It is a source of ultraviolet light. What is this radiation. The positive effect of ultraviolet radiation

Ultraviolet affects precisely living cells, without affecting the chemical composition of water and air, which exceptionally favorably distinguishes it from all chemical methods of disinfection and disinfection of water.

Achievements recent years in lighting engineering and electrical engineering make it possible to ensure a high degree of reliability of water disinfection by ultraviolet rays.

What is this radiation

Ultraviolet radiation, ultraviolet rays, UV radiation, electromagnetic radiation not visible to the eye, occupying the spectral region between visible and X-ray radiation within wavelengths of 400-10 nm. The entire region of UV radiation is conditionally divided into near (400-200 nm) and far, or vacuum (200-10 nm); the last name is due to the fact that the UV radiation of this area is strongly absorbed by air and its study is carried out using vacuum spectral instruments.

Natural sources of UV radiation - the Sun, stars, nebulae and other space objects. However, only the long-wave part of UV radiation - 290 nm reaches the earth's surface. Shorter wavelength UV radiation is absorbed by ozone, oxygen, and other components of the atmosphere at an altitude of 30-200 km from the Earth's surface, which plays an important role in atmospheric processes.

Artificial sources of UV radiation. For various applications of UV radiation, the industry produces mercury, hydrogen, xenon, etc. discharge lamps, the windows of which (or the entire flask) are made of materials that are transparent to UV radiation (often quartz). Any high-temperature plasma (plasma of electric sparks and arcs, plasma formed by focusing high-power laser radiation in gases or on a surface solids, etc.) is a powerful source of UV radiation.

Despite the fact that ultraviolet is given to us by nature itself, it is not safe.

Ultraviolet is of three types: "A"; "B"; "WITH". Ozone layer prevents ultraviolet "C" from reaching the surface of the earth. Light in the ultraviolet "A" spectrum has a wavelength of 320 to 400 nm, light in the ultraviolet "B" spectrum has a wavelength of 290 to 320 nm. UV radiation has enough energy to affect chemical bonds, including those in living cells.

The energy of the ultraviolet component sunlight causes damage to microorganisms at the cellular and genetic levels, the same damage is done to humans, but it is limited to the skin and eyes. Sunburn is caused by exposure to ultraviolet "B". Ultraviolet "A" penetrates much deeper than ultraviolet "B" and contributes to premature aging of the skin. In addition, exposure to ultraviolet "A" and "B" leads to skin cancer.

From the history of ultraviolet rays

The bactericidal effect of ultraviolet rays was discovered about 100 years ago. The first laboratory tests of UVR in the 1920s were so promising that the complete elimination of airborne infections seemed possible in the very near future. UV radiation has been actively used since the 1930s and in 1936 was first used to sterilize the air in a surgical operating room. In 1937, the first use of UV radiation in the ventilation system of an American school dramatically reduced the incidence of measles and other infections among students. Then it seemed that a wonderful remedy had been found to combat airborne infections. However, further study of UVR and hazardous side effects severely limited its use in the presence of people.

The force of penetration of ultraviolet rays is small and they propagate only in a straight line, i.e. in any working room, a lot of shaded areas are formed that are not subject to bactericidal treatment. As you move away from the source of ultraviolet radiation, the biocidal effect of its action decreases sharply. The action of the rays is limited to the surface of the irradiated object, and its purity is of great importance.

The bactericidal effect of ultraviolet radiation

The disinfecting effect of UV radiation is mainly due to photochemical reactions, which result in irreversible DNA damage. In addition to DNA, ultraviolet also affects other cell structures, in particular, RNA and cell membranes. Ultraviolet, as a high-precision weapon, affects precisely living cells without affecting the chemical composition of the environment, which is the case for chemical disinfectants. The latter property distinguishes it exceptionally favorably from all chemical methods of disinfection.

Application of ultraviolet

Ultraviolet is currently used in various areas: medical institutions (hospitals, clinics, hospitals); food industry (products, drinks); pharmaceutical industry; veterinary medicine; for disinfection of drinking, circulating and waste water.

Modern achievements in lighting and electrical engineering provided the conditions for creating large complexes UV disinfection. The widespread introduction of UV technology in municipal and industrial water supply systems allows for effective disinfection (disinfection) as drinking water before being supplied to the city water supply network, and wastewater before being released into water bodies. This makes it possible to exclude the use of toxic chlorine, significantly improve the reliability and safety of water supply and sewerage systems in general.

Disinfection of water with ultraviolet light

One of the urgent tasks in the disinfection of drinking water, as well as industrial and domestic effluents after their clarification (biotreatment) is the use of technology that does not use chemical reagents, i.e. technology that does not lead to the formation of toxic compounds during the disinfection process (as in the case of using compounds of chlorine and ozonation) with simultaneous complete destruction of pathogenic microflora.

There are three sections of the spectrum of ultraviolet radiation, which have different biological effects. Weak biological impact has ultraviolet radiation with a wavelength of 390-315 nm. Antirachitic action is possessed by UV rays in the range of 315-280 nm, and ultraviolet radiation with a wavelength of 280-200 nm has the ability to kill microorganisms.

Ultraviolet rays with a wavelength of 220-280 have a detrimental effect on bacteria, and the maximum bactericidal action corresponds to a wavelength of 264 nm. This circumstance is used in bactericidal installations intended for disinfection mainly of groundwater. The source of ultraviolet rays is a mercury-argon or mercury-quartz lamp installed in a quartz case in the center of a metal case. The cover protects the lamp from contact with water, but freely transmits ultraviolet rays. Disinfection occurs during the flow of water in the space between the body and the case with direct exposure to ultraviolet rays on microbes.

The bactericidal action is evaluated in units called bacts (b). To ensure the bactericidal effect of ultraviolet irradiation, approximately 50 μb min / cm2 is sufficient. UV irradiation is the most promising method of water disinfection with high efficiency in relation to pathogenic microorganisms, which does not lead to the formation of harmful by-products, which ozonation sometimes sins.

UV irradiation is ideal for the disinfection of artesian waters

The point of view that groundwater is considered free from microbial contamination as a result of water filtering through the soil is not entirely correct. Studies have shown that groundwater is free from large microorganisms such as protosis or helminths, but smaller microorganisms such as viruses can penetrate the soil into underground springs water. Even if bacteria are not found in the water, disinfection equipment should act as a barrier against seasonal or accidental contamination.

UV irradiation should be used to ensure the disinfection of water to a microbiological quality standard, while the necessary doses are selected based on the required reduction in the concentration of pathogenic and indicator microorganisms.

UV irradiation does not form by-products of the reaction, its dose can be increased to values ​​that ensure epidemiological safety, both for bacteria and viruses. It is known that UV radiation acts on viruses much more effectively than chlorine, so the use of ultraviolet in the preparation of drinking water makes it possible, in particular, to solve the problem of removing hepatitis A viruses, which is not always solved with traditional chlorination technology.

The use of UV irradiation as a disinfectant is recommended for water that has already been treated for color, turbidity and iron content. The effect of water disinfection is controlled by determining the total number of bacteria in 1 cm3 of water and the number of indicator bacteria of the Escherichia coli group in 1 liter of water after its disinfection.

To date, UV lamps of the flow type have become widespread. The main element of this installation is a block of irradiators consisting of UV spectrum lamps in an amount determined by the required capacity for treated water. Inside the lamp has a cavity for the duct. Contact with UV rays occurs through special windows inside the lamp. The body of the unit is made of metal, which protects against the penetration of rays into the environment.

