UV radiation in medicine. Ultraviolet disinfection of water. Basic safety measures and protection against exposure to ultraviolet radiation

Life-giving rays.

The sun emits three types of ultraviolet rays. Each of these types has a different effect on the skin.

Most of us feel healthier and more full of life after relaxing on the beach. Thanks to the life-giving rays, vitamin D is formed in the skin, which is necessary for the full assimilation of calcium. But only small doses of solar radiation have a beneficial effect on the body.

But severely tanned skin is still damaged skin and, as a result, premature aging and a high risk of developing skin cancer.

Sunlight is electromagnetic radiation. In addition to the visible spectrum of radiation, it contains ultraviolet radiation, which is actually responsible for tanning. Ultraviolet light stimulates the ability of the pigment cells of melanocytes to produce more melanin, which has a protective function.

Types of UV rays.

There are three types of UV rays that differ in wavelength. Ultraviolet radiation is able to penetrate the epidermis of the skin into deeper layers. This activates the production of new cells and keratin, resulting in a tighter and tighter skin. The sun's rays, penetrating the dermis, destroy collagen and lead to changes in the thickness and texture of the skin.

Ultraviolet rays A.

These rays have the lowest radiation levels. It used to be considered that they are harmless, however, it has now been proven that this is not the case. The level of these rays remains practically constant throughout the day and year. They even penetrate glass.

Type A UV rays penetrate through the layers of the skin, reaching the dermis, damaging the base and structure of the skin, destroying collagen and elastin fibers.

A-rays contribute to the appearance of wrinkles, reduce skin elasticity, accelerate the appearance of signs of premature aging, weaken the skin's defense system, making it more susceptible to infections and, possibly, cancer.

Ultraviolet rays B.

This type of rays is emitted by the sun only at certain times of the year and hours of the day. Depending on the air temperature and geographical latitude, they usually penetrate the atmosphere from 10 am to 4 pm.

Type B UV rays cause more serious damage to the skin, as they interact with DNA molecules that are contained in skin cells. B-rays damage the epidermis, resulting in sunburn. B-rays damage the epidermis, resulting in sunburn. This type of radiation enhances the activity of free radicals, which weaken the skin's natural defense system.

Ultraviolet B rays contribute to the appearance of sunburn and cause sunburn, lead to premature aging and the appearance of dark age spots, make the skin rough and rough, accelerate the appearance of wrinkles, and can provoke the development of precancerous diseases and skin cancer.

general characteristics

Ultraviolet rays have the greatest 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 an altitude 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 radiation is used in the synthesis of a number of substances, bleaching fabrics, making patent leather, blueprinting drawings, obtaining vitamin D and other manufacturing processes.

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

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

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

Ultraviolet 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. Shorter wavelengths are more biologically active. Ultraviolet rays with a length of 315-280 mμ have a strong cutaneous and antirachitic effect. Radiation with a wavelength of 280-200 mμ is especially active. (bactericidal effect, the ability to actively affect tissue proteins and lipoids, as well as cause hemolysis).

In industrial conditions, exposure to ultraviolet rays with a wavelength of 36 to 220 mμ takes place. that is, possessing significant biological activity.

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 relatively little through the skin 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 on the part of the skin will not be the same.

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

Usually, when using infrared rays, no pronounced changes on the part of the skin are observed, since the resulting burning sensation and pain prevent the prolonged exposure of these rays. Erythema, which develops as a result of the action of infrared rays, arises immediately after irradiation, is unstable, does not last long (30-60 minutes) and is mainly nested in nature. After prolonged exposure to infrared rays, a brown spotted pigmentation appears.

Ultraviolet erythema appears after irradiation following some latency period. This period varies from 2 to 10 hours for different people. 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.

Erythema caused by ultraviolet rays has a bright red color with sharp boundaries that exactly correspond to the irradiated area. The skin becomes somewhat swollen and painful. The greatest development of erythema reaches 6-12 hours after the onset, 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 desquamation is observed.

The degree of development of erythema depends on the magnitude of the dose of ultraviolet rays and individual sensitivity. All other things being equal, the higher the dose of ultraviolet rays, the more intense the inflammatory response of the skin. The most pronounced erythema is caused by rays with wavelengths of about 290 mμ. In case of an overdose of ultraviolet irradiation, the erythema acquires a bluish tint, the edges of the erythema become blurred, the irradiated area is swollen and painful. Intense radiation can cause blistering burns.

