Types of ultraviolet radiation. How are infrared rays different from ultraviolet rays?

Everyone knows that the Sun - the center of our planetary system and an aging star - emits rays. Solar radiation consists of ultraviolet rays (UV / UV) type A, or UVA - long wavelength, type B, or UVB - short wavelength. Our understanding of the types of damage they can cause to the skin and how best to protect against UV seems to change every year as new research emerges. For example, it was once believed that only UVBs were harmful to the skin, but we are learning more and more from research about the damage caused by UVA. As a result, improved forms of UVA protection are emerging that can, when applied correctly, prevent sun damage.

What is UV radiation?

UV radiation is part of the electromagnetic (light) spectrum that reaches the Earth from the Sun. The wavelength of UV radiation is shorter than the visible light spectrum, making it invisible to the naked eye. Radiation by wavelength is divided into UVA, UVB and UVC, with UVA being the longest wavelength (320-400 nm, where nm is a billionth of a meter). UVA is subdivided into two more wavelength ranges: UVA I (340-400 nm) and UVA II (320-340 nm). The UVB range is from 290 to 320 nm. The shorter UVC rays are absorbed by the ozone layer and do not reach the earth's surface.

However, two types of rays - UVA and UVB - penetrate the atmosphere and are the cause of many diseases - premature skin aging, eye damage (including cataracts) and skin cancer. They also suppress the immune system, reducing the body's ability to fight these and other diseases.

UV radiation and skin cancer

By damaging the skin's cellular DNA, excessive UV radiation causes genetic mutations that can lead to skin cancer. Therefore, both the US Department of Health and Human Services and the World Health Organization have recognized UV as a proven human carcinogen. UV radiation is considered the main cause of non-melanoma skin cancer (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). These cancers affect more than a million people worldwide each year, of which more than 250,000 are US citizens. Many experts believe that, especially for people with pale skin, UV radiation often plays a key role in the development of melanoma, the deadliest form of skin cancer that kills more than 8,000 Americans every year.

UV A radiation

Most of us are exposed to a lot of UV light throughout our lives. UVA rays account for up to 95% of the UV radiation that reaches the Earth's surface. Although they are less intense than UVB, UVA rays are 30 to 50 times more common. They are present with relatively equal intensity throughout the daylight hours throughout the year and can penetrate clouds and glass.

It is UVA, which penetrates the skin more deeply than UVB, that is to blame for skin aging and wrinkling (so-called solar geroderma), but until recently, scientists believed that UVA did not cause significant damage to the epidermis (the outermost layer of the skin), where most cases of skin cancer. However, studies over the past two decades show that it is UVA that damages skin cells called keratinocytes in the basal layer of the epidermis, where most skin cancers develop. Basal and squamous cells are types of keratinocytes.

UVA is also the main cause of tanning, and we now know that tanning (whether outdoors or in a tanning bed) causes damage to the skin that gets worse over time as the skin's DNA gets damaged. It turns out that the skin darkens precisely because in this way the body tries to prevent further DNA damage. These mutations can lead to skin cancer.

An upright tanning bed mainly emits UVA. The lamps used in tanning salons emit 12 times more UVA than the sun. Not surprisingly, people who use a tanning salon are 2.5 times more likely to develop squamous cell carcinoma and 1.5 times more likely to develop basal cell carcinoma. According to recent studies, first exposure to a tanning bed at a young age increases the risk of melanoma by 75%.

UV B radiation

UVB, which are the main cause of skin redness and sunburn, mainly damages the more superficial epidermal layers of the skin. UVB plays a key role in the development of skin cancer, aging and skin darkening. The intensity of radiation depends on the season, location and time of day. The most significant amount of UVB hits the US between 10:00 am and 4:00 pm from April to October. However, UVB rays can damage the skin all year round, especially at high altitudes and on reflective surfaces such as snow or ice, which bounce back up to 80% of the rays so that they hit the skin twice. The only good news is that UVB practically does not penetrate glass.

Protective measures

Remember to protect yourself from UV radiation both indoors and outdoors. Always look for shade outside, especially between 10:00 and 16:00. And since UVA penetrates glass, consider adding a tinted UV protection film to the top of your car's side and rear windows, as well as your home and office windows. This film blocks up to 99.9% of UV radiation and transmits up to 80% of visible light.

When outdoors, wear sun protection clothing with UPF (Ultra Violet Protection Factor) to limit UV exposure. The higher the UPF values, the better. For example, a shirt with UPF 30 means that only 1/30th of the sun's ultraviolet radiation can reach the skin. There are special additives in laundry detergents that provide higher UPF values ​​in ordinary fabrics. Do not ignore the opportunity to protect yourself - choose those fabrics that have the best protection from the sun's rays. For example, bright or dark shiny clothes reflect more UV radiation than light and bleached cotton fabrics; however, loose clothing provides a greater barrier between your skin and the sun's rays. Finally, wide-brimmed hats and UV-protective sunglasses help protect the sensitive skin on the forehead, neck, and around the eyes—these areas typically suffer the most damage.

Protective Factor (SPF) and UV B radiation

With the advent of modern sunscreens, it has become a tradition to measure their effectiveness with the sun protection factor, or SPF. Oddly enough, SPF is not a factor or a measure of protection as such.