The water supplied to the installation must meet the following requirements:

• total iron content - no more than 0.3 mg / l, manganese - 0.1 mg / l;


• hydrogen sulfide content - no more than 0.05 mg / l;


• turbidity - no more than 2 mg / l for kaolin;


• chromaticity - no more than 35 degrees.

The ultraviolet disinfection method has the following advantages in relation to oxidative disinfection methods (chlorination, ozonation):

• UV exposure is lethal to most aquatic bacteria, viruses, spores and protozoa. It destroys the causative agents of such infectious diseases as typhus, cholera, dysentery, viral hepatitis, poliomyelitis, etc. The use of ultraviolet radiation makes it possible to achieve more effective disinfection than chlorination, especially with respect to viruses;


• disinfection with ultraviolet light occurs due to photochemical reactions inside microorganisms, therefore, its effectiveness is much less affected by changes in the characteristics of water than during disinfection with chemical reagents. In particular, the effect of ultraviolet radiation on microorganisms is not affected by the pH and temperature of the water;


• in water treated with ultraviolet radiation, toxic and mutagenic compounds are not detected, which have Negative influence on the biocenosis of water bodies;


• unlike oxidative technologies, there are no negative effects in case of overdose. This makes it possible to significantly simplify the control over the disinfection process and not to carry out analyzes to determine the content of the residual concentration of the disinfectant in the water;


• disinfection time under UV irradiation is 1-10 seconds in flow mode, so there is no need to create contact containers;


• Recent advances in lighting and electrical engineering make it possible to ensure a high degree of reliability of UV complexes. Modern UV lamps and ballasts for them are mass-produced and have a high service life;


• disinfection by ultraviolet radiation is characterized by lower operating costs than chlorination and, especially, ozonation. This is due to the relatively low cost of electricity (3-5 times less than with ozonation); no need for expensive reagents: liquid chlorine, sodium or calcium hypochlorite, and no need for dechlorination reagents;


• there is no need to create warehouses for toxic chlorine-containing reagents that require compliance with special technical and environmental safety measures, which increases the reliability of water supply and sewerage systems in general;


• ultraviolet equipment is compact, requires minimal space, its implementation is possible in existing technological processes treatment facilities without stopping them, with a minimum amount of construction and installation work.

I remember disinfection with UV lamps from childhood - in the kindergarten, sanatorium and even in the summer camp there were somewhat frightening structures that glowed with a beautiful purple light in the dark and from which the educators drove us away. So what exactly is ultraviolet radiation and why does a person need it?

Perhaps the first question to be answered is what ultraviolet rays are and how they work. This is usually called electromagnetic radiation, which is in the range between visible and x-rays. Ultraviolet is characterized by a wavelength from 10 to 400 nanometers.
It was discovered back in the 19th century, and this happened thanks to the discovery of infrared radiation. Having discovered the IR spectrum, in 1801 I.V. Ritter drew attention to the opposite end of the light spectrum during experiments with silver chloride. And then several scientists at once came to the conclusion about the heterogeneity of the ultraviolet.

Today it is divided into three groups:

• UV-A radiation - near ultraviolet;
• UV-B - medium;
• UV-C - far.

This division is largely due to the impact of rays on a person. The natural and main source of ultraviolet radiation on Earth is the Sun. In fact, it is from this radiation that we are saved by sunscreens. At the same time, far ultraviolet is completely absorbed by the Earth's atmosphere, and UV-A just reaches the surface, causing a pleasant tan. And on average, 10% of UV-B provokes the same sunburn, and can also lead to the formation of mutations and skin diseases.

Artificial sources of ultraviolet are created and used in medicine, agriculture, cosmetology and various sanitary institutions. Generation of ultraviolet radiation is possible in several ways: temperature (incandescent lamps), movement of gases ( gas lamps) or metal vapors (mercury lamps). At the same time, the power of such sources varies from a few watts, usually small mobile radiators, to a kilowatt. The latter are mounted in volumetric stationary installations. The areas of application of UV rays are due to their properties: the ability to accelerate chemical and biological processes, the bactericidal effect and the luminescence of certain substances.

Ultraviolet is widely used to solve a variety of problems. In cosmetology, the use of artificial UV radiation is used primarily for tanning. Solariums produce rather mild UV-A according to the introduced standards, and the share of UV-B in tanning lamps is no more than 5%. Modern psychologists recommend tanning beds for the treatment of "winter depression", which is mainly caused by vitamin D deficiency, since it is formed under the influence of UV rays. Also, UV lamps are used in manicure, since it is in this spectrum that especially resistant gel polishes, shellac and the like dry out.

Ultraviolet lamps are used to create photographs in non-standard situations, for example, to capture space objects that are invisible with a conventional telescope.

Ultraviolet is widely used in expert activities. With its help, the authenticity of the paintings is checked, since fresher paints and varnishes in such rays look darker, which means that the real age of the work can be established. Forensics also use UV rays to detect traces of blood on objects. In addition, ultraviolet light is widely used to develop hidden seals, security features and document authentication threads, as well as in lighting design shows, restaurant signs or scenery.

In medical institutions ultraviolet lamps used to sterilize surgical instruments. In addition, air disinfection using UV rays is still widespread. There are several types of such equipment.

So called high and low pressure mercury lamps, as well as xenon flash lamps. The bulb of such a lamp is made of quartz glass. The main advantage of germicidal lamps is their long service life and instantaneous ability to work. Approximately 60% of their rays are in the bactericidal spectrum. Mercury lamps are quite dangerous in operation; in case of accidental damage to the housing, thorough cleaning and demercurization of the room is necessary. Xenon lamps are less dangerous if damaged and have a higher bactericidal activity. Also germicidal lamps divided into ozone and non-ozone. The former are characterized by the presence in their spectrum of a wave with a length of 185 nanometers, which interacts with oxygen in the air and turns it into ozone. High concentrations of ozone are dangerous for humans, and the use of such lamps is strictly limited in time and is recommended only in a ventilated area. All this led to the creation of ozone-free lamps, the bulb of which is coated with a special coating that does not transmit a wave of 185 nm to the outside.

Regardless of the type, bactericidal lamps have common drawbacks: they work in complex and expensive equipment, the average life of the emitter is 1.5 years, and the lamps themselves, after burnout, must be stored packed in a separate room and disposed of in a special way in accordance with current regulations.

Consist of a lamp, reflectors and other auxiliary elements. Such devices are of two types - open and closed, depending on whether UV rays pass out or not. Open emit ultraviolet, enhanced by reflectors, into the space around, capturing almost the entire room at once, if installed on the ceiling or wall. It is strictly forbidden to treat the premises with such an irradiator in the presence of people.
Closed irradiators work on the principle of a recirculator, inside which a lamp is installed, and the fan draws air into the device and releases the already irradiated air to the outside. They are placed on the walls at a height of at least 2 m from the floor. They can be used in the presence of people, but long-term exposure is not recommended by the manufacturer, as part of the UV rays can pass out.
Among the shortcomings of such devices, one can note immunity to mold spores, as well as all the difficulties of recycling lamps and strict regulations for use, depending on the type of emitter.

Germicidal installations

A group of irradiators combined into one device used in one room is called a bactericidal installation. Usually they are quite large and are characterized by high power consumption. Air treatment with bactericidal installations is carried out strictly in the absence of people in the room and is monitored according to the Commissioning Certificate and the Registration and Control Log. It is used only in medical and hygienic institutions for disinfection of both air and water.