Sensitivity of various areas of the skin to ultraviolet light

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

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

It has been established that the sensitivity of the skin to ultraviolet rays can vary depending on the physiological state of the body. 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 the protein metabolism of the skin (an organic dye - 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 the sensory nerves (analgesic effect) and also have antispastic and antirachitic effects. Under the influence of ultraviolet rays, vitamin D, which is very important for phosphorus-calcium metabolism, is formed (ergosterol in the skin is converted into vitamin D). Under the influence of ultraviolet rays, oxidative processes in the body intensify, the absorption of oxygen by tissues and the release of carbon dioxide increases, enzymes are activated, and protein and carbohydrate metabolism improves. The content of calcium and phosphate in the blood rises. Hematopoiesis, regenerative processes, blood supply and trophism of tissues are improved. The vessels of the skin expand, blood pressure decreases, and the general biotone of the body increases.

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

A number of substances of animal and plant origin (hematoporphyrin, chlorophyll, etc.), some chemicals (quinine, streptocid, sulfidine, etc.), especially fluorescent dyes (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 to visible rays and to a lesser extent to ultraviolet rays.

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

According to modern concepts, the effect of light on the body is based mainly on the reflex mechanism, although great importance is attached to humoral factors. This especially applies to the action of ultraviolet rays. It is also necessary to bear 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 when exposed to 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 by a neurohumoral path to the development of a general reaction of the organism. This reaction is mainly determined by the state of the higher regulatory parts 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-wavelength - photolytic decay. The specific effect of different parts of the spectrum of ultraviolet radiation is revealed mainly in the initial stage.

Application of ultraviolet radiation

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

For ultraviolet irradiation, they use sunlight, as well as artificial sources of radiation: 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 the procedures is performed according to the biodose principle.

Currently, ultraviolet irradiation is widely used, primarily for the prevention of various diseases. For this purpose, ultraviolet irradiation is used to improve the environment around a person and change his reactivity (first of all, to increase his immunobiological properties).

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

Ultraviolet rays are especially widely used to irradiate 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, sleep improves, weight increases, morbidity decreases, the frequency of catarrhal phenomena decreases and the duration of diseases decreases. General physical development improves, blood is normalized, vascular permeability.

Ultraviolet irradiation of miners has also become widespread in photoariums, which are organized in large numbers at the enterprises of the mining industry. With systematic mass irradiation 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 rises, monocytosis appears, the number of cases of influenza decreases, the incidence of the musculoskeletal system, peripheral nervous system decreases, pustular skin diseases, catarrh of the upper respiratory tract and tonsillitis are less often observed, 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-neurological 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) with tuberculous diseases of bones, joints, lymph nodes;

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

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

6) for skin diseases;

7) in case of burns and frostbite;

8) with purulent complications of wounds;

9) with resorption of infiltrates;

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

Contraindications to radiation are:

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

2) severe exhaustion;

3) increased thyroid function;

4) severe cardiovascular disease;

5) active pulmonary tuberculosis;

6) kidney disease;

7) pronounced changes in the central nervous system.

It should be remembered that getting pigmentation, especially in a short time, 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

Long-term and intense ultraviolet irradiation can have an adverse effect on the body and cause pathological changes. With significant radiation, rapid fatigue, headaches, drowsiness, memory impairment, irritability, palpitations, and decreased appetite are noted. Excessive radiation exposure can cause hypercalcemia, hemolysis, growth retardation, and decreased resistance to infection. With strong radiation, 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 caused by solar radiation are mainly associated with the influence of ultraviolet rays. People working outdoors under the influence of solar radiation may experience long-term and severe dermatitis. It is necessary to remember about the possibility of the transition of the described dermatitis into cancer.

Eye changes may develop depending on the penetration depth of the rays of different parts of the solar spectrum. Under the influence of infrared and visible rays, acute retinitis occurs. A well-known so-called glassblowing cataract develops as a result of prolonged absorption of infrared rays by the lens. Lens clouding occurs slowly, mainly among workers in hot shops with a work experience of 20-25 years and more. Currently, professional cataracts in hot shops are rare due to significant improvements in working conditions. The cornea and conjunctiva respond primarily to ultraviolet rays. These rays (especially those 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, there is hyperemia and swelling of the mucous membrane, blepharospasm, photophobia, lacrimation. Corneal lesions are often found. The duration of the acute period of the disease is 1-2 days. In people working outdoors in bright sunlight of wide spaces covered with snow, photophthalmia sometimes occurs in the form of so-called snow blindness. Treatment of photoophthalmia consists in staying in the dark, using 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 those around them - insulating screens, portable screens, and protective clothing.

