UV radiation is electromagnetic waves that are invisible to the human eye. It occupies a spectral position between visible and X-ray radiation. The interval of ultraviolet radiation is usually divided into near, middle and far (vacuum).
Biologists have made this division of UV light in order to better see the difference in the effect of rays of different lengths on a person.
- Near ultraviolet is usually called UV-A,
- medium - UV-B,
- far - UV-C.
Ultraviolet radiation comes from the sun and the atmosphere of our planet Earth protects us from the powerful effects of ultraviolet rays... The sun is one of the few natural UV emitters. In this case, the far ultraviolet UV-C is almost completely blocked by the Earth's atmosphere. Those 10% of the long-wavelength ultraviolet rays reach us in the form of the sun. Accordingly, the ultraviolet that hits the planet is mainly UV-A, and in small amounts UV-B.
One of the main properties of ultraviolet radiation is its chemical activity, due to which UV radiation produces great effect on the human body... The most dangerous for our body is considered to be short-wave ultraviolet light. Despite the fact that our planet protects us as much as possible from exposure to ultraviolet rays, if you do not follow some precautions, you can still suffer from them. Sources of short-wave radiation are welding machines and UV lamps.
The positive properties of ultraviolet radiation
Only in the XX century, studies began to be carried out that proved positive effect of UV radiation on the human body... The result of these studies was the identification of the following useful properties: strengthening of human immunity, activation of defense mechanisms, improvement of blood circulation, vasodilation, increased vascular permeability, increased secretion of a number of hormones.
Another property of ultraviolet radiation is its ability change carbohydrate and protein metabolism human substances. UV rays can also affect the ventilation of the lungs - the frequency and rhythm of breathing, increased gas exchange, the level of oxygen consumption. The functioning of the endocrine system also improves, vitamin D is formed in the body, which strengthens the human musculoskeletal system.
The use of ultraviolet radiation in medicine
Ultraviolet light is often used in medicine. While ultraviolet rays can be bad for the human body in some cases, they can be beneficial if used correctly.
Medical institutions have long come up with a useful application of artificial ultraviolet light. There are various emitters that can help a person with ultraviolet rays cope with various diseases... They are also classified into those that emit long, medium and short wavelengths. Each of them applies in a specific case. Thus, long-wave radiation is suitable for the treatment of the respiratory tract, for injuries of the osteoarticular apparatus, as well as in the case of various skin injuries. We can also see long-wave radiation in tanning salons.
Treatment performs a slightly different function medium-wave ultraviolet... It is prescribed mainly to people suffering from immunodeficiency, metabolic disorders. It is also used in the treatment of disorders of the musculoskeletal system, has an analgesic effect.
Shortwave radiation it is also used in the treatment of skin diseases, in diseases of the ears, nose, in case of damage to the respiratory tract, in diabetes mellitus, in case of damage to the heart valves.
In addition to various devices emitting artificial ultraviolet light, which are used in mass medicine, there are also ultraviolet laserswith a more targeted action. These lasers are used, for example, in eye microsurgery. Such lasers are also used for scientific research.
The use of ultraviolet radiation in other areas
In addition to medicine, ultraviolet radiation is used in many other areas, significantly improving our lives. So, ultraviolet light is excellent disinfectant, and is used, among other things, for the treatment of various objects, water, indoor air. Ultraviolet and in printing: it is with the help of ultraviolet radiation that various seals and stamps are produced, paints and varnishes are dried, banknotes are protected from counterfeiting. In addition to its useful properties, with the correct supply, ultraviolet light can create beauty: it is used for various lighting effects (most often this happens at discos and performances). UV rays also help in finding fires.
One of the negative effects of UV exposure on the human body is electrophthalmia... This term is called damage to the human organ of vision, in which the cornea of \u200b\u200bthe eye burns and swells, and a cutting pain appears in the eyes. This disease can occur if a person looks at the rays of the sun without a special protective device (sunglasses) or stays in a snowy area in sunny weather, with very bright light. Also, electrophthalmia can be earned by quartzing rooms.
Negative effects can also be achieved due to the long, intense exposure to ultraviolet rays on the body. There can be a lot of such consequences, up to the development of various pathologies. The main symptoms of over-exposure are
The consequences of strong radiation are as follows: hypercalcemia, growth retardation, hemolysis, impairment of immunity, various burns and skin diseases. Most exposed to excessive radiation are people who constantly work outdoors, as well as those who constantly work with devices that emit artificial ultraviolet light.
Unlike UV emitters used in medicine, tanning salons are more dangerous for a person. Visiting tanning salons is not controlled by anyone other than the person himself. People who often visit tanning salons in order to achieve a beautiful tan often neglect the negative effects of UV radiation, despite the fact that frequent visits to tanning salons can even be fatal.
The acquisition of a darker skin color occurs due to the fact that our body fights against the traumatic effects of UV radiation on it, and produces a coloring pigment called melanin. And if the redness of the skin is a temporary defect that passes after some time, then freckles appearing on the body, age spots that occur as a result of the proliferation of epithelial cells - persistent skin damage.
Ultraviolet light, penetrating deep into the skin, can change skin cells at the genetic level and lead to ultraviolet mutagenesis... One of the complications of this mutagenesis is melanoma - a tumor of the skin. It is she who is able to lead a person to death.
In order to avoid the negative effects of exposure to UV rays, need to provide yourself with some protection... At various enterprises working with devices emitting artificial ultraviolet light, it is necessary to use overalls, helmets, shields, insulating screens, goggles, and a portable screen. People who are not involved in the activities of such enterprises need to limit themselves to excessive visits to tanning salons and long exposure to the open sun, to use sunscreens, sprays or lotions in the summer, and to wear sunglasses and closed clothing made from natural fabrics.
There are also negative consequences from a lack of UV radiation... Prolonged absence of UVR can lead to a disease called "light starvation". Its main symptoms are very similar to those of excessive exposure to ultraviolet radiation. With this disease, a person's immunity decreases, metabolism is disturbed, fatigue, irritability, etc. appear.
In 1801 I. Ritter (Germany) and W. Walstone (England) using a photographic plate proved the presence of ultraviolet rays. Beyond the violet end of the spectrum, it turns black faster than under the influence of visible rays. Since the blackening of the plate occurs as a result of a photochemical reaction, scientists have come to the conclusion that ultraviolet rays are very active.
Ultraviolet rays cover a wide range of radiation: 400 ... 20 nm. The radiation region 180 ... 127 nm is called vacuum. By means of artificial sources (mercury-quartz, hydrogen and arc lamps), giving both a linear and a continuous spectrum, ultraviolet rays are obtained with a wavelength of up to 180 nm. In 1914, Lyman explored the range up to 50 nm.