These numbers simply indicate how long it takes for UVB rays to redden the skin when using sunscreen compared to how long the skin would redden without the product. For example, using sunscreen with SPF 15, a person will prolong the time of safe exposure to the sun by 15 times compared to exposure in similar conditions without sunscreen. Sunscreen SPF 15 blocks 93% of the sun's UVB rays; SPF 30 - 97%; and SPF 50 - up to 98%. A cream with an SPF of 15 or even higher is essential for adequate day-to-day skin protection during the sunny season. For longer or more intense sun exposure, such as being at the beach, SPF 30 or higher is recommended.

sunscreen component

Since UVA and UVB are harmful to the skin, protection from both types of rays is essential. Effective protection starts with an SPF of 15 or higher, and the following ingredients are also important: stabilized avobenzone, ecamsule ( also known as MexorylTM), oxybenzone, titanium dioxide, and zinc oxide. On sunscreen labels, phrases like “multiple spectrum protection,” “broad spectrum protection,” or “UVA/UVB protection” all indicate that UVA protection is included. However, such phrases may not be entirely true.

There are currently 17 active ingredients approved by the FDA (Food and Drug Administration) for use in sunscreens. These filters fall into two broad categories: chemical and physical. Most UV filters are chemical, meaning they form a thin protective film on the surface of the skin and absorb UV radiation before the rays penetrate the skin. Physical sunscreens most often consist of insoluble particles that reflect UV rays away from the skin. Most sunscreens contain a mixture of chemical and physical filters.

• Look for shade, especially between 10:00 and 16:00.
• Don't get burned.
• Avoid intense tanning and vertical tanning beds.
• Wear covered clothing, including a wide-brimmed hat and UV-blocking sunglasses.
• Use a broad spectrum (UVA/UVB) sunscreen with SPF 15 or higher every day. For prolonged outdoor activity, use a waterproof, broad-spectrum (UVA/UVB) sunscreen with an SPF of 30 or higher.
• Apply a generous amount (2 tablespoons minimum) of sunscreen all over your body 30 minutes before going outside. Reapply the cream every two hours or immediately after swimming/excessive sweating.
• Keep newborns out of the sun, as sunscreen can only be used on babies over six months old.
• Every month, check your skin from head to toe - if you find something suspicious, then run to the doctor.
• See your doctor for a professional skin exam annually.

Ultraviolet radiation in medicine is used in the optical range of 180-380 nm (integrated spectrum), which is divided into the short-wave region (C or UV) - 180-280 nm, medium-wave (B) - 280-315 nm and long-wave (A) - 315- 380 nm (DUV).

Physical and physiological effects of ultraviolet radiation

Penetrates into biological tissues to a depth of 0.1-1 mm, absorbed by molecules of nucleic acids, proteins and lipids, has photon energy sufficient to break covalent bonds, electronic excitation, dissociation and ionization of molecules (photoelectric effect), which leads to the formation of free radicals, ions, peroxides (photochemical effect), i.e. there is a consistent transformation of the energy of electromagnetic waves into chemical energy.

The mechanism of action of UV radiation - biophysical, humoral and neuro-reflex:

Change in the electronic structure of atoms and molecules, ionic conjuncture, electrical properties of cells;
- inactivation, denaturation and coagulation of the protein;
- photolysis - the breakdown of complex protein structures - the release of histamine, acetylcholine, biogenic amines;
- photooxidation - increased oxidative reactions in tissues;
- photosynthesis - reparative synthesis in nucleic acids, elimination of damage in DNA;
- photoisomerization - internal rearrangement of atoms in a molecule, substances acquire new chemical and biological properties (provitamin - D2, D3),
- photosensitivity;
- erythema, with KUF develops 1.5-2 hours, with DUV - 4-24 hours;
- pigmentation;
- thermoregulation.

Ultraviolet radiation has an effect on the functional state of various human organs and systems:

Leather;
- central and peripheral nervous system;
- autonomic nervous system;
- the cardiovascular system;
- blood system;
- hypothalamus-pituitary-adrenal glands;
- endocrine system;
- all types of metabolism, mineral metabolism;
- respiratory organs, respiratory center.

Therapeutic effect of ultraviolet radiation

The reaction from organs and systems depends on the wavelength, dose and method of exposure to UV radiation.

Local exposure:

Anti-inflammatory (A, B, C);
- bactericidal (C);
- painkiller (A, B, C);
- epithelizing, regenerating (A, B)

General exposure:

Stimulating immune reactions (A, B, C);
- desensitizing (A, B, C);
- regulation of vitamin balance "D", "C" and metabolic processes (A, B).

Indications for UV therapy:

Acute, subacute and chronic inflammatory process;
- injury of soft tissues and bones;
- wound;
- skin diseases;
- burns and frostbite;
- trophic ulcer;
- rickets;
- diseases of the musculoskeletal system, joints, rheumatism;
- infectious diseases - influenza, whooping cough, erysipelas;
- pain syndrome, neuralgia, neuritis;
- bronchial asthma;
- ENT diseases - tonsillitis, otitis media, allergic rhinitis, pharyngitis, laryngitis;
- compensation of solar insufficiency, increase of firmness and endurance of an organism.

Indications for ultraviolet irradiation in dentistry

Diseases of the oral mucosa;
- periodontal diseases;
- dental diseases - non-carious diseases, caries, pulpitis, periodontitis;
- inflammatory diseases of the maxillofacial area;
- TMJ diseases;
- facial pain.

