What causes ultraviolet radiation. UV lamp for home use: types, how to choose which manufacturer is better

Theoretically, the question How are infrared rays different from ultraviolet rays?' could be of interest to anyone. After all, both those and other rays are part of the solar spectrum - and we are exposed to the Sun every day. In practice, it is most often asked by those who are going to purchase devices known as infrared heaters, and would like to make sure that such devices are absolutely safe for human health.

How infrared rays differ from ultraviolet rays in terms of physics

As you know, in addition to the seven visible colors of the spectrum beyond its limits, there are radiation invisible to the eye. In addition to infrared and ultraviolet, these include x-rays, gamma rays and microwaves.

Infrared and UV rays are similar in one thing: they both belong to that part of the spectrum that is not visible to the naked eye of a person. But this is where their similarity ends.

Infrared radiation

Infrared rays were found outside the red border, between the long and short wavelengths of this part of the spectrum. It is worth noting that almost half of the solar radiation is infrared radiation. The main characteristic of these rays, invisible to the eye, is strong thermal energy: all heated bodies continuously radiate it.
Radiation of this type is divided into three regions according to such a parameter as wavelength:

• from 0.75 to 1.5 microns - near area;
• from 1.5 to 5.6 microns - medium;
• from 5.6 to 100 microns - far.

It must be understood that infrared radiation is not a product of all kinds of modern technical devices, for example, infrared heaters. This is a factor of the natural environment, which constantly acts on a person. Our body continuously absorbs and emits infrared rays.

Ultraviolet radiation

The existence of rays beyond the violet end of the spectrum was proved in 1801. The range of ultraviolet rays emitted by the Sun is from 400 to 20 nm, but only a small part of the short-wave spectrum reaches the earth's surface - up to 290 nm.
Scientists believe that ultraviolet radiation plays a significant role in the formation of the first organic compounds on Earth. However, the impact of this radiation is also negative, leading to the decay of organic substances.
When answering a question, How is infrared radiation different from ultraviolet radiation?, it is necessary to consider the impact on the human body. And here the main difference lies in the fact that the effect of infrared rays is limited mainly to thermal effects, while ultraviolet rays can also have a photochemical effect.
UV radiation is actively absorbed by nucleic acids, resulting in changes in the most important indicators of cell vital activity - the ability to grow and divide. It is DNA damage that is the main component of the mechanism of exposure to ultraviolet rays on organisms.
The main organ of our body that is affected by ultraviolet radiation is the skin. It is known that thanks to UV rays, the process of formation of vitamin D, which is necessary for the normal absorption of calcium, is triggered, and serotonin and melatonin are also synthesized - important hormones that affect circadian rhythms and human mood.

Exposure to IR and UV radiation on the skin

When a person is exposed to sunlight, infrared, ultraviolet rays also affect the surface of his body. But the result of this impact will be different:

• IR rays cause a rush of blood to the surface layers of the skin, an increase in its temperature and redness (caloric erythema). This effect disappears as soon as the effect of irradiation stops.
• Exposure to UV radiation has a latent period and may appear several hours after exposure. The duration of ultraviolet erythema ranges from 10 hours to 3-4 days. The skin turns red, may peel off, then its color becomes darker (tan).

It has been proven that excessive exposure to ultraviolet radiation can lead to the occurrence of malignant skin diseases. At the same time, in certain doses, UV radiation is beneficial for the body, which allows it to be used for prevention and treatment, as well as for the destruction of bacteria in indoor air.

Is infrared radiation safe?

People's fears in relation to such a type of device as infrared heaters are quite understandable. In modern society, a stable tendency has already formed with a fair amount of fear to treat many types of radiation: radiation, X-rays, etc.
For ordinary consumers who are going to purchase devices based on the use of infrared radiation, the most important thing to know is the following: infrared rays are completely safe for human health. This is what needs to be emphasized when considering How are infrared rays different from ultraviolet rays?.
Studies have proven that long-wave infrared radiation is not only useful for our body - it is absolutely necessary for it. With a lack of infrared rays, the body's immunity suffers, and the effect of its accelerated aging is also manifested.


The positive impact of infrared radiation is no longer in doubt and manifests itself in various aspects.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Table 10.1.Erythema effectiveness of monochromatic UV radiation

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Source of UV radiation;

How to use it;

The area of ​​the irradiated surface;

The season of the beginning of irradiation;

Photosensitivity of the skin (biodose);

Irradiation intensity (irradiance);

Irradiation time.

