Oxygen, sunlight and water contained in the Earth's atmosphere are the main conditions conducive to the continuation of life on the planet. Researchers have long proven that the intensity and spectrum of solar radiation in the vacuum that exists in space remains unchanged.
On Earth, the intensity of its impact, which we call ultraviolet radiation, depends on many factors. Among them: the season, the geographical location of the area above sea level, the thickness of the ozone layer, cloudiness, as well as the level of concentration of industrial and natural impurities in the air masses.
Ultra-violet rays
Sunlight reaches us in two ranges. The human eye can only distinguish one of them. Ultraviolet rays are in the spectrum invisible to humans. What are they? It is nothing but electromagnetic waves. The length of ultraviolet radiation is in the range from 7 to 14 nm. Such waves carry huge flows of thermal energy to our planet, which is why they are often called thermal waves.
By ultraviolet radiation it is customary to understand an extensive spectrum consisting of electromagnetic waves with a range conditionally divided into far and near rays. The first of them are considered vacuum. They are completely absorbed by the upper atmosphere. Under the conditions of the Earth, their generation is possible only in the conditions of vacuum chambers.
As for near ultraviolet rays, they are divided into three subgroups, classified by range into:
Long, ranging from 400 to 315 nanometers;
Medium - from 315 to 280 nanometers;
Short - from 280 to 100 nanometers.
Measuring instruments
How does a person determine ultraviolet radiation? To date, there are many special devices designed not only for professional, but also for domestic use. They measure the intensity and frequency, as well as the magnitude of the received dose of UV rays. The results allow us to assess their possible harm to the body.
UV Sources
The main "supplier" of UV rays on our planet is, of course, the Sun. However, to date, artificial sources of ultraviolet radiation have been invented by man, which are special lamp devices. Among them:
High pressure mercury-quartz lamp capable of operating in the general range of 100 to 400 nm;
Fluorescent vital lamp generating wavelengths from 280 to 380 nm, the maximum peak of its radiation is between 310 and 320 nm;
Ozone-free and ozone germicidal lamps that produce ultraviolet rays, 80% of which are 185 nm long.
The benefits of UV rays
Similar to the natural ultraviolet radiation coming from the Sun, the light produced by special devices affects the cells of plants and living organisms, changing their chemical structure. Today, researchers know only a few varieties of bacteria that can exist without these rays. The rest of the organisms, once in conditions where there is no ultraviolet radiation, will certainly die.
UV rays can have a significant impact on ongoing metabolic processes. They increase the synthesis of serotonin and melatonin, which has a positive effect on the work of the central nervous system, as well as the endocrine system. Under the influence of ultraviolet light, the production of vitamin D is activated. And this is the main component that promotes the absorption of calcium and prevents the development of osteoporosis and rickets.
Harm of UV rays
Harsh ultraviolet radiation, detrimental to living organisms, does not let the ozone layers in the stratosphere reach the Earth. However, rays in the middle range, reaching the surface of our planet, can cause:
Ultraviolet erythema - a severe burn of the skin;
Cataract - clouding of the lens of the eye, which leads to blindness;
Melanoma is skin cancer.
In addition, ultraviolet rays can have a mutagenic effect, cause malfunctions in the immune forces, which causes oncological pathologies.
Skin lesion
Ultraviolet rays sometimes cause:
- Acute skin lesions. Their occurrence is facilitated by high doses of solar radiation containing mid-range rays. They act on the skin for a short time, causing erythema and acute photodermatosis.
- Delayed skin injury. It occurs after prolonged exposure to long-wave UV rays. These are chronic photodermatitis, solar geroderma, photoaging of the skin, the occurrence of neoplasms, ultraviolet mutagenesis, basal cell and squamous cell skin cancer. This list also includes herpes.
Both acute and delayed damage is sometimes caused by excessive exposure to artificial sunbathing, as well as visits to those tanning salons that use non-certified equipment or where UV lamps are not calibrated.