Contraindications to UV therapy:

malignant neoplasms,
- predisposition to bleeding
- active tuberculosis,
- functional insufficiency of the kidneys,
- hypertension stage III,
- severe forms of atherosclerosis.
- thyrotoxicosis.

UV devices:

Integrated sources using DRT lamps (arc mercury tubular) of various power:

ORK-21M (DRT-375) - local and general exposure
- OKN-11M (DRT-230) - local irradiation
- Beacon OKB-ZO (DRT-1000) and OKM-9 (DRT-375) - group and general exposure
- OH-7 and UGN-1 (DRT-230). OUN-250 and OUN-500 (DRT-400) - local exposure
- OUP-2 (DRT-120) - otolaryngology, ophthalmology, dentistry.

Selective short-wavelength (180-280 nm) use arc bactericidal lamps (DB) in the glow electric discharge mode in a mixture of mercury vapor with argon. Lamps of three types: DB-15, DB-30-1, DB-60.

Radiators available:

Wall mounted (OBN)
- ceiling (OBP)
- on a tripod (OBSH) and mobile (OBP)
- local (BOD) with lamp DRB-8, BOP-4, OKUF-5M
- for blood irradiation (AUFOK) - MD-73M "Izolda" (with a low pressure lamp LB-8).

Selective long-wavelength (310-320 nm) use erythemal luminescent lamps (LE) with a power of 15-30 W from uveolive glass with an internal coating with a phosphor:

Wall type irradiators (OE)
- suspended reflected distribution (OED)
- mobile (OEP).

Beacon type irradiators (EOKS-2000) with xenon arc lamp (DKS TB-2000).

An ultraviolet irradiator on a tripod (ОУШ1) with a fluorescent lamp (LE153), a large beacon ultraviolet irradiator (ОУН), a desktop ultraviolet irradiator (ОУН-2).

Low-pressure gas discharge lamp LUF-153 in the UUD-1, UDD-2L units for Puva and therapy, in the UV irradiator for the limbs OUK-1, for the head OUG-1 and in the irradiators EOD-10, EGD-5. Plants for general and local irradiation are produced abroad: Puva, Psolylux, Psorymox, Valdman.

Technique and methodology of UV therapy

General exposure

Carried out according to one of the schemes:

Basic (from 1/4 to 3 biodoses, adding 1/4 each)
- slow (from 1/8 to 2 biodoses, adding 1/8 each)
- accelerated (from 1/2 to 4 biodoses, adding 1/2 each).

Local exposure

Irradiation of the affected area, fields, reflexogenic zones, staged or by zones, extrafocal. fractional.

Features of irradiation with erythemal doses:

One area of ​​the skin can be irradiated no more than 5 times, and the mucous membrane - no more than 6-8 times. Repeated irradiation of the same area of ​​the skin is possible only after the extinction of the erythema. The subsequent radiation dose is increased by 1/2-1 biodose. When treating with UV rays, light-protective glasses are used for the patient and medical staff.

Dosing

Dosing of UV radiation is carried out by determining the biodose, biodose is the minimum amount of UV radiation sufficient to obtain the weakest threshold erythema on the skin in the shortest time, with a fixed distance from the irradiator (20 - 100 cm). Determination of biodose is carried out by biodosimeter BD-2.

There are doses of ultraviolet radiation:

Suberythemal (less than 1 biodose)
- erythema small (1-2 biodoses)
- medium (3-4 biodoses)
- large (5-6 biodoses)
- hypererythemic (7-8 biodoses)
- massive (over 8 biodoses).

For air disinfection:

Indirect radiation for 20-60 minutes, in the presence of people,
- direct radiation for 30-40 minutes, in the absence of people.

Ultraviolet radiation is electromagnetic waves with a length of 180 to 400 nm. This physical factor has many positive effects on the human body and is successfully used to treat a number of diseases. We will talk about what these effects are, about indications and contraindications for the use of ultraviolet radiation, as well as about the devices used and methods of carrying out procedures in this article.

Ultraviolet rays penetrate the skin to a depth of 1 mm and cause many biochemical changes in it. There are long-wave (region A - the wavelength is from 320 to 400 nm), medium-wave (region B - the wavelength is 275-320 nm) and short-wave (region C - the wavelength is in the range from 180 to 275 nm) ultraviolet radiation. It is worth noting that different types of radiation (A, B or C) affect the body in different ways, and therefore they should be considered separately.

longwave radiation

One of the main effects of this type of radiation is pigmenting: getting on the skin, the rays stimulate the occurrence of certain chemical reactions, as a result of which the melanin pigment is formed. Granules of this substance are secreted into the skin cells and cause its tan. The maximum amount of melanin in the skin is determined after 48-72 hours from the moment of exposure.

The second important effect of this method of physiotherapy is immunostimulatory: photodegradation products bind to skin proteins and induce a chain of biochemical transformations in cells. The result of this is the formation of an immune response after 1-2 days, that is, local immunity and non-specific resistance of the body to a variety of adverse environmental factors increase.

The third effect of ultraviolet radiation is photosensitizing. A number of substances have the ability to increase the sensitivity of the skin of patients to the effects of this type of radiation and stimulate the formation of melanin. That is, taking such a drug and subsequent ultraviolet irradiation will lead to swelling of the skin and its redness (the appearance of erythema) in people suffering from dermatological diseases. The result of the course of such treatment will be the normalization of pigmentation and skin structure. This method of treatment is called "photochemotherapy".

Of the negative effects of excessive long-wave ultraviolet irradiation, it is important to mention the inhibition of antitumor reactions, that is, an increase in the likelihood of developing a tumor process, in particular, melanoma - skin cancer.

Indications and contraindications

Indications for treatment with ultraviolet long-wave radiation are:

• chronic inflammatory processes in the respiratory system;
• diseases of the osteoarticular apparatus of an inflammatory nature;
• frostbite;
• burns;
• skin diseases - psoriasis, mycosis fungoides, vitiligo, seborrhea and others;
• wounds that are difficult to treat;
• trophic ulcers.

For some diseases, the use of this method of physiotherapy is not recommended. Contraindications are:

• acute inflammatory processes in the body;
• severe chronic renal and hepatic insufficiency;
• individual hypersensitivity to ultraviolet radiation.

Devices

Sources of UV rays are divided into integrated and selective. Integral ones emit UV rays of all three spectra, while selective ones emit only the A region or the B + C regions. As a rule, selective radiation is used in medicine, which is obtained using a LUF-153 lamp in irradiators UUD-1 and 1A, OUG-1 (for the head), OUK-1 (for the limbs), EGD-5, EOD-10, PUVA , Psorymox and others. Also, long-wave UV radiation is used in solariums designed to obtain a uniform tan.

This type of radiation can affect the whole body at once or any part of it.

If the patient is to undergo general exposure, he should undress and sit quietly for 5-10 minutes. Creams or ointments should not be applied to the skin. The whole body is exposed at once or its parts in turn - it depends on the type of installation.

The patient is at a distance of at least 12-15 cm from the apparatus, and his eyes are protected by special glasses. The duration of irradiation directly depends on the type of skin pigmentation - there is a table with irradiation schemes depending on this indicator. The minimum exposure time is 15 minutes, and the maximum is half an hour.

Medium wave ultraviolet radiation

This type of UV radiation has the following effects on the human body:

• immunomodulatory (in suberythemal doses);
• vitamin-forming (promotes the formation of vitamin D 3 in the body, improves the absorption of vitamin C, optimizes the synthesis of vitamin A, stimulates metabolism);
• anesthetic;
• anti-inflammatory;
• desensitizing (the body's sensitivity to protein photodegradation products decreases - in erythemal doses);
• trophostimulating (stimulates a number of biochemical processes in cells, as a result of which the number of functioning capillaries and arterioles increases, blood flow in tissues improves - erythema is formed).

Indications and contraindications

Indications for the use of medium-wave ultraviolet radiation are:

• inflammatory diseases of the respiratory system;
• post-traumatic changes in the musculoskeletal system;
• inflammatory diseases of bones and joints (arthritis, arthrosis);
• vertebrogenic radiculopathy, neuralgia, myositis, plexitis;
• solar fasting;
• metabolic diseases;
• erysipelas.

Contraindications are:

• individual hypersensitivity to UV rays;
• hyperfunction of the thyroid gland;
• chronic renal failure;
• systemic connective tissue diseases;
• malaria.

Devices

Radiation sources of this type, like the previous one, are divided into integral and selective.

Integral sources are DRT lamps of various power, which are installed in the irradiators OKN-11M (quartz desktop), ORK-21M (mercury-quartz), UGN-1 (for group irradiation of the nasopharynx), OUN 250 (table). Another type of lamp - DRK-120 is designed for cavity irradiators OUP-1 and OUP-2.

A selective source is a fluorescent lamp LZ 153 for irradiators OUSh-1 (on a tripod), OUN-2 (tabletop). Erythema lamps LE-15 and LE-30, made of glass that transmits UV rays, are also used in wall-mounted, suspended and mobile irradiators.

Ultraviolet irradiation is dosed, as a rule, by a biological method, which is based on the ability of UV rays to cause reddening of the skin after its irradiation - erythema. The unit of measurement is 1 biodose (the minimum time of exposure of the patient's skin to ultraviolet radiation on any part of his body, causing the appearance of the least intense erythema during the day). Gorbachev's biodosimeter has the form of a metal plate, on which there are 6 rectangular holes closed by a damper. The device is fixed on the patient's body, UV radiation is directed at it, and 1 plate window is opened in turn every 10 seconds. It turns out that the skin under the first hole is exposed to radiation for 1 minute, and under the last - only 10 seconds. After 12-24 hours, threshold erythema occurs, which determines the biodose - the time of exposure to UV radiation on the skin under this hole.

There are the following types of doses:

• suberythemal (0.5 biodose);
• small erythema (1-2 biodoses);
• medium (3-4 biodoses);
• high (5-8 biodoses);
• hypererythemic (more than 8 biodoses).

Procedure procedure

There are 2 methods - local and general.

Local exposure is carried out on a skin area, the area of ​​which does not exceed 600 cm 2 . Apply, as a rule, erythemal doses of radiation.

The procedure is carried out 1 time in 2-3 days, each time increasing the dose by 1/4-1/2 from the previous one. One site can be exposed to no more than 3-4 times. A second course of treatment is recommended to the patient after 1 month.

With a general exposure, the patient is in the supine position; surfaces of his body are irradiated alternately. There are 3 treatment regimens - basic, accelerated and delayed, according to which, depending on the procedure number, the biodose is determined. The course of treatment is up to 25 exposures and can be repeated after 2-3 months.

Electrophthalmia

This term refers to the negative impact of medium-wavelength radiation on the organ of vision, which consists in damage to its structures. Such an effect can occur while observing the sun without the use of protective devices, while staying in a snowy area or in very bright, sunny weather at sea, as well as during quartzization of premises.

The essence of electrophthalmia is a burn of the cornea, which is manifested by severe lacrimation, redness and cutting pains in the eyes, photophobia and swelling of the cornea.

Fortunately, in the vast majority of cases, this condition is short-lived - as soon as the epithelium of the eye heals, its functions will be restored.

To alleviate your condition or the condition of those around you with electrophthalmia, you should:

• rinse eyes with clean, preferably running water;
• drip moisturizing drops into them (preparations such as artificial tears);
• put on protective goggles;
• if the patient complains of pain in the eyes, you can alleviate his suffering with compresses of grated raw potatoes or black tea bags;
• If the above measures do not give the desired effect, you should seek the help of a specialist.

shortwave radiation

It has the following effects on the human body:

• bactericidal and fungicidal (stimulates a number of reactions, as a result of which the structure of bacteria and fungi is destroyed);
• detoxification (under the influence of UV radiation, substances appear in the blood that neutralize toxins);
• metabolic (during the procedure, microcirculation improves, as a result of which organs and tissues receive more oxygen);
• correcting blood coagulation (with UV irradiation of blood, the ability of erythrocytes and platelets to form blood clots changes, coagulation processes normalize).

Indications and contraindications

The use of short-wave ultraviolet radiation is effective in the following diseases:

• skin diseases (psoriasis, neurodermatitis);
• erysipelas;
• rhinitis, tonsillitis;
• otitis;
• wounds;
• lupus;
• abscesses, boils, carbuncles;
• osteomyelitis;
• rheumatic heart valve disease;
• essential hypertension I-II;
• acute and chronic respiratory diseases;
• diseases of the digestive system (peptic ulcer of the stomach and duodenum, gastritis with high acidity);
• diabetes;
• long-term non-healing ulcers;
• chronic pyelonephritis;
• acute adnexitis.

A contraindication to this type of treatment is individual hypersensitivity to UV rays. Blood irradiation is contraindicated in the following diseases:

• diseases of the mental sphere;
• chronic renal and hepatic insufficiency;
• porphyria;
• thrombocytopenia;
• callous ulcer of the stomach and duodenum;
• decreased blood clotting ability;
• strokes;
• myocardial infarction.

Devices

Integral radiation sources - DRK-120 lamp for OUP-1 and OUP-2 cavity irradiators, DRT-4 lamp for nasopharyngeal irradiator.

Selective sources are bactericidal lamps DB of various power - from 15 to 60 W. They are installed in irradiators of types OBN, OBSH, OBP.

In order to carry out autotransfusions with ultraviolet irradiated blood, the MD-73M Izolda apparatus is used. The source of radiation in it is the LB-8 lamp. It is possible to regulate the dose and the area of ​​irradiation.

Procedure procedure

The affected areas of the skin and mucous membranes are affected according to the schemes of general UV irradiation.

In diseases of the nasal mucosa, the patient is in a sitting position on a chair, slightly throwing his head back. The emitter is introduced to a shallow depth alternately in both nostrils.

Irradiating the tonsils, use a special mirror. Reflected from it, the rays are directed to the left and right tonsils. The patient's tongue is protruded, he holds it with a gauze napkin.

The effects are dosed by determining the biodose. In acute conditions, they start with 1 biodose, gradually increasing it to 3. You can repeat the course of treatment after 1 month.

The blood is irradiated for 10-15 minutes during 7-9 procedures with a possible repetition of the course in 3-6 months.

Ultraviolet rays have the highest biological activity. Under natural conditions, the sun is a powerful source of ultraviolet rays. However, only its long-wavelength part reaches the earth's surface. Shorter wavelength radiation is absorbed by the atmosphere already at a height of 30-50 km from the earth's surface.

The highest intensity of the ultraviolet radiation flux is observed shortly before noon with a maximum in the spring months.

As already mentioned, ultraviolet rays have significant photochemical activity, which is widely used in practice. Ultraviolet irradiation is used in the synthesis of a number of substances, the bleaching of fabrics, the manufacture of patent leather, the blueprinting of drawings, the production of vitamin D, and other production processes.

An important property of ultraviolet rays is their ability to cause luminescence.

In some processes, exposure to ultraviolet rays takes place, for example, electric arc welding, oxyfuel cutting and welding, the production of radio lamps and mercury rectifiers, casting and smelting of metals and certain minerals, blueprinting, water sterilization, etc. Medical and technical personnel servicing mercury-quartz lamps.

Ultraviolet rays have the ability to change the chemical structure of tissues and cells.

UV wavelength

The biological activity of ultraviolet rays of different wavelengths is not the same. Ultraviolet rays with a wavelength of 400 to 315 mμ. have a relatively weak biological effect. Rays with a shorter wavelength are more biologically active. Ultraviolet rays with a length of 315-280 mμ have a strong skin and anti-rachitic effect. Radiation with a wavelength of 280-200 mμ has a particularly high activity. (bactericidal action, the ability to actively affect tissue proteins and lipoids, as well as cause hemolysis).

Under production conditions, exposure to ultraviolet rays with a wavelength of 36 to 220 mμ ., i.e., with significant biological activity, takes place.

Unlike heat rays, the main property of which is the development of hyperemia in areas exposed to radiation, the effect of ultraviolet rays on the body seems to be much more complex.

Ultraviolet rays penetrate the skin relatively little and their biological effect is associated with the development of many neurohumoral processes that determine the complex nature of their influence on the body.

Ultraviolet erythema

Depending on the intensity of the light source and the content of infrared or ultraviolet rays in its spectrum, changes in the skin will not be the same.

Exposure to ultraviolet rays on the skin causes a characteristic reaction from the skin vessels - ultraviolet erythema. Ultraviolet erythema is significantly different from thermal erythema caused by infrared radiation.

Usually, when using infrared rays, pronounced changes in the skin are not observed, since the resulting burning sensation and pain prevent prolonged exposure to these rays. Erythema, which develops as a result of the action of infrared rays, occurs immediately after irradiation, is unstable, does not last long (30-60 minutes) and is mainly of a nested nature. After prolonged exposure to infrared rays, brown pigmentation of a spotted appearance appears.

Ultraviolet erythema appears after irradiation following a certain latent period. This period varies in different people from 2 to 10 hours. The duration of the latent period of ultraviolet erythema is in a known dependence on the wavelength: erythema from long-wave ultraviolet rays appears later and lasts longer than from short-wave ones.

Erythema caused by ultraviolet rays has a bright red color with sharp borders, exactly corresponding to the site of exposure. The skin becomes somewhat swollen and painful. The greatest development of erythema reaches 6-12 hours after the appearance, lasts for 3-5 days and gradually turns pale, acquiring a brown tint, and there is a uniform and intense darkening of the skin due to the formation of pigment in it. In some cases, during the period of disappearance of erythema, slight peeling is observed.

The degree of development of erythema depends on the dose of ultraviolet rays and individual sensitivity. Ceteris paribus, the greater the dose of ultraviolet rays, the more intense the inflammatory reaction of the skin. The most pronounced erythema is caused by rays with wavelengths of about 290 mμ. With an overdose of ultraviolet radiation, erythema acquires a bluish tint, the edges of the erythema become blurry, the irradiated area is swollen and painful. Intense irradiation can cause a burn with the development of a bubble.

Sensitivity of different parts of the skin to ultraviolet light

The skin of the abdomen, lower back, lateral surfaces of the chest are most sensitive to ultraviolet rays. The skin of the hands and face is the least sensitive.

Persons with delicate, slightly pigmented skin, children, as well as those suffering from Graves' disease and vegetative dystonia are more sensitive. Increased sensitivity of the skin to ultraviolet rays is observed in spring.

It has been established that the sensitivity of the skin to ultraviolet rays can vary depending on the physiological state of the organism. The development of an erythemal reaction depends primarily on the functional state of the nervous system.

In response to ultraviolet irradiation, a pigment is formed and deposited in the skin, which is a product of skin protein metabolism (organic coloring matter - melanin).

Long-wave UV rays cause a more intense tan than short-wave UV rays. With repeated ultraviolet irradiation, the skin becomes less susceptible to these rays. Skin pigmentation often develops without previously visible erythema. In pigmented skin, ultraviolet rays do not cause photoerythema.

The positive effect of ultraviolet radiation

Ultraviolet rays reduce the excitability of sensory nerves (analgesic effect) and also have an antispastic and antirachitic effect. Under the influence of ultraviolet rays, the formation of vitamin D, which is very important for phosphorus-calcium metabolism, occurs (ergosterol in the skin is converted into vitamin D). Under the influence of ultraviolet rays, oxidative processes in the body increase, oxygen uptake by tissues and carbon dioxide release increase, enzymes are activated, and protein and carbohydrate metabolism improves. The content of calcium and phosphates in the blood increases. Blood formation, regenerative processes, blood supply and tissue trophism improve. Skin vessels dilate, blood pressure decreases, and the overall biotonus of the body increases.

The beneficial effect of ultraviolet rays is expressed in a change in the immunobiological reactivity of the body. Irradiation stimulates the production of antibodies, increases phagocytosis, tones the reticuloendothelial system. This increases the body's resistance to infections. The dosage of radiation is important in this regard.

A number of substances of animal and vegetable origin (hematoporphyrin, chlorophyll, etc.), some chemicals (quinine, streptocide, sulfidine, etc.), especially fluorescent paints (eosin, methylene blue, etc.), have the property increase the body's sensitivity to light. In industry, people working with coal tar have skin diseases of exposed parts of the body (itching, burning, redness), and these phenomena disappear at night. This is due to the photosensitizing properties of acridine contained in coal tar. Sensitization occurs predominantly in relation to visible rays and to a lesser extent in relation to ultraviolet rays.

Of great practical importance is the ability of ultraviolet rays to kill various bacteria (the so-called bactericidal effect). This action is especially pronounced in ultraviolet rays with wavelengths less than (265 - 200 mμ). The bactericidal effect of light is associated with the effect on the protoplasm of bacteria. It has been proven that mitogenetic radiation in cells and blood increases after ultraviolet irradiation.