The researchers discovered the fact that the spectrum of ultraviolet rays from the Sun reaching the earth's surface is very narrow - 400 ... 290 nm. Doesn't the sun emit light with wavelengths shorter than 290 nm?
The answer to this question was found by A. Cornu (France). He found that ozone absorbs ultraviolet rays shorter than 295 nm, after which he put forward the assumption: the sun emits short-wave ultraviolet radiation, under its action oxygen molecules break down into individual atoms, forming ozone molecules, therefore, in the upper atmosphere, ozone should cover the earth with a protective shield. Cornu's hypothesis was confirmed when people ascended to the upper atmosphere. Thus, under terrestrial conditions, the sun's spectrum is limited by the transmission of the ozone layer.
The amount of ultraviolet rays reaching the earth's surface depends on the height of the sun above the horizon. During the period of normal illumination, the illumination changes by 20%, while the amount of ultraviolet rays reaching the earth's surface is reduced by 20 times.
Special experiments have established that when climbing upwards, the intensity of ultraviolet radiation increases by 3 ... 4% for every 100 m. The share of scattered ultraviolet radiation in the summer noon accounts for 45 ... 70% of the radiation, and reaching the earth's surface - 30 ... 55%. On cloudy days, when the Sun's disk is covered with clouds, the Earth's surface is mainly reached by diffuse radiation. Therefore, you can tan well not only in direct sunlight, but also in the shade and on cloudy days.
When the Sun is at its zenith, rays with a length of 290 ... 289 nm reach the equatorial region of the earth's surface. In mid-latitudes, the short-wavelength boundary, in the summer months, is approximately 297 nm. During the effective illumination period, the upper limit of the spectrum is about 300 nm. Beams with a wavelength of 350 ... 380 nm reach the earth's surface beyond the polar circle.
Influence of ultraviolet radiation on the biosphere
Above the range of vacuum radiation, ultraviolet rays are easily absorbed by water, air, glass, quartz and do not reach the Earth's biosphere. In the range of 400 ... 180 nm, the effect on living organisms of rays of different wavelengths is not the same. The most energetic short-wave rays played an essential role in the formation of the first complex organic compounds on Earth. However, these rays contribute not only to the formation, but also to the decomposition of organic substances. Therefore, the progress of life forms on Earth began only after, thanks to the activity of green plants, the atmosphere was enriched with oxygen and, under the influence of ultraviolet rays, a protective ozone layer was formed.We are interested in ultraviolet radiation from the Sun and artificial sources of ultraviolet radiation in the range of 400 ... 180 nm. Three areas are highlighted within this range:
A - 400 ... 320 nm;
B - 320 ... 275 nm;
C - 275 ... 180nm.
There are significant differences in the effect of each of these ranges on a living organism. Ultraviolet rays act on matter, including living matter, according to the same laws as visible light. Some of the absorbed energy is converted into heat, but the thermal effect of ultraviolet rays does not have a noticeable effect on the body. Another way of transferring energy is luminescence.
Photochemical reactions under the influence of ultraviolet rays are most intense. The energy of photons of ultraviolet light is very high, therefore, when absorbed, the molecule ionizes and breaks down. Sometimes a photon knocks an electron out of the atom. Most often, the excitation of atoms and molecules occurs. Upon absorption of one quantum of light with a wavelength of 254 nm, the energy of the molecule increases to a level corresponding to the energy of thermal motion at a temperature of 38,000 ° C.
Most of the solar energy reaches the earth as visible light and infrared radiation, and only a small part in the form of ultraviolet radiation. The UV flux reaches its maximum values \u200b\u200bin the middle of summer in the Southern Hemisphere (the Earth is 5% closer to the Sun) and 50% of the daily amount of UV is received during 4 noon hours. Diffey found that for geographic latitudes with temperatures of 20-60 °, a person sunbathing from 10:30 to 11:30 and then from 16:30 to sunset will receive only 19% of the daily dose of UV. At noon, the UV intensity (300 nm) is 10 times higher than three hours earlier or later: an unburned person needs 25 minutes to get a light tan at noon, but to achieve the same effect after 15:00, he does not need to lie in the sun less than 2 hours.
The ultraviolet spectrum, in turn, is divided into ultraviolet-A (UV-A) with a wavelength of 315-400 nm, ultraviolet-B (UV-B) -280-315 nm and ultraviolet-C (UV-C) - 100-280 nm which differ in penetrating ability and biological effect on the body.
UV-A is not retained by the ozone layer, it passes through glass and the stratum corneum. The UV-A flux (mean at noon) is twice as high at the Arctic Circle as at the equator, so its absolute value is greater at high latitudes. There are also no significant fluctuations in UV-A intensity at different times of the year. Due to absorption, reflection and scattering when passing through the epidermis, only 20-30% of UV-A penetrates into the dermis and about 1% of its total energy reaches the subcutaneous tissue.
Most of the UV-B is absorbed by the ozone layer, which is transparent to UV-A. So the proportion of UV-B in the total UV energy in the summer afternoon is only about 3%. It practically does not penetrate through the glass, 70% is reflected by the stratum corneum, 20% is weakened when passing through the epidermis - less than 10% penetrates into the dermis.
However, for a long time it was believed that the share of UV-B in the damaging effect of ultraviolet radiation is 80%, since it is this spectrum that is responsible for the occurrence of sunburn erythema.
It is necessary to take into account the fact that UV-B is more strongly (shorter wavelength) scattered than UV-A when passing through the atmosphere, which leads to a change in the ratio between these fractions with increasing latitude (in northern countries) and time of day.
UV-C (200-280 nm) is absorbed by the ozone layer. In the case of using an artificial source of ultraviolet radiation, it is retained by the epidermis and does not penetrate into the dermis.
The action of ultraviolet radiation on the cell
In the action of short-wave radiation on a living organism, the effect of ultraviolet rays on biopolymers - proteins and nucleic acids - is of greatest interest. Biopolymer molecules contain ring groups of molecules containing carbon and nitrogen, which intensively absorb radiation with a wavelength of 260 ... 280 nm. The absorbed energy can migrate along a chain of atoms within a molecule without significant loss until it reaches weak bonds between atoms and does not break the bond. During this process, called photolysis, fragments of molecules are formed, which have a strong effect on the body. So, for example, histamine is formed from the amino acid histidine - a substance that expands blood capillaries and increases their permeability. In addition to photolysis under the action of ultraviolet rays, denaturation occurs in biopolymers. When irradiated with light of a certain wavelength, the electric charge of the molecules decreases, they stick together and lose their activity - enzymatic, hormonal, antigenic, etc.The processes of photolysis and denaturation of proteins proceed in parallel and independently of each other. They are caused by different radiation ranges: the rays of 280 ... 302 nm mainly cause photolysis, and 250 ... 265 nm - mainly denaturation. The combination of these processes determines the picture of the action of ultraviolet rays on the cell.
