegetables (especially tomatoes), and legumes. Limit your intake of meat, dairy products (including butter), and sweets.



6. Beware of the influence of ultraviolet rays on the body of the alpine sun - it is the most aggressive. When sunbathing on a sea beach, do not forget that the sun's rays reflected by the water surface, combined with a light and so pleasant sea breeze, are fraught with great danger.
7. Snow also reflects the sun beautifully, increasing UV radiation by 10% for every 1,000 meters. And this means that the higher you climb in the mountains, the more likely you are to get a sunburn. Moreover, if the sand reflects 10% of the sun's rays, and the water surface 20%, then freshly fallen snow reflects 90% of the sun's rays. Thus, the dose of UV radiation that your eyes and skin receive is multiplied many times over.
8. So how can you protect yourself from the influence of ultraviolet rays on a person: sunscreens, covering the body with a thin protective film, create a certain barrier that limits the sun's rays on the skin. This method of protection is only effective if you apply sunscreen to all exposed surfaces every 2 hours of sun exposure. However, the first manifestation of a tan indicates that UV rays have finally reached your skin! Remember that they cause significant harm to the body, enhance oxidation processes that accelerate cell aging. Taking sunscreen nutritional supplements that supply the body with the necessary antioxidants allows you to fight these processes from the inside. Among other things, nutritional supplements are aimed at the prevention of cancer, prevent the occurrence of allergic reactions to the sun (summer radiation dermatitis). No sunscreen can do this! Taking 1-2 capsules a day will provide reliable protection in the summer! In addition, taking the right nutritional supplements speeds up the time of obtaining a beautiful tan and makes it more long-lasting, moisturizing the skin and keeping it soft from the inside.



9. All devices for artificial tanning, standing in beauty salons and solariums, cause irreparable harm to health. For many years, dermatologists around the world have been doing everything possible to achieve a ban on their use. If you need to look tanned, it is better to use self-tanning products that do not burn or dry the skin. Opt for gel forms that contain fewer hazardous ingredients. However, in the presence of millet, freckles or enlarged pores, it is not recommended to use self-tanning products.
10. Self-tanning products do not prevent tanning, which means that they do not protect the skin from the harmful effects of sunlight.
11. Use sunscreen with an SPF of at least 30 daily. Apply sunscreen several times a day, especially after swimming or if you sweat excessively, even if the bottle is labeled "waterproof".
12. Drink plenty of water: Summer fluid intake ranges from 1 to 2 liters per day.
13. Don't confuse sun exposure with heat exposure. Ultraviolet rays do not cause a feeling of heat and retain their harmful effect on the body even at 40 ° C. It is necessary to protect yourself from the sun from the very first sunny days of spring, when the air is still quite cool. In the period from the beginning of June to the end of September, it is advisable to use day or foundation creams with the appropriate SPF. SPF is a sun protection factor that refers to the ability of cosmetics to increase the time of safe exposure to the sun. The value of the SPF factor can be in the range from 2 to 50 units. It is calculated in special laboratories, based on the fact that a certain agent will be used in an amount of 2 mg per 1 sq. see skin surface. Most often, sunscreens and lotions are produced with an SPF value, as well as day creams, foundations, powders, lipsticks and lip balms.



14. Don't forget to put sunscreen on your ears.
15. Don't rely on being in the city to save you from the harmful rays of the sun. The sun combined with polluted air is much more dangerous.
16. For children, the sun's rays are hundreds of times more dangerous, so protect them from the sun. Remember that for a child, the dose of ultraviolet rays of the sun received in 4 minutes is equivalent to the dose that an adult receives in 1 hour.
17. Do not think that solar radiation is most dangerous between 12 and 16 hours. In this interval, the greatest intensity of UVB rays is noted, while the rest of the time we are attacked by UVA rays.
18. Don't consider yourself invulnerable. The use of sunscreen and nutritional supplements helps protect against the sun, but common sense dictates that sunglasses, a hat, and a tank top are also essential.

Candidate of Physical and Mathematical Sciences E. LOZOVSKAYA.

With the onset of warm summer days, we are drawn to bask in the sun. Sunlight improves mood, stimulates the production of vital vitamin D in the skin, but at the same time, unfortunately, contributes to the appearance of wrinkles and increases the risk of skin cancer. A significant part of both beneficial and harmful effects is associated with that part of solar radiation that is invisible to the human eye - ultraviolet.

The spectrum of electromagnetic radiation and the spectrum of the sun. The boundary between ultraviolet B and C corresponds to the transmission of the earth's atmosphere.