General characteristics of ultraviolet radiation

Remark 1

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

Currently ultraviolet radiation is widely used in various fields of activity. The peak of activity for exposure to ultraviolet light reaches in the range of high temperatures. This type of spectrum appears when the temperature reaches from $ 1500 to $ 20,000 degrees.

Conventionally, the radiation range is divided into 2 areas:

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

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

The spectrum of ultraviolet sun raysreaching the Earth's surface is narrow - $ 400… $ 290 $ nm. It turns out that the Sun does not emit light with a wavelength shorter than $ 290 $ nm. Is it true or not? The answer to this question was found by a Frenchman A. Cornu, who established that ultraviolet rays shorter than $ 295 $ nm are absorbed by ozone. Based on this A.Cornu suggestedthat the sun emits shortwave ultraviolet radiation. Oxygen molecules under its action break down into individual atoms and form ozone molecules. Ozone covers the planet in the upper atmosphere protective shield.

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

Sources of ultraviolet radiation

Ultraviolet radiation has its own sources:

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

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

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

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

Artificial sources ultraviolet light is usually created by humans. These can be human-made devices, devices, technical means. They are created to obtain the desired spectrum of light with specified wavelength parameters. The purpose of their creation is that the obtained ultraviolet radiation can be used with benefit in various fields of activity.

Sources of artificial origin include:

1. Possessing the ability to activate the synthesis of vitamin D in human skin erythema lamps... They not only protect against rickets, but also treat this disease;
2. Special devices for tanning salonspreventing winter depression and giving a beautiful natural tan;
3. Indoor insect control attractant lamps... They do not pose a danger to humans;
4. Mercury-quartz devices;
5. Excilamps;
6. Luminescent devices;
7. Xenon lamps;
8. Gas discharge devices;
9. High temperature plasma;
10. Synchrotron radiation in accelerators.

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

Application of ultraviolet radiation

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

UV radiation characteristics:

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

On this basis, ultraviolet radiation can be widely used, for example, in spectrometric analyzes, astronomy, medicine, disinfection of drinking water, analytical research of minerals, for the destruction of insects, bacteria and viruses. Each region uses a different type of UV with its own spectrum and wavelength.

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

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

Medical indications for UV treatment:

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

This is not the whole list of diseases for the treatment of which ultraviolet light is used.

Remark 2

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

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

Today, very often the question arises about the potential danger of ultraviolet radiation and the most effective ways to protect the organ of vision.

Today, very often the question arises about the potential danger of ultraviolet radiation and the most effective ways to protect the organ of vision. We have prepared a list of the most frequently asked questions about ultraviolet radiation and answers to them.

What is ultraviolet radiation?

The spectrum of electromagnetic radiation is quite wide, but the human eye is sensitive only to a certain area, called the visible spectrum, which covers the wavelength range from 400 to 700 nm. Radiations outside the visible range are potentially hazardous and include infrared (over 700 nm) and ultraviolet (less than 400 nm). Radiations that have a shorter wavelength than ultraviolet are called X-rays and γ-rays. If the wavelength is longer than that of infrared radiation, then these are radio waves. Thus, ultraviolet (UV) radiation is electromagnetic radiation invisible to the eye, occupying the spectral region between visible and X-ray radiation within the wavelength range of 100-380 nm.

What ranges does ultraviolet radiation have?

Just as visible light can be divided into different color components that we observe when a rainbow occurs, so the UV range, in turn, has three components: UV-A, UV-B and UV-C, with the latter being the most shortwave and high-energy ultraviolet radiation with a wavelength range of 200-280 nm, but it is mainly absorbed by the upper atmosphere. UV-B radiation has a wavelength of 280 to 315 nm and is considered a medium energy radiation hazardous to the human eye. UV-A radiation is the longest wavelength component of ultraviolet radiation with a wavelength range of 315-380 nm, which has a maximum intensity by the time it reaches the Earth's surface. UV-A radiation penetrates deepest into biological tissues, although its damaging effect is less than that of UV-B rays.