The cell's most sensitive function to the action of ultraviolet rays is division. Irradiation at a dose of 10 (-19) J / m2 causes a cessation of division of about 90% of bacterial cells. But the growth and vital activity of cells does not stop. Over time, their division is restored. To cause the death of 90% of cells, suppression of the synthesis of nucleic acids and proteins, the formation of mutations, it is necessary to bring the radiation dose to 10 (-18) J / m2. Ultraviolet rays cause changes in nucleic acids that affect the growth, division, heredity of cells, i.e. on the main manifestations of life.
The significance of the mechanism of action on nucleic acid is explained by the fact that each DNA molecule (deoxyribonucleic acid) is unique. DNA is the hereditary memory of the cell. Its structure encodes information about the structure and properties of all cellular proteins. If any protein is present in a living cell in the form of tens and hundreds of identical molecules, then DNA stores information about the structure of the cell as a whole, about the nature and direction of metabolic processes in it. Therefore, violations in the structure of DNA can be irreparable or lead to serious disruption of life.
Effect of ultraviolet radiation on the skin
Exposure to ultraviolet radiation on the skin noticeably affects the metabolism of our body. It is generally known that it is UV rays that initiate the formation of ergocalciferol (vitamin D), which is necessary for the absorption of calcium in the intestine and ensuring the normal development of the bone skeleton. In addition, ultraviolet light actively affects the synthesis of melatonin and serotonin - hormones responsible for the circadian (daily) biological rhythm. Studies by German scientists have shown that when exposed to UV rays, blood serum in it increased by 7% in the content of serotonin - the "vigor hormone" involved in the regulation of the emotional state. Its deficiency can lead to depression, mood swings, and seasonal functional disorders. At the same time, the amount of melatonin, which has an inhibitory effect on the endocrine and central nervous systems, decreased by 28%. It is this double effect that explains the invigorating effect of the spring sun, which uplifts mood and vitality.The effect of radiation on the epidermis, the outer surface layer of the skin of vertebrates and humans, consisting of human stratified squamous epithelium, is an inflammatory reaction called erythema. The first scientific description of erythema was given in 1889 by A.N. Maklanov (Russia), who also studied the effect of ultraviolet rays on the eye (photophthalmia) and found that they are based on common causes.
Distinguish between caloric and ultraviolet erythema. Caloric erythema is caused by the effect of visible and infrared rays on the skin and the rush of blood to it. It disappears almost immediately after the cessation of exposure.
After cessation of exposure to UV radiation, after 2..8 hours, skin redness (ultraviolet erythema) appears simultaneously with a burning sensation. Erythema appears after a latent period, within the irradiated area of \u200b\u200bthe skin, and is replaced by sunburn and peeling. The duration of erythema has a duration from 10 ... 12 hours to 3 ... 4 days. The reddened skin is hot to the touch, slightly painful and appears to be swollen, slightly edematous.
Essentially, erythema is an inflammatory response, skin burn. This is a special, aseptic (Aseptic - aseptic) inflammation. If the dose of radiation is too high or the skin is especially sensitive to them, the edematous liquid, accumulating, exfoliates in places the outer skin of the skin, forms bubbles. In severe cases, areas of necrosis (death) of the epidermis appear. A few days after the disappearance of erythema, the skin darkens and begins to peel off. As the desquamation proceeds, part of the cells containing melanin are exfoliated (Melanin is the main pigment of the human body; it gives color to the skin, hair, iris of the eye. It is also contained in the pigment layer of the retina, participates in the perception of light), the tan turns pale. The thickness of the human skin varies depending on gender, age (thinner in children and old people) and localization - on average 1..2 mm. Its purpose is to protect the body from damage, temperature fluctuations, pressure.
The main layer of the epidermis is adjacent to the skin itself (dermis), in which blood vessels and nerves pass. In the main layer, there is a continuous process of cell division; older ones are forced out by young cells and die off. Layers of dead and dying cells form the outer stratum corneum of the epidermis 0.07 ... 2.5 mm thick (On the palms and soles, mainly due to the stratum corneum, the epidermis is thicker than on other parts of the body), which is continuously exfoliated from the outside and restored from the inside.
If the rays falling on the skin are absorbed by the dead cells of the stratum corneum, they have no effect on the body. The effect of radiation depends on the penetrating ability of the rays and on the thickness of the stratum corneum. The shorter the radiation wavelength, the less their penetrating ability. Beams shorter than 310 nm do not penetrate deeper than the epidermis. The longer wavelengths reach the papillary dermis, where the blood vessels pass. Thus, the interaction of ultraviolet rays with the substance occurs exclusively in the skin, mainly in the epidermis.
The main amount of ultraviolet rays is absorbed in the germ (main) layer of the epidermis. The processes of photolysis and denaturation lead to the death of the styloid cells of the germ layer. Active products of protein photolysis cause vasodilation, skin edema, leukocyte release and other typical signs of erythema.
Photolysis products, spreading along the bloodstream, also irritate the nerve endings of the skin and reflexively affect all organs through the central nervous system. It has been established that the frequency of electrical impulses increases in the nerve extending from the irradiated skin area.
Erythema is considered as a complex reflex, in the occurrence of which active photolysis products are involved. The severity of erythema and the possibility of its formation depends on the state of the nervous system. On the affected skin areas, with frostbite, inflammation of the nerves, erythema either does not appear at all, or is very weakly expressed, despite the action of ultraviolet rays. The formation of erythema is inhibited by sleep, alcohol, physical and mental fatigue.
N. Finzen (Denmark) first used ultraviolet radiation for the treatment of a number of diseases in 1899. At present, the manifestations of the action of different areas of ultraviolet radiation on the body have been studied in detail. Of the ultraviolet rays contained in sunlight, erythema is caused by rays with a wavelength of 297 nm. The erythemal sensitivity of the skin decreases to rays with a longer or shorter wavelength.
With the help of artificial radiation sources, erythema was induced by rays of the range 250 ... 255 nm. Beams with a wavelength of 255 nm are produced by a resonant emission line of mercury vapor used in mercury-quartz lamps.
Thus, the curve of erythemal sensitivity of the skin has two maxima. The cavity between the two peaks is provided by the shielding effect of the stratum corneum.
Protective functions of the body
Under natural conditions, after erythema, skin pigmentation develops - tan. The spectral maximum of pigmentation (340 nm) does not coincide with any of the peaks of erythemal sensitivity. Therefore, choosing a radiation source can cause pigmentation without erythema and vice versa.Erythema and pigmentation are not stages of the same process, although they follow one after the other. This is a manifestation of different processes related to each other. In the cells of the lowest layer of the epidermis - melanoblasts - the skin pigment melanin is formed. Amino acids and adrenaline breakdown products are the starting material for the formation of melanin.