Ultraviolet causes various damage to DNA molecules in living organisms.

The intensity of ultraviolet B depends on latitude and time of year.

Cotton clothing provides good UV protection.

The sun is the main source of energy for our planet, and this energy comes in the form of radiation - infrared, visible and ultraviolet. The ultraviolet region is located beyond the short-wavelength edge of the visible spectrum. When it comes to the effects on living organisms, three areas are usually distinguished in the ultraviolet spectrum of the sun: ultraviolet A (UV-A; 320-400 nanometers), ultraviolet B (UV-B; 290-320 nm) and ultraviolet C (UV-C ; 200-290 nm). The division is quite arbitrary: the boundary between UV-B and UV-C is chosen on the basis that light with a wavelength of less than 290 nm does not reach the Earth's surface, since the earth's atmosphere, thanks to oxygen and ozone, acts as an effective natural light filter. The boundary between UV-B and UV-A is based on the fact that radiation shorter than 320 nm causes much more erythema (reddening of the skin) than light in the 320-400 nm range.

The spectral composition of sunlight largely depends on the time of year, weather, geographic latitude and height above sea level. For example, the farther from the equator, the stronger the short-wave boundary shifts towards long waves, since in this case the light falls on the surface at an oblique angle and travels a greater distance in the atmosphere, which means it is more absorbed. The thickness of the ozone layer also affects the position of the short-wave boundary, so more ultraviolet reaches the Earth's surface under the "ozone holes".

At noon, the intensity of radiation at a wavelength of 300 nm is 10 times higher than three hours before or three hours later. Clouds scatter ultraviolet, but only dark clouds can block it completely. Ultraviolet rays are well reflected from sand (up to 25%) and snow (up to 80%), worse from water (less than 7%). The ultraviolet flux increases with height, approximately 6% per kilometer. Accordingly, in places located below sea level (for example, off the coast of the Dead Sea), the radiation intensity is less.

LIFE UNDER THE SUN

Without light, life on Earth could not exist. Plants use solar energy, store it with the help of photosynthesis and provide energy through food to all other living beings. For humans and other animals, light provides the ability to see the world around them, regulates the biological rhythms of the body.

This cheerful picture is slightly complicated by ultraviolet, since its energy is enough to cause serious damage to DNA. Scientists have counted more than two dozen different diseases that occur or are aggravated by the action of sunlight, among them xeroderma pigmentosum, squamous cell skin cancer, basalioma, melanoma, cataracts.

Of course, in the process of evolution, our body has developed mechanisms to protect against ultraviolet radiation. The first barrier that blocks potentially dangerous radiation from entering the body is the skin. Almost all ultraviolet is absorbed in the epidermis, the outer layer of the skin with a thickness of 0.07-0.12 mm. Light sensitivity is largely determined by the body's inherited ability to produce melanin, a dark pigment that absorbs light in the epidermis and thereby protects the deeper layers of the skin from photodamage. Melanin is produced by specialized skin cells called melanocytes. UV radiation stimulates the production of melanin. This biological pigment is formed most intensively when irradiated with UV-B light. True, the effect does not appear immediately, but after 2-3 days after exposure to the sun, but it persists for 2-3 weeks. At the same time, the division of melanocytes is accelerated, the number of melanosomes (granules containing melanin) increases, and their size increases. Light in the UV-A range is also capable of causing a tan, but weaker and less persistent, since the number of melanosomes does not increase, but only photochemical oxidation of the melanin precursor to melanin occurs.

According to the susceptibility to sunlight, six types of skin are distinguished. Type I skin is very light, burns easily, and does not tan at all. Type II skin burns easily and becomes slightly tanned. Type III skin tans quickly and burns less. Type IV skin is even more resistant to sunlight. The skin of types V and VI is naturally dark (for example, in the natives of Australia and Africa) and is almost unaffected by the damaging effects of the sun. Blacks have a 100 times lower risk of developing non-melanoma skin cancer, and 10 times less melanoma than Europeans.

People with very fair skin are most vulnerable to UV exposure. In them, even a short stay in the bright sun causes erythema - redness of the skin. Erythema is caused mainly by UV-B radiation. As a measure of the effect of ultraviolet radiation on the body, such a concept as the minimum erythemal dose (MED) is often used, that is, one at which a slight redness is noticeable to the eye. In fact, the MED value is different not only in different people, but also in one person in different parts of the body. For example, for the skin of the abdomen of a white non-tanned person, the MED value is about 200 J/m 2 , and on the legs it is more than three times higher. Erythema usually occurs several hours after exposure. In severe cases, a real sunburn with blisters develops.