What does the very name "ultraviolet" mean?

This word means "over (above) violet" and comes from the Latin word ultra ("over") and the name of the shortest radiation in the visible range - violet. Although UV radiation is not perceived by the human eye in any way, some animals - birds, reptiles, and insects such as bees - can see in this light. Many birds have a plumage pattern that is invisible in visible light, but clearly visible in ultraviolet light. Certain animals are also easier to spot in ultraviolet light. Many fruits, flowers and seeds are perceived more clearly by the eye in this light.

Where does ultraviolet radiation come from?

Outdoors, the sun is the main source of UV radiation. As already mentioned, it is partially absorbed by the upper atmosphere. Since a person rarely looks directly at the sun, the main harm to the organ of vision arises from exposure to diffuse and reflected ultraviolet radiation. Indoors, UV radiation occurs when sterilizers are used for medical and cosmetic instruments, in tanning salons for tanning, during the use of various medical diagnostic and therapeutic devices, as well as when filling compositions are cured in dentistry.

In tanning salons, UV radiation is generated to form a tan

In industry, UV radiation is generated during welding, and its level is so high that it can cause serious damage to the eyes and skin, therefore the use of protective equipment is prescribed as mandatory for welders. Fluorescent lamps, which are widely used for lighting at work and home, are also sources of UV radiation, but the level of the latter is very low and does not pose a serious hazard. Halogen lamps, which are also used for lighting, produce light with a UV component. If a person is close to a halogen lamp without a protective cap or shield, the level of UV radiation can cause serious eye problems.

In industry, UV radiation is generated during welding and is so high that it can cause serious eye and skin damage.

What determines the intensity of exposure to ultraviolet radiation?

Its intensity depends on many factors. First, the sun's height above the horizon changes with the time of year and day. In summer, during the daytime, the intensity of UV-B radiation is at its highest. There is a simple rule of thumb: when your shadow is shorter than your height, then you risk getting 50% more of this radiation.

Secondly, the intensity depends on the geographical latitude: in the equatorial regions (latitude is close to 0 °), the intensity of UV radiation is the highest - 2-3 times higher than in northern Europe.
Third, the intensity increases with altitude, as the atmospheric layer capable of absorbing ultraviolet light decreases accordingly, so that more of the highest-energy short-wave UV radiation reaches the Earth's surface.
Fourth, the scattering power of the atmosphere affects the radiation intensity: the sky appears to us blue due to the scattering of short-wavelength blue radiation in the visible range, and even shorter-wavelength ultraviolet light is scattered much more strongly.
Fifth, the intensity of radiation depends on the presence of clouds and fog. When the sky is cloudless, UV radiation reaches its maximum; dense clouds reduce its level. However, transparent and sparse clouds have little effect on the level of UV radiation, the water vapor of the fog can lead to an increase in the scattering of ultraviolet radiation. A person can perceive low-cloud and foggy weather as colder, but the intensity of UV radiation remains practically the same as on a clear day.

When the sky is clear, UV radiation reaches its maximum

Sixth, the amount of reflected ultraviolet radiation varies depending on the type of reflective surface. So, for snow, the reflection is 90% of the incident UV radiation, for water, soil and grass - about 10%, and for sand - from 10 to 25%. This must be borne in mind when on the beach.

What is the effect of ultraviolet radiation on the human body?

Prolonged and intense exposure to UV radiation can be harmful to living organisms - animals, plants and humans. Note that some insects see in the UV-A range, and they are an integral part of the ecological system and in some way benefit humans. The most famous result of exposure to ultraviolet radiation on the human body is a tan, which is still a symbol of beauty and a healthy lifestyle. However, prolonged and intense exposure to UV radiation can lead to the development of skin cancers. It must be remembered that clouds do not block ultraviolet light, so the absence of bright sunlight does not mean that UV protection is unnecessary. The most harmful component of this radiation is absorbed by the ozone layer of the atmosphere. The fact that the thickness of the latter has been reduced means that UV protection will become even more important in the future. According to scientists, a decrease in the amount of ozone in the Earth's atmosphere by only 1% will lead to an increase in skin cancers by 2-3%.

What is the danger of ultraviolet light for the organ of vision?

