UV radiation is electromagnetic waves that are invisible to the human eye. It occupies a spectral position between visible and X-ray radiation. Interval ultraviolet radiation It is customary to divide into near, middle and far (vacuum).
Biologists have made such a division of UFL in order to better see the difference in the effect of rays of different lengths on a person.
- Near ultraviolet is commonly referred to as 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. At the same time, far ultraviolet UV-C is almost completely blocked by the Earth's atmosphere. Those 10% of long-wave 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 is its chemical activity, due to which UV radiation has great impact on the human body. The most dangerous for our body is short-wave ultraviolet. 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 the short-wave type of radiation are welders and ultraviolet lamps.
Positive properties of ultraviolet
It was only in the 20th century that studies began to be carried out that proved positive influence UV radiation on the human body. The result of these studies was the identification of the following useful properties: strengthening human immunity, activation defense mechanisms, improved blood circulation, vasodilation, increased vascular permeability, increased secretion of a number of hormones.
Another property of ultraviolet light is its ability to 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, and the level of oxygen consumption. It also improves performance endocrine system, the body produces vitamin D, which strengthens the human musculoskeletal system.
The use of ultraviolet in medicine
Ultraviolet light is often used in medicine. Despite the fact that in some cases ultraviolet rays can adversely affect the human body, when correct use they can be useful as well.
In medical institutions, a useful application of artificial ultraviolet has long been invented. There are various emitters that can help a person with the help of ultraviolet rays. cope with various diseases. They are also divided into those that emit long, medium and short waves. Each of them is used in a specific case. Thus, long-wave radiation is suitable for treatment respiratory tract, for damage to the osteoarticular apparatus, as well as in case of various damage skin. We can also see long-wave radiation in solariums.
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, with damage to the respiratory tract, with diabetes with damage to the heart valves.
In addition to various devices that emit artificial ultraviolet radiation, which are used in mass medicine, there are also ultraviolet lasers, which have a more precise action. These lasers are used, for example, in eye microsurgery. Such lasers are also used for scientific research.
The use of ultraviolet in other areas
In addition to medicine, ultraviolet radiation is used in many other areas, significantly improving our lives. So, ultraviolet is great disinfectant, and is used, among other things, for the treatment of various objects, water, indoor air. Widely used ultraviolet and in printing: it is with the help of ultraviolet that various seals and stamps are produced, paints and varnishes are dried, banknotes protected from forgery. In addition to its useful properties, when properly applied, ultraviolet can create beauty: it is used for various lighting effects (most often this happens in discos and performances). UV rays also help in finding fires.
One of the negative consequences of ultraviolet exposure to the human body is electrophthalmia. This term is called a lesion of the human organ of vision, in which the cornea of the eye is burned 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 the premises.
Negative effects can also be achieved due to the long, intense exposure to ultraviolet rays on the body. There can be quite a lot of such consequences, up to the development of various pathologies. The main symptoms of overexposure are
The consequences of strong exposure are as follows: hypercalcemia, growth retardation, hemolysis, impaired immunity, various burns and skin diseases. The most susceptible to excessive exposure are people who constantly work outdoors, as well as those people who constantly work with devices that emit artificial ultraviolet radiation.
Unlike UV emitters used in medicine, tanning beds are more dangerous for a person. Visiting solariums is not controlled by anyone, except for the person himself. People who frequent 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 beds 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 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 growth of epithelial cells - permanent skin damage.
Ultraviolet, penetrating deeply into the skin, can change skin cells at the gene level and lead to ultraviolet mutagenesis. One of the complications of this mutagenesis is melanoma, a skin tumor. It is she who can lead a person to death.
To avoid the negative effects of UV exposure, need some protection. At various enterprises working with devices emitting artificial ultraviolet, 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 in excessive visits to solariums and in a long stay in the open sun, in summer time use sunscreen, sprays or lotions, and wear sunglasses and close-fitting clothing made from natural fabrics.
There are also Negative consequences from lack of UV radiation. Prolonged absence of UV radiation can lead to a disease called "light starvation". Its main symptoms are very similar to those of excessive UV exposure. With this disease, a person's immunity decreases, metabolism is disturbed, fatigue, irritability, etc. appear.
In 1801, I. Ritter (Germany) and W. Walaston (England), using a photographic plate, proved the presence of ultraviolet rays. Beyond the violet end of the spectrum, it blackens 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), which give both a line and a continuous spectrum, ultraviolet rays with a wavelength of up to 180 nm are obtained. In 1914, Lyman explored the range up to 50 nm.