Disadvantages of ultraviolet air disinfection

In addition to those already listed, the use of UV emitters has other disadvantages. First of all, ultraviolet itself is dangerous for the human body, it can not only cause skin burns, but also affect the functioning of the cardiovascular system, it is dangerous for the retina. In addition, it can cause the appearance of ozone, and with it the unpleasant symptoms inherent in this gas: irritation of the respiratory tract, stimulation of atherosclerosis, exacerbation of allergies.

The effectiveness of UV lamps is quite controversial: the inactivation of pathogens in the air by permitted doses of ultraviolet radiation occurs only when these pests are static. If microorganisms move, interact with dust and air, then the required radiation dose increases by 4 times, which a conventional UV lamp cannot create. Therefore, the efficiency of the irradiator is calculated separately, taking into account all the parameters, and it is extremely difficult to choose the right ones for influencing all types of microorganisms at once.

Penetration of UV rays is relatively shallow, and even if the immobile viruses are under a layer of dust, the upper layers protect the lower ones by reflecting ultraviolet from themselves. So, after cleaning, disinfection must be carried out again.
UV irradiators cannot filter the air, they only fight microorganisms, keeping all mechanical pollutants and allergens in their original form.

The ultraviolet radiation of the Sun and artificial sources, depending on the wavelength, is divided into three ranges:

• - region A - wavelength 400-320 nm (long-wave ultraviolet radiation UV-A);
• - region B - wavelength 320-275 nm (mid-wave ultraviolet UV-B radiation);
• - region C - wavelength 275-180 nm (short-wave ultraviolet radiation UV-C).

There are significant differences in the action of long, medium and short-wave radiation on cells, tissues and the body.

Area A (UV-A) long-wave radiation has a variety of biological effects, causes skin pigmentation and fluorescence of organic substances. UV-A rays have the highest penetrating power, which allows some atoms and molecules of the body to selectively absorb the energy of UV radiation and go into an unstable excited state. The subsequent transition to the initial state is accompanied by the release of light quanta (photons) capable of initiating various photochemical processes, primarily affecting DNA, RNA, and protein molecules.

Phototechnical processes cause reactions and changes on the part of various organs and systems, which form the basis of the physiological and therapeutic effect of UV rays. The shifts and effects occurring in an organism irradiated with UV rays (photoerythema, pigmentation, desensitization, bactericidal effect, etc.) have a clear spectral dependence (Fig. 1), which serves as the basis for the differentiated use of various sections of the UV spectrum.

Figure 1 - Spectral dependence of the most important biological effects of ultraviolet radiation

Exposure to medium-wavelength UV rays causes protein photolysis with the formation of biologically active substances, and exposure to short-wavelength rays often leads to coagulation and denaturation of protein molecules. Under the influence of UV rays of the B and C ranges, especially in high doses, changes occur in nucleic acids, resulting in cell mutations.

At the same time, long-wavelength rays lead to the formation of a specific photoreactivation enzyme that promotes the recovery of nucleic acids.

1. The most widely used UV radiation is for therapeutic purposes.
2. UV rays are also used to sterilize and disinfect water, air, rooms, objects, etc.
3. Their use for preventive and cosmetic purposes is very common.
4. UV radiation is also used for diagnostic purposes, to determine the reactivity of the organism, in luminescent methods.

UV radiation is a vital factor, and its prolonged disadvantage leads to the development of a peculiar symptom complex with "light starvation" or "UV deficiency". Most often, it is manifested by the development of avitaminosis D, weakening of the protective immunobiological reactions of the body, exacerbation of chronic diseases, functional disorders of the nervous system, etc. workshops, engine rooms and in the Far North.

ultraviolet irradiation

Ultraviolet irradiation is produced by various artificial products with different wavelengths λ. The absorption of UV rays is accompanied by a number of primary photochemical and photophysical processes, which depend on their spectral composition and determine the physiological and therapeutic effect of the factor on the body.

Longwave ultraviolet(DUV) rays stimulate the proliferation of cells of the malpighian layer of the epidermis and the decarboxylation of tyrosine, followed by the formation of a spiny layer in the cells. Next comes the stimulation of the synthesis of ACTH and other hormones, etc. Various immunological changes are obtained.

DUV rays have a weaker biological effect than other UV rays, including the erythema-forming effect. To enhance the sensitivity of the skin to them, photosensitizers are used, most often compounds of the furocoumarin series (puvalen, beroxan, psoralen, amminofurin, etc.)

This property of long-wave radiation allows it to be used in the treatment of skin diseases. PUVA therapy method (salicylic alcohol is also used).

Thus, it is possible to highlight the main characteristics healing effects UV rays:

1. Therapeutic effects are

• - photosensitizing,
• - pigment-forming,
• - immunostimulating.

1. UV rays, like other areas of UV radiation, cause a change in the functional state of the central nervous system and its higher part of the cerebral cortex. Due to the reflex reaction, blood circulation improves, the sectoral activity of the digestive organs and the functional state of the kidneys increase.
2. UV rays affect metabolism, primarily mineral and nitrogen.
3. Local applications of photosensitizers are widely used for limited forms of psoriasis. V Lately UV-B is successfully used as a sensitizer as it has a greater biological activity. The combined exposure of UV-A and UV-B is called selective exposure.
4. UV rays are used for both local and general exposures. The main indications for their use are:

• - skin diseases (psoriasis, eczema, vitiligo, seborrhea, etc.)
• - chronic inflammatory diseases of internal organs (especially respiratory organs)
• - diseases of the organs of support and movement of various ethnologies
• - burns, frostbite
• - sluggish wounds and ulcers, cosmetic purposes.

Contraindications

• - acute anti-inflammatory processes,
• - diseases of the liver and kidneys with a pronounced violation of their functions,
• - hyperthyroidism,
• - increased sensitivity to UV radiation.

medium wave ultraviolet(SUV) radiation has a pronounced and versatile biological effect.

When UV radiation quanta are absorbed in the skin, low-molecular products of protein photolysis and products of lipid peroxidation are formed. They cause changes in the ultrastructural organization of biological membranes, protein-lipid complexes, membrane enzymes and their most important physicochemical and functional properties.

Photodegradation products activate the system of mononuclear phagocytes and cause degranulation of mastocytes and basophils. As a result, biologically active substances (kinin, prostaglandin, heparin, leukotrienes, thromboxanes, etc.) and vasoactive mediators (acetylcholine, histamine) are released in the irradiated area and adjacent tissues, which significantly increase vascular permeability and tone, and also help to relax smooth muscles. . Due to humoral mechanisms, the number of functioning capillaries of the skin increases, the rate of local blood flow increases, which leads to the formation erythoma.

Repeated UV irradiations can lead to the appearance of rapidly disappearing pigmentation, which contributes to an increase in the barrier function of the skin, increase its cold sensitivity and resistance to action. toxic substances and adverse factors.

Both the erythema response and other shifts induced by UV rays depend not only on the wavelength, but also on the dosage. In phototherapy, it is used in erythemal and suberythemal doses.