There are serious laboratory and epidemiological data linking the duration of exposure to ultraviolet radiation with eye diseases:, pterygium, etc. Compared with the lens of an adult, the lens of a child is significantly more permeable to solar radiation, and 80% of the cumulative effects of exposure to ultraviolet waves accumulate in the human body until it reaches 18 -years old. The lens is most exposed to radiation immediately after the birth of the baby: it transmits up to 95% of the incident UV radiation. With age, the lens begins to acquire a yellow tint and becomes less transparent. By the age of 25, less than 25% of the incident ultraviolet rays reach the retina. With aphakia, the eye is deprived of the natural protection of the lens, so it is important to use UV absorbing lenses or filters in this situation.
It should be borne in mind that a number of medicines have photosensitizing properties, that is, they increase the effects of exposure to ultraviolet radiation. Opticians and optometrists should have an understanding of the general condition of a person and the drugs they use in order to make recommendations on the use of protective equipment.

What kind of eye protection are there?

The most effective way to protect yourself from ultraviolet radiation is to cover your eyes with special goggles, masks, and shields that completely absorb UV radiation. In production where UV sources are used, the use of such products is mandatory. When outdoors on a bright sunny day, it is recommended to wear sunglasses with special lenses that reliably protect against UV radiation. Such goggles should have wide temples or an adjoining shape to prevent the penetration of radiation from the side. Colorless spectacle lenses can also perform this function if they contain additives-absorbers or special surface treatment. Well-fitting sunglasses protect against both direct incident radiation and scattered and reflected from various surfaces. The effectiveness of the use of sunglasses and recommendations for their use are determined by specifying the category of the filter, the light transmission of which corresponds to the spectacle lenses.

The most effective way to protect against ultraviolet radiation is to cover your eyes with special goggles, masks that completely absorb UV radiation

What are the standards governing the light transmission of sunglasses lenses?

Currently, in our country and abroad, regulatory documents have been developed that regulate the light transmission of sun-protection lenses in accordance with the categories of filters and the rules for their use. In Russia it is GOST R 51831-2001 “Sunglasses. General technical requirements ”, and in Europe - EN 1836: 2005“ Personal eye protection - Sunglasses for general use and filters for direct observation of the sun ”.

Each type of sun lens is designed for specific lighting conditions and can be classified into one of the filter categories. There are five of them in total, and they are numbered from 0 to 4. According to GOST R 51831-2001, the light transmission T,%, of sun-protection lenses in the visible region of the spectrum can be from 80 to 3-8%, depending on the filter category. For the UV-B-range (280-315 nm), this indicator should not be more than 0.1T (depending on the filter category, it can be from 8.0 to 0.3-0.8%), and for UV-A - radiation (315-380 nm) - no more than 0.5T (depending on the filter category - from 40.0 to 1.5-4.0%). At the same time, manufacturers of high-quality lenses and glasses set more stringent requirements and guarantee the consumer a complete cut off of ultraviolet radiation up to a wavelength of 380 nm or even up to 400 nm, as evidenced by a special marking on the lenses of glasses, their packaging or accompanying documentation. It should be noted that for the lenses of sunglasses, the effectiveness of UV protection cannot be unambiguously determined by the degree of their darkening or the cost of the glasses.

Is it true that ultraviolet light is more dangerous if a person wears low-quality sunglasses?

This is indeed the case. Under natural conditions, when a person does not wear glasses, his eyes automatically respond to excessive brightness of sunlight by changing the size of the pupil. The brighter the light, the smaller the pupil, and with a proportional ratio of visible and ultraviolet radiation, this defense mechanism works very effectively. If a tinted lens is used, the lighting appears dimmer and the pupils are enlarged, allowing more light to reach the eyes. In the event that the lens does not provide adequate protection against ultraviolet radiation (the amount of visible radiation decreases more than ultraviolet radiation), the total amount of ultraviolet radiation entering the eyes is more significant than in the absence of sunglasses. This is why tinted and light-absorbing lenses must contain UV absorbers that reduce the amount of UV radiation in proportion to the reduction in visible light. According to international and domestic standards, the light transmission of sunscreen lenses in the UV region is regulated as proportional to the light transmission in the visible part of the spectrum.

What optical material for spectacle lenses provides UV protection?