Researchers have discovered the fact that the spectrum of ultraviolet rays of the Sun reaching the earth's surface is very narrow - 400...290 nm. Does the sun not emit light with a wavelength 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 suggested: the Sun emits short-wave ultraviolet radiation, under its action oxygen molecules break up into individual atoms, forming ozone molecules, therefore, in the upper atmosphere, ozone should cover the earth with a protective screen. Cornu's hypothesis was confirmed when people rose into the upper atmosphere. Thus, under terrestrial conditions, the spectrum of the sun 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 decreases by a factor of 20.
Special experiments have established that when ascending for every 100 m, the intensity of ultraviolet radiation increases by 3 ... 4%. The share of scattered ultraviolet radiation in summer noon accounts for 45 ... 70% of the radiation, and reaching the earth's surface - 30 ... 55%. On cloudy days, when the disk of the Sun is covered by clouds, the Earth's surface is reached mainly by scattered radiation. Therefore, you can tan well not only under the direct rays of the sun, but also in the shade and on cloudy days.
When the Sun is at its zenith, in the equatorial region of the earth's surface, rays with a length of 290 ... 289 nm reach. In the middle latitudes, the short-wave boundary, in the summer months, is approximately 297 nm. During the period of effective illumination, the upper limit of the spectrum is about 300 nm. Behind the Arctic Circle, the earth's surface is reached by rays with a wavelength of 350 ... 380 nm.
Effect 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 energy-rich short-wave rays played a significant 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 decay of organic substances. Therefore, the progress of life forms on Earth came only after, thanks to the activity of green plants, the atmosphere was enriched with oxygen and, under the action of ultraviolet rays, a protective ozone layer was formed.We are interested in the ultraviolet radiation of the Sun and artificial sources of ultraviolet radiation in the range of 400...180 nm. Within this range, three areas are distinguished:
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. Part of the absorbed energy is converted into heat, but thermal action ultraviolet rays do not have a noticeable effect on the body. Another way to transfer energy is luminescence.
Photochemical reactions under the action of ultraviolet rays are most intense. The energy of photons of ultraviolet light is very high, therefore, when they are absorbed, the molecule ionizes and breaks up into parts. Sometimes a photon knocks an electron out of the atom. Most often, the excitation of atoms and molecules occurs. When one quantum of light with a wavelength of 254 nm is absorbed, the energy of the molecule increases to a level corresponding to the energy of thermal motion at a temperature of 38000°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 in the middle of summer in the Southern Hemisphere (the Earth is 5% closer to the Sun) and 50% of the daily amount of UV arrives 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 would receive only 19% of the daily UV dose. At noon, the intensity of UV (300 nm) is 10 times higher than three hours earlier or later: an untanned person needs 25 minutes to get a light tan at noon, but to achieve the same effect after 15:00, he will need to lie in the sun not 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 effects on the body.
UV-A is not retained by the ozone layer, it passes through glass and the stratum corneum of the skin. 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 no significant fluctuations in UV-A intensity in 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 UV-B is absorbed by the ozone layer, which is "transparent" to UV-A. So the share of UV-B in all ultraviolet radiation energy on a summer afternoon is only about 3%. It practically does not penetrate glass, is reflected by the stratum corneum by 70%, weakens by 20% when passing through the epidermis - less than 10% penetrates into the dermis.
However 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 also necessary to take into account the fact that UV-B is stronger (shorter wavelength) than UV-A is scattered when passing through the atmosphere, which also leads to a change in the ratio between these fractions with increasing geographical 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, 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 most interesting is the effect of ultraviolet rays on biopolymers - proteins and nucleic acids. 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 the chain of atoms within the molecule without significant loss until it reaches weak bonds between atoms and destroys the bond. During this process, called photolysis, fragments of molecules are formed that have a strong effect on the body. So, for example, from the amino acid histidine, histamine is formed - a substance that expands blood capillaries and increases their permeability. In addition to photolysis, denaturation occurs in biopolymers under the action of ultraviolet rays. When irradiated with light of a certain wavelength, the electric charge of molecules decreases, they stick together and lose their activity - enzymatic, hormonal, antigenic, etc.The processes of photolysis and protein denaturation proceed in parallel and independently of each other. They are caused by different radiation ranges: 280 ... 302 nm rays cause mainly 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 most sensitive function of the cell to the action of ultraviolet rays is division. Irradiation at a dose of 10 (-19) j/m2 causes the division of about 90% of bacterial cells to stop. 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 increase 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. to 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 cell's hereditary memory. 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 a serious disruption of life.
The effect of ultraviolet radiation on the skin
Exposure to ultraviolet radiation on the skin significantly affects the metabolism of our body. It is well known that it is UV rays that initiate the formation of ergocalciferol (vitamin D), which is necessary for the absorption of calcium in the intestines and to ensure 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 the blood serum is irradiated with UV rays, the content of serotonin, the "hormone of vivacity" involved in the regulation of the emotional state, increased by 7%. Its deficiency can lead to depression, mood swings, 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.