Melanin is not just a pigment or a passive protective shield that wards off living tissue. Melanin molecules are huge, cross-linked molecules. In the links of these molecules, fragments of molecules destroyed by ultraviolet light are bound and neutralized, not letting them into the blood and the internal environment of the body.
The function of tanning is to protect the cells of the dermis, the vessels and nerves located in it, from long-wave ultraviolet, visible and infrared rays, which cause overheating and heatstroke. Near infrared rays and visible light, especially its long-wave, "red" part, can penetrate into tissues much deeper than ultraviolet rays - to a depth of 3 ... 4 mm. Melanin granules - a dark brown, almost black pigment - absorb radiation in a wide range of the spectrum, protecting delicate internal organs accustomed to constant temperature from overheating.
The operative mechanism of the body's defense against overheating is blood flow to the skin and expansion of blood vessels. This leads to an increase in heat transfer through radiation and convection (The total surface of the skin of an adult is 1.6 m2). If the air and surrounding objects are hot, another cooling mechanism comes into play - evaporation due to perspiration. These thermoregulatory mechanisms are designed to protect against the sun's visible and infrared rays.
Sweating, along with thermoregulatory function, inhibits human exposure to ultraviolet radiation. Sweat contains urocanic acid, which absorbs short-wave radiation due to the presence of a benzene ring in its molecules.
Light starvation (deficiency of natural UV radiation)
Ultraviolet radiation supplies energy for photochemical reactions in the body. Under normal conditions, sunlight causes the formation of a small amount of active photolysis products, which have a beneficial effect on the body. Ultraviolet rays in doses that cause the formation of erythema, enhance the work of hematopoietic organs, the reticulo-endothelial system (the physiological system of connective tissue, which produces antibodies that destroy foreign bodies and microbes), the barrier properties of the skin, and eliminate allergies.Under the influence of ultraviolet radiation, fat-soluble vitamin D is formed in human skin from steroid substances. Unlike other vitamins, it can enter the body not only with food, but also be formed in it from provitamins. Under the influence of ultraviolet rays with a wavelength of 280 ... 313 nm, the provitamins contained in the skin lubricant secreted by the sebaceous glands are converted into vitamin D and absorbed into the body.
The physiological role of vitamin D is that it promotes calcium absorption. Calcium is a part of bones, participates in blood coagulation, thickens cell and tissue membranes, and regulates enzyme activity. The disease that occurs with a lack of vitamin D in children in the first years of life, which caring parents hide from the sun, is called rickets.
In addition to natural sources of vitamin D, artificial ones are also used, irradiating provitamins with ultraviolet rays. When using artificial sources of ultraviolet radiation, it should be remembered that rays shorter than 270 nm destroy vitamin D. Therefore, using filters in the light flux of ultraviolet lamps, the short-wave part of the spectrum is suppressed. Solar starvation manifests itself in irritability, insomnia, and rapid fatigability of a person. In large cities, where the air is polluted with dust, ultraviolet rays causing erythema hardly reach the Earth's surface. Prolonged work in mines, engine rooms and closed factory workshops, work at night, and sleep in the daytime lead to light starvation. Light starvation is facilitated by window glass, which absorbs 90 ... 95% of ultraviolet rays and does not transmit rays in the range of 310 ... 340 nm. Wall painting is also essential. For example, a yellow color completely absorbs ultraviolet rays. The lack of light, especially ultraviolet radiation, is felt by people, pets, birds and houseplants in the fall, winter and spring.
To compensate for the lack of ultraviolet rays, lamps allow, which, along with visible light, emit ultraviolet rays in the wavelength range of 300 ... 340 nm. It should be borne in mind that errors in prescribing a dose of radiation, inattention to issues such as the spectral composition of ultraviolet lamps, the direction of radiation and the height of the lamps, the duration of the lamp burning, can cause harm instead of benefit.
The bactericidal effect of ultraviolet radiation
The bactericidal function of UV rays should also be noted. In medical institutions, this property is actively used to prevent nosocomial infection and ensure the sterility of operating units and dressings. The effect of ultraviolet radiation on bacterial cells, namely on DNA molecules, and the development of further chemical reactions in them leads to the death of microorganisms.Air pollution with dust, gases, water vapor has a harmful effect on the body. Ultraviolet rays of the Sun enhance the process of natural self-cleaning of the atmosphere from pollution, contributing to the rapid oxidation of dust, smoke particles and soot, destroying microorganisms on the dust particles. The natural ability to self-purify has limits and is insufficient when the air is very polluted.
Ultraviolet radiation with a wavelength of 253 ... 267 nm most effectively destroys microorganisms. If we take the maximum effect as 100%, then the activity of rays with a wavelength of 290 nm will be 30%, 300 nm - 6%, and rays lying on the border of visible light at 400 nm - 0.01% of the maximum.
Microorganisms have different sensitivity to ultraviolet rays. Yeasts, molds and bacterial spores are much more resistant to their action than vegetative forms of bacteria. The spores of individual fungi, surrounded by a thick and dense shell, feel great in the high layers of the atmosphere, and it is possible that they can even travel in space.
The sensitivity of microorganisms to ultraviolet rays is especially great during the division period and immediately before it. Curves of bactericidal effect, inhibition and growth of cells practically coincide with the curve of absorption by nucleic acids. Consequently, denaturation and photolysis of nucleic acids leads to the cessation of division and growth of cells of microorganisms, and in high doses to their death.
The bactericidal properties of ultraviolet rays are used to disinfect air, tools, dishes, with their help they increase the shelf life of food products, disinfect drinking water, and inactivate viruses when preparing vaccines.
The negative effects of ultraviolet radiation
A number of negative effects arising from exposure to UV radiation on the human body are also well known, which can lead to a number of serious structural and functional damage to the skin. As you know, these injuries can be divided into:The role of UV-A rays in the etiology of photoaging has been proven by the works of many foreign and Russian scientists, but nevertheless, the mechanisms of photoaging continue to be studied using modern scientific and technical base, cell engineering, biochemistry and methods of cellular functional diagnostics.
The mucous membrane of the eye - the conjunctiva - does not have a protective stratum corneum, so it is more sensitive to UV radiation than the skin. Cutting in the eye, redness, watery eyes, partial blindness appear as a result of degeneration and death of cells in the conjunctiva and cornea. In this case, the cells become opaque. Long-wave ultraviolet rays, reaching the lens, in large doses can cause clouding - cataracts.
Artificial sources of UV radiation in medicine
Germicidal lampsAs sources of UV radiation, discharge lamps are used, in which radiation is generated in the process of an electric discharge, containing a wavelength range of 205-315 nm (the rest of the radiation spectrum plays a secondary role). These lamps include low and high pressure mercury lamps and xenon flash lamps.