Some spectacle lens materials provide UV absorption due to their chemical structure. It activates photochromic lenses, which, under appropriate conditions, block its access to the eye. Polycarbonate contains groups that absorb radiation in the ultraviolet region, so it protects the eyes from ultraviolet radiation. CR-39 and other organic materials for spectacle lenses in their pure form (without additives) transmit a certain amount of UV radiation, and special absorbers are introduced into their composition for reliable eye protection. These components not only protect the eyes of users, providing cut-off of ultraviolet light up to 380 nm, but also prevent photo-oxidative degradation of organic lenses and their yellowing. Mineral eyeglass lenses made of ordinary crown glass are unsuitable for reliable protection against UV radiation, unless special additives are added to the batch for its production. These lenses can only be used as sunscreens after applying high-quality vacuum coatings.

Is it true that the effectiveness of UV protection for photochromic lenses is determined by their light absorption in the activated stage?

Some eyeglass wearers ask a similar question, as they are worried about whether they will be reliably protected from ultraviolet radiation on a cloudy day when there is no bright sunlight. It should be noted that modern photochromic lenses absorb from 98 to 100% of UV radiation at all light levels, that is, regardless of whether they are currently colorless, medium or dark colored. Thanks to this feature, photochromic lenses are suitable for eyeglass wearers outdoors in various weather conditions. As a growing number of people are beginning to understand the dangers of long-term exposure to UV radiation to eye health, many are opting for photochromic lenses. The latter are distinguished by high protective properties in combination with a special advantage - automatic change in light transmission depending on the level of illumination.

Does a dark lens color guarantee UV protection?

The intense coloration of sunscreen lenses alone does not guarantee UV protection. It should be noted that cheap organic sun lenses produced in high volume production conditions can have a fairly high level of protection. Typically, a special UV absorber is first mixed with lens raw materials and colorless lenses are made, and then dyeing is carried out. It is more difficult to achieve UV protection for sunscreen mineral lenses, as their glass transmits more radiation than many types of polymer materials. For guaranteed protection, it is necessary to introduce a number of additives into the composition of the charge for the production of lens blanks and the use of additional optical coatings.
Tinted prescription lenses are made from suitable clear lenses that may or may not have a sufficient amount of UV absorber to reliably cut off the appropriate range of radiation. If lenses with 100% UV protection are needed, the task of monitoring and ensuring such an indicator (up to 380-400 nm) is entrusted to an optician-consultant and a master - glasses collector. In this case, the introduction of UV absorbers into the surface layers of organic spectacle lenses is carried out using a technology similar to the coloring of lenses in dye solutions. The only exception is that UV protection cannot be seen with the eye and special devices are needed to check it - UV testers. Manufacturers and suppliers of equipment and colorants for dyeing organic lenses include a variety of surface treatment formulations to provide different levels of UV and short wavelength visible light protection. It is not possible to control the light transmission of the ultraviolet component in a standard optical workshop.

Should an UV absorber be inserted into colorless lenses?

Many experts believe that the introduction of a UV absorber into colorless lenses will only be beneficial, as it will protect the eyes of the wearer and prevent deterioration of the properties of the lenses under the influence of UV radiation and atmospheric oxygen. In some countries where there is a high level of solar radiation, such as Australia, this is mandatory. As a rule, they try to ensure that the radiation is cut off to 400 nm. Thus, the most dangerous and high-energy components are excluded, and the remaining radiation is sufficient for the correct perception of the color of objects in the surrounding reality. If the cut-off border is shifted to the visible region (up to 450 nm), then the lenses will have a yellow color, with an increase up to 500 nm - orange.

How can you be sure your lenses provide UV protection?

There are many different UV testers on the optical market that allow you to check the light transmission of spectacle lenses in the ultraviolet range. They show what level of transmission a given lens has in the UV range. However, it should be borne in mind that the optical power of the correcting lens may affect the measurement data. More accurate data can be obtained using sophisticated instruments - spectrophotometers, which not only show the light transmission at a certain wavelength, but also take into account the optical power of the correcting lens when measuring.

UV protection is an important aspect to consider when fitting new spectacle lenses. We hope that the answers to questions about ultraviolet radiation and how to protect against it, given in this article, will help you choose spectacle lenses that will make it possible to keep your eyes healthy for years to come.