There are caloric and ultraviolet erythema. Caloric erythema is caused by the action of visible and infrared rays on the skin and a rush of blood to it. It disappears almost immediately after the cessation of exposure to radiation.
After cessation of exposure to UV radiation, after 2..8 hours, reddening of the skin (ultraviolet erythema) appears simultaneously with a burning sensation. Erythema appears after a latent period, within the irradiated area of the skin, and is replaced by sunburn and peeling. The duration of erythema has a duration of 10...12 hours to 3...4 days. The reddened skin is hot to the touch, a little sore and feels swollen, slightly swollen.
Essentially, erythema is an inflammatory reaction, a skin burn. This is a special, aseptic (Aseptic - aseptic) inflammation. If the radiation dose is too high or the skin is especially sensitive to them, the edematous fluid, accumulating, exfoliates the outer skin in places and forms blisters. In severe cases, areas of necrosis (necrosis) of the epidermis appear. A few days after the disappearance of erythema, the skin darkens and begins to peel off. As peeling, part of the cells containing melanin is exfoliated (Melanin is the main pigment of the human body; it gives color to the skin, hair, iris. 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 (in children and the elderly - thinner) and localization - an average of 1..2 mm. Its purpose is to protect the body from damage, fluctuations in temperature, 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. Layers of dead and dying cells form the outer stratum corneum of the epidermis with a thickness of 0.07 ... 2.5 mm (On the palms and soles, mainly due to the stratum corneum, the epidermis is thicker than in other parts of the body), which is continuously sloughed off from the outside and restored from within.
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 irradiation depends on the penetrating power of the rays and on the thickness of the stratum corneum. The shorter the wavelength of radiation, the lower their penetrating power. Rays shorter than 310 nm do not penetrate deeper than the epidermis. Rays with a longer wavelength reach the papillary dermis, in which blood vessels pass. Thus, the interaction of ultraviolet rays with a substance occurs exclusively in the skin, mainly in the epidermis.
The main amount of ultraviolet rays is absorbed in the germinal (basic) layer of the epidermis. The processes of photolysis and denaturation lead to the death of the styloid cells of the germ layer. The active products of protein photolysis cause vasodilation, skin edema, leukocyte release, and other typical signs of erythema.
The products of photolysis, spreading through 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 in the nerve extending from the irradiated area of the skin, the frequency of electrical impulses increases.
Erythema is considered as a complex reflex, in the occurrence of which the active products of photolysis are involved. The severity of erythema and the possibility of its formation depends on the condition nervous system. On the affected areas of the skin, with frostbite, inflammation of the nerves, erythema either does not appear at all, or is very weakly expressed, despite the action of ultraviolet rays. Inhibits the formation of erythema sleep, alcohol, physical and mental fatigue.
N. Finsen (Denmark) first used ultraviolet radiation for the treatment of a number of diseases in 1899. At present, the manifestations of the action of different sections 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. To rays with a longer or shorter wavelength, the erythemal sensitivity of the skin decreases.
With the help of artificial radiation sources, erythema was caused by rays in the range of 250 ... 255 nm. Rays with a wavelength of 255 nm gives the resonant emission line of mercury vapor used in mercury-quartz lamps.
Thus, the skin erythema sensitivity curve has two maxima. The depression between the two maxima is provided by the shielding action of the stratum corneum.
Protective functions of the body
Under natural conditions, after erythema, skin pigmentation develops - sunburn. The spectral maximum of pigmentation (340 nm) does not coincide with any of the peaks of erythemal sensitivity. Therefore, by choosing a radiation source, it is possible to 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, interconnected processes. In the cells of the lowest layer of the epidermis - melanoblasts - the skin pigment melanin is formed. The starting material for the formation of melanin are amino acids and breakdown products of adrenaline.
Melanin is not just a pigment or passive protective screen enclosing living tissue. Melanin molecules are huge molecules with a mesh structure. In the links of these molecules, fragments of molecules destroyed by ultraviolet light are bound and neutralized, preventing them from passing into the blood and internal environment organism.
The function of sunburn 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 heat stroke. Near infrared rays and visible light, especially its long-wavelength, "red" part, can penetrate 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 operational mechanism for protecting the body from overheating is the rush of blood to the skin and the 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 have high temperature, another cooling mechanism comes into play - evaporation due to sweating. These thermoregulatory mechanisms are designed to protect against exposure to the visible and infrared rays of the sun.
Sweating, along with the function of thermoregulation, prevents the effects of ultraviolet radiation on a person. 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 products of photolysis, which have a beneficial effect on the body. Ultraviolet rays in doses that cause the formation of erythema enhance the work of the hematopoietic organs, the reticulo-endothelial system (Physiological system of connective tissue that produces antibodies that destroy foreign bodies and microbes), the barrier properties of the skin, eliminate allergies.Under the influence of ultraviolet radiation in human skin, fat-soluble vitamin D is formed 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, 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 the absorption of calcium. Calcium is a part of bones, participates in blood coagulation, thickens cell and tissue membranes, and regulates the activity of enzymes. A disease that occurs with a lack of vitamin D in children of 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 is manifested in irritability, insomnia, and rapid fatigue of a person. In large cities, where the air is polluted with dust, ultraviolet rays that cause erythema hardly reach the surface of the Earth. Long work in mines, engine rooms and closed factory floors, work at night, and sleep during 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. The color of the walls is also essential. For example, yellow color completely absorbs ultraviolet rays. The lack of light, especially ultraviolet radiation, is felt by people, pets, birds and houseplants during autumn, winter and spring periods.
To compensate for the lack of ultraviolet rays, lamps, which, along with visible light, emit ultraviolet rays in the wavelength range of 300 ... 340 nm, allow. It should be borne in mind that errors in prescribing the dose of radiation, inattention to such issues as the spectral composition of ultraviolet lamps, the direction of radiation and the height of the lamps, the duration of the lamps, can be harmful instead of good.
Bactericidal action of ultraviolet radiation
It is impossible not to note the bactericidal function of UV rays. In medical institutions, this property is actively used to prevent nosocomial infections and ensure the sterility of operative blocks and dressing rooms. The impact of ultraviolet radiation on bacterial cells, namely 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. The ultraviolet rays of the Sun enhance the process of natural self-purification of the atmosphere from pollution, contributing to the rapid oxidation of dust, smoke particles and soot, destroying microorganisms on dust particles. The natural ability to self-purify has limits and with very strong air pollution is insufficient.
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 400 nm - 0.01% of the maximum.
Microorganisms have different sensitivity to ultraviolet rays. Yeasts, molds and spores of bacteria are much more resistant to their action than vegetative forms of bacteria. Spores of individual fungi, surrounded by a thick and dense shell, feel great in 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 period of division and immediately before it. Curves of the bactericidal effect, inhibition and growth of cells practically coincide with the curve of absorption by nucleic acids. Consequently, the denaturation and photolysis of nucleic acids leads to the cessation of division and growth of microbial cells, and in large doses to their death.
The bactericidal properties of ultraviolet rays are used to disinfect air, tools, utensils, with their help they increase the shelf life of food products, disinfect drinking water, inactivate viruses in the preparation of vaccines.
The negative effects of ultraviolet radiation
A number of negative effects that occur when exposed to UV radiation on the human body are well known, which can lead to a number of serious structural and functional damage to the skin. As you know, these damages 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 cell 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. Pain in the eye, redness, lacrimation, partial blindness appear as a result of degeneration and death of cells of the conjunctiva and cornea. The cells then become opaque. Long-wave ultraviolet rays, reaching the lens, in large doses can cause its clouding - a cataract.
Artificial sources of UV radiation in medicine
germicidal lampsDischarge lamps are used as sources of UV radiation, in which radiation is generated during an electric discharge, containing in its composition a wavelength range of 205-315 nm (the rest of the radiation spectrum plays a secondary role). These lamps include mercury lamps of low and high pressure and xenon flash lamps.
Low-pressure mercury lamps are structurally and according to electrical parameters practically do not differ from conventional lighting fluorescent lamps, except that their bulb is made of special quartz or uvio glass with high coefficient transmission of UV radiation, on the inner surface of which a layer of phosphor 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 h and an instantaneous ability to work after their ignition.
The flask of mercury-quartz lamps of high pressure is made of quartz glass. The advantage of these lamps is that, despite their 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 they have a low bactericidal output and a short service life of 500-1,000 hours. In addition, the normal combustion mode occurs 5-10 minutes after their ignition.
A significant disadvantage of continuous radiant lamps is the risk of mercury vapor contamination of the environment when the lamp is destroyed. In case of violation of the integrity of bactericidal lamps and mercury ingress 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 emitters with much greater biocidal activity. The principle of their operation is based on high-intensity pulsed irradiation of air and surfaces with continuous spectrum UV radiation. Pulsed radiation is obtained using xenon lamps, as well as using lasers. There are currently no data on the difference between the biocidal action of pulsed UV radiation and that of conventional UV radiation.