Skin protection
The human body, with a limited amount of any sunbathing, is able to cope with ultraviolet radiation on its own. The fact is that over 20% of such rays can delay a healthy epidermis. To date, protection from ultraviolet radiation, in order to avoid the occurrence of malignant tumors, will require:
Limiting the time spent in the sun, which is especially important during the summer midday hours;
Wearing light, but at the same time closed clothing;
Selection of effective sunscreens.
Using the bactericidal properties of ultraviolet light
UV rays can kill fungus, as well as other microbes that are on objects, wall surfaces, floors, ceilings and in the air. In medicine, these bactericidal properties of ultraviolet radiation are widely used, and their use is appropriate. Special lamps that produce UV rays ensure the sterility of surgical and manipulation rooms. However, ultraviolet bactericidal radiation is used by doctors not only to combat various nosocomial infections, but also as one of the methods for eliminating many diseases.
Phototherapy
The use of ultraviolet radiation in medicine is one of the methods of getting rid of various diseases. In the process of such treatment, a dosed effect of UV rays on the patient's body is produced. At the same time, the use of ultraviolet radiation in medicine for these purposes becomes possible due to the use of special phototherapy lamps.
A similar procedure is carried out to eliminate diseases of the skin, joints, respiratory organs, peripheral nervous system, and female genital organs. Ultraviolet light is prescribed to accelerate the healing process of wounds and to prevent rickets.
Especially effective is the use of ultraviolet radiation in the treatment of psoriasis, eczema, vitiligo, some types of dermatitis, prurigo, porphyria, pruritis. It is worth noting that this procedure does not require anesthesia and does not cause discomfort to the patient.
The use of a lamp that produces ultraviolet allows you to get a good result in the treatment of patients who have undergone severe purulent operations. In this case, the bactericidal property of these waves also helps patients.
The use of UV rays in cosmetology
Infrared waves are actively used in the field of maintaining human beauty and health. Thus, the use of ultraviolet germicidal radiation is necessary to ensure the sterility of various rooms and devices. For example, it can be the prevention of infection of manicure tools.
The use of ultraviolet radiation in cosmetology is, of course, a solarium. In it, with the help of special lamps, customers can get a tan. It perfectly protects the skin from possible subsequent sunburns. That is why cosmetologists recommend having several sessions in the solarium before traveling to hot countries or to the sea.
Necessary in cosmetology and special UV lamps. Thanks to them, there is a rapid polymerization of a special gel used for manicure.
Determination of electronic structures of objects
Ultraviolet radiation also finds its application in physical research. With its help, the spectra of reflection, absorption and emission in the UV region are determined. This makes it possible to refine the electronic structure of ions, atoms, molecules, and solids.
The UV spectra of stars, the Sun and other planets carry information about the physical processes that occur in the hot regions of the studied space objects.
Water purification
Where else are UV rays used? Ultraviolet bactericidal radiation finds its application for the disinfection of drinking water. And if earlier chlorine was used for this purpose, today its negative effect on the body has already been studied quite well. So, vapors of this substance can cause poisoning. The ingestion of chlorine itself provokes the occurrence of oncological diseases. That is why ultraviolet lamps are increasingly being used to disinfect water in private homes.
UV rays are also used in swimming pools. Ultraviolet emitters to eliminate bacteria are used in the food, chemical and pharmaceutical industries. These areas also need clean water.
Air disinfection
Where else does a person use UV rays? The use of ultraviolet radiation for air disinfection is also becoming more common in recent years. Recirculators and emitters are installed in crowded places, such as supermarkets, airports and train stations. The use of UV radiation, which affects microorganisms, makes it possible to disinfect their habitat to the highest degree, up to 99.9%.
domestic use
Quartz lamps that produce UV rays have been disinfecting and purifying the air in clinics and hospitals for many years. However, in recent years, ultraviolet radiation has been increasingly used in everyday life. It is highly effective in eliminating organic contaminants such as fungus and mold, viruses, yeasts and bacteria. These micro-organisms spread particularly rapidly in rooms where people, for various reasons, tightly close windows and doors for a long time.
The use of a bactericidal irradiator in domestic conditions becomes advisable with a small area of \u200b\u200bhousing and a large family with small children and pets. A UV lamp will allow rooms to be disinfected periodically, minimizing the risk of the onset and further transmission of diseases.