Exposure to suberythemal doses of UV rays promotes the formation of vitamin D in the skin, which, after its biotransformation in the liver and kidneys, is involved in the regulation of phosphorus-calcium metabolism in the body. UV irradiation contributes to the formation of not only vitamin D1, but also its isomer, ergocalcifemin (vitamin D2). The latter has an antirachitic effect, stimulates the aerobic and anaerobic pathways of cellular respiration. SUV rays in small doses also modulate the metabolism of other vitamins (A and C) and cause activation of metabolic processes in irradiated tissues. Under their influence, the adaptive-trophic function of the sympathetic nervous system is activated, disturbed processes are normalized various kinds metabolism, cardiovascular activity.

Thus, UV radiation has a pronounced biological effect. Depending on the phase of irradiation, erythema on the skin and mucous membranes can be obtained or treated at a dose that does not cause it. The mechanism of the therapeutic action of erythemal and non-erythemal doses of SUF is different, therefore, the indications for the use of ultraviolet radiation will also be different.

Ultraviolet erythema appears at the site of UV-B irradiation after 2-8 hours and is associated with the death of epidermal cells. The products of protein photolysis enter the blood stream and cause vasodilation, skin edema, migration of leukocytes, irritation of numerous receptors, leading to a number of reflex reactions of the body.

In addition, the products of photolysis entering the blood stream have a humoral effect on individual organs, the nervous and endocrine systems of the body. The phenomena of aseptic inflammation gradually subside by the seventh day, leaving behind skin pigmentation at the site of irradiation.

The main therapeutic effects of UV radiation:

1. SUV-radiations are vitamin-forming, trophostimulating, immunomodulatory - these are suberythemal doses.
2. Anti-inflammatory, analgesic, desensitizing - this is an erythemal dose.
3. Bronchial diseases, asthma, hardening - this is an erythema-free dose.

Indications for topical use of UV-B (suberythemal and erythemal doses):

• - acute neuritis
• - acute meositis
• - pustular skin diseases (furucle, carbuncle, sycosis, etc.)
• - erysipelas
• - trophic ulcers
• - sluggish wounds
• - bedsores
• - inflammatory and post-traumatic diseases of the joints
• - rheumatoid arthritis
• - bronchial asthma
• - acute and chronic bronchitis
• - acute respiratory diseases
• - inflammation of the uterine appendages
• - chronic tonsillitis.

Erythema-free zones of ultraviolet radiation of spectrum B during general irradiation of the body eliminate the effects of D-hypovitaminosis associated with a lack of sunlight. Normalizes phosphorus-calcium metabolism, stimulates the function of the sympathetic-adrenal and pituitary-adrenal systems, increases the mechanical strength of bone tissue and stimulates the formation of callus, increases the resistance of the skin of the body and the body as a whole to harmful factors external environment. Allergic and exudative reactions decrease, mental and physical performance increases. Other disorders in the body caused by solar starvation are weakened.

Indications for general application UV-B (erythema-free doses):

• - D-hypovitaminosis
• - metabolic disease
• - predisposition to pustular diseases
• - neurodermatitis
• - psoriasis
• - bone fractures and violation of the formation of callus
• - bronchial asthma
• - chronic diseases of the bronchial apparatus
• - hardening of the body.

Contraindications:

• - malignant neoplasms
• - tendency to bleed
• - systemic blood diseases
• - thyrotoxicosis
• - active tuberculosis
• - peptic ulcer of the stomach and duodenum in the acute stage
• - hypertension stage II and III
• - advanced atherosclerosis of the arteries of the brain and coronary arteries.

shortwave ultraviolet spectrum radiation(UV) radiation.

UV radiation of the short-wave range is an active physical factor, since its quanta have the largest energy reserve. It is capable of causing denaturation and photolysis of nucleic acids and proteins due to the excessive absorption of the energy of its quanta by various molecules, primarily DNA and RNA.

When acting on microorganisms, on cells, this leads to inactivation of their genome and protein denaturation, which leads to their death.

When emitting KuV rays, a bactericidal effect occurs, since their direct hit on the protein is fatal for the cells of viruses, microorganisms and fungi.

After a short spasm, the UV rays cause dilation of the blood vessels, especially the subcapillary veins.

Indications for the use of UV radiation:

• - irradiation of wound surfaces
• - bedsores and almond-shaped niches after tonsillectomy with a bactericidal chain
• - sanitation of the nasopharynx in acute respiratory diseases
• - treatment of otitis externa
• - air disinfection in operating rooms, procedural rooms, inhalation rooms, intensive care units, patient wards, children's institutions and schools.

Skin and its function

Human skin makes up 18% of the human body weight and has a total area of ​​2m2. The skin consists of three anatomically and physiologically closely interconnected layers:

• - epidermis or cuticle
• - dermis (skin itself)
• - hypodermis (subcutaneous fat lining).

The epidermis is built from different in shape and structure, layered epithelial cells (epithermocytes). Moreover, each overlying cell comes from the underlying one, reflecting a certain phase of its life.

The layers of the epidermis are located in the following sequence (from bottom to top):

• - basal (D) or germinal;
• - a layer of spiny cells;
• - a layer of keratohyalin or granular cells;
• - epeidinovy ​​or brilliant;
• - horny.

In addition to epidermocytes, in the epidermis (in the basal layer) there are cells capable of producing melanin (melanocytes), Lagerhans, Greenstein cells, etc.

The dermis is located directly below the epidermis and is separated from it by the main membrane. The dermis is divided into papillary and reticular layers. It consists of collagen, elastic and reticulin (argyrophilic) fibers, between which the main substance is located.

In the dermis, in fact, in the skin is the papillary layer, richly supplied with blood and lymphatic vessels. There are also tangles here. nerve fibers, giving rise to numerous nerve endings in the epidermis and dermis. In the dermis, sweat and sebaceous glands, hair follicles are laid at various levels.

Subcutaneous fat is the deepest layer of the skin.

The functions of the skin are complex and varied. The skin performs barrier-protective, thermoregulatory, excretory, metabolic, receptor, etc.

The barrier-protective function, which is considered the most important function of the skin of humans and animals, is carried out through various mechanisms. Thus, the strong and elastic horny layer of the skin resists mechanical influences and reduces the harmful effects of chemicals. The stratum corneum, being a poor conductor, protects the deeper layers from drying out, cooling and the action of electric current.

Figure 2 - The structure of the skin

Sebum, a product of the secretion of sweat glands and flakes of exfoliating epithelium, form an emulsion film (protective mantle) on the surface of the skin, which plays an important role in protecting the skin from exposure to chemical, biological and physical agents.

The acidic reaction of the water-lipid mantle and surface layers of the skin, as well as the bactericidal properties of the skin secretion, are an important barrier mechanism for microorganisms.

The pigment melanin plays a role in protecting against light rays.

The electrophysiological barrier is the main obstacle to the penetration of substances into the depths of the skin, including during electrophoresis. It is located at the level of the basal layer of the epidermis and is an electrical layer with heterogeneous layers. outer layer due to the acid reaction, it has a “+” charge, and a “-” facing inward. It should be borne in mind that, on the one hand, the barrier-protective function of the skin weakens the effect of physical factors on the body, and on the other hand, physical factors can stimulate the protective properties of the skin and thereby realize a therapeutic effect.

Physical thermoregulation body is also one of the most important physiological functions of the skin and is directly related to the mechanism of action of hydrotherapy factors. It is carried out by the skin by heat radiation in the form of infrared rays (44%), heat conduction (31%) and water evaporation from the skin surface (21%). It is important to note that the skin with its thermoregulatory mechanisms plays an important role in the acclimatization of the body.