The advantage of xenon flash lamps is due to the higher bactericidal activity and shorter exposure time. Another 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 hinder their widespread use, is the need to use high-voltage, complex and expensive equipment for their operation, as well as a limited emitter life (average 1-1.5 years).
Germicidal lamps are divided into ozone and non-ozone.
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 effects on human health. The use of these lamps requires control of the ozone content in the air and thorough ventilation of the room.
To eliminate the possibility of ozone generation, so-called bactericidal "ozone-free" lamps have been developed. For such lamps, due to the manufacture of a bulb from special material(coated quartz glass) or its design, the output of the 185 nm line radiation is excluded.
Germicidal lamps that have outlived their service life or 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 bactericidal irradiator is an electrical device that contains: a bactericidal lamp, a reflector and other auxiliary elements, as well as devices for its fastening. 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 direct germicidal flux from the lamps and reflector (or without it), which covers a wide area of space around them. Mounted on the ceiling or wall. Irradiators installed in doorways, are called barrier irradiators or ultraviolet curtains, in which the bactericidal flux is limited to a small solid angle.
A special place is occupied by open combined irradiators. In these irradiators, due to the rotary screen, the bactericidal flow from the lamps can be directed to the upper or lower zone 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 direct flow from the lamp or reflector to the lower zone. At the same time, the irradiance from reflected flows 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 has no outlet to the outside, while air disinfection is carried out in the process of pumping it through the ventilation openings of the recirculator. When using supply and exhaust ventilation, bactericidal lamps are placed in the outlet chamber. The airflow 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 appliances) at a height of at least 2 m from the floor.
According to the list of typical rooms divided into 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 - when they are turned on in the absence of people.
In rooms for children and pulmonary patients, it is recommended to use irradiators with ozone-free lamps. Artificial ultraviolet irradiation, even indirect, is contraindicated in children with active tuberculosis, nephrosonephritis, fever and severe exhaustion.
The use of ultraviolet bactericidal installations requires strict implementation of safety measures that exclude possible harmful effects on humans of ultraviolet bactericidal radiation, ozone and mercury vapor.
Basic safety measures and contraindications for the use of therapeutic UV irradiation.
Before using UV irradiation 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.Since individual sensitivity varies widely, it is recommended that the duration of the first session be halved compared to the recommended time in order to ascertain the skin reaction of the user. If any adverse reaction is found after the first session, further use of UV irradiation is not recommended.
Regular exposure 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 minimum erythemal doses (MED) per year, no matter how small the erythema-effective exposure. It is recommended to occasionally interrupt regular irradiation sessions.
Therapeutic irradiation must be carried out with the obligatory use of reliable protective goggles for the eyes.
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 cannot feel completely safe either.
Very careful with natural and artificial UV exposure of the whole body should be the following categories of people:
Light therapy is actively used in medical practice for the treatment various diseases. It includes the use of visible light, laser, infrared, and ultraviolet rays (UVR). The most commonly prescribed UFO-physiotherapy.
It is used for the treatment of ENT pathologies, diseases of the musculoskeletal system, immunodeficiencies, bronchial asthma and other diseases. Ultraviolet irradiation is also used for a bacteriostatic effect in infectious diseases, for indoor air treatment.
General concept of ultraviolet irradiation, types of devices, mechanism of action, indications
Ultraviolet irradiation (UVR) is a physiotherapeutic procedure based on the effect 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 (DUV) (400–320 nm).
- Medium wave (SUV) (320–280 nm).
- Shortwave (CUV) (280–180 nm).
For physiotherapy, special devices are used. They generate ultraviolet rays of different lengths.
UV-devices for physiotherapy:
- Integral. Generate the entire spectrum of UV radiation.
- Selective. They produce one type of ultraviolet radiation: short-wave, a combination of short-wave and medium-wave spectra.
| Integral | selective |
|
OUSh-1 (for individual use, local exposure, general effects on the body); OH-7 (suitable for the nasopharynx) OUN 250, OUN 500 - desktop type for local use). The radiation source is a mercury-quartz tubular lamp. Power can be different: from 100 to 1000 watts. |
Shortwave Spectrum (SHF). Sources of bactericidal action: OBN-1 (wall-mounted), OBP-300 (ceiling-mounted). Used for disinfection of premises. Short rays for local exposure (irradiation of the skin, mucous membranes): BOP-4. The medium wave spectrum is generated by luminescent erythemal sources with ultraviolet-transmitting glass: LE-15, LE-30. Sources of long waves (DUV) are used for general effects on the body. |
In physiotherapy, ultraviolet irradiation is prescribed for the prevention and treatment of various diseases. The mechanism of exposure to 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 resulting erythematous formation remains on the skin for several more days, it has clear boundaries.
The long-wave spectrum does not cause very pronounced erythema. Medium-wave rays are able to reduce the number of free radicals, stimulate the synthesis of ATP molecules. Short UV rays very quickly provoke an erythematous rash.
Small doses of medium and long UV waves are not capable of causing erythema. They are needed for a general effect on the body.
Benefits of small doses of UVR:
- 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 naming 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, increases blood flow and lymph outflow.
Radiation doses that do not cause redness have the following properties: increase regenerative function, enhance tissue nutrition, stimulate the appearance of melanin in the skin, increase immunity, stimulate the formation of vitamin D. Higher doses that cause erythema (often CUF) are able to kill bacterial agents, reduce the intensity of pain, reduce inflammation on the mucous membranes and skin.
Indications for physiotherapy
| General impact | Local impact |
| Stimulation of immunity in immunodeficiencies. Prevention and treatment of rickets (vitamin D deficiency) in children, during pregnancy, breastfeeding. Purulent lesions of the skin, soft tissues. Increased immunity in chronic processes. Increased production of blood cells. Replacement therapy for UVR deficiency. |
Diseases of the joints. Pathology of the respiratory system. Bronchial asthma. Surgical purulent wounds, bedsores, burns, frostbite, abscesses, erysipelas, fractures. Extrapyramidal syndrome, demyelinating pathologies, head injuries, radiculopathy, different kinds 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, skin lesions with staphylococcus aureus. Psoriasis, eczematous rashes, purulent skin lesions in dermatological patients. |
Contraindications to radiation are:
- tumor process.
- Hyperthermia.
- Infectious diseases.
- Hyperproduction of thyroid hormones.
- Lupus erythematosus.
- Hepatic and renal dysfunction.
The method of conducting ultraviolet irradiation
Before treatment, the physiotherapist must decide on the type of rays. A prerequisite is the calculation of radiation exposure to the patient. The load is measured in biodoses. The calculation of the number of biodoses is carried out according to the Gorbachev-Dalfeld method. It is based on the speed of formation of reddening of the skin. One biodose is capable of causing minimal redness from a distance of 50 cm. This dosage is erythematous.
Erythemal doses are divided 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 hypererythemic. Irradiation is divided into general and local. The general may be intended 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 UV very carefully. For a child and a student, an incomplete biodose is used. Start with the smallest dosage.
With the general exposure of newborns and very weak babies to UV rays, initial stage 1/10–1/8 of the biodose is affected. Schoolchildren and preschoolers use 1/4 of the biodose. Over time, the load is increased to 1 1/2-1 3/4 biodoses. This dosage remains for the entire stage of therapy. Sessions are held every other day. 10 sessions are enough for treatment.
During the procedure, the patient must be undressed, put on the couch. The device is placed at a distance of 50 cm from the surface of the patient's body. The lamp should be covered with a cloth or blanket along with the patient. This ensures that the maximum dose of radiation is obtained. If you do not cover with a blanket, then part of the rays emanating from the source is scattered. The effectiveness of therapy in this case will be low.
Local exposure to UV radiation is carried out by devices of a mixed type, as well as emitting short waves of the UV spectrum. During local physiotherapy, it is possible to influence reflexogenic zones, irradiate with fractions, fields, near the injury site.
Local irradiation often causes reddening of the skin, which healing effect. In order to properly stimulate the formation of erythema, after its appearance, the following sessions begin after its blanching. The intervals between physiotherapy are 1-3 days. The dosage in subsequent sessions is increased by a third or more.
For intact skin, 5-6 physiotherapy procedures are enough. If on skin there are purulent lesions, bedsores, then it is necessary to irradiate up to 12 sessions. For mucous membranes, course therapy is 10-12 sessions.
For children, local use of UVR is permitted from birth. It is limited in area. In a newborn child, the impact area is 50 cm2 or more, for schoolchildren it is not more than 300 cm2. The dosage for erythemotherapy is 0.5-1 biodose.
In acute respiratory diseases, the nasopharyngeal mucosa is treated with UV. 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. Sessions take place every day. The multiplicity of field irradiation per course is 2-3 times, oilcloth or perforated fabric is used to isolate it.
With a runny nose in the 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. The course of treatment is 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, irradiation is performed along the anterior upper part of the chest. The number of procedures per course is up to 6.
With tracheitis, pharyngitis, tonsillitis, irradiation of the back wall of the pharynx (throat) can be done using tubes. During the session, the patient should say the sound "a". The duration of the physiotherapy is 1-5 minutes. Treatment is carried out every 2 days. Course therapy is 6 sessions.
Pustular skin lesions are treated by UVI after treatment of the wound surface. The source of ultraviolet light is set at a distance of 10 cm. The duration of the session is 2-3 minutes. Treatment continues for 3 days.
Furuncles and abscesses are irradiated after opening the formation. The treatment is carried out at a distance of 10 cm to the surface of the body. The duration of one physiotherapy is 3 minutes. Course therapy 10 sessions.
UV treatment at home
Ultraviolet irradiation is permissible to carry out at home. To do this, you can purchase a UFO device at any medical equipment store. For the implementation of UV-physiotherapy at home, the apparatus "Sun" (OUFb-04) was developed. It is intended for local action on mucous membranes and skin.
For general irradiation, you can purchase a mercury-quartz lamp "Sun". It will replace part of the missing ultraviolet light in winter, disinfect the air. There are also home irradiators for shoes, water.
The device "Sun" for local use is equipped with a tube for the nose, throat, treatment of other parts of the body. The device has small size. Before purchasing, you should make sure that the device is in good condition, that there are certificates and quality assurance. 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 for the treatment of various diseases. In addition to treatment, UV devices can be used for disinfection of premises. They are used in hospitals and at home. At correct application lamp exposure does not cause harm, and the effectiveness of treatment is quite high.
Beneficial effects of UV rays on the body
The rays of the sun provide warmth and light that improve overall well-being and stimulate blood circulation. A small amount of ultraviolet light is necessary for 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 arms, face and hands two to three times a week during the summer months is enough to maintain normal vitamin D levels. Closer to the equator, where UV radiation is more intense, an even shorter period is sufficient.
Therefore, for most people, vitamin D deficiency is unlikely. 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 levels of UV radiation. Vitamin D of natural origin is very rare in our food, it is present mainly in fish oil and cod liver oil.
Ultraviolet radiation is successfully used in the treatment of many diseases, including rickets, psoriasis, eczema, etc. This therapeutic effect does not exclude negative side effects 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 immediate effects of excess ultraviolet exposure, such as burns or allergic reactions, long-term effects pose a lifelong health risk. Excessive tanning contributes to damage to the skin, eyes, and possibly the immune system. Many people forget that UV radiation accumulates throughout life. How you feel about tanning now determines your chances of developing skin cancer or cataracts later in life! The risk of developing skin cancer is directly related to the duration and frequency of tanning.
Impact atultraviolet on the skin
There is no such thing as a healthy tan! Skin cells produce a dark pigment only for the purpose of protection from subsequent radiation. Sunburn provides some protection against ultraviolet light. A dark tan on white skin is equivalent to an SPF between 2 and 4. However, this is not protection against long-term effects such as skin cancer. A tan may be cosmetically attractive, but it really only means that your skin has been damaged and is trying to protect itself.
There are two different mechanisms for the formation of a tan: a quick tan, when under the influence of ultraviolet light, the pigment already existing in the cells darkens. This tan begins to fade a few hours after exposure has ended. Long-term tanning occurs within about three days when new melanin is produced and distributed between skin cells. This tan can last for several weeks.
Sunburn- High doses of ultraviolet radiation are detrimental to most cells of the epidermis, and the surviving cells are damaged. AT best case sunburn causes redness of the skin, called erythema. It appears shortly after insolation and reaches its maximum intensity between 8 and 24 hours. In this case, the effects disappear within a few days. However, severe sunburn can leave painful blisters and white spots on the skin, the new skin in place of which is unprotected and more susceptible to UV damage.
Photosensitivity - A small percentage of the population have the ability to react very sharply to ultraviolet radiation. Even a minimal dose of ultraviolet radiation is enough to trigger allergic reactions in them, leading to a quick and severe sunburn. Photosensitivity is often associated with the use of certain medications, including some non-steroidal anti-inflammatory drugs, pain relievers, tranquilizers, oral antidiabetics, antibiotics, and antidepressants. If you constantly take any drugs, carefully read the annotation or consult with your doctor about possible photosensitivity reactions. Some food and cosmetic products, such as perfumes or soaps, may also contain ingredients that increase UV sensitivity.
Photoaging Sun 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 top 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 structures of the connective tissue and the skin gradually loses its elasticity. Wrinkles, flabbiness of the skin is a common result of this loss. A phenomenon that we often see in older people is localized overproduction of melanin resulting in dark patches or liver spots. In addition, the sun's rays dry out your skin, leaving it rough and rough.
Non-melanoma skin cancers Unlike melanoma, basal cell and squamous cell carcinomas are not usually fatal, but their surgical removal can be painful and lead to scarring.
Non-melanoma cancers are most commonly found on sun-exposed parts of the body, 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 prolonged 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 aged 20-35, especially in Australia and New Zealand. All forms of skin cancer have been on the rise over the past twenty years, however, melanoma remains the highest worldwide.