Low-pressure mercury lamps structurally and in terms of electrical parameters practically do not differ from ordinary fluorescent lighting lamps, except that their bulb is made of special quartz or UV glass with a high UV transmission coefficient, on the inner surface of which a phosphor layer is not applied ... These lamps are available in a wide power range from 8 to 60 watts. The main advantage of low-pressure mercury lamps is that more than 60% of the radiation falls on the line with a wavelength of 254 nm, which lies in the spectral region of maximum bactericidal action. They have a long service life of 5,000-10,000 hours and an instantaneous ability to work after they are ignited.
The high pressure mercury-quartz lamp bulb is made of quartz glass. The advantage of these lamps is that, with small dimensions, they have a large unit power from 100 to 1,000 W, which makes it possible to reduce the number of lamps in a room, but have a low bactericidal efficiency and a short service life of 500-1,000 hours. In addition, normal combustion comes in 5-10 minutes after ignition.
A significant disadvantage of continuous emitting lamps is the risk of contamination by mercury vapors of the environment when the lamp breaks. If the integrity of the germicidal lamps is damaged and mercury gets into the room, a thorough demercurization of the contaminated room should be carried out.
In recent years, a new generation of emitters has appeared - short-pulse ones with a much higher biocidal activity. The principle of their operation is based on high-intensity pulsed irradiation of air and surfaces with UV radiation of a continuous spectrum. Pulsed radiation is obtained using xenon lamps, as well as using lasers. To date, there are no data on the difference between the biocidal action of pulsed UV radiation from that of conventional UV radiation.
The advantage of xenon flash lamps is due to their higher bactericidal activity and shorter exposure time. The advantage of xenon lamps is that if they are accidentally destroyed, the environment is not polluted by mercury vapor. The main disadvantages of these lamps, which restrain their widespread use, are the need to use high-voltage, complex and expensive equipment for their operation, as well as the limited life of the emitter (on average 1-1.5 years).
Germicidal lamps are divided into ozone and ozone-free.
Ozone lamps have a spectral line with a wavelength of 185 nm in the emission spectrum, which, as a result of interaction with oxygen molecules, forms ozone in the air. High concentrations of ozone can have adverse health effects. The use of these lamps requires monitoring of the ozone content in the air and careful ventilation of the room.
To exclude the possibility of ozone generation, the so-called bactericidal "ozone-free" lamps have been developed. In such lamps, due to the manufacture of a bulb from a special material (coated quartz glass) or its design, the emission of the 185 nm line is excluded.
Germicidal lamps that have worn out or have failed should be stored packed in a separate room and require special disposal in accordance with the requirements of the relevant regulatory documents.
Bactericidal irradiators.
A germicidal irradiator is an electrical device that contains: a germicidal lamp, a reflector and other auxiliary elements, as well as fixtures for its attachment. Bactericidal irradiators redistribute the radiation flux into the surrounding space in a given direction and are divided into two groups - open and closed.
Open irradiators use a direct germicidal stream from lamps and a reflector (or without it) that covers a wide area of \u200b\u200bspace around them. Ceiling or wall mounted. Illuminators installed in doorways are called barrier irradiators or ultraviolet curtains, in which the bactericidal flow is limited to a small solid angle.
A special place is occupied by open combined irradiators. In these irradiators, due to the rotating screen, the bactericidal flow from the lamps can be directed to the upper or lower zone of the space. However, the efficiency of such devices is much lower due to the change in wavelength during reflection and some other factors. When using combined irradiators, the bactericidal flow from shielded lamps should be directed to the upper zone of the room in such a way as to exclude the direct flow from the lamp or reflector to the lower zone. In this case, the irradiance from the reflected fluxes from the ceiling and walls on a conditional surface at a height of 1.5 m from the floor should not exceed 0.001 W / m2.
In closed irradiators (recirculators), the bactericidal flow from the lamps is distributed in a limited small enclosed space and does not have an outlet to the outside, while air disinfection is carried out during its pumping through the ventilation holes of the recirculator. When using supply and exhaust ventilation, germicidal lamps are placed in the outlet chamber. The air flow rate is provided either by natural convection or forced by a fan. Closed-type irradiators (recirculators) should be placed indoors on the walls along the main air flows (in particular, near heating devices) at a height of at least 2 m from the floor.
According to the list of typical rooms, broken down by categories (GOST), it is recommended to equip rooms of categories I and II with both closed irradiators (or supply and exhaust ventilation) and open or combined ones when they are turned on in the absence of people.
It is recommended to use irradiators with ozone-free lamps in rooms for children and pulmonary patients. Artificial ultraviolet irradiation, even indirect, is contraindicated for children with active tuberculosis, nephroso-nephritis, fever and severe exhaustion.
The use of ultraviolet germicidal installations requires strict implementation of safety measures to exclude possible harmful effects on humans of ultraviolet germicidal radiation, ozone and mercury vapor.
Basic safety measures and contraindications for the use of therapeutic UV radiation.
Before using UV radiation from artificial sources, it is necessary to visit a doctor in order to select and establish the minimum erythemal dose (MED), which is a purely individual parameter for each person.As individual sensitivities vary widely, it is recommended that the duration of the first session be halved from the recommended time in order to establish the user's skin response. If after the first session any adverse reaction is detected, further use of UV irradiation is not recommended.
Regular irradiation for a long time (a year or more) should not exceed 2 sessions per week, and there can be no more than 30 sessions or 30 minimal erythemal doses (MED) per year, no matter how small the erythema-effective exposure. It is recommended that you sometimes interrupt regular radiation sessions.
Therapeutic irradiation must be carried out with the obligatory use of reliable goggles.
The skin and eyes of any person can become a "target" for ultraviolet radiation. It is believed that people with fair skin are more susceptible to damage, however, dark-skinned, dark-skinned people also cannot feel completely safe.
Very careful with natural and artificial UV radiation of the whole body should be the following categories of people:
Phototherapy is actively used in medical practice to treat various diseases. It includes the use of visible light, laser, infrared, and ultraviolet rays (UV). The most commonly prescribed UFO physiotherapy.
It is used for the treatment of ENT pathologies, diseases of the musculoskeletal system, with immunodeficiencies, bronchial asthma and other diseases. Ultraviolet irradiation is also used for the bacteriostatic effect in infectious diseases, for the treatment of indoor air.
The general concept of ultraviolet irradiation, types of devices, mechanism of action, indications
Ultraviolet irradiation (UFO) is a physiotherapeutic procedure that is based on the effects of ultraviolet rays on tissues and organs. The effect on the body may differ when using different wavelengths.