Similar devices are also used by tuberculosis patients. After all, such patients do not always receive treatment in a hospital. While at home, they need to disinfect their home, including using ultraviolet radiation.
Application in forensics
Scientists have developed a technology that allows detecting the minimum doses of explosives. For this, a device is used in which ultraviolet radiation is produced. Such a device is capable of detecting the presence of hazardous elements in the air and in water, on fabric, and also on the skin of a suspect in a crime.
Ultraviolet and infrared radiation also finds its application in macro photography of objects with invisible and hardly visible traces of a committed offense. This allows forensic scientists to study documents and traces of a shot, texts that have undergone changes as a result of their flooding with blood, ink, etc.
Other uses of UV rays
Ultraviolet radiation is used:
In show business to create lighting effects and lighting;
In currency detectors;
In printing;
In animal husbandry and agriculture;
For catching insects;
In restoration;
For chromatographic analysis.
Ultraviolet rays have the highest biological activity. Under natural conditions, the sun is a powerful source of ultraviolet rays. However, only its long-wavelength part reaches the earth's surface. Shorter wavelength radiation is absorbed by the atmosphere already at a height of 30-50 km from the earth's surface.
The highest intensity of the ultraviolet radiation flux is observed shortly before noon with a maximum in the spring months.
As already mentioned, ultraviolet rays have significant photochemical activity, which is widely used in practice. Ultraviolet irradiation is used in the synthesis of a number of substances, the bleaching of fabrics, the manufacture of patent leather, the blueprinting of drawings, the production of vitamin D, and other production processes.
An important property of ultraviolet rays is their ability to cause luminescence.
In some processes, exposure to working ultraviolet rays takes place, for example, electric welding with a voltaic arc, oxyfuel cutting and welding, the production of radio lamps and mercury rectifiers, casting and smelting of metals and certain minerals, blueprinting, sterilization of water, etc. Medical and technical personnel servicing mercury-quartz lamps.
Ultraviolet rays have the ability to change the chemical structure of tissues and cells.
UV wavelength
The biological activity of ultraviolet rays of different wavelengths is not the same. Ultraviolet rays with a wavelength of 400 to 315 mμ. have a relatively weak biological effect. Rays with a shorter wavelength are more biologically active. Ultraviolet rays with a length of 315-280 mμ have a strong skin and anti-rachitic effect. Radiation with a wavelength of 280-200 mμ has a particularly high activity. (bactericidal action, the ability to actively affect tissue proteins and lipoids, as well as cause hemolysis).
Under production conditions, exposure to ultraviolet rays with a wavelength of 36 to 220 mμ ., i.e., with significant biological activity, takes place.
Unlike thermal rays, the main property of which is the development of hyperemia in areas exposed to radiation, the effect of ultraviolet rays on the body seems to be much more complex.
Ultraviolet rays penetrate the skin relatively little and their biological effect is associated with the development of many neurohumoral processes that determine the complex nature of their influence on the body.
Ultraviolet erythema
Depending on the intensity of the light source and the content of infrared or ultraviolet rays in its spectrum, changes in the skin will not be the same.
Exposure to ultraviolet rays on the skin causes a characteristic reaction from the skin vessels - ultraviolet erythema. Ultraviolet erythema is significantly different from thermal erythema caused by infrared radiation.
Usually, when using infrared rays, pronounced changes in the skin are not observed, since the resulting burning sensation and pain prevent prolonged exposure to these rays. Erythema, which develops as a result of the action of infrared rays, occurs immediately after irradiation, is unstable, does not last long (30-60 minutes) and is mainly of a nested nature. After prolonged exposure to infrared rays, brown pigmentation of a spotted appearance appears.
Ultraviolet erythema appears after irradiation following a certain latent period. This period varies in different people from 2 to 10 hours. The duration of the latent period of ultraviolet erythema is in a known dependence on the wavelength: erythema from long-wave ultraviolet rays appears later and lasts longer than from short-wave ones.