Melanoma can appear as a new mole, or as a change in color, shape, size, or sensation in pre-existing spots, freckles, or moles. Melanomas usually have an uneven contour and heterogeneous color. Itching is another common symptom, but it can also occur with normal moles. If the disease is recognized and treated in a timely manner, the prognosis for life is favorable. Left untreated, the tumor can grow rapidly and the cancer cells can spread to other parts of the body.
Effects of ultraviolet radiation on the eyes
The eyes occupy less than 2 percent of the surface of the body, but they are the only organ system that allows visible light to penetrate deep into the body. Over the course of evolution, a number of mechanisms have evolved to protect this highly sensitive organ from the harmful effects of the sun's rays:
The eye is located in the anatomical recesses of the head, protected by the brow ridges, eyebrows and eyelashes. However, this anatomical adaptation only partially protects against ultraviolet rays under extreme conditions such as tanning bed use or when light is strongly reflected off snow, water and sand.
Constriction of the pupil, closing of the eyelids and squinting minimizes the penetration of the sun's rays into the eye.
However, these mechanisms are activated by bright visible light, not ultraviolet rays, but on a cloudy day, ultraviolet radiation can also be high. Therefore, the effectiveness of these natural defense mechanisms against UV exposure is limited.
Photokeratitis and photoconjunctivitis Photokeratitis is inflammation of the cornea, while photoconjunctivitis refers to inflammation of the conjunctiva, the membrane that limits the scope of the eye and covers the inner surface of the eyelids. Inflammatory reactions of the eyeball and eyelids can be on a par with sunburn of the skin very sensitive and usually appear within a few hours after exposure. Photokeratitis and photoconjunctivitis can be very painful, but they are reversible and do not appear to cause long-term 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 high 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 blemish, thought to be related to long-term UV exposure. The pterygium may extend to the center of the cornea and thus reduce vision. This phenomenon can also be inflamed. Although the disease can be corrected surgically, it tends to recur.
Cataract- leading cause of blindness in the world. Proteins in the lens accumulate pigments that coat the lens and eventually lead to blindness. Although most people develop cataracts to varying degrees with age, they appear to be more likely to develop with exposure to ultraviolet light.
Cancers of the eyes Recent scientific evidence suggests that various forms of eye cancer may be linked to lifetime exposure to ultraviolet radiation.
Melanoma- Frequent eye cancer and sometimes requiring surgical removal. Basal cell carcinoma most often located in the region of the eyelids.
The effect of UV radiation on the immune system
Exposure to sunlight may precede cold sores. In all likelihood, UVB radiation reduces the effectiveness of the immune system and it can no longer keep the herpes simplex virus under control. As a result, the infection is released. One study in the United States examined the effect of sunscreen on the severity of herpes rashes. Of 38 patients with herpes simplex infection, 27 developed rashes after exposure to UV radiation. When using sunscreen, in contrast, none of the patients developed rashes. Therefore, in addition to protecting against the sun, sunscreen can be effective in preventing the recurrence of herpes rashes caused by sunlight.
Recent studies have increasingly shown that exposure to environmental ultraviolet radiation can alter the activity and distribution of some of the 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 itself against skin cancer. Where levels of ultraviolet radiation are 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, not many studies have been conducted to describe the potential impact of immunomodulation on cancer development.
life rays.
The sun emits three types of ultraviolet rays. Each of these types affects the skin differently.
Most of us feel more healthy and full of life after relaxing on the beach. Thanks to 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 strongly tanned skin is still damaged skin and, as a result, premature aging and high risk development of skin cancer.
Sunlight is electromagnetic radiation. In addition to the visible spectrum of radiation, it contains ultraviolet, which is actually responsible for tanning. Ultraviolet stimulates the ability of melanocyte pigment cells to produce more melanin, which performs a protective function.
Types of UV rays.
There are three types of ultraviolet rays, which differ in wavelength. Ultraviolet radiation is able to penetrate the epidermis of the skin into deeper layers. This activates the production of new cells and keratin, resulting in the skin becoming tougher and rougher. 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 level of radiation. It used to be believed that they were harmless, however, it has now been proven that this is not the case. The level of these rays remains almost 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.
UV rays B.
Rays of this type are emitted by the sun only at certain times of the year and hours of the day. Depending on air temperature and geographic latitude, they usually enter the atmosphere between 10:00 and 16:00.
Type B UV rays cause more serious damage to the skin, as they interact with DNA molecules that are 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 natural defense system of the skin.
Ultraviolet B rays cause tanning and sunburn, lead to premature aging and the appearance of dark pigment spots, make the skin rough and rough, accelerate the appearance of wrinkles, and can provoke the development of precancerous diseases and skin cancer.