What substances in the epidermis, besides melanin, absorb ultraviolet radiation? Nucleic acids, amino acids tryptophan and tyrosine, urocanic acid. Nucleic acid damage is the most dangerous for the body. Under the action of light in the UV-B range, dimers are formed due to covalent bonds between adjacent pyrimidine (cytosine or thymine) bases. Since pyrimidine dimers do not fit into the double helix, this part of the DNA loses its ability to perform its functions. If the damage is small, special enzymes cut out the defective area (and this is another fairly effective defense mechanism). However, if the damage is greater than the cell's ability to repair, the cell dies. Outwardly, this is manifested in the fact that the burned skin "peels off". DNA damage can lead to mutations and, as a result, to cancer. Other molecular damage also occurs, for example, DNA cross-links with proteins. By the way, visible light contributes to the healing of damaged nucleic acids (this phenomenon is called photoreactivation). Antioxidants contained in the body help prevent the dangerous consequences of photochemical reactions.

Another consequence of ultraviolet radiation is immune suppression. Perhaps this reaction of the body is designed to reduce the inflammation caused by sunburn, but it also reduces resistance to infections. The photochemical reactions of urocanic acid and DNA serve as a signal for immune suppression.

FASHION FOR TANNING - A SYMBOL OF INDUSTRIAL SOCIETY

For a long time, white skin was considered a hallmark of the noble and rich: it was immediately clear that its owners did not have to work in the field from morning to night. But in the twentieth century, everything changed, the poor now spent whole days in factories and factories, and the rich could afford to relax in the fresh air, by the sea, showing a beautiful golden tan. After the Second World War, the fashion for tanning became massive; tanned skin began to be considered a sign of not only wealth, but also excellent health. The tourism industry has grown, offering holidays by the sea at any time of the year. But some time passed, and the doctors sounded the alarm: it turned out that the frequency of skin cancer among tan lovers increased several times. And as a lifesaver, it was suggested that everyone, without exception, use sunscreens and lotions, which include substances that reflect or absorb ultraviolet radiation.

It is known that even in the time of Columbus, the Indians used to paint themselves with red paint to protect themselves from the sun. Perhaps the ancient Greeks and Romans used a mixture of sand and vegetable oil for this purpose, since the sand reflected the sun's rays. The use of chemical sunscreens began in the 1920s when para-aminobenzoic acid (PABA) was patented as a sunscreen. However, it was soluble in water, so that the protective effect disappeared after bathing, and besides, it irritated the skin. In the 1970s, PABA was replaced by its esters, which are almost insoluble in water and do not cause severe irritation. The real boom in the field of sunscreen cosmetics began in the 1980s. Substances absorbing ultraviolet (in cosmetology they were called "UV filters") began to be added not only to special "beach" creams, but also to almost all cosmetic products intended for use in the daytime: cream, liquid powder, lipstick.

According to the principle of operation, UV filters can be divided into two groups: reflecting light ("physical") and absorbing ("chemical"). Reflective agents include various kinds of mineral pigments, primarily titanium dioxide, zinc oxide, magnesium silicate. The principle of their action is simple: they scatter ultraviolet, preventing it from penetrating into the skin. Zinc oxide captures the wavelength range from 290 to 380 nm, the rest are somewhat smaller. The main disadvantage of reflective agents is that they are powder, opaque and give the skin a white color.

Naturally, cosmetics manufacturers were more attracted to transparent and highly soluble "chemical" UV filters (known in photochemistry as UV absorbers). These include the already mentioned PABA and its esters (now they are almost never used, since there is evidence that they decompose to form mutagens), salicylates, cinnamic acid derivatives (cinnamates), anthranilic esters, oxybenzophenones. The principle of operation of a UV absorber is that, having absorbed a quantum of ultraviolet radiation, its molecule changes its internal structure and converts light energy into heat. The most efficient and light-resistant UV absorbers operate on an intramolecular proton transfer cycle.

Most UV absorbers only absorb light in the UV-B region. Usually sunscreens contain not one UV filter, but several, both physical and chemical. The total content of UV filters can exceed 15 percent.