Erythema caused by ultraviolet rays has a bright red color with sharp borders, exactly corresponding to the site of exposure. The skin becomes somewhat swollen and painful. The greatest development of erythema reaches 6-12 hours after the 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 peeling is observed.
The degree of development of erythema depends on the dose of ultraviolet rays and individual sensitivity. Ceteris paribus, the greater the dose of ultraviolet rays, the more intense the inflammatory reaction of the skin. The most pronounced erythema is caused by rays with wavelengths of about 290 mμ. With an overdose of ultraviolet radiation, erythema acquires a bluish tint, the edges of the erythema become blurry, the irradiated area is swollen and painful. Intense irradiation can cause a burn with the development of a bubble.
Sensitivity of different parts of the skin to ultraviolet light
The skin of the abdomen, lower back, lateral surfaces of the chest are most sensitive to ultraviolet rays. The skin of the hands and face is the least sensitive.
Persons with delicate, slightly pigmented skin, children, as well as those suffering from Graves' disease and vegetative dystonia are more sensitive. Increased sensitivity of the skin to ultraviolet rays is observed in spring.
It has been established that the sensitivity of the skin to ultraviolet rays can vary depending on the physiological state of the organism. The development of an erythemal reaction depends primarily on the functional state of the nervous system.
In response to ultraviolet irradiation, a pigment is formed and deposited in the skin, which is a product of skin protein metabolism (organic coloring matter - melanin).
Long-wave UV rays cause a more intense tan than short-wave UV rays. With repeated ultraviolet irradiation, the skin becomes less susceptible to these rays. Skin pigmentation often develops without previously visible erythema. In pigmented skin, ultraviolet rays do not cause photoerythema.
The positive effect of ultraviolet radiation
Ultraviolet rays reduce the excitability of sensory nerves (analgesic effect) and also have an antispastic and antirachitic effect. Under the influence of ultraviolet rays, the formation of vitamin D, which is very important for phosphorus-calcium metabolism, occurs (ergosterol in the skin is converted into vitamin D). Under the influence of ultraviolet rays, oxidative processes in the body increase, oxygen uptake by tissues and carbon dioxide release increase, enzymes are activated, and protein and carbohydrate metabolism improves. The content of calcium and phosphates in the blood increases. Blood formation, regenerative processes, blood supply and tissue trophism improve. Skin vessels dilate, blood pressure decreases, and the overall biotonus of the body increases.
The beneficial effect of ultraviolet rays is expressed in a change in the immunobiological reactivity of the body. Irradiation stimulates the production of antibodies, increases phagocytosis, tones the reticuloendothelial system. This increases the body's resistance to infections. The dosage of radiation is important in this respect.
A number of substances of animal and vegetable origin (hematoporphyrin, chlorophyll, etc.), some chemicals (quinine, streptocide, sulfidine, etc.), especially fluorescent paints (eosin, methylene blue, etc.), have the property increase the body's sensitivity to light. In industry, people working with coal tar have skin diseases of exposed parts of the body (itching, burning, redness), and these phenomena disappear at night. This is due to the photosensitizing properties of acridine contained in coal tar. Sensitization occurs predominantly in relation to visible rays and to a lesser extent in relation to ultraviolet rays.
Of great practical importance is the ability of ultraviolet rays to kill various bacteria (the so-called bactericidal effect). This action is especially pronounced in ultraviolet rays with wavelengths less than (265 - 200 mμ). The bactericidal effect of light is associated with the effect on the protoplasm of bacteria. It has been proven that mitogenetic radiation in cells and blood increases after ultraviolet irradiation.
According to modern concepts, the action of light on the body is based mainly on the reflex mechanism, although great importance is also attached to humoral factors. This is especially true for the action of ultraviolet rays. One must also keep in mind the possibility of the action of visible rays through the organs of vision on the cortex and vegetative centers.
In the development of erythema caused by light, significant importance is attached to the influence of rays on the receptor apparatus of the skin. When exposed to ultraviolet rays, as a result of the breakdown of proteins in the skin, histamine and histamine-like products are formed, which dilate the skin vessels and increase their permeability, which leads to hyperemia and swelling. The products formed in the skin under the influence of ultraviolet rays (histamine, vitