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Ultraviolet radiation. How does ultraviolet radiation affect the human body? Effect of UV on the eyes

The spectrum of rays visible to the human eye does not have a sharp, clearly defined boundary. Some researchers call the upper limit of the visible spectrum 400 nm, others 380, and still others shift it to 350...320 nm. This is explained by different light sensitivity of vision and indicates the presence of rays invisible to the eye.
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 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 concluded that ultraviolet rays are very active.
Ultraviolet rays cover a wide range of radiation: 400...20 nm. The radiation region of 180... 127 nm is called vacuum. Using artificial sources (mercury-quartz, hydrogen and arc lamps), producing both line and 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 from the sun reaching earth's surface, very narrow - 400...290 nm. Doesn't the sun 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 put forward a hypothesis: the Sun emits short-wave ultraviolet radiation, under its influence oxygen molecules break down into individual atoms, forming ozone molecules, therefore, in the upper layers of the atmosphere, ozone should cover the earth with a protective screen. Cornu's hypothesis was confirmed when people rose to 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 20 times.
Special experiments have established that when rising upward for every 100 m, the intensity of ultraviolet radiation increases by 3...4%. The share of scattered ultraviolet radiation at summer noon accounts for 45...70% of the radiation, and that reaching the earth's surface - 30...55%. On cloudy days, when the solar disk is covered with clouds, mainly scattered radiation reaches the Earth's surface. 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 earth's surface in the equatorial region. In mid-latitudes, the short-wave limit, during the summer months, is approximately 297 nm. During the period of effective illumination, the upper limit of the spectrum is about 300 nm. Beyond the Arctic Circle, rays with a wavelength of 350...380 nm reach the earth's surface.

The 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 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 disintegration of organic substances. Therefore, the progress of life forms on Earth occurred 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.
Of interest to us are ultraviolet radiation from the Sun and artificial sources of ultraviolet radiation in the range of 400...180 nm. Within this range there are three areas:

A - 400...320 nm;
B - 320...275 nm;
C - 275...180 nm.

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 thermal effect ultraviolet rays have no noticeable effect on the body. Another way of transmitting energy is luminescence.
Photochemical reactions under the influence of ultraviolet rays are most intense. The energy of ultraviolet light photons is very high, so when they are absorbed, the molecule ionizes and breaks into pieces. Sometimes a photon knocks an electron out of the atom. Most often, excitation of atoms and molecules occurs. When absorbing 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 38000°C.
The bulk of solar energy reaches the earth in the form of visible light and infrared radiation, and only a small part in the form of ultraviolet radiation. Maximum values The UV flux reaches mid-summer in the Southern Hemisphere (the Earth is 5% closer to the Sun) and 50% of the daily amount of UV arrives within 4 midday hours. Diffey found that for 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 UV. At noon, the UV intensity (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 and passes through glass and the stratum corneum of the skin. The UV-A flux (mean value 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 at different times of the year. Due to absorption, reflection and dispersion 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 through glass, 70% is reflected by the stratum corneum, and is weakened by 20% 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 effects 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 scattered stronger (shorter wavelength) than UV-A when passing through the atmosphere, which leads to a change in the ratio between these fractions with increasing geographic latitude (in northern countries) and time of day.
UV-C (200-280 nm) is absorbed by the ozone layer. If an artificial ultraviolet source is used, it is retained by the epidermis and does not penetrate the dermis.

The effect of ultraviolet radiation on the cell

In the effect of short-wave radiation on a living organism, the greatest interest 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. Absorbed energy can migrate along a chain of atoms within a molecule without significant loss until it reaches weak bonds between atoms and breaks the bond. During this process, called photolysis, fragments of molecules are formed that have strong effect on the body. For example, histamine is formed from the amino acid histidine, a substance that dilates blood capillaries and increases their permeability. In addition to photolysis, denaturation occurs in biopolymers under the influence of ultraviolet rays. When irradiated with light of a certain wavelength, the electrical charge of molecules decreases, they stick together and lose their activity - enzymatic, hormonal, antigenic, etc.
The processes of photolysis and denaturation of proteins occur in parallel and independently of each other. They are caused by different radiation ranges: rays of 280...302 nm cause mainly photolysis, and 250...265 nm - mainly denaturation. The combination of these processes determines the pattern of action of ultraviolet rays on the cell.
The most sensitive cell function to ultraviolet rays is division. Irradiation at a dose of 10(-19) J/m2 causes about 90% fission arrest 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, and 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, and heredity of cells, i.e. on the main manifestations of life.
The importance of the mechanism of action on nucleic acid is explained by the fact that each DNA (deoxyribonucleic acid) molecule is unique. DNA is the cell's hereditary memory. Its structure encrypts information about the structure and properties of all cellular proteins. If any protein is present in a living cell in the form of tens or 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, disturbances in the DNA structure may be irreparable or lead to serious disruption of life.

The effect of ultraviolet radiation on the skin

Exposure to ultraviolet radiation on the skin significantly affects our body's metabolism. It is well known that it is UV rays that initiate the process of 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. Research by German scientists has shown that when blood serum is irradiated with UV rays, the content of serotonin, the “hormone of vigor”, which is involved in the regulation of the emotional state, increases by 7%. 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 lifts your 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 (photoophthalmia) and found that they are based on common causes.
There are caloric and ultraviolet erythema. Caloric erythema is caused by the effect of visible and infrared rays on the skin and the flow of blood to it. It disappears almost immediately after the irradiation ceases.
After the cessation of exposure to UV irradiation, after 2..8 hours, redness 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 tanning and peeling. The duration of erythema ranges from 10...12 hours to 3...4 days. The reddened skin is hot to the touch, slightly painful and appears swollen and slightly swollen.
Essentially, erythema is an inflammatory reaction, a burn of the skin. This is a special, aseptic (Aseptic - putrefactive) inflammation. If the radiation dose is too high or the skin is especially sensitive to it, the edematous fluid accumulates, peels off the outer layer of the skin in places, and forms blisters. In severe cases, areas of necrosis (death) of the epidermis appear. A few days after the erythema disappears, the skin darkens and begins to peel. As peeling occurs, some of the cells containing melanin are exfoliated (Melanin is the main pigment of the human body; it gives color to the skin, hair, and iris of the eye. It is also contained in the pigment layer of the retina and is involved in the perception of light), the tan fades. Thickness skin a person varies depending on gender, age (in children and the elderly - thinner) and localization - on average 1..2 mm. Its purpose is to protect the body from damage, temperature fluctuations, and pressure.
The main layer of the epidermis is adjacent to the skin itself (dermis), which contains blood vessels and nerves. 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 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 dead cells of the stratum corneum, they have no effect on the body. The effect of irradiation depends on the penetrating ability of the rays and the thickness of the stratum corneum. The shorter the radiation wavelength, the lower their penetrating ability. Rays shorter than 310 nm do not penetrate deeper than the epidermis. Rays with a longer wavelength reach the papillary layer of the dermis, in which 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 germinal (basic) layer of the epidermis. The processes of photolysis and denaturation lead to the death of styloid cells of the germ layer. Active protein photolysis products cause vasodilation, skin swelling, release of leukocytes and other typical signs of erythema.
Photolysis products, spreading through the bloodstream, also irritate the nerve endings of the skin and, through the central nervous system, reflexively affect all organs. 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, the occurrence of which involves active products of photolysis. The severity of erythema and the possibility of its formation depends on the condition nervous system. On affected areas of the skin, with frostbite, or 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. Finsen (Denmark) first used ultraviolet radiation to treat a number of diseases in 1899. Currently, the manifestations of the effects 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. To rays with longer or shorter wavelengths, 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 are produced by the resonant emission line of mercury vapor used in mercury-quartz lamps.
Thus, the curve of erythemal sensitivity of the skin has two maxima. The depression between the two maxima is provided by the shielding effect of the stratum corneum of the skin.

Protective functions of the body

Under natural conditions, after erythema, skin pigmentation develops - tanning. The spectral maximum of pigmentation (340 nm) does not coincide with any of the peaks of erythemal sensitivity. Therefore, by selecting a radiation source, you can cause pigmentation without erythema and vice versa.
Erythema and pigmentation are not stages of the same process, although they follow one another. This is a manifestation of different processes related to each other. The skin pigment melanin is formed in the cells of the lowest layer of the epidermis - melanoblasts. The starting material for the formation of melanin are amino acids and adrenaline breakdown products.
Melanin is not just a pigment or a passive protective screen that fences off living tissue. Melanin molecules are huge molecules with a network structure. In the links of these molecules, fragments of molecules destroyed by ultraviolet radiation are bound and neutralized, preventing them from entering 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 heat stroke. Near-infrared rays and visible light, especially its long-wave, “red” part, can penetrate tissue 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 a constant temperature, from overheating.
The body's operational mechanism to protect itself from overheating is a rush of blood to the skin and dilation 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 at a high temperature, another cooling mechanism comes into play - evaporation due to sweating. These thermoregulatory mechanisms are designed to protect against exposure to visible and infrared rays from the Sun.
Sweating, along with the function of thermoregulation, prevents the effects of ultraviolet radiation on humans. 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 small amounts 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 the hematopoietic organs, the reticuloendothelial system (the physiological system of connective tissue that produces antibodies that destroy bodies and microbes foreign to the body), the barrier properties of the skin, and 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 part of bones, participates in blood clotting, compacts cell and tissue membranes, and regulates enzyme activity. A disease that occurs due to a lack of vitamin D in children in the first years of life, whom 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 fatigue of a person. In large cities, where the air is polluted with dust, ultraviolet rays that cause erythema almost do not reach the surface of the Earth. Long-term work in mines, engine rooms and closed factory workshops, 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 significant. For example, yellow color completely absorbs ultraviolet rays. The lack of light, especially ultraviolet radiation, is felt by people, pets, birds and houseplants during the autumn, winter and spring periods.
Lamps that, along with visible light, emit ultraviolet rays in the wavelength range 300...340 nm can compensate for the lack of ultraviolet rays. It should be borne in mind that errors in prescribing the radiation dose, inattention to such issues as the spectral composition of ultraviolet lamps, the direction of radiation and the height of the lamps, the duration of lamp burning, can cause harm instead of benefit.

Bactericidal effect of ultraviolet radiation

It is impossible not to note the bactericidal function of UV rays. IN medical institutions They actively use this property to prevent nosocomial infections and ensure the sterility of surgical units and dressing rooms. The effect 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, and 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, promoting 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 varying sensitivity to ultraviolet rays. Yeasts, molds and bacterial spores are much more resistant to their action than vegetative forms of bacteria. Spores of individual fungi, surrounded by a thick and dense shell, thrive in high layers of the atmosphere and it is possible that they can travel even in space.
The sensitivity of microorganisms to ultraviolet rays is especially great during the period of division and immediately before it. The curves for the bactericidal effect, inhibition and cell growth practically coincide with the absorption curve for nucleic acids. Consequently, denaturation and photolysis of nucleic acids leads to the cessation of division and growth of microorganism cells, and in large doses to their death.
The bactericidal properties of ultraviolet rays are used to disinfect air, tools, dishes, and with their help increase shelf life food products, disinfect drinking water, inactivate viruses when preparing vaccines.

Negative effects of ultraviolet radiation

A number of negative effects that occur when exposed 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 is known, these damages can be divided into:
  • acute, caused by a large dose of radiation received during a short time(for example, sunburn or acute photodermatoses). They occur primarily due to UV-B rays, the energy of which is many times greater than the energy of UVA rays. Solar radiation is distributed unevenly: 70% of the dose of UV-B rays received by humans occurs in the summer and midday, when the rays fall almost vertically and do not slide tangentially - under these conditions the maximum amount of radiation is absorbed. Such damage is caused by the direct effect of UV radiation on chromophores - it is these molecules that selectively absorb UV rays.
  • delayed, caused by long-term irradiation with moderate (suberythemal) doses (for example, such damage includes photoaging, skin neoplasms, some photodermatitis). They arise mainly due to spectrum A rays, which carry less energy, but are able to penetrate deeper into the skin, and their intensity varies little during the day and practically does not depend on the time of year. As a rule, this type of damage is the result of exposure to the products of free radical reactions (remember that free radicals are highly reactive molecules that actively interact with proteins, lipids and the genetic material of cells).
    The role of UV rays of the A spectrum in the etiology of photoaging has been proven by the work 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. Pain in the eye, redness, lacrimation, and partial blindness occur as a result of degeneration and death of cells of the conjunctiva and cornea. 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 lamps
    Discharge lamps are used as sources of UV radiation, in which, during the process of electrical discharge, radiation is generated containing a wavelength range of 205-315 nm (the rest of the radiation spectrum plays a secondary role). These lamps include low and low mercury lamps. high pressure, as well as xenon flash lamps.
    Mercury vapor lamps low pressure constructively and electrical parameters practically no different from conventional fluorescent lighting lamps, except that their bulb is made of special quartz or uviol glass with a high transmittance of UV radiation, on the inner surface of which there is no layer of phosphor applied. These lamps are available in a wide range of wattages from 8 to 60 W. 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 instantaneous ability to work after they are ignited.
    The bulb of high-pressure mercury-quartz lamps 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 the room, but they have low bactericidal efficiency and a short service life of 500-1,000 hours. In addition, normal combustion mode occurs 5-10 minutes after they are ignited.
    A significant disadvantage of continuous radiant lamps is the risk of contamination of the environment with mercury vapor if the lamp is destroyed. If the integrity of bactericidal lamps is damaged and mercury enters the room, thorough demercurization of the contaminated room must be carried out.
    IN last years A new generation of emitters has appeared - short-pulse ones, which have 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 produced using xenon lamps, as well as using lasers. There is currently no data on the difference between the biocidal effect of pulsed UV radiation and that of traditional UV radiation.
    The advantage of xenon flash lamps is due to their higher bactericidal activity and shorter exposure time. Another advantage of xenon lamps is that if they are accidentally destroyed environment not contaminated by mercury vapor. The main disadvantages of these lamps that hold them back wide application, is the need to use high-voltage, complex and expensive equipment for their operation, as well as the limited resource of the emitter (on 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 their 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 monitoring of the ozone content in the air and careful 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 the bulb from a special material (coated quartz glass) or its design, the output of the 185 nm line radiation is eliminated.
    Germicidal lamps that have expired or are out of order must be stored packaged 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. Germicidal 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 flow from lamps and a reflector (or without it), which covers a wide area of ​​\u200b\u200bthe space around them. Installed on the ceiling or wall. Irradiators 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 changes in wavelength upon reflection and some other factors. When using combined irradiators, the bactericidal flow from shielded lamps must be directed to the upper zone of the room in such a way as to prevent direct flow from the lamp or reflector from escaping into the lower zone. In this case, the irradiance from reflected fluxes from the ceiling and walls on a conventional 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 holes of the recirculator. When using supply and exhaust ventilation, bactericidal lamps are placed in the exit chamber. The air flow speed is provided either by natural convection or forced by a fan. Closed-type irradiators (recirculators) must 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 premises divided into categories (GOST), it is recommended that rooms of categories I and II be equipped with both closed irradiators (or supply and exhaust ventilation) and open or combined ones - 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 for children with active form tuberculosis, nephroso-nephritis, feverish condition 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 precautions 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 reduced to half the recommended time in order to establish the user's skin reaction. If any adverse reaction is detected after the first session, further use of UV irradiation is not recommended.
    Regular irradiation over a long period of 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 erythemal-effective irradiation may be. It is recommended to occasionally interrupt regular radiation sessions.
    Therapeutic irradiation must be carried out with the mandatory use of reliable eye protection.
    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, but dark-skinned people may not feel completely safe either.

    Very careful with natural and artificial UV exposure of the whole body should be the following categories of people:

  • Gynecological patients (ultraviolet light can increase inflammation).
  • Having a large number of birthmarks on the body, or areas of accumulation of birthmarks, or large birthmarks
  • Have been treated for skin cancer in the past
  • Working indoors during the week and then sunbathing for long periods of time on the weekends
  • Living or vacationing in the tropics and subtropics
  • Those with freckles or burns
  • Albinos, blondes, fair-haired and red-haired people
  • Having close relatives with skin cancer, especially melanoma
  • Living or vacationing in the mountains (every 1000 meters above sea level adds 4% - 5% solar activity)
  • Staying in the open air for a long time for various reasons
  • Having undergone any organ transplantation
  • Suffering from certain chronic diseases, such as systemic lupus erythematosus
  • Receiving the following medications: Antibacterials (tetracyclines, sulfonamides and some others) Non-steroidal anti-inflammatory drugs, for example, naproxen Phenothiazides, used as sedatives and antinausea agents Tricyclic antidepressants Thiazide diuretics, for example, hypothiazide Sulfourea drugs, tablets that reduce blood glucose Immunosuppressants
    • Long-term, uncontrolled exposure to ultraviolet radiation is especially dangerous for children and adolescents, as it can cause the development of melanoma, the most rapidly progressing skin cancer, in adulthood.

    Over the many years of its development, medicine has achieved significant success. This science widely uses the developments of physicists and chemists in everyday practice, which facilitates the diagnosis of diseases and makes their therapy as effective as possible. Modern methods treatments are now practiced even in small medical institutions; almost every clinic has a special physiotherapeutic treatment room, where many unique devices operate. Doctors widely use ultraviolet radiation in their practice, let's talk about its place in medicine, and discuss the use of ultraviolet radiation in medicine in a little more detail.

    Ultraviolet radiation is electromagnetic waves, the length of which ranges from 180 to 400 nm. Such physical factor It is characterized by many properties and can have a pronounced positive effect on the human body. It is actively used in physiotherapy for more successful treatment of a number of diseases.

    Ultraviolet rays can penetrate the skin to a depth of no more than one millimeter, causing a number of different biochemical changes in it. Experts identify several types of such radiation, they can be presented:

    Long-wave radiation (wavelength ranges from 320 to 400 nm);
    - medium-wave radiation (wavelength indicators are in the range from 275 to 320 nm);
    - short-wave radiation (wavelength varies from 180 to 275 nm).

    All types of ultraviolet radiation have different effects on the human body.

    Long wave radiation

    This ultraviolet radiation is characterized by pigmenting qualities. When it comes into contact with the skin, it provokes the development of a number of chemical reactions, which are accompanied by the production of melanin, and the skin appears to tan.

    Also, long-wave radiation has a pronounced immunostimulating effect, increasing local immunity and nonspecific resistance of the human body to the aggression of many unfavorable factors.

    In addition, this type of ultraviolet irradiation is characterized by photosensitizing properties. Its effect leads to increased skin sensitivity and active production of melanin. Therefore, in people with dermatological diseases, long-wave radiation causes swelling of the skin and erythema. Therapy in this case leads to normalization of pigmentation and structural features of the skin. This type of treatment is classified as photochemotherapy.

    Long-wave ultraviolet radiation in medicine is used to treat chronic inflammatory processes of the respiratory system and ailments of the osteoarticular system, which are of an inflammatory nature. This effect is also used in the treatment of burns, frostbite, trophic ulcers and skin diseases such as vitiligo, psoriasis, mycosis fungoides, seborrhea, etc.

    Medium wave radiation
    This type of ultraviolet therapy has a pronounced immunostimulating effect, promotes the production and absorption of a number of vitamins, and helps eliminate pain and inflammation. In addition, medium-wave radiation is characterized by desensitizing qualities (reduces the body’s sensitivity to the effects of protein photodestruction products) and stimulates trophism (improves blood flow, increases the number of working vessels).

    This type of ultraviolet therapy helps to cope with inflammatory lesions of the respiratory system and post-traumatic changes in the musculoskeletal system. It is used in the treatment of inflammatory lesions of bones and joints, represented by arthritis and arthrosis, as well as in the elimination of vertebrogenic radiculopathies, neuralgia, myositis and plexitis. In addition, mid-wave ultraviolet radiation is indicated for patients with sun starvation, metabolic diseases and erysipelas.

    Shortwave radiation

    This type of ultraviolet radiation has a pronounced bactericidal and fungicidal effect (activates reactions that help destroy the structure of bacteria and fungi), promotes detoxification of the body (helps to produce substances in the body that can neutralize toxins). In addition, short-wave radiation is characterized by metabolic properties - during its implementation, microcirculation improves, as a result of which organs and tissues are saturated with a significant amount of oxygen. This therapy also corrects blood clotting abilities - it changes the ability of blood cells to form blood clots and optimizes coagulation processes.

    Short-wave radiation is used in the treatment of a number of skin diseases, including psoriasis, neurodermatitis, and skin tuberculosis. Neem treats various wounds, erysipelas, abscesses, as well as boils and carbuncles. This therapy helps to cope with otitis and tonsillitis, cure osteomyelitis and eliminate long-term non-healing ulcerative lesions on the skin.

    Short-wave ultraviolet radiation is used in complex treatment rheumatic damage to the heart valves, coronary heart disease, hypertension (first or second degree) and a number of gastrointestinal ailments (peptic ulcers and gastritis). In addition, this effect helps eliminate acute and chronic diseases respiratory organs, treatment of diabetes mellitus, acute andexitis and chronic pyelonephritis.

    Like any other effect on the body, ultraviolet radiation has a number of contraindications for use.

    Ultraviolet light is a type of electromagnetic radiation that causes black light posters to glow, is responsible for summer tanning, and sunburn. However, too much exposure to UV radiation damages living tissue.

    Electromagnetic radiation comes from the sun and is transmitted in waves or particles at different wavelengths and frequencies. This broad range of wavelengths is known as the electromagnetic (EM) spectrum. The spectrum is usually divided into seven regions in order of decreasing wavelength and increasing energy and frequency. Common designations are radio waves, microwaves, infrared (IR), visible, ultraviolet (UV), x-rays and gamma rays.

    Ultraviolet (UV) light falls in the range of the EM spectrum between visible light and X-rays. It has frequencies of approximately 8 × 1014 to 3 × 1016 cycles per second or hertz (Hz) and wavelengths of about 380 nanometers (1.5 × 10-5 in) to about 10 nm (4 × 10-7 in). According to "Ultraviolet Radiation" by U.S. Navy, UV is usually divided into three subranges:

    • UVA or near UV (315-400 nm)
    • UVB or mid UV (280-315 nm)
    • UVC, or far UV (180-280 nm)

    Ultraviolet light has enough energy to break chemical bonds. Because of their higher energies, UV photons can cause ionization, a process in which they are separated from atoms. The resulting vacancy affects Chemical properties atoms and causes them to form or break chemical bonds that they would not otherwise have. This may be useful for chemical treatment, or it may damage materials and living tissue. This damage can be useful, for example on disinfecting surfaces, but it can also be harmful, especially to the skin and eyes, which are most adversely affected by ultraviolet radiation.


    Most of natural light with ultraviolet rays from the sun. However, only about 10 percent of sunlight is ultraviolet radiation, and only about a third of this penetrates the atmosphere when it reaches the ground. Of the sunlight, 95% reaches the equator, and 5% is ultraviolet. No measurable UFC from solar radiation does not reach the Earth's surface because ozone, molecular oxygen and water vapor in the upper atmosphere completely absorb the shortest UV wavelengths. However, “broad-spectrum ultraviolet radiation is the strongest and most destructive to living things,” according to the 13th NTP Carcinogen Report.”


    Tanning is a reaction to exposure to harmful rays. In fact, tanning is due to natural defense mechanism organism, which consists of a pigment called melanin, which is produced by cells in the skin called melanocytes. Melanin absorbs ultraviolet light and dissipates it as heat. When the body senses sun damage, it sends melanin to surrounding cells and tries to protect them from further damage. The pigment causes the skin to darken.

    “Melanin is a natural sunscreen,” the assistant professor of dermatology at Tufts University School of Medicine said in a 2013 interview. However, constant exposure to ultraviolet light can suppress the body's defenses. When this happens, a toxic reaction occurs, leading to sunburn. Ultraviolet light can damage the DNA in the body's cells. The body senses this destruction and floods the area with blood to aid in the healing process. Painful inflammation also occurs. Usually during the afternoon, due to overexposure from the sun, the characteristic red-lobster appearance of a sunburn begins to become known and felt.

    Sometimes cells with DNA mutated by sunlight turn into problem cells that do not die but continue to spread like cancer. “Ultraviolet light causes random damage during the DNA repair process, so that cells gain the ability to avoid death,” Zhuang said.

    The result is skin cancer, the most common form of cancer. People who get sunburn are at significantly higher risk. The risk of a deadly form of skin cancer called melanoma doubles for those who have five or more sunburns, according to the Skin Cancer Foundation.


    A number of artificial sources have been developed to produce ultraviolet light. According to the Society for Health Physics, "Artificial sources include tanning booths, black lights, vulcanization lamps, germicidal lamps, mercury lamps, halogen lamps, high-intensity discharge lamps, fluorescent and incandescent lamps and some types of lasers.”

    One of the most common ways to produce ultraviolet light is to pass an electric current through vaporized mercury or some other gas. This type of lamp is commonly used in tanning booths and for disinfecting surfaces. Lamps are also used in black lamps, which cause fluorescent paints and dyes. Light-emitting diodes (LEDs), lasers, and arc lamps are also available as ultraviolet sources in a variety of wavelengths for industrial, medical, and research applications.


    Many substances, including minerals, plants, fungi and microbes, as well as organic and inorganic chemicals, can absorb ultraviolet light. Absorption causes electrons in the material to jump more high level energy. These electrons can then return to a lower energy level in a series of smaller steps, emitting some of their absorbed energy as visible light—fluorescence. Materials used as pigments in paint or dye that exhibit such fluorescence become brighter under sunlight because they absorb invisible ultraviolet light and re-emit it at visible wavelengths. For this reason, they are commonly used for signs, life jackets and other applications where high visibility is important.

    Fluorescence can also be used to detect and identify certain minerals and organic materials. Fluorescent probes allow researchers to detect specific components of complex biomolecular assemblies, such as living cells, with elegant sensitivity and selectivity.

    In fluorescent lamps used for lighting, ultraviolet light with a wavelength of 254 nm is produced together with blue light, which is emitted when an electric current passes through mercury vapor. This ultraviolet radiation is invisible, but contains more energy than the visible light emitted. Ultraviolet light energy is absorbed by the fluorescent coating inside the fluorescent lamp and emitted as visible light. Similar tubes without the same fluorescent coating emit ultraviolet light, which can be used to disinfect surfaces since the ionizing effects of UV radiation can kill most bacteria.


    Besides the sun, there are numerous celestial sources of ultraviolet light. In space, very large young stars shine most of their light at ultraviolet wavelengths, according to NASA. Because the Earth's atmosphere blocks most ultraviolet light, especially at shorter wavelengths, observations are made using high-altitude balloons and orbiting telescopes equipped with specialized image sensors and filters for observing in the UV region of the EM spectrum.

    Most observations are made using charge-coupled devices (CCDs), detectors designed to be sensitive to short-wave photons, according to Robert Patterson, a professor of astronomy at the University of Missouri. These observations can determine the surface temperatures of the hottest stars and reveal the presence of intervening gas clouds between Earth and quasars.

    Treatment of cancer with ultraviolet light

    While exposure to ultraviolet light can lead to skin cancer, some skin conditions can be treated with ultraviolet light. In a procedure called psoraline ultraviolet light treatment (PUVA), patients take medication or apply lotion to make the skin sensitive to light. Ultraviolet light is then shined onto the skin. PUVA is used to treat lymphoma, eczema, psoriasis and vitiligo.

    It may seem counterintuitive to treat skin cancer with the same thing that caused it, but PUVA may be beneficial due to the effect of ultraviolet light on skin cell production. This slows down growth, which plays an important role in the development of the disease.

    The key to the origin of life?


    Recent research suggests that ultraviolet light may have played a key role in the origin of life on Earth, especially in the origin of RNA. In a 2017 paper in the Astrophysics Journal, the study's authors note that red dwarf stars cannot emit enough ultraviolet light to initiate the biological processes needed to produce the ribonucleic acid needed for all life on Earth. The study also suggests that this finding could help in the search for life in other parts of the universe.

    General characteristics of ultraviolet radiation

    Note 1

    Ultraviolet radiation discovered I.V. Ritter in $1842$. Subsequently, the properties of this radiation and its application were subjected to the most careful analysis and study. Scientists such as A. Becquerel, Warshawer, Danzig, Frank, Parfenov, Galanin and many others made a great contribution to this study.

    Currently ultraviolet radiation widely used in various fields of activity. Peak activity due to ultraviolet radiation reaches in the interval high temperatures. This type of spectrum appears when the temperature reaches from $1500$ to $20000$ degrees.

    Conventionally, the radiation range is divided into 2 areas:

    1. Near spectrum, which reaches the Earth from the Sun through the atmosphere and has a wavelength of $380$-$200$ nm;
    2. Distant Spectrum absorbed by ozone, air oxygen and other atmospheric components. This spectrum can be studied using special vacuum devices, which is why it is also called vacuum. Its wavelength is $200$-$2$ nm.

    Ultraviolet radiation can be short-range, long-range, extreme, medium, vacuum, and each type has its own properties and finds its own application. Each type of ultraviolet radiation has its own wavelength, but within the limits indicated above.

    Spectrum of ultraviolet sunlight, reaching the Earth's surface, is narrow - $400$...$290$ nm. It turns out that the Sun does not emit light with a wavelength shorter than $290$ nm. Is this true or not? The answer to this question was found by a Frenchman A. Cornu, who established that ultraviolet rays shorter than $295$ nm are absorbed by ozone. Based on this, A. Cornu suggested that the Sun emits short-wave ultraviolet radiation. Oxygen molecules under its influence disintegrate into individual atoms and form ozone molecules. Ozone in the upper atmosphere covers the planet protective screen.

    Scientist's guess confirmed when man managed to rise to the upper layers of the atmosphere. The height of the Sun above the horizon and the amount of ultraviolet rays reaching the earth's surface are directly related. When the illumination changes by $20$%, the amount of ultraviolet rays reaching the surface will decrease by $20$ times. Experiments have shown that for every $100$ m of ascent, the intensity of ultraviolet radiation increases by $3$-$4$%. In the equatorial region of the planet, when the Sun is at its zenith, rays with a length of $290$...$289$ nm reach the earth's surface. The earth's surface above the Arctic Circle receives rays with a wavelength of $350$...$380$ nm.

    Ultraviolet radiation sources

    Ultraviolet radiation has its sources:

    1. Natural springs;
    2. Man-made sources;
    3. Laser sources.

    Natural source ultraviolet rays is their only concentrator and emitter - this is our Sun. The star closest to us emits a powerful charge of waves that can pass through the ozone layer and reach the earth's surface. Numerous studies have allowed scientists to put forward the theory that only with the advent of the ozone layer was life able to arise on the planet. It is this layer that protects all living things from harmful excessive penetration of ultraviolet radiation. The ability for the existence of protein molecules, nucleic acids and ATP became possible precisely during this period. Ozone layer performs a very important function, interacting with the bulk UV-A, UV-B, UV-C, it neutralizes them and does not allow them to reach the surface of the Earth. Ultraviolet radiation arriving at the earth's surface has a range that ranges from $200$ to $400$ nm.

    The concentration of ultraviolet radiation on Earth depends on a number of factors:

    1. The presence of ozone holes;
    2. Position of the territory (height) above sea level;
    3. The height of the Sun itself;
    4. The ability of the atmosphere to scatter rays;
    5. Reflectivity of the underlying surface;
    6. States of cloud vapors.

    Artificial sources Ultraviolet radiation is usually created by humans. These can be instruments, devices, and technical means designed by people. They are created to obtain the desired spectrum of light with specified wavelength parameters. The purpose of their creation is so that the resulting ultraviolet radiation can be usefully used in various fields of activity.

    Sources of artificial origin include:

    1. Having the ability to activate the synthesis of vitamin D in human skin erythema lamps. They not only protect against rickets, but also treat this disease;
    2. Special apparatus for solariums, preventing winter depression and giving a beautiful natural tan;
    3. Used indoors to control insects attractant lamps. They pose no danger to humans;
    4. Mercury-quartz devices;
    5. Excilamps;
    6. Luminescent devices;
    7. Xenon lamps;
    8. Gas discharge devices;
    9. High temperature plasma;
    10. Synchrotron radiation in accelerators.

    Artificial sources of ultraviolet radiation include lasers, whose operation is based on the generation of inert and non-inert gases. This can be nitrogen, argon, neon, xenon, organic scintillators, crystals. Currently exists laser working for free electrons. It produces a length of ultraviolet radiation equal to that observed under vacuum conditions. Laser ultraviolet is used in biotechnological, microbiological research, mass spectrometry, etc.

    Application of ultraviolet radiation

    Ultraviolet radiation has characteristics that allow it to be used in various fields.

    UV characteristics:

    1. High level of chemical activity;
    2. Bactericidal effect;
    3. The ability to cause luminescence, i.e. glow of different substances in different shades.

    Based on this, ultraviolet radiation can be widely used, for example, in spectrometric analyses, astronomy, medicine, and disinfection drinking water, analytical study of minerals, for the destruction of insects, bacteria and viruses. Each area uses a different type of UV with its own spectrum and wavelength.

    Spectrometry specializes in identifying compounds and their composition based on their ability to absorb UV light of a specific wavelength. Based on the results of spectrometry, the spectra for each substance can be classified, because they are unique. The destruction of insects is based on the fact that their eyes detect short-wave spectra that are invisible to humans. Insects fly to this source and are destroyed. Special installations in solariums expose the human body to UV-A. As a result, melanin production is activated in the skin, which gives it a darker and more even color. Here, of course, it is important to protect sensitive areas and eyes.

    Medicine. The use of ultraviolet radiation in this area is also associated with the destruction of living organisms - bacteria and viruses.

    Medical indications for ultraviolet treatment:

    1. Trauma to tissues, bones;
    2. Inflammatory processes;
    3. Burns, frostbite, skin diseases;
    4. Acute respiratory diseases, tuberculosis, asthma;
    5. Infectious diseases, neuralgia;
    6. Diseases of the ear, nose and throat;
    7. Rickets and trophic gastric ulcers;
    8. Atherosclerosis, renal failure, etc.

    This is not the entire list of diseases for which ultraviolet radiation is used.

    Note 2

    Thus, ultraviolet helps doctors save millions of human lives and restore their health. Ultraviolet light is also used to disinfect premises and sterilize medical instruments and work surfaces.

    Analytical work with minerals. Ultraviolet radiation causes luminescence in substances, and this makes it possible to use it to analyze the qualitative composition of minerals and valuable rocks. Very interesting results produce precious, semi-precious and ornamental stones. When irradiated with cathode waves, they give amazing and unique shades. The blue color of topaz, for example, when irradiated turns out to be bright green, emerald - red, pearls shimmer with multicolors. The spectacle is amazing, fantastic.

    In agricultural production, for the technological impact of optical radiation on living organisms and plants, special sources of ultraviolet (100...380 nm) and infrared (780...106 nm) radiation, as well as sources of photosynthetically active radiation (400...700 nm) are widely used.

    Based on the distribution of the optical radiation flux between different areas of the ultraviolet spectrum, sources of general ultraviolet (100...380 nm), vital (280...315 nm) and predominantly bactericidal (100...280 nm) effects are distinguished.

    Sources of general ultraviolet radiation- high-pressure mercury tube arc lamps of the DRT type (mercury-quartz lamps). A DRT lamp is a quartz glass tube with tungsten electrodes soldered into the ends. A dosed amount of mercury and argon is introduced into the lamp. For ease of fastening to the fittings, DRT lamps are equipped with metal holders. DRT lamps are available with a power of 2330, 400, 1000 W.

    Vital fluorescent lamps of the LE type are made in the form of cylindrical tubes made of uviol glass, the inner surface of which is covered with a thin layer of phosphor, emitting a light flux in the ultraviolet region of the spectrum with a wavelength of 280...380 nm (maximum radiation in the region of 310...320 nm). Apart from the type of glass, tube diameter and phosphor composition, tubular vital lamps are structurally no different from tubular low-pressure fluorescent lamps and are connected to the network using the same devices (throttle and starter) as fluorescent lamps of the same power. LE lamps are available in 15 and 20 W outputs. In addition, vital lighting fluorescent lamps have been developed.

    Germicidal lamps- these are sources of short-wave ultraviolet radiation, most of which (up to 80%) occurs at a wavelength of 254 nm. The design of bactericidal lamps is not fundamentally different from tubular low-pressure fluorescent lamps, but the glass with alloying additives used for their manufacture transmits radiation well in the spectral range less than 380 nm. In addition, the bulb of bactericidal lamps is not coated with phosphor and has slightly reduced dimensions (diameter and length) compared to similar general-purpose fluorescent lamps of the same power.

    Germicidal lamps are connected to the network using the same devices as fluorescent lamps.

    Lamps with increased photosynthetically active radiation. These lamps are used for artificial irradiation of plants. These include low-pressure fluorescent photosynthetic lamps of the LF and LFR types (P means reflector), high-pressure mercury arc fluorescent photosynthetic lamps of the DRLF type, high-pressure metal halide mercury arc lamps of the DRF, DRI, DROT, DMC types, and tungsten arc mercury lamps of the DRV type.

    Low-pressure fluorescent photosynthetic lamps of the LF and LFR types are similar in design to low-pressure fluorescent lamps and differ from them only in the composition of the phosphor, and, consequently, in the emission spectrum. In LF type lamps, the relatively high radiation density lies in the wave ranges of 400...450 and 600...700 nm, which account for the maximum spectral sensitivity of green plants.

    DRLF lamps are structurally similar to DRL type lamps, but unlike the latter, they have increased radiation in the red part of the spectrum. Under the phosphor layer, DRLF lamps have a reflective coating that ensures the required distribution of the radiant flux in space.

    In the simplest case, the source of infrared radiation can be an ordinary incandescent lighting lamp. In its emission spectrum, the infrared region occupies almost 75%, and the flow of infrared rays can be increased by reducing the voltage supplied to the lamp by 10...15% or by painting the bulb blue or red. However, the main source of infrared radiation is special infrared reflector lamps.

    Infrared mirror lamps(thermal emitters) differ from conventional lighting lamps in the paraboloid shape of the bulb and the lower temperature of the filament. The relatively low temperature of the filament of thermal emitter lamps makes it possible to shift the spectrum of their radiation to the infrared region and increase the average burning time to 5000 hours.

    The inner part of the bulb of such lamps, adjacent to the base, is covered with a mirror layer, which allows the emitted infrared flux to be redistributed and concentrated in a given direction. To reduce the intensity of visible radiation, the lower part of the bulb of some infrared lamps is coated with red or blue heat-resistant varnish.

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