Secret-excretory function skin is associated with the activity of sweat and sebaceous glands. It plays an important role in maintaining the homeostasis of the body, in the performance of skin barrier properties.

Respiratory and resorption function are closely interconnected. The respiratory function of the skin, consisting in the absorption of oxygen and the release of carbon dioxide, is of little importance in the overall balance of respiration for the body. However, respiration through the skin can increase significantly in conditions of high air temperature.

The resorption function of the skin, its permeability are of great importance not only in dermatology and toxicology. Its significance for physiotherapy is determined by the fact that the chemical component of the action of many therapeutic factors (medicinal, gas and mineral baths, mud therapy, etc.) depends on the penetration of their constituent ingredients through the skin.

exchange function skin has specific features. On the one hand, only its inherent metabolic processes occur in the skin (the formation of keratin, melanin, vitamin D, etc.), on the other hand, it takes an active part in the general metabolism in the body. Its role in fat, mineral, carbohydrate and vitamin metabolism is especially great.

The skin is also a site for the synthesis of biologically active substances (heparin, histamine, serotonin, etc.).

Receptor function skin provides its connection with the external environment. The skin performs this function in the form of numerous conditioned and unconditioned reflexes due to the presence in it of the various receptors mentioned above.

It is believed that there are 100-200 pain points per 1 cm2 of skin, 12-15 cold, 1-2 heat, 25 pressure points.

Relationship with internal organs closely related - skin changes affect the activity of internal organs, and violations of the internal organs are accompanied by shifts in the skin. This relationship is especially clearly manifested in internal diseases in the form of the so-called reflexogenic, or painful, Zakharin-Ged zones.

Zakharyin-Geda zone certain areas of the skin, in which, in diseases of the internal organs, reflected pain often appears, as well as pain and temperature hyperesthesia.

Figure 3 - Location of the Zakharyin-Ged zone

Such zones in diseases of the internal organs were also found in the head area. For example, pain in frontonasal region corresponds to the defeat of the tops of the lungs, stomach, liver, aortic mouth.

pain in the mid-eye region damage to the lungs, heart, ascending aorta.

pain in the frontotemporal region damage to the lungs and heart.

pain in the parietal region damage to the pylorus and upper intestine, etc.

Comfort zone region temperature conditions external environment, causing a subjectively good heat sensation in a person without signs of cooling or overheating.

For a naked person 17.3 0С - 21.7 0С

For a dressed person 16.7 0С - 20.6 0С

Pulsed Ultraviolet Therapy

Research Institute of Energy Engineering, Moscow State Technical University. N. E. Bauman (Shashkovsky S. G. 2000) developed a portable device "Melitta 01" for local irradiation of the affected surfaces of skin coatings, mucous membranes with highly efficient pulsed continuous spectrum ultraviolet radiation in the range of 230-380 nm.

The operating mode of this device is pulse-periodic with a frequency of 1 Hz. The device provides automatic generation of 1, 4, 8, 16, 32 pulses. Output pulsed power density at a distance of 5 cm from the burner 25 W/cm2

Indications:

• - purulent-inflammatory diseases of the skin and subcutaneous tissue (furuncle, carbuncle, hydradenitis) in the initial period of hydration and after surgical opening of the purulent cavity;
• - extensive purulent wounds, wounds after necrectomy, wounds before and after autodermoplasty;
• - granulating wounds after thermal, chemical, radiation burns;
• - trophic ulcers and sluggish wounds;
• - erysipelas;
• - herpetic inflammation of the skin and mucous membranes;
• - irradiation of wounds before and after primary surgical treatment in order to prevent the development of purulent complications;
• - disinfection of indoor air, car interior, bus and ambulance.

Pulse magnetic therapy with a rotating field and changing the frequency of repetition of impulses automatically.

The therapeutic effect is based on well-known physical laws. On the electric charge, moving through a blood vessel in a magnetic field, the Lorentz force acts, perpendicular to the charge velocity vector, constant in a constant and alternating sign, in an alternating, rotating magnetic field. This phenomenon is realized at all levels of the organism (atomic, molecular, subcellular, cellular, tissue).

The action of low-intensity pulsed magnetic therapy has an active effect on deeply located muscle, nervous, bone tissue, internal organs, improving microcirculation, stimulating metabolic processes and regeneration. Electric currents high density, induced by pulsed magnetic field, I activate the myelinated thick fibers of the nerves, as a result of which the afferent impulse from the painful focus is blocked by the spinal mechanism of the "gate block". The pain syndrome is weakened or eliminated completely already during the procedure or after the first procedures. In terms of the severity of the analgesic effect, pulsed magnetic therapy is much superior to other types of magnetic therapy.

Thanks to pulsed rotating magnetic fields, it becomes possible to indicate in the depths of tissues without damage to electric fields and currents of significant intensity. This allows you to get a pronounced therapeutic decongestant, analgesic, anti-inflammatory, stimulating regeneration processes, biostimulating effects of action, which are several times more pronounced than the therapeutic effects obtained from all known low-frequency magnetic therapy devices.

Pulsed magnetic therapy devices are modern effective tool treatment of traumatic injuries, inflammatory, degenerative-dystrophic diseases of the nervous and musculoskeletal systems.

Therapeutic effects of pulsed magnetic therapy: analgesic, decongestant, anti-inflammatory, vasoactive, stimulating regeneration processes in damaged tissues, neurostimulating, myostimulating.

Indications:

• - diseases and traumatic injuries of the central nervous system (ischemic stroke of the brain, transient cerebrovascular accident, consequences of traumatic brain injury with movement disorders, closed injuries spinal cord with motor disorders, cerebral palsy, functional hysterical paralysis),
• - traumatic injuries of the musculoskeletal system (bruises of soft tissues, joints, bones, sprains, closed fractures of bones and joints during immobilization, in the stage of reparative regeneration, open fractures of bones, joints, soft tissue injuries during immobilization, in the stage of reparative regeneration, malnutrition , muscle atrophy as a result of hypodynamia caused by traumatic injuries of the musculoskeletal system),
• - inflammatory degenerative-dystrophic injuries of the musculoskeletal system (deforming osteoarthritis of the joints with synovitis and without synovitis, widespread osteochondrosis, deforming spondylosis of the spine with symptoms of secondary radicular syndrome, cervical sciatica with symptoms of humeroscapular periatritis, thoracic sciatica, sciatica, ankylosing spondyloatritis, scoliosis in children),
• - surgical inflammatory diseases ( postoperative period after surgical interventions on the musculoskeletal system, skin and subcutaneous tissue, sluggish wounds, trophic ulcers, boils, carbuncles, phlegmon after surgery, mastitis),
• - diseases of the bronchopulmonary system (bronchial asthma of mild and moderate severity, chronic bronchitis),
• - diseases of the digestive system (hypomotor-evacuation disorders of the stomach after the stomach and vagotomy, hypomotor dysfunction of the colon, stomach and gallbladder, chronic hepatitis with moderate liver dysfunction, chronic pancreatitis with secretory insufficiency),
• - diseases of the cardiovascular system (occlusive lesions of peripheral arteries of atherosclerotic origin),
• - urological diseases (stone in the ureter, condition after lithotripsy, atony of the bladder, weakness of the sphinker and detrusor, prostatitis),
• - gynecological diseases (inflammatory diseases of the uterus and appendages, diseases caused by ovarian hypofunction),
• - chronic prostatitis and sexual disorders in men,
• - dental diseases (periodontal disease, filling pain).