UV rays have different wavelengths:
- Long-wavelength (FUV) (400-320 nm).
- Medium wavelength (SUF) (320-280 nm).
- Shortwave (KUV) (280-180 nm).
For physiotherapy, special devices are used. They generate UV rays of various lengths.
UFO devices for physiotherapy:
- Integral. They generate the entire range of UFOs.
- Selective. They produce one type of ultraviolet radiation: shortwave, a combination of shortwave and mediumwave spectra.
| Integral | Selective |
|
OUSH-1 (for individual use, local radiation, general effects on the body); OH-7 (suitable for nasopharynx) OUN 250, OUN 500 - tabletop type for local use). The source of radiation is a mercury-quartz tube lamp. The power can be different: from 100 to 1000 W. |
Shortwave spectrum (KUV). Sources of bactericidal action: OBN-1 (wall), OBP-300 (ceiling). Used for disinfecting premises. Short beams for local exposure (irradiation of the skin, mucous membranes): BOP-4. The mid-wavelength spectrum is generated by luminescent erythemal sources with ultraviolet-transmitting glass: LE-15, LE-30. Sources of long waves (LUV) are used for general effects on the body. |
In physiotherapy, ultraviolet radiation is prescribed for the prevention and treatment of various diseases. The mechanism of action of ultraviolet radiation is as follows: metabolic processes are activated, the transmission of impulses along nerve fibers improves. When UV rays hit the skin, the patient develops erythema. It looks like redness of the skin. The invisible period of erythema formation is 3-12 hours. The emerging erythematous formation remains on the skin for several more days, it has clear boundaries.
The long-wavelength spectrum does not cause very pronounced erythema. Medium-wave rays are able to reduce the amount of free radicals, stimulate the synthesis of ATP molecules. Short rays of ultraviolet irradiation very quickly provoke an erythematous rash.
Small doses of medium to long UV wavelengths are not capable of causing erythema. They are needed for a general effect on the body.
The benefits of small dosages of UFO:
- Enhances the formation of red blood cells and other blood cells.
- Increases the function of the adrenal glands, the sympathetic system.
- Reduces the formation of fat cells.
- Improves the performance of the name system.
- Stimulates immune responses.
- Normalizes blood glucose levels.
- Reduces the amount of blood cholesterol.
- Regulates the excretion and absorption of phosphorus and calcium.
- Improves heart and lung function.
Local radiation helps to stimulate immune responses in the area where the rays hit, and increases blood flow and lymph outflow.
Doses of radiation that do not provoke the appearance of redness have the following properties: they increase the regenerative function, enhance tissue nutrition, stimulate the appearance of melanin in the skin, increase immunity, stimulate the formation of vitamin D. reduce the intensity of pain, reduce inflammation on the mucous membranes and skin.
Indications for physiotherapy
| Overall impact | Local impact |
| Stimulation of immunity in immunodeficiencies. Prevention and therapy of rickets (vitamin D deficiency) in children, during pregnancy, breastfeeding. Purulent lesions of the skin, soft tissues. Increased immunity in chronic processes. Increased formation of blood cells. Substitution therapy for UFO deficiency. |
Diseases of the joints. Respiratory system pathologies. Bronchial asthma. Surgical purulent wounds, bedsores, burns, frostbite, abscesses, erysipelas, fractures. Extrapyramidal syndrome, demyelinating pathologies, head trauma, radiculopathy, various types of pain. Stomatitis, gingivitis, periodontal disease, infiltrative formation after tooth extraction. Rhinitis, tonsillitis, sinusitis. Cracks in the nipples in women, acute gynecological inflammatory diseases. Weeping umbilical wound in newborns, diathesis with exudation, rheumatoid diseases, pneumonia, staphylococcal skin lesions. Psoriasis, eczematous eruptions, purulent skin lesions in dermatological patients. |
Contraindications to radiation are:
- Tumor process.
- Hyperthermia.
- Infectious diseases.
- Overproduction of thyroid hormones.
- Lupus erythematosus.
- Hepatic and renal dysfunction.
Ultraviolet irradiation technique
Before treatment, the physiotherapist must determine the type of rays. A prerequisite is the calculation of the radiation exposure of the patient. The load is measured in biodoses. The number of biodoses is calculated according to the Gorbachev-Dalfeld method. It is based on the rapidity of the formation of redness of the skin. One biodose is capable of causing minimal redness from a distance of 50 cm. This dosage is erythemal.
Erythemal doses are subdivided into:
- small (one or two biodoses);
- medium (three to four biodoses);
- high (five to eight biodoses).
If the radiation dose is more than eight biodoses, then it is called hypererythemal. Irradiation is divided into general and local. The general can be for one person or a group of patients. Such radiation is produced by integral devices or sources of long waves.
Children need to be irradiated with general UFO very carefully. An incomplete biodose is used for a child and a student. Start with the smallest dosage.
With the general exposure to ultraviolet rays of newborns and very weak babies, at the initial stage 1 / 10–1 / 8 biodoses are affected. Schoolchildren and preschoolers use 1/4 biodoses. The load is increased over time to 1 1/2 - 1 3/4 biodoses. This dosage remains for the entire treatment phase. The sessions are held every other day. For treatment, 10 sessions are enough.
During the procedure, the patient must be undressed, laid on a couch. The device is placed at a distance of 50 cm from the patient's body surface. Cover the lamp with a cloth or blanket with the patient. This ensures that the maximum dose of radiation is obtained. If you do not cover it with a blanket, then some of the rays emanating from the source are scattered. In this case, the effectiveness of therapy will be low.
Local exposure to UFOs is carried out with devices of a mixed type, as well as those emitting short waves of the UV spectrum. During local physiotherapy, it is possible to influence the reflexogenic zones, irradiate with fractions, fields, near the injury site.
Local irradiation often causes skin redness, which has a healing effect. In order to properly stimulate the formation of erythema, after its appearance, the next sessions begin after it turns pale. The intervals between physiotherapy procedures are 1-3 days. The dosage for subsequent sessions is increased by a third or more.
For intact skin, 5-6 physiotherapy procedures are enough. If there are purulent lesions, bedsores on the skin, then it is necessary to irradiate up to 12 sessions. For mucous membranes, the course therapy is 10-12 sessions.
For children, local use of the UFO is permitted from birth. It is limited in area. In a newborn child, the exposure area is 50 cm2 and more, for schoolchildren no more than 300 cm2. The dosage for erythema therapy is 0.5-1 biodoses.
In acute respiratory diseases, UV treatment of the nasopharyngeal mucosa is performed. For this, special tubes are used. The session lasts 1 minute (adults), half a minute (children). Course therapy is 7 days.