According to modern concepts, the action of light on the body is based mainly on the reflex mechanism, although great importance is also attached to humoral factors. This is especially true for the action of ultraviolet rays. One must also keep in mind the possibility of the action of visible rays through the organs of vision on the cortex and vegetative centers.

In the development of erythema caused by light, significant importance is attached to the influence of rays on the receptor apparatus of the skin. When exposed to ultraviolet rays, as a result of the breakdown of proteins in the skin, histamine and histamine-like products are formed, which dilate the skin vessels and increase their permeability, which leads to hyperemia and swelling. The products formed in the skin under the influence of ultraviolet rays (histamine, vitamin D, etc.) enter the bloodstream and cause those general changes in the body that occur during irradiation.

Thus, the processes developing in the irradiated area lead in a neurohumoral way to the development of a general reaction of the organism. This reaction is determined mainly by the state of the higher regulatory divisions of the central nervous system, which, as you know, can change under the influence of various factors.

It is impossible to talk about the biological effect of ultraviolet radiation in general, regardless of the wavelength. Short-wave ultraviolet radiation causes denaturation of protein substances, long-wave - photolytic decay. The specific action of different parts of the spectrum of ultraviolet radiation is revealed mainly in the initial stage.

Application of ultraviolet radiation

The wide biological effect of ultraviolet rays makes it possible to use them in certain doses for preventive and therapeutic purposes.

For ultraviolet irradiation, sunlight is used, as well as artificial sources of irradiation: mercury-quartz and argon-mercury-quartz lamps. The emission spectrum of mercury-quartz lamps is characterized by the presence of shorter ultraviolet rays than in the solar spectrum.

Ultraviolet irradiation can be general or local. The dosage of procedures is carried out according to the principle of biodoses.

Currently, ultraviolet irradiation is widely used, primarily for the prevention of various diseases. For this purpose, ultraviolet irradiation is used to improve the human environment and change its reactivity (primarily to increase its immunobiological properties).

With the help of special bactericidal lamps, air can be sterilized in medical institutions and residential premises, sterilization of milk, water, etc. Ultraviolet irradiation is widely used to prevent rickets, influenza, in order to generally strengthen the body in medical and children's institutions, schools, gyms , fotaria at coal mines, when training athletes, for acclimatization to the conditions of the north, when working in hot shops (ultraviolet irradiation gives a greater effect in combination with infrared radiation).

Ultraviolet rays are especially widely used for irradiating children. First of all, such exposure is shown to weakened, often ill children living in the northern and middle latitudes. At the same time, the general condition of children improves, sleep increases, weight increases, morbidity decreases, the frequency of catarrhal phenomena and the duration of diseases decrease. Improves overall physical development, normalizes blood, vascular permeability.

Ultraviolet irradiation of miners in fotaria, which are organized in large numbers at mining enterprises, has also become widespread. With systematic mass exposure of miners employed in underground work, there is an improvement in well-being, an increase in working capacity, a decrease in fatigue, a decrease in morbidity with temporary disability. After irradiation of miners, the percentage of hemoglobin increases, monocytosis appears, the number of cases of influenza decreases, the incidence of the musculoskeletal system, the peripheral nervous system decreases, pustular skin diseases, catarrhs ​​of the upper respiratory tract and tonsillitis are less common, and the readings of vital capacity and lungs improve.

The use of ultraviolet radiation in medicine

The use of ultraviolet rays for therapeutic purposes is based mainly on the anti-inflammatory, anti-neuralgic and desensitizing effects of this type of radiant energy.

In combination with other therapeutic measures, ultraviolet irradiation is carried out:

1) in the treatment of rickets;

2) after suffering infectious diseases;

3) in case of tuberculosis diseases of bones, joints, lymph nodes;

4) with fibrous pulmonary tuberculosis without phenomena indicating activation of the process;

5) in diseases of the peripheral nervous system, muscles and joints;

6) with skin diseases;

7) with burns and frostbite;

8) with purulent complications of wounds;

9) with resorption of infiltrates;

10) in order to accelerate regenerative processes in case of injuries of bones and soft tissues.

Contraindications to radiation are:

1) malignant neoplasms (since radiation accelerates their growth);

2) severe exhaustion;

3) increased function of the thyroid gland;

4) severe cardiovascular diseases;

5) active pulmonary tuberculosis;

6) kidney disease;

7) pronounced changes in the central nervous system.

It should be remembered that obtaining pigmentation, especially in the short term, should not be the goal of treatment. In some cases, a good therapeutic effect is observed with weak pigmentation.

The negative effect of ultraviolet radiation

Prolonged and intense ultraviolet irradiation can have an adverse effect on the body and cause pathological changes. With significant exposure, fatigue, headaches, drowsiness, memory impairment, irritability, palpitations, and loss of appetite are noted. Excessive exposure can cause hypercalcemia, hemolysis, growth retardation and decreased resistance to infection. With strong exposure, burns and dermatitis develop (burning and itching of the skin, diffuse erythema, swelling). At the same time, there is an increase in body temperature, headache, weakness. Burns and dermatitis that occur under the influence of solar radiation are associated mainly with the influence of ultraviolet rays. People working outdoors under the influence of solar radiation may develop long-term and severe dermatitis. It is necessary to remember about the possibility of the transition of the described dermatitis into cancer.