Beneficial effects of UV rays on the body

The sun's rays provide warmth and light that improve overall well-being and stimulate blood circulation. A small amount of UV light is needed by the body for the production of vitamin D. Vitamin D plays an important role in the absorption of calcium and phosphorus from food, as well as in skeletal development, the functioning of the immune system, and in the formation of blood cells. Without a doubt, a small amount of sunlight is good for us. Exposure to sunlight for 5 to 15 minutes on the skin of the hands, face and hands two to three times a week during the summer months is sufficient to maintain normal vitamin D levels. Closer to the equator, where UV radiation is more intense, an even shorter interval is sufficient.

Therefore, vitamin D deficiency is unlikely for most people. Possible exceptions are those who have significantly limited their exposure to the sun: elderly people who do not leave their homes or people with highly pigmented skin who live in countries with low UV radiation. Naturally occurring vitamin D is very rare in our food, it is found mainly in fish oil and cod liver oil.

Ultraviolet radiation has been used successfully in the treatment of many conditions, including rickets, psoriasis, eczema, and others. This therapeutic treatment does not exclude the negative side effects of UV radiation, but it is administered under medical supervision to ensure that the benefits outweigh the risks.

Despite its significant role in medicine, the negative effects of UV radiation usually far outweigh the positive ones. In addition to the well-known direct effects of excess ultraviolet radiation, such as burns or allergic reactions, long-term effects pose a lifelong health hazard. Excessive tanning can damage the skin, eyes, and possibly the immune system. Many people forget that UV radiation accumulates throughout life. Your attitude towards tanning now determines the possibility of developing skin cancer or cataracts in later life! The risk of developing skin cancer is directly related to the duration and frequency of sunburn.

Impact atlight violet on the skin

There is no healthy tan! Skin cells produce dark pigment only to protect against subsequent radiation. Tanning provides some protection against UV light. A dark tan on white skin is equivalent to an SPF between 2 and 4. However, this does not provide protection against long-term effects such as skin cancer. A tan can be cosmetically attractive, but in fact it only means that your skin has been damaged and is trying to protect itself.

There are two different mechanisms for the formation of tanning: quick tanning, when the pigment already existing in the cells darkens under the influence of ultraviolet radiation. This tan begins to fade within a few hours after exposure has ceased. Long-term tanning occurs within about three days when new melanin is produced and distributed among the skin cells. This tan can last for several weeks.

Sunburn-High doses of ultraviolet radiation are detrimental to most cells of the epidermis, and the surviving cells are damaged. At best, a sunburn causes a reddening of the skin called erythema. It appears shortly after sun exposure and reaches its maximum intensity between 8 and 24 hours. In this case, the consequences disappear within a few days. However, heavy tanning can leave painful blisters and white patches on the skin, where new skin is devoid of protection and is more susceptible to UV damage.

Photosensitization -A small percentage of the population is highly sensitive to ultraviolet radiation. Even a minimal dose of ultraviolet radiation is enough to trigger allergic reactions in them, leading to rapid and severe sunburn. Photosensitization is often associated with the use of certain medications, including some nonsteroidal anti-inflammatory drugs, pain relievers, tranquilizers, oral antidiabetic drugs, antibiotics, and antidepressants. If you are constantly taking any medications, carefully read the annotation or consult with your doctor about possible photosensitization reactions. Certain food and cosmetic products such as perfumes or soaps may also contain UV-sensitizing ingredients.

PhotoagingSun exposure contributes to the aging of your skin through a combination of several factors. UVB stimulates a rapid increase in the number of cells in the upper layer of the skin. As more and more cells are produced, the epidermis thickens.

UVA penetrating into the deeper layers of the skin damages the connective tissue structures and the skin gradually loses its elasticity. Wrinkles and sagging skin are a common result of this loss. A phenomenon that we can often see in older people is the localized excess production of melanin, leading to dark areas or liver spots. In addition, the sun's rays dry out your skin, making it rough and rough.

Non-melanoma skin cancersUnlike melanoma, basal cell and squamous carcinomas are usually not fatal, but surgical removal can be painful and scarring.

Non-melanoma cancers are most often located on parts of the body exposed to the sun, such as the ears, face, neck, and forearms. They have been found to be more common in outdoor workers than in indoor workers. This suggests that long-term accumulation of UV exposure plays a major role in the development of non-melanoma skin cancers.

Melanoma-Malignant melanoma is the rarest, but also the most dangerous, type of skin cancer. It is one of the most common cancers in people between the ages of 20 and 35, especially in Australia and New Zealand. All forms of skin cancer have tended to increase over the past twenty years, however, the highest worldwide remains with melanoma.