Contraindications:

• - marked hypotension
• - systemic blood diseases,
• - tendency to bleed
• - thrombophlebitis,
• - thromboembolic disease, bone fractures before immobilization,
• - pregnancy,
• - thyrotoxicosis and nodular goiter,
• - abscess, phlegmon (before opening and draining the cavities),
• - malignant neoplasms,
• - feverish state
• - cholelithiasis,
• - epilepsy.

Warning:

Pulsed magnetic therapy cannot be used in the presence of an implanted pacemaker, since induced electrical potentials can disrupt its operation; with various metal objects freely lying in the tissues of the body (for example, fragments in case of injuries), if they are at a distance of less than 5 cm from the inductors, since when passing magnetic field pulses, objects made of electrically conductive materials (steel, copper, etc.) can move and cause damage to surrounding tissues. It is not allowed to influence the area of ​​the brain, heart and eyes.

Of great interest is the creation of low-intensity pulsed magnetic devices (20-150 mT) with a pulse repetition rate approximately coinciding with the frequency of the organs' own biopotentials (2-4-6-8-10-12 Hz). This would make it possible to exert a bioresonance effect on the internal organs (liver, pancreas, stomach, lungs) with a pulsed magnetic field and positively influence their function. It is already known that UTI has a positive effect at a frequency of 8-10 Hz on liver function in patients with toxic (alcoholic) hepatitis.

Ultraviolet radiation (UVR) - electromagnetic radiation of the optical range, which is conditionally divided into short-wave (UVI C - with a wavelength of 200-280 nm), medium-wave (UVI B - with a wavelength of 280-320 nm) and long-wave (UVI A - with a wavelength of 320-400 nm ).

UV radiation is generated by both natural and artificial sources. The main natural source of UV radiation is the Sun. UVR reaches the Earth's surface in the range of 280-400 nm, since shorter waves are absorbed in the upper layers of the stratosphere.

Artificial UVR sources are widely used in industry, medicine, etc.

Virtually any material heated to temperatures above 2500 eK generates UV radiation. The sources of UVR are welding with oxy-acetylene, oxy-hydrogen, and plasma torches.

Sources of biologically effective UV radiation can be divided into gas-discharge and fluorescent. The gas-discharge lamps include low-pressure mercury lamps with a maximum emission at a wavelength of 253.7 nm, i.e. corresponding to the maximum bactericidal effectiveness, and high pressure with wavelengths of 254, 297, 303, 313 nm. The latter are widely used in photochemical reactors, in printing, and for phototherapy of skin diseases. Xenon lamps are used for the same purposes as mercury lamps. The optical spectra of flash lamps depend on the gas used in them - xenon, krypton, argon, neon, etc.

In fluorescent lamps, the spectrum depends on the mercury phosphor used.

Workers of industrial enterprises and medical institutions where the above listed sources are used, as well as people working outdoors due to solar radiation (agricultural, construction, railway workers, fishermen, etc.) can be exposed to excessive exposure to UV radiation.

It has been established that both a deficiency and an excess of UV radiation adversely affect the state of human health. With UVR deficiency, children develop rickets due to a lack of vitamin D and a violation of phosphorus-calcium metabolism, the activity of the body's defense systems, primarily the immune system, decreases, which makes it more vulnerable to adverse factors.

The critical organs for the perception of UV radiation are the skin and eyes. Acute eye lesions, the so-called electrophthalmia (photophthalmia), are acute conjunctivitis. The disease is preceded by a latent period, the duration of which is about 12 hours. Chronic conjunctivitis, blepharitis, cataracts of the lens are associated with chronic eye lesions.

Skin lesions occur in the form of acute dermatitis with erythema, sometimes swelling, up to the formation of blisters. Along with a local reaction, general toxic phenomena may be observed. Further hyperpigmentation and peeling are observed. chronic changes skin caused by UV radiation are expressed in skin aging, the development of keratosis, atrophy of the epidermis, malignant neoplasms are possible.

Recently, interest in improving the health of the population through prophylactic ultraviolet irradiation has increased significantly. Indeed, ultraviolet starvation, usually observed in the winter season and especially among the inhabitants of the North of Russia, leads to a significant decrease in the body's defenses and an increase in the level of morbidity. Children are the first to suffer.

Our country is the founder of the movement to compensate for ultraviolet deficiency in the population using artificial sources of ultraviolet radiation, the spectrum of which is close to natural. Experience with artificial sources of ultraviolet radiation requires appropriate adjustment in terms of dose and methods of use.

The territory of Russia from south to north extends from 40 to 80? NL and is conditionally divided into five climatic regions of the country. Let us estimate the natural ultraviolet climate of two extreme and one middle geographic regions. These are the regions of the North (70? N - Murmansk, Norilsk, Dudinka, etc.), Middle lane(55? N - Moscow, etc.) and the South (40? N - Sochi, etc.) of our country.

Recall that according to the biological effect, the spectrum of ultraviolet radiation from the Sun is divided into two areas: "A" - radiation with a wavelength of 400-315 nm, and "B" - radiation with a wavelength of less than 315 nm (up to 280 nm). However, rays shorter than 290 nm do not reach practically the earth's surface. Ultraviolet radiation with a wavelength of less than 280 nm, which is found only in the spectrum of artificial sources, belongs to the "C" region of ultraviolet radiation. A person does not have receptors that urgently (with a small latent period) react to ultraviolet radiation. A feature of natural UV radiation is its ability to cause (with a relatively long latent period) erythema, which is a specific reaction of the body to the action of UV radiation from the solar spectrum. UV radiation with a wavelength of maximum 296.7 nm is capable of forming erythema to the greatest extent. (Table 10.1).

Table 10.1.Erythema effectiveness of monochromatic UV radiation

As seen from tab. 10.1, radiation with a wavelength of 285 nm 10 times, and rays with a wavelength of 290 nm and 310 nm 3 times less actively form erythema than radiation with a wavelength of 297 nm.

The arrival of the daily UV radiation of the sun for the above regions of the country in the summer (Table 10.2) relatively high 35-52 er-h / m -2 (1 er-h / m -2 \u003d 6000 μW-min / cm 2). However, in other periods of the year there is a significant difference, and in winter, especially in the North, there is no natural radiation from the sun.

Table 10.2.Average distribution of erythemal radiation of the area (er-h/m -2)

northern latitude	Month
	III	VI	IX	XII
			18,2
	26,7		46,5

Value total radiation reflects the daily arrival of radiation at different latitudes. However, when taking into account the amount of radiation that arrives on average not for 24, but only for 1 hour, the following picture emerges. So, in June at latitude 70? NL 35 er-h / m -2 arrives per day. At the same time, the sun does not leave the sky for 24 hours, therefore, erythemal radiation per hour will be 1.5 er-h / m -2. In the same period of the year at latitude 40? The sun emits 77 er-h/m -2 and shines for 15 hours, therefore, the hourly erythemal irradiance will be 5.13 er-h/m -2, i.e. the value is 3 times greater than at latitude 70?. To determine the irradiation mode, it is advisable to assess the arrival of the total UV solar radiation not in 24, but in 15 hours, i.e. for the period of wakefulness of a person, since in the end we are interested in the amount of natural radiation that affects a person, and not the amount of solar energy falling on the surface of the Earth in general.