To characterize the protective effectiveness of creams, lotions and other cosmetic products, the so-called sun protection factor (in English "sun protection factor", or SPF) began to be used. The idea of ​​a sun protection factor was first proposed in 1962 by the Austrian scientist Franz Greiter and adopted by the cosmetics and pharmaceutical industries. The sun protection factor is defined as the ratio of the minimum dose of ultraviolet radiation required to cause erythema when exposed to protected skin to the dose that causes the same effect on unprotected skin. A popular interpretation has become widespread: if without protection you burn in 20 minutes, then by smearing your skin with a cream with a protective factor of, say, 15, you will get a sunburn only after being in the sun 15 times longer, that is, after 5 hours.

A FALSE SENSE OF PROTECTION

It would seem that a solution to the problem of ultraviolet radiation has been found. But in reality, everything is not so simple. In the scientific literature, reports began to appear that in people who constantly use sunscreens, the incidence of skin cancers such as melanoma and basalioma, not only did not decrease, but increased. Several explanations for this discouraging fact have been proposed.

First of all, scientists suggested that consumers use sunscreens incorrectly. When testing creams, it is customary to apply 2 mg of cream per 1 cm 2 to the skin. But, as studies have shown, people often apply a thinner layer, 2-4 times less, and the protection factor decreases accordingly. In addition, creams and lotions are partially washed off with water, for example during bathing.

There was also another explanation. As already noted, most chemical UV absorbers (namely, they are most widely used in cosmetics) absorb light only in the UV-B region, preventing the development of sunburn. But, according to some reports, melanoma occurs under the influence of UV-A radiation. By blocking UV-B radiation, sunscreens block the natural warning signal of skin redness, slow down the formation of a protective tan, and as a result, a person receives an excessive dose in the UV-A area, which can provoke cancer.

Survey results show that those who use sunscreens with a higher SPF spend more time in the sun and therefore unknowingly put themselves at greater risk.

We must not forget that a mixture of chemicals that are part of protective creams, with prolonged exposure to ultraviolet radiation, can become a source of free radicals - initiators of the oxidation of biomolecules. Some of the UV filters are potentially toxic or allergenic.

"SUNNY" VITAMIN

It is time to remember that in addition to the numerous negative effects of ultraviolet radiation, there are also positive ones. And the most striking example is the photosynthesis of vitamin D 3 .

The epidermis contains quite a lot of 7-dihydrocholesterol, a precursor of vitamin D 3 . Irradiation with UV-B light starts a chain of reactions, as a result of which cholecalciferol (vitamin D 3) is obtained, which is not yet active. This substance binds to one of the blood proteins and is transferred to the kidneys. There it is converted into the active form of vitamin D 3 - 1, 25-dihydroxycholecalciferol. Vitamin D 3 is necessary for calcium absorption in the small intestine, normal phosphorus-calcium metabolism and bone formation, with a lack of it, children develop a serious disease - rickets.

After irradiation of the whole body at a dose of 1 MED, the concentration of vitamin D 3 in the blood increases 10 times and returns to the previous level in a week. The use of sunscreens inhibits the synthesis of vitamin D 3 in the skin. The doses required for its synthesis are small. It is considered sufficient to spend about 15 minutes in the sun every day, exposing the face and hands to the sun's rays. The total annual dose required to maintain the level of vitamin D 3 is 55 MED.

Chronic deficiency of vitamin D 3 leads to weakening of bone tissue. The risk group includes dark-skinned children living in northern countries, and older people who are little in the fresh air. Some researchers believe that the increase in the incidence of cancer with the use of sunscreens is associated precisely with blocking the synthesis of vitamin D 3 . It is possible that its deficiency leads to an increased risk of colon and breast cancer.

Other beneficial effects of ultraviolet radiation are mainly related to medicine. Diseases such as psoriasis, eczema, pink lichen are treated with ultraviolet light. Danish physician Niels Finsen received the Nobel Prize in 1903 for the use of ultraviolet light in the treatment of lupus skin tuberculosis. The method of blood irradiation with ultraviolet is now successfully used to treat inflammatory and other diseases.

STRAW SUN HATS

The question of whether ultraviolet is useful or harmful does not have a clear answer: yes and no. Much depends on the dose, spectral composition and characteristics of the organism. Too much ultraviolet light is definitely dangerous, but you can't rely on protective creams. More research is needed to determine the extent to which sunscreen use may contribute to the development of cancer.

The best way to protect the skin from sunburn, premature aging, and at the same time reduce the risk of cancer is clothing. For ordinary summer clothes, protective factors above 10 are characteristic. Cotton has good protective properties, though in a dry form (when wet, it transmits more ultraviolet radiation). Don't forget a wide-brimmed hat and sunglasses.