Depending on the depth of penetration of the rays of different parts of the solar spectrum, changes in the eyes may develop. Under the influence of infrared and visible rays, acute retinitis occurs. The so-called glassblower's cataract, which develops as a result of prolonged absorption of infrared rays by the lens, is well known. Clouding of the lens occurs slowly, mainly among workers in hot shops with work experience of 20-25 years or more. Currently, professional cataracts in hot shops are rare due to a significant improvement in working conditions. The cornea and conjunctiva react mainly to ultraviolet rays. These rays (especially with a wavelength of less than 320 mμ.) cause in some cases an eye disease known as photophthalmia or electrophthalmia. This disease is most common in electric welders. In such cases, acute keratoconjunctivitis is often observed, which usually occurs 6-8 hours after work, often at night.

With electrophthalmia, hyperemia and swelling of the mucosa, blepharospasm, photophobia, and lacrimation are noted. Corneal lesions are often found. The duration of the acute period of the disease is 1-2 days. Photophthalmia sometimes occurs in people working outdoors in bright sunlight in wide snow-covered spaces in the form of so-called snow blindness. Treatment of photophthalmia is to stay in the dark, the use of novocaine and cold lotions.

UV protection

To protect the eyes from the adverse effects of ultraviolet rays in production, they use shields or helmets with special dark glasses, goggles, and to protect the rest of the body and surrounding people - insulating screens, portable screens, and overalls.

The concept of ultraviolet rays is first encountered by a 13th century Indian philosopher in his work. The atmosphere of the area he described Bhootakasha contained violet rays that cannot 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.

Subtypes

Degradation of polymers and dyes

Scope of application

Black light

Chemical analysis

UV spectrometry

UV spectrophotometry is based on irradiating a substance with monochromatic UV radiation, the wavelength of which changes with time. The substance absorbs UV radiation with different wavelengths to varying degrees. The graph, on the y-axis of which the amount of transmitted or reflected radiation is plotted, and on the abscissa - the wavelength, forms a spectrum. The spectra are unique for each substance; this is the basis for the identification of individual substances in a mixture, as well as their quantitative measurement.

Mineral analysis

Many minerals contain substances that, when illuminated with ultraviolet radiation, begin to emit visible light. Each impurity glows in its own way, which makes it possible to determine the composition of a given mineral by the nature of the glow. A. A. Malakhov in his book “Interesting about Geology” (M., “Molodaya Gvardiya”, 1969. 240 s) talks about this as follows: “The unusual glow of minerals is caused by cathode, ultraviolet, and x-rays. In the world of dead stone, those minerals light up and shine most brightly, which, having fallen into the zone of ultraviolet light, tell about the smallest impurities of uranium or manganese included in the composition of the rock. Many other minerals that do not contain any impurities also flash with a strange "unearthly" color. I spent the whole day in the laboratory, where I observed the luminescent glow of minerals. Ordinary colorless calcite colored miraculously under the influence of various light sources. Cathode rays made the crystal ruby ​​red, in ultraviolet it lit up crimson red tones. Two minerals - fluorite and zircon - did not differ in x-rays. Both were green. But as soon as the cathode light was turned on, the fluorite turned purple, and the zircon turned lemon yellow.” (p. 11).

Qualitative chromatographic analysis

Chromatograms obtained by TLC are often viewed in ultraviolet light, which makes it possible to identify a number of organic substances by the color of the glow and the retention index.

Catching insects

Ultraviolet radiation is often used when catching insects in the light (often in combination with lamps emitting in the visible part of the spectrum). This is due to the fact that in most insects the visible range is shifted, compared to human vision, to the short-wavelength part of the spectrum: insects do not see what a person perceives as red, but they see soft ultraviolet light.

Faux tan and "Mountain sun"

At certain dosages, artificial tanning can improve the condition and appearance of human skin, promotes the formation of vitamin D. At present, photariums are popular, which in everyday life are often called solariums.

Ultraviolet in restoration

One of the main tools of experts is ultraviolet, x-ray and infrared radiation. Ultraviolet rays allow you to determine the aging of the varnish film - a fresher varnish in the ultraviolet looks darker. In the light of a large laboratory ultraviolet lamp, restored areas and handicraft signatures appear as darker spots. X-rays are delayed by the heaviest elements. In the human body, this is bone tissue, and in the picture it is white. The basis of whitewash in most cases is lead, in the 19th century zinc began to be used, and in the 20th century titanium. These are all heavy metals. Ultimately, on the film we get the image of the bleach underpainting. Underpainting is an artist's individual "handwriting", an element of his own unique technique. For the analysis of underpainting, bases of radiographs of paintings by great masters are used. Also, these pictures are used to recognize the authenticity of the picture.

Notes

1. ISO 21348 Process for Determining Solar Irradiances. Archived from the original on June 23, 2012.
2. Bobukh, Evgeny On the vision of animals. Archived from the original on November 7, 2012. Retrieved November 6, 2012.
3. Soviet Encyclopedia
4. V. K. Popov // UFN. - 1985. - T. 147. - S. 587-604.
5. A. K. Shuaibov, V. S. Shevera Ultraviolet nitrogen laser at 337.1 nm in the mode of frequent repetitions // Ukrainian Physics Journal. - 1977. - T. 22. - No. 1. - S. 157-158.
6. A. G. Molchanov