An important feature of the effect of natural UV radiation on humans is the ability to prevent the so-called D-vitamin deficiency. Unlike conventional vitamins, vitamin D is not actually found in natural foods (the exceptions are the liver of some fish, especially cod and halibut, as well as egg yolk and milk). This vitamin is synthesized in the skin under the influence of UV radiation.

Insufficient exposure to UV radiation without the simultaneous action of visible radiation on the human body leads to various manifestations of D-avitaminosis.

In the process of D-vitamin deficiency, the trophism of the central nervous system and cellular respiration, as a substrate of nervous trophism, are primarily disturbed. This disturbance, leading to a weakening of redox processes, should obviously be considered the main one, while all other diverse manifestations will be secondary. The most sensitive to the absence of UV radiation are young children, who, as a result of D-avitaminosis, may develop rickets and, as a result of rickets, myopia.

The ability to prevent and cure rickets to the greatest extent has UV radiation in the B region.

The process of synthesizing vitamin D under the influence of UV radiation is quite complex.

In our country, vitamin D was obtained synthetically in 1952. Cholesterol served as the raw material for the synthesis. During the conversion of cholesterol to provitamin, a double bond was formed in the B ring of the sterol by successive bromination. The resulting 7-dehydrocholesterol benzoate is saponified to G-dehydrocholesterol, which is already converted into a vitamin under the influence of UV radiation. Complex processes of transition of provitamin into vitamin depend on the spectral composition of UV radiation. So, rays with a wavelength of maximum 310 nm are able to convert ergosterol into lumisterol, which turns into techisterol, and, finally, under the action of rays with a wavelength of 280-313 nm, techisterol is converted into vitamin D.

Vitamin D in the body regulates the content of calcium and phosphorus in the blood. With a deficiency of this vitamin, phosphorus-calcium metabolism is disturbed, which is closely related to the processes of ossification of the skeleton, acid-base balance, blood clotting, etc.

With rickets, conditioned reflex activity is disturbed, while the formation of conditioned reflexes occurs more slowly than in healthy people, and they quickly disappear, i.e. the excitability of the cerebral cortex in children suffering from rickets is significantly reduced. At the same time, the cells of the cortex function poorly and are easily depleted. In addition, there is a disorder of the inhibitory function of the cerebral hemispheres.

Inhibition for a long time can be widely distributed throughout the cerebral cortex.

It is quite clear that it is necessary to carry out appropriate preventive measures, i.e. use a full UV climate.

Source type	Power, W	Irradiance in energy units at a distance of 1 m
		UV radiation area A		UV radiation area B		UV radiation area C
		μW / cm 2	%	μW / cm 2	%	μW / cm 2	%
PRK-7 (DRK-7)	1000
LER-40		28,6		22,6

However, it should be noted that the spectral composition of the artificial radiation climate that occurs under the conditions of a photorium with a PRK-type lamp differs significantly from the natural one in the presence of short-wave UV radiation.

With the release of low-power erythemal luminescent lamps in our country, it became possible to use artificial sources of UV radiation in photorium conditions and in the general lighting system.

Dose of prophylactic UV radiation. A few words from history. Prophylactic irradiation of miners began in the 1930s. At that time, there was no relevant experience and the necessary theoretical basis regarding the choice of dose specifically

prophylactic exposure. It was decided to use the medical experience used in physiotherapy practice in the treatment of various diseases. Borrowed were not only sources of UV radiation, but also the irradiation scheme. The biological effect of irradiation with PRK lamps, in the spectrum of which there is bactericidal radiation, was very doubtful. Thus, we found that the ratio of the biological activity of areas "B" and "C", involved in the formation of erythema, is 1:8. The first methodological guidelines for the use of fotaries were developed mainly by physiotherapists. In the future, hygienists and biologists dealt with the issues of preventive exposure. In the 1950s, the problem of prophylactic exposure acquired a hygienic focus. Numerous studies have been carried out in different cities and climatic regions of Russia, which have allowed a new approach to the dose of prophylactic UV radiation.

Establishment prophylactic dose UV radiation is a very difficult task, because a number of interrelated factors must be addressed and taken into account, such as:

Source of UV radiation;

How to use it;

The area of ​​the irradiated surface;

The season of the beginning of irradiation;

Photosensitivity of the skin (biodose);

Irradiation intensity (irradiance);

Irradiation time.

In the work, erythema lamps were used, in the spectrum of which there is no bactericidal UV radiation. Erythema biodose

Table 10.4.The relationship of physical and reduced units for

Dose expressions for UV radiation in region B (280-350 nm)

	μW / cm 2	mEr-h / m 2	μEr-h / cm 2	mEr-min / m 2
μW / cm 2		0,0314
mEr-h / m 2
μEr-h / m 2		0,157
mEr-min / m 2		0,0157

expressed in physical (μW / cm 2) or reduced (μEr / cm 2) values, the ratios of which are presented in tab. 10.4.

It should be emphasized that the irradiance of the erythemal flux of UV radiation can be assessed in effective (or reduced) units - eras (Er is the erythemal flux of radiation with a wavelength of 296.7 nm with a power of 1 W) only when the area "B" is radiated.

To express the irradiance of the “B” section of the UV spectrum in eras, its irradiance, expressed in physical units (W), should be multiplied by the coefficient of erythemal sensitivity of the skin. The coefficient of erythemal sensitivity of the skin for rays with a wavelength of 296.7 nm was adopted in 1935 by the International Commission on Illumination as a unit.

Using LER lamps, we started to find the optimal prophylactic dose of UV radiation and evaluate the "irradiation method", which refers mainly to the duration of daily exposure, lasting from a minute to several hours.

In turn, the duration of prophylactic irradiation depends on the method of using artificial emitters (using emitters in a general lighting system or in photarium conditions) and on skin photosensitivity (on the value of erythemal biodose).

Of course, with different methods of using artificial emitters, different areas of the surface of the body are exposed to radiation. So, when using fluorescent lamps in the general lighting system, only open parts of the body are irradiated - the face, hands, neck, scalp, and in the photorium - almost the entire body.

UV exposure in the room when using erythemal lamps is small, hence the duration of exposure is 6-8 hours, while in the photorium, where the exposure reaches a significant value, the effect of radiation does not exceed 5-6 minutes.

When finding the optimal dose of prophylactic exposure, one should be guided by the fact that the initial dose of prophylactic exposure should be lower than the biodose, i.e. suberythemal. Otherwise, skin burns may occur. The prophylactic dose of the UV component should be expressed in absolute terms.

Raising the question of expressing the prophylactic dose in absolute physical (reduced) quantities is by no means

means eliminating the need to determine individual skin sensitivity to UV radiation. Determining the biodose before the start of irradiation is necessary, but only to find out if it is not less than the recommended prophylactic dose. In practice, when determining biodose (according to Gorbachev), it is possible to use a biodimeter that has not 8 or 10 holes, as is the case in medical practice, but much less or even one, which can be irradiated with a dose equal to prophylactic. If the irradiated area of ​​the skin turns red, i.e. If the biodose is less than the prophylactic one, then the initial dose of irradiation should be reduced, and the irradiation is carried out with increasing doses at an initial dose equal to the biodose.

A comparative analysis of such physiological indicators as erythemal biodose, phagocytic activity of blood leukocytes, capillary fragility, alkaline phosphatase activity indicated that additional artificial exposure to UV radiation with erythemal lamps, carried out in winter, causing a very positive effect, does not fully contribute to maintaining the studied physiological reactions at the level that is observed in autumn after prolonged exposure to natural UV radiation.