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

Table 10.4.The relationship of physical and reduced units for

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

protective clothing, sunscreens (canopies), special creams.

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

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 action 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 improves 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

General characteristics of ultraviolet radiation

Remark 1

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

Currently ultraviolet radiation widely used in various fields of activity. The peak of ultraviolet activity reaches in the range of high temperatures. This kind of spectrum appears when the temperature reaches $1500$ to $20000$ degrees.

Conventionally, the radiation range is divided into 2 areas:

1. near spectrum, which reaches the Earth from the Sun through the atmosphere and has a wavelength of $380$-$200$ nm;
2. far spectrum absorbed by ozone, atmospheric oxygen and other components of the atmosphere. This spectrum can be studied using special vacuum devices, so 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.

Spectrum of ultraviolet rays of the sun reaching the Earth's surface is narrow - $400$…$290$ nm. It turns out that the Sun does not emit light with a wavelength shorter than $290$ nm. So is it or isn't it? The answer to this question was found by the French A. Cornu who found that ultraviolet rays shorter than $295$ nm are absorbed by ozone. Based on this, A. Cornu suggested that the sun emits short-wavelength 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 screen.

Scientist's assumption confirmed when a person managed to rise into the upper layers of the atmosphere. The height of the sun above the horizon and the amount of ultraviolet rays reaching the earth's surface are directly related. When the illumination changes by $20$%, the number of ultraviolet rays reaching the surface will decrease by $20$ times. The experiments performed showed that for every $100$ m of ascent, the intensity of ultraviolet radiation increases by $3$-$4$ %. In the equatorial region of the planet, when the Sun is at its zenith, the earth's surface is reached by rays with a length of $290$…$289$ nm. Beams with a wavelength of $350$…$380$ nm arrive at the earth's surface beyond the Arctic Circle.

Sources of ultraviolet radiation

Ultraviolet radiation has its sources:

1. Natural sources;
2. Sources created by man;
3. laser sources.

natural source ultraviolet rays is their only concentrator and emitter - this is our 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 advent of the ozone layer on the planet could life arise. It is this layer that protects all living things from harmful excessive penetration of ultraviolet radiation. The ability to exist of 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 let them to the surface of the Earth. The ultraviolet radiation reaching the earth's surface has a range that ranges from $200$ to $400$ nm.

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

1. The presence of ozone holes;
2. Position of the territory (height) above sea level;
3. The height of the Sun itself;
4. The ability of the atmosphere to scatter rays;
5. The reflectivity of the underlying surface;
6. Cloud vapor states.

artificial sources ultraviolet light is usually created by man. It can be devices, devices, technical means designed by people. They are created to obtain the desired spectrum of light with given wavelength parameters. The purpose of their creation is that the resulting ultraviolet radiation can be usefully applied in various fields of activity.

Artificial sources 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 solariums that prevent winter depression and give a beautiful natural tan;
3. Used indoors to control insects attractant lamps. For humans, they do not pose a danger;
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.

Man-made sources of ultraviolet light 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. There is currently laser working on free electrons. It produces a length of ultraviolet radiation equal to that observed in vacuum conditions. Laser ultraviolet is used in biotechnological, microbiological research, mass spectrometry, etc.

Application of ultraviolet radiation

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

UV characteristics:

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

Based on this, ultraviolet radiation can be widely used, for example, in spectrometric analysis, astronomy, medicine, drinking water disinfection, mineral analysis, insect, bacteria and virus destruction. Each area 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, because they are unique. The destruction of insects is based on the fact that their eyes pick up short-wave spectra invisible to humans. Insects fly to this source and are destroyed. Special installations in solariums expose the human body UV-A. As a result, melanin production is activated in the skin, which gives it a darker and more even color. Here, of course, it is important to protect sensitive areas and eyes.

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 ultraviolet 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 ulcers of the stomach;
8. Atherosclerosis, kidney failure, etc.

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

Remark 2

In this way, ultraviolet 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 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 ornamental 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 bright green, emerald - red, pearls shimmer with multicolor. The spectacle is amazing, fantastic.