The recommendations are quite simple. Avoid sun exposure during the hottest hours. Be especially careful with the sun if you are taking medications that have photosensitizer properties: sulfonamides, tetracyclines, phenothiazines, fluoroquinolones, non-steroidal anti-inflammatory drugs, and some others. Photosensitizers are also included in some plants, such as St. John's wort (see "Science and Life" No. 3, 2002). The effect of light can be enhanced by aromatic substances that are part of cosmetics and perfumes.

Given that scientists have doubts about the effectiveness and safety of sunscreens and lotions, do not use them (and daytime cosmetics with a high content of UV filters) unless absolutely necessary. If such a need arose, give preference to those means that provide protection in a wide range - from 280 to 400 nm. As a rule, such creams and lotions contain zinc oxide or other mineral pigments, so it makes sense to carefully read the composition on the label.

Sun protection should be individual, depending on the place of residence, season and skin type.

The sun plays an important role for us on Earth. It provides the planet and everything on it with important factors such as light and heat. But what is solar radiation, the spectrum of sunlight, how does all this affect us and the global climate in general?

What is solar radiation?

Bad thoughts usually come to mind when you think of the word "radiation". But solar radiation is actually a very good thing - it's sunlight! Every living being on Earth depends on him. It is necessary for survival, warms the planet, provides food for plants.

Solar radiation is all the light and energy that comes from the sun, and there are many different forms of it. In the electromagnetic spectrum, different types of light waves emitted by the sun are distinguished. They are like the waves you see in the ocean: they move up and down and from one place to another. The spectrum of solar study can have different intensities. Distinguish between ultraviolet, visible and infrared radiation.

Light is moving energy

The spectrum of solar radiation figuratively resembles a piano keyboard. One end of it has low notes, while the other end has high notes. The same applies to the electromagnetic spectrum. One end has low frequencies and the other end has high frequencies. Low frequency waves are long for a given period of time. These are things like radar, television and radio waves. High-frequency radiations are high-energy waves with a short wavelength. This means that the wavelength itself is very short for a given time period. These are, for example, gamma rays, x-rays and ultraviolet rays.

You can think of it this way: low frequency waves are like going up a hill with a gradual rise, while high frequency waves are like going up a steep, almost vertical hill quickly. The height of each hill is the same. The frequency of an electromagnetic wave determines how much energy it carries. Electromagnetic waves that are longer and therefore lower frequencies carry much less energy than shorter wavelengths and higher frequencies.

This is why x-rays can be dangerous. They carry so much energy that if they get into your body, they can damage cells and cause problems like cancer and DNA changes. Things like radio and infrared waves, which carry much less energy, don't really have any effect on us. This is good, because you certainly don't want to put yourself at risk by simply turning on the stereo.

Visible light, which we and other animals can see with our eyes, is located almost in the middle of the spectrum. We don't see any other waves, but that doesn't mean they aren't there. In fact, insects can see ultraviolet light, but not our visible light. Flowers look very different to them than they do to us, and this helps them know which plants to visit and which ones to stay away from.

Source of all energy

We take sunlight for granted, but it doesn't have to be because, in fact, all energy on Earth depends on this big, bright star at the center of our solar system. And while we're in it, we should also say thank you to our atmosphere, because it absorbs some of the radiation before it reaches us. It's an important balance: too much sunlight and the Earth gets hot, too little and it starts to freeze.

Passing through the atmosphere, the spectrum of solar radiation near the surface of the Earth gives energy in different forms. First, let's look at the different ways to transfer it:

1. Conduction (conduction) is when energy is transferred from direct contact. When you burn your hand with a hot frying pan because you forgot to put on an oven mitt, that's conduction. The cookware transfers heat to your hand through direct contact. Also, when your feet touch the cold tiles in the bathroom in the morning, they transfer heat to the floor through direct contact - conduction in action.
2. Dissipation is when energy is transferred through currents in a fluid. It can also be gas, but the process is the same anyway. When the liquid is heated, the molecules are excited, dispersed and less dense, so they tend to rise. When they cool down, they fall down again, creating a cellular flow path.
3. is when energy is transmitted in the form of electromagnetic waves. Think about how good it is to sit next to a fire and feel the welcome warmth radiate from it to you - that's radiation. Radio waves, light and can travel by moving from one place to another without the help of any materials.

The main spectra of solar radiation

The sun has different radiation: from x-rays to radio waves. Solar energy is light and heat. Its composition:

• 6-7% UV light,
• about 42% of visible light,
• 51% near infrared.

We receive solar energy at an intensity of 1 kilowatt per square meter at sea level for many hours a day. About half of the radiation is in the visible short-wavelength part of the electromagnetic spectrum. The other half is in the near infrared, and a little bit in the ultraviolet part of the spectrum.

Ultraviolet radiation

It is ultraviolet radiation in the solar spectrum that has an intensity greater than others: up to 300-400 nm. Some of this radiation that is not absorbed by the atmosphere produces sunburn or sunburn for people who have been in sunlight for long periods of time. UV radiation in sunlight has both positive and negative health effects. It is the main source of vitamin D.

Visible radiation

Visible radiation in the solar spectrum has an average intensity. Quantitative estimates of the flux and variations in its spectral distribution in the visible and near infrared ranges of the electromagnetic spectrum are of great interest in the study of solar-terrestrial impacts. The range from 380 to 780 nm is visible to the naked eye.

The reason is that the bulk of the energy of solar radiation is concentrated in this range and it determines the thermal equilibrium of the Earth's atmosphere. Sunlight is a key factor in the process of photosynthesis used by plants and other autotrophic organisms to convert light energy into chemical energy that can be used as fuel for the body.

Infrared radiation

The infrared spectrum, which spans from 700 nm to 1,000,000 nm (1 mm), contains an important part of the electromagnetic radiation that reaches the Earth. Infrared radiation in the solar spectrum has three types of intensity. Scientists divide this range into 3 types based on wavelength:

1. A: 700-1400 nm.
2. B: 1400-3000 nm.
3. C: 3000-1mm.

Conclusion

Many animals (including humans) have sensitivity in the range of about 400-700 nm, and the usable color vision spectrum in humans, for example, is about 450-650 nm. In addition to the effects that occur at sunset and sunrise, the spectral composition changes primarily in relation to how directly sunlight hits the ground.

Every two weeks, the Sun supplies our planet with enough energy to last the whole year. In this regard, solar radiation is increasingly being considered as an alternative source of energy.

The sun radiates its energy in all wavelengths, but in different ways. Approximately 44% of the radiation energy is in the visible part of the spectrum, and the maximum corresponds to the yellow-green color. About 48% of the energy lost by the Sun is carried away by infrared rays of the near and far range. Gamma rays, X-rays, ultraviolet and radio radiation account for only about 8%.

The visible part of solar radiation, when studied with the help of spectrum-analyzing instruments, turns out to be inhomogeneous - absorption lines are observed in the spectrum, first described by J. Fraunhofer in 1814. These lines arise when photons of certain wavelengths are absorbed by atoms of various chemical elements in the upper, relatively cold, layers of the Sun's atmosphere. Spectral analysis makes it possible to obtain information about the composition of the Sun, since a certain set of spectral lines characterizes a chemical element extremely accurately. So, for example, with the help of observations of the spectrum of the Sun, the discovery of helium was predicted, which was isolated on Earth later.

In the course of observations, scientists found that the Sun is a powerful source of radio emission. Radio waves penetrate into interplanetary space, which are emitted by the chromosphere (centimeter waves) and the corona (decimeter and meter waves). The radio emission of the Sun has two components - constant and variable (bursts, "noise storms"). During strong solar flares, the radio emission from the Sun increases thousands and even millions of times compared to the radio emission from the quiet Sun. This radio emission has a non-thermal nature.

X-rays come mainly from the upper layers of the chromosphere and the corona. The radiation is especially strong during the years of maximum solar activity.

The sun emits not only light, heat and all other types of electromagnetic radiation. It is also a source of a constant flow of particles - corpuscles. Neutrinos, electrons, protons, alpha particles, as well as heavier atomic nuclei, all together make up the corpuscular radiation of the Sun. A significant part of this radiation is a more or less continuous outflow of plasma - the solar wind, which is a continuation of the outer layers of the solar atmosphere - the solar corona. Against the background of this constantly blowing plasma wind, individual regions on the Sun are sources of more directed, enhanced, so-called corpuscular flows. Most likely, they are associated with special regions of the solar corona - coronary holes, and also, possibly, with long-lived active regions on the Sun. Finally, the most powerful short-term particle fluxes, mainly electrons and protons, are associated with solar flares. As a result of the most powerful flashes, particles can acquire velocities that make up a significant fraction of the speed of light. Particles with such high energies are called solar cosmic rays.

Solar corpuscular radiation has a strong influence on the Earth, and above all on the upper layers of its atmosphere and magnetic field, causing many geophysical phenomena. The magnetosphere and the Earth's atmosphere protect us from the harmful effects of solar radiation.