The chest is irradiated in the fields. The duration of the procedure is 3-5 minutes. The fields are processed separately on different days. The sessions are carried out every day. The frequency of irradiation of the field for the course is 2-3 times; oilcloth or perforated fabric is used to isolate it.
With a runny nose in an acute period, ultraviolet exposure is carried out on the legs from the side of the sole. The source is installed at a distance of 10 cm. Course treatment up to 4 days. Irradiation is also done with a tube in the nose and throat. The first session lasts 30 seconds. In the future, therapy is extended to 3 minutes. Course therapy is 6 sessions.
With otitis media, ultraviolet exposure is carried out on the site of the ear canal. The session lasts 3 minutes. The therapy includes 6 physiotherapy procedures. In patients with pharyngitis, laryngitis, tracheitis, radiation is performed on the front upper part of the chest. The number of procedures per course is up to 6.
With tracheitis, pharyngitis, sore throat, you can irradiate the back of the pharynx (throat) with the help of tubes. During the session, the patient should say the sound "a". The duration of the physiotherapy procedure is 1-5 minutes. Treatment is carried out every 2 days. Course therapy is 6 sessions.
Pustular skin lesions are treated by UV after treatment of the wound surface. The ultraviolet source is set at a distance of 10 cm. The session duration is 2-3 minutes. The treatment lasts 3 days.
Furuncles and abscesses are irradiated after opening the formation. The treatment is carried out at a distance of 10 cm to the body surface. The duration of one physiotherapy is 3 minutes. Course therapy 10 sessions.
Home UV treatment
Ultraviolet irradiation is acceptable at home. To do this, you can purchase an UFO apparatus at any medical equipment store. For the implementation of UFO-physiotherapy at home, the device "Solnyshko" (OUFb-04) was developed. It is intended for local action on mucous membranes and skin.
For general exposure, you can purchase a mercury-quartz lamp "Solnyshko". It will replace part of the missing ultraviolet light in winter and disinfect the air. There are also home irradiators for shoes and water.
The device "Solnyshko" for local use is equipped with a tube for the nose, throat, treatment of other parts of the body. The device is small in size. Before purchasing, you should make sure that the device is in good working order, there are certificates and quality guarantees. To clarify the rules for using the device, you must read the instructions, or contact your doctor.
Conclusion
Ultraviolet radiation is often used in medicine to treat various diseases. In addition to treatment, UFO devices can be used to disinfect premises. They are used in hospitals and at home. With the correct use of lamps, irradiation does not harm, and the effectiveness of the treatment is quite high.
The beneficial effects of UV rays on the body
The sun's rays provide warmth and light that improve overall well-being and stimulate blood circulation. A small amount of UV light is needed by the body to produce vitamin D. Vitamin D plays an important role in the absorption of calcium and phosphorus from food, as well as in skeletal development, the functioning of the immune system, and in the formation of blood cells. Without a doubt, a small amount of sunlight is good for us. Exposure to sunlight for 5 to 15 minutes on the skin of the hands, face and hands two to three times a week during the summer months is sufficient to maintain normal vitamin D levels. Closer to the equator, where UV radiation is more intense, an even shorter interval is sufficient.
Therefore, vitamin D deficiency is unlikely for most people. Possible exceptions are those who have significantly limited their exposure to the sun: elderly people who do not leave their homes or people with highly pigmented skin who live in countries with low UV radiation. Naturally occurring vitamin D is very rare in our food, it is found mainly in fish oil and cod liver oil.
Ultraviolet radiation has been used successfully in the treatment of many conditions, including rickets, psoriasis, eczema, and others. This therapeutic treatment does not exclude the negative side effects of UV radiation, but it is administered under medical supervision to ensure that the benefits outweigh the risks.
Despite its significant role in medicine, the negative effects of UV radiation usually far outweigh the positive ones. In addition to the well-known direct effects of excess UV radiation, such as burns or allergic reactions, long-term effects pose a health hazard throughout life. Excessive sunburn can damage the skin, eyes, and possibly the immune system. Many people forget that UV radiation builds up throughout life. Your attitude towards tanning now determines the possibility of developing skin cancer or cataracts in later life! The risk of developing skin cancer is directly related to the duration and frequency of sunburn.
Impact atlight violet on the skin
There is no healthy tan! Skin cells produce dark pigment only to protect against subsequent radiation. Tanning provides some protection against UV light. A dark tan on white skin is equivalent to an SPF of between 2 and 4. However, this does not provide protection against long-term effects such as skin cancer. A tan can be cosmetically attractive, but in fact it only means that your skin has been damaged and is trying to protect itself.
There are two different mechanisms for the formation of tanning: fast tanning, when the pigment already existing in the cells darkens under the influence of ultraviolet radiation. This tan begins to fade within a few hours after the exposure has ceased. Long-term tanning occurs within about three days when new melanin is produced and distributed among the skin cells. This tan can last for several weeks.
Sunburn-High doses of ultraviolet radiation are destructive for most cells of the epidermis, and the surviving cells are damaged. At best, a sunburn causes a reddening of the skin called erythema. It appears shortly after sun exposure and reaches its maximum intensity between 8 and 24 hours. In this case, the consequences disappear within a few days. However, heavy tanning can leave painful blisters and white patches on the skin, where the new skin is devoid of protection and is more sensitive to UV damage.
Photosensitization -A small percentage of the population is highly sensitive to ultraviolet radiation. Even a minimal dose of ultraviolet radiation is enough to trigger allergic reactions in them, leading to rapid and severe sunburn. Photosensitization is often associated with the use of certain medications, including some nonsteroidal anti-inflammatory drugs, pain relievers, tranquilizers, oral antidiabetic drugs, antibiotics, and antidepressants. If you are constantly taking any medications, carefully read the annotation or consult with your doctor about possible photosensitization reactions. Certain food and cosmetic products, such as perfumes and soaps, may also contain UV-sensitizing ingredients.
PhotoagingSun exposure contributes to the aging of your skin through a combination of several factors. UVB stimulates a rapid increase in the number of cells in the upper layer of the skin. As more and more cells are produced, the epidermis thickens.
UVA, penetrating into the deeper layers of the skin, damages the connective tissue structures and the skin gradually loses its elasticity. Wrinkles and sagging skin are a common result of this loss. A phenomenon that we can often see in older people is localized excess production of melanin, resulting in dark patches or liver spots. In addition, the sun's rays dry out your skin, making it rough and rough.
Non-melanoma skin cancersUnlike melanoma, basal cell and squamous carcinomas are usually not fatal, but surgical removal can be painful and scarring.
Non-melanoma cancers are most often located on parts of the body that are exposed to the sun, such as the ears, face, neck, and forearms. They have been found to be more common in outdoor workers than in indoor workers. This suggests that long-term accumulation of UV exposure plays a major role in the development of non-melanoma skin cancers.