An analysis of the levels of physiological parameters of those exposed to a dose of UV radiation with different methods of irradiation, due to the method of using artificial emitters, made it possible to conclude that the biological effect of exposure to UV radiation does not depend on the methods of irradiation used.

The dynamics of skin sensitivity to UV radiation in a known way reflects the processes occurring in the body as a result of a long absence of natural UV radiation.

In preventive UV exposure, it is necessary to take into account the climatic features of the area where the irradiated people live (to determine the timing of exposure), the average value of their erythemal biodose (to select the initial dose of exposure) and the fact that the prophylactic exposure dose, normalized in absolute terms, should not be lower than 2000 μW-min / cm 2 (60-62 mEr-h / m 2).

Preventive measures to prevent acute conjunctivitis when exposed to UV radiation are reduced to the use of light-protective glasses or shields for electric welding and other work with UV sources. Used to protect the skin from UV radiation

protective clothing, sunscreens (canopies), special creams.

The main role in the prevention of the adverse effects of UV radiation on the body belongs to hygienic standards. Currently, there are "Sanitary standards for ultraviolet radiation in industrial premises" CH? 4557-88. The normalized value is the irradiance, W/m1. These standards regulate the allowable UVR values ​​for the skin, taking into account the duration of exposure during a work shift and the area of ​​the irradiated skin surface.

Ultraviolet radiation (ultraviolet, UV, UV) - electromagnetic radiation, occupying the range between the violet border of visible radiation and X-ray radiation (380 - 10 nm, 7.9 1014 - 3 1016 Hertz).

The concept of ultraviolet rays first encountered by a 13th-century Indian philosopher in his work. The atmosphere of the Bhootakasha area he described contained violet rays that could not be seen with the naked eye.

Shortly after infrared radiation was discovered, the German physicist Johann Wilhelm Ritter began looking for radiation at the opposite end of the spectrum, with a wavelength shorter than that of violet. In 1801, he discovered that silver chloride, which decomposes under the influence of light, is faster decomposes under the action of invisible radiation outside the violet region of the spectrum. White silver chloride darkens in the light for several minutes. Different parts of the spectrum have different effects on the darkening rate. This happens most quickly before the violet region of the spectrum. It was then agreed by many scientists, including Ritter, that light consisted of three separate components: an oxidizing or thermal (infrared) component, an illuminating component (visible light), and a reducing (ultraviolet) component. At that time, ultraviolet radiation was also called actinic radiation. The ideas about the unity of the three different parts of the spectrum were first voiced only in 1842 in the works of Alexander Becquerel, Macedonio Melloni and others.

The electromagnetic spectrum of ultraviolet radiation can be divided into subgroups in different ways. The ISO standard for the definition of solar radiation (ISO-DIS-21348) gives the following definitions:

Name	Abbreviation	Wavelength in nanometers	The amount of energy per photon
Near		400 nm - 300 nm	3.10 - 4.13 eV
Average		300 nm - 200 nm	4.13 - 6.20 eV
Further		200 nm - 122 nm	6.20 - 10.2 eV
Extreme		121 nm - 10 nm	10.2 - 124 eV
Ultraviolet A, long wavelength		400 nm - 315 nm	3.10 - 3.94 eV
Ultraviolet B, medium wave		315 nm - 280 nm	3.94 - 4.43 eV
UV C, shortwave		280 nm - 100 nm	4.43 - 12.4 eV

The near ultraviolet range is often referred to as "black light" because it is not recognizable by the human eye, but when reflected from some materials, the spectrum goes into the visible radiation region.

The term "vacuum" (VUV) is often used for the far and extreme range, due to the fact that waves in this range are strongly absorbed by the Earth's atmosphere.

The biological effects of ultraviolet radiation in the three spectral regions are significantly different, so biologists sometimes distinguish the following ranges as the most important in their work:

Near ultraviolet, UV-A rays (UVA, 315-400 nm)

UV-B rays (UVB, 280-315 nm)

Far ultraviolet, UV-C rays (UVC, 100-280nm)

Virtually all UVC and approximately 90% UVB are absorbed by ozone, as well as water vapour, oxygen and carbon dioxide as sunlight passes through the earth's atmosphere. Radiation from the UVA range is rather weakly absorbed by the atmosphere. Therefore, the radiation that reaches the Earth's surface contains a large part of the near ultraviolet UVA and a small proportion - UVB.

Somewhat later, in the works (O. G. Gazenko, Yu. E. Nefedov, E. A. Shepelev, S. N. Zaloguev, N. E. Panferova, I. V. Anisimova), the indicated specific effect of radiation was confirmed in space medicine . Prophylactic UV irradiation was introduced into the practice of space flights along with the Guidelines (MU) 1989 "Prophylactic ultraviolet irradiation of people (using artificial sources of UV radiation)". Both documents are a reliable basis for further improvement of UV prevention.

Skin exposure to ultraviolet radiation that exceeds the skin's natural protective ability to tan leads to burns.

Long-term exposure to ultraviolet radiation can contribute to the development of melanoma and premature aging.

Ultraviolet radiation is imperceptible to the human eye, but with intense exposure it causes a typical radiation injury (retinal burn).

natural springs

The main source of ultraviolet radiation on Earth is the Sun. The ratio of UV-A to UV-B radiation intensity, the total amount of ultraviolet rays reaching the Earth's surface, depends on the following factors:

on the concentration of atmospheric ozone above the earth's surface (see ozone holes)

from the height of the sun above the horizon

from height above sea level

from atmospheric dispersion

from cloud cover

on the degree of reflection of UV rays from the surface (water, soil)

Thanks to the creation and improvement of artificial sources of UV radiation, which went in parallel with the development of electric sources of visible light, today specialists working with UV radiation in medicine, preventive, sanitary and hygienic institutions, agriculture, etc., are provided with significantly greater opportunities than with using natural UV radiation.

There are a number of lasers operating in the ultraviolet region. The laser makes it possible to obtain coherent radiation of high intensity. However, the ultraviolet region is difficult for laser generation, so there are no sources as powerful here as in the visible and infrared ranges. Ultraviolet lasers find their application in mass spectrometry, laser microdissection, biotechnology and other scientific research.

Many polymers used in consumer products degrade when exposed to UV light. To prevent degradation, special substances capable of absorbing UV are added to such polymers, which is especially important when the product is exposed to direct sunlight. The problem manifests itself in the disappearance of color, tarnishing of the surface, cracking, and sometimes the complete destruction of the product itself. The rate of destruction increases with increasing time of exposure and intensity of sunlight.

The described effect is known as UV aging and is one of the varieties of polymer aging. Sensitive polymers include thermoplastics such as polypropylene, polyethylene, polymethyl methacrylate (organic glass) as well as special fibers such as aramid fiber. UV absorption leads to the destruction of the polymer chain and loss of strength at a number of points in the structure. The action of UV on polymers is used in nanotechnologies, transplantation, X-ray lithography, and other fields to modify the properties (roughness, hydrophobicity) of the surface of polymers. For example, the smoothing effect of vacuum ultraviolet (VUV) on the surface of polymethyl methacrylate is known.

Applications: Ultraviolet (UV) disinfection, Air and hard surface sterilization, Drinking water disinfection, Chemical analysis, UV spectrometry, Mineral analysis, Qualitative chromatographic analysis, Insect trapping, Fake tanning and "Mountain Sun", restoration.