Water, sunlight and oxygen contained in the earth's atmosphere are the main conditions for the emergence and factors that ensure the continuation of life on our planet. At the same time, it has long been proven that the spectrum and intensity of solar radiation in space vacuum are unchanged, and on Earth the impact of ultraviolet radiation depends on many factors: time of year, geographic location, altitude, ozone layer thickness, cloud cover and the level of concentration of natural and industrial impurities in the air.

What are ultraviolet rays

The sun emits rays in the ranges visible and invisible to the human eye. The invisible spectrum includes infrared and ultraviolet rays.

Infrared radiation is electromagnetic waves with a length of 7 to 14 nm, which carry a colossal flow of thermal energy to the Earth, and therefore they are often called thermal. The share of infrared rays in solar radiation is 40%.

Ultraviolet radiation is a spectrum of electromagnetic waves, the range of which is conditionally divided into near and far ultraviolet rays. Far or vacuum rays are completely absorbed by the upper atmosphere. Under terrestrial conditions, they are artificially generated only in vacuum chambers.

Near ultraviolet rays are divided into three subgroups of ranges:

• long - A (UVA) from 400 to 315 nm;
• medium - B (UVB) from 315 to 280 nm;
• short - C (UVC) from 280 to 100 nm.

How is ultraviolet radiation measured? Today, there are many special devices, both for domestic and professional use, that allow you to measure the frequency, intensity and magnitude of the received dose of UV rays, and thereby assess their likely harm to the body.

Despite the fact that ultraviolet radiation in the composition of sunlight occupies only about 10%, it was due to its influence that a qualitative leap occurred in the evolutionary development of life - the emergence of organisms from water to land.

The main sources of ultraviolet radiation

The main and natural source of ultraviolet radiation is, of course, the Sun. But man also learned to "produce ultraviolet" with the help of special lamp devices:

• high-pressure mercury-quartz lamps operating in the general range of UV radiation - 100-400 nm;
• vital fluorescent lamps generating wavelengths from 280 to 380 nm, with a maximum emission peak between 310 and 320 nm;
• ozone and ozone-free (with quartz glass) germicidal lamps, 80% of the ultraviolet rays of which fall at a length of 185 nm.

Both the ultraviolet radiation of the sun and artificial ultraviolet light have the ability to influence the chemical structure of the cells of living organisms and plants, and at the moment, only a few varieties of bacteria are known that can do without it. For everyone else, the absence of ultraviolet radiation will lead to imminent death.

So what is the real biological effect of ultraviolet rays, what are the benefits and is there any harm from ultraviolet radiation for humans?

The effect of ultraviolet rays on the human body

The most insidious ultraviolet radiation is short-wave ultraviolet radiation, as it destroys any kind of protein molecules.

So why is terrestrial life possible and continuing on our planet? What layer of the atmosphere blocks harmful ultraviolet rays?

From hard ultraviolet radiation, living organisms protect the ozone layers of the stratosphere, which completely absorb the rays of this range, and they simply do not reach the Earth's surface.

Therefore, 95% of the total mass of solar ultraviolet is in long wavelengths (A), and approximately 5% is in medium wavelengths (B). But here it is important to clarify. Despite the fact that there are many more long UV waves, and they have a large penetrating power, affecting the reticular and papillary layers of the skin, it is 5% of medium waves that cannot penetrate beyond the epidermis that have the greatest biological effect.

It is ultraviolet radiation of the middle range that intensively affects the skin, eyes, and also actively affects the work of the endocrine, central nervous and immune systems.

On the one hand, ultraviolet irradiation can cause:

• severe sunburn of the skin - ultraviolet erythema;
• clouding of the lens, leading to blindness - cataract;
• skin cancer is melanoma.

In addition, ultraviolet rays have a mutagenic effect and cause malfunctions in the immune system, which cause other oncological pathologies.

On the other hand, it is the action of ultraviolet radiation that has a significant impact on the metabolic processes occurring in the human body as a whole. The synthesis of melatonin and serotonin increases, the level of which has a positive effect on the work of the endocrine and central nervous system. Ultraviolet light activates the production of vitamin D, which is the main component for the absorption of calcium, and also prevents the development of rickets and osteoporosis.

Skin irradiation with ultraviolet light

Skin lesions can be both structural and functional in nature, which, in turn, can be divided into:

1. Acute injury- arise due to high doses of solar radiation of the rays of the medium range, received in this case in a short time. These include acute photodermatosis and erythema.
2. Delayed Damage- occur against the background of prolonged irradiation with long-wave ultraviolet rays, the intensity of which, by the way, does not depend on either the season or the time of daylight hours. These include chronic photodermatitis, photoaging of the skin or solar geroderma, ultraviolet mutagenesis and the occurrence of neoplasms: melanoma, squamous and basal cell skin cancer. Among the list of delayed injuries is herpes.