Melanoma can appear under the guise of a new mole or as a change in color, shape, size, or sensation change in pre-existing spots, freckles, or moles. Melanomas usually have an uneven outline and uneven coloration. Itching is another common symptom, but it can also occur with normal moles. If the disease is recognized and treatment is carried out in a timely manner, the prognosis for life is favorable. If left untreated, the tumor can grow rapidly and cancer cells can spread to other parts of the body.

Eye exposure to ultraviolet radiation

The eyes occupy less than 2 percent of the surface of the body, but they are the only organ system that allows visible light to penetrate deep into the body. Over the course of evolution, many mechanisms have evolved to protect this highly sensitive organ from the harmful effects of sunlight:

The eye is located in the anatomical recesses of the head, protected by the brow arches, eyebrows and eyelashes. However, this anatomical adaptation only partially protects against ultraviolet rays in extreme conditions, such as the use of a tanning bed or when light is strongly reflected from snow, water and sand.

Narrowing the pupil, closing the eyelids and squinting minimizes the penetration of the sun's rays into the eye.

However, these mechanisms are activated by bright visible light rather than ultraviolet rays, but ultraviolet radiation can also be high on a cloudy day. Therefore, the effectiveness of these natural defense mechanisms against UV exposure is limited.

Photokeratitis and photoconjunctivitisPhotokeratitis is inflammation of the cornea, while photoconjunctivitis refers to inflammation of the conjunctiva, the membrane that limits the sphere of the eye and covers the inner surface of the eyelids. Inflammatory reactions of the eyeball and eyelids can be, along with sunburn of the skin, very sensitive and usually appear within a few hours after exposure. Photokeratitis and photoconjunctivitis can be very painful, however, they are reversible and do not appear to cause permanent eye damage or visual impairment.

The extreme form of photokeratitis is snow blindness. This sometimes occurs in skiers and climbers who are exposed to very high doses of ultraviolet rays due to altitude conditions and very strong reflections. Fresh snow can reflect up to 80 percent of UV rays. These ultra-high doses of ultraviolet radiation are detrimental to the cells of the eye and can lead to blindness. Snow blindness is very painful. Most often, new cells grow quickly and vision is restored within a few days. In some cases, sun blindness can lead to complications such as chronic irritation or watery eyes.

Pterygium -This overgrowth of the conjunctiva on the surface of the eye is a common cosmetic defect, presumably associated with prolonged exposure to ultraviolet radiation. The pterygium can spread to the center of the cornea and thus reduce vision. This phenomenon can also become inflamed. Although the disease can be surgically removed, it tends to recur.

Cataract-the leading cause of blindness in the world. Lens proteins accumulate pigments that coat the lens and ultimately lead to blindness. Despite the fact that cataracts appear to varying degrees in most people with age, it seems that the likelihood of cataracts increases with exposure to ultraviolet radiation.

Cancer lesions of the eyesRecent scientific evidence suggests that various forms of eye cancer may be associated with lifetime exposure to ultraviolet radiation.

Melanoma - frequent cancerous lesions of the eyes and sometimes requiring surgical removal. Basal cell carcinoma most often located in the area of \u200b\u200bthe eyelids.

Effect of UV radiation on the immune system

Exposure to sunlight can precede herpes sores. In all likelihood, UVB radiation reduces the effectiveness of the immune system and it can no longer control the herpes simplex virus. As a result, the infection is released. One study in the United States examined the effect of sunscreen on the severity of cold sores. Of the 38 patients with herpes simplex infection, 27 developed rashes after exposure to UV radiation. In contrast, when using sunscreen, none of the patients developed rashes. Therefore, in addition to protecting from the sun, sunscreen can be effective in preventing the recurrence of sun-induced cold sores.

Research in recent years is increasingly proving that exposure to ultraviolet radiation from the external environment can change the activity and distribution of certain cells responsible for the immune response in the human body. As a consequence, excess UV radiation can increase the risk of infection or decrease the body's ability to defend against skin cancer. Where UV radiation is high (mainly in developing countries) this can reduce the effectiveness of vaccinations.

It has also been suggested that ultraviolet radiation can cause cancer in two different ways: by directly damaging DNA and by weakening the immune system. To date, few studies have been conducted to describe the potential effects of immunomodulation on cancer development.