Melanoma-Malignant melanoma is the rarest but also the most dangerous type of skin cancer. It is one of the most common cancers in people between the ages of 20 and 35, especially in Australia and New Zealand. All forms of skin cancer have tended to increase over the past twenty years, however, the highest worldwide remains with melanoma.
Melanoma can appear under the guise of a new mole or as a change in color, shape, size or sensation change in pre-existing spots, freckles, or moles. Melanomas usually have an uneven outline and uneven coloration. Itching is another common symptom, but it can also occur with normal moles. If the disease is recognized and treatment is carried out in a timely manner, the prognosis for life is favorable. If left untreated, the tumor can grow rapidly and cancer cells can spread to other parts of the body.
Eye exposure to ultraviolet radiation
The eyes occupy less than 2 percent of the body's surface, but they are the only organ system that allows visible light to penetrate deep into the body. Over the course of evolution, many mechanisms have evolved to protect this highly sensitive organ from the harmful effects of sunlight:
The eye is located in the anatomical recesses of the head, protected by the brow arches, eyebrows and eyelashes. However, this anatomical adaptation only partially protects against ultraviolet rays in extreme conditions, such as the use of a tanning bed or when light is strongly reflected from snow, water and sand.
Narrowing the pupil, closing the eyelids and squinting minimizes the penetration of the sun's rays into the eye.
However, these mechanisms are activated by bright visible light rather than ultraviolet rays, but ultraviolet radiation can also be high on a cloudy day. Therefore, the effectiveness of these natural defense mechanisms against UV exposure is limited.
Photokeratitis and photoconjunctivitisPhotokeratitis is inflammation of the cornea, while photoconjunctivitis refers to inflammation of the conjunctiva, the membrane that limits the sphere of the eye and covers the inner surface of the eyelids. Inflammatory reactions of the eyeball and eyelids can be, along with sunburn of the skin, very sensitive and usually appear within a few hours after exposure. Photokeratitis and photoconjunctivitis can be very painful, however, they are reversible and do not appear to result in permanent eye damage or visual impairment.
The extreme form of photokeratitis is snow blindness. This sometimes occurs in skiers and climbers who are exposed to very high doses of ultraviolet rays due to altitude conditions and very strong reflections. Fresh snow can reflect up to 80 percent of UV rays. These ultra-high doses of ultraviolet radiation are detrimental to the cells of the eye and can lead to blindness. Snow blindness is very painful. Most often, new cells grow quickly and vision is restored within a few days. In some cases, sun blindness can lead to complications such as chronic irritation or watery eyes.
Pterygium -This overgrowth of the conjunctiva on the surface of the eye is a common cosmetic defect, presumably associated with prolonged exposure to ultraviolet radiation. The pterygium can spread to the center of the cornea and thus reduce vision. This phenomenon can also become inflamed. Despite the fact that the disease can be corrected by surgery, it tends to recur.
Cataract-the leading cause of blindness in the world. Lens proteins accumulate pigments that coat the lens and ultimately lead to blindness. Despite the fact that cataracts appear to varying degrees in most people with age, it seems that the likelihood of cataracts increases with exposure to ultraviolet radiation.
Cancer eye lesionsRecent scientific evidence suggests that various forms of eye cancer may be associated with lifetime exposure to ultraviolet radiation.
Melanoma - frequent cancerous lesions of the eyes and sometimes requiring surgical removal. Basal cell carcinoma most often located in the eyelids.
Effect of UV radiation on the immune system
Exposure to sunlight may precede herpes sores. In all likelihood, UVB radiation reduces the effectiveness of the immune system and it can no longer control the herpes simplex virus. As a result, the infection is released. One study in the United States examined the effect of sunscreen on the severity of cold sores. Of the 38 patients with herpes simplex infection, 27 developed rashes after exposure to UV radiation. In contrast, when using sunscreen, none of the patients developed rashes. Therefore, in addition to protecting from the sun, sunscreen can be effective in preventing the recurrence of sun-induced cold sores.
Research in recent years is increasingly proving that exposure to ultraviolet radiation from the external environment can change the activity and distribution of certain cells responsible for the immune response in the human body. As a consequence, excess UV radiation can increase the risk of infection or decrease the body's ability to defend against skin cancer. Where UV radiation is high (mainly in developing countries) this can reduce the effectiveness of vaccinations.
It has also been suggested that ultraviolet radiation can cause cancer in two different ways: by directly damaging DNA and by weakening the immune system. To date, few studies have been conducted to describe the potential effects of immunomodulation on cancer development.
Life-giving rays.
The sun emits three types of ultraviolet rays. Each of these types has a different effect on the skin.
Most of us feel healthier and fuller after a beach holiday. Thanks to the life-giving rays, vitamin D is formed in the skin, which is necessary for the full absorption of calcium. But only small doses of solar radiation have a beneficial effect on the body.
But severely tanned skin is still damaged skin and, as a result, premature aging and a high risk of developing skin cancer.
Sunlight is electromagnetic radiation. In addition to the visible spectrum of radiation, it contains ultraviolet, which is actually responsible for tanning. Ultraviolet light stimulates the ability of the pigment cells of melanocytes to produce more melanin, which has a protective function.
Types of UV rays.
There are three types of UV rays that differ in wavelength. Ultraviolet radiation is able to penetrate the skin epidermis into deeper layers. This activates the production of new cells and keratin, resulting in a tighter and tighter skin. The sun's rays penetrating the dermis destroy collagen and lead to changes in the thickness and texture of the skin.
Ultraviolet rays A.
These rays have the lowest radiation levels. It used to be considered that they are harmless, however, it has now been proven that this is not the case. The level of these rays remains practically constant throughout the day and year. They even penetrate glass.
Type A UV rays penetrate through the layers of the skin, reaching the dermis, damaging the base and structure of the skin, destroying collagen and elastin fibers.
A-rays contribute to the appearance of wrinkles, reduce skin elasticity, accelerate the appearance of signs of premature aging, weaken the skin's defense system, making it more susceptible to infections and, possibly, cancer.
Ultraviolet B.
Rays of this type are emitted by the sun only at certain times of the year and hours of the day. Depending on the air temperature and latitude, they usually enter the atmosphere from 10 to 16 hours.
Type B UV rays cause more serious damage to the skin, as they interact with DNA molecules contained in skin cells. B-rays damage the epidermis, leading to sunburn. B-rays damage the epidermis, leading to sunburn. This type of radiation enhances the activity of free radicals, which weaken the skin's natural defense system.
Ultraviolet B rays contribute to the appearance of sunburn and cause sunburn, lead to premature aging and the appearance of dark age spots, make the skin rough and rough, accelerate the appearance of wrinkles, and can provoke the development of precancerous diseases and skin cancer.