It is important to note that both acute and delayed damage can be caused by excessive exposure to artificial sunbathing, not wearing sunglasses, and visiting tanning salons that use non-certified equipment and / or do not carry out special preventive calibration of UV lamps.

UV skin protection

If you do not abuse any "sunbathing", then the human body will cope with radiation protection on its own, because more than 20% is retained by a healthy epidermis. Today, protection from ultraviolet radiation of the skin is reduced to the following methods that minimize the risk of malignant neoplasms:

• limiting the time spent in the sun, especially during the midday summer hours;
• wearing light but closed clothing, because to get the required dose that stimulates the production of vitamin D, it is not at all necessary to be covered with a tan;
• selection of sunscreens depending on the specific ultraviolet index characteristic of the area, time of year and day, as well as your own skin type.

Attention! For the indigenous people of central Russia, a UV index above 8 not only requires the use of active protection, but also poses a real threat to health. Radiation measurements and solar index forecasts can be found on leading weather websites.

The effect of ultraviolet light on the eyes

Damage to the structure of the eye cornea and lens (electrophthalmia) is possible with eye contact with any source of ultraviolet radiation. Despite the fact that a healthy cornea does not transmit and reflects hard ultraviolet by 70%, there are a lot of reasons that can become a source of serious diseases. Among them:

• unprotected observation of flares, solar eclipses;
• a casual glance at a luminary on the sea coast or in high mountains;
• photo-trauma from a camera flash;
• monitoring the operation of the welding machine or neglecting safety precautions (lack of a protective helmet) when working with it;
• long work of a stroboscope at discos;
• violation of the rules for visiting the solarium;
• prolonged stay in a room in which quartz bactericidal ozone lamps work.

What are the first signs of electrophthalmia? Clinical symptoms, namely redness of the eye sclera and eyelids, pain when moving the eyeballs and a sensation of a foreign body in the eye, usually occur 5-10 hours after the above circumstances. However, UV protection is available to everyone, because even ordinary glass lenses do not let through most of the UV rays.

The use of protective glasses with a special photochromic coating on the lenses, the so-called "chameleon glasses", will be the best "household" option for eye protection. You don't have to worry about what color and degree of shading a UV filter actually provides effective protection in a given circumstance.

And of course, with the expected eye contact with flashes of ultraviolet, it is necessary to put on goggles in advance or use other devices that delay the rays that are harmful to the cornea and lens.

The use of ultraviolet in medicine

Ultraviolet kills fungus and other microbes that are in the air and on the surface of walls, ceilings, floors and objects, and after exposure to special lamps, mold is cleansed. This bactericidal property of ultraviolet is used by people to ensure the sterility of manipulation and surgical rooms. But ultraviolet radiation in medicine is used not only to combat nosocomial infections.

The properties of ultraviolet radiation have found their application in a variety of diseases. At the same time, new methods are constantly being developed and improved. For example, ultraviolet blood irradiation, invented about 50 years ago, was originally used to suppress the growth of bacteria in the blood in sepsis, severe pneumonia, extensive purulent wounds and other purulent-septic pathologies.

Today, ultraviolet blood irradiation or blood purification helps to fight acute poisoning, drug overdose, furunculosis, destructive pancreatitis, atherosclerosis obliterans, ischemia, cerebral atherosclerosis, alcoholism, drug addiction, acute mental disorders and many other diseases, the list of which is constantly expanding. .

Diseases for which the use of ultraviolet radiation is indicated, and when any procedure with UV rays is harmful:

In order to live without pain, for people with joint damage, an ultraviolet lamp will bring invaluable help in general complex therapy.

The influence of ultraviolet radiation in rheumatoid arthritis and arthrosis, the combination of the method of ultraviolet therapy with the correct selection of a biodose and a competent antibiotic regimen is a 100% guarantee of achieving a systemic healing effect with a minimum drug load.

In conclusion, we note that the positive effect of ultraviolet radiation on the body and just one single procedure of ultraviolet irradiation (purification) of blood + 2 sessions in the solarium will help a healthy person look and feel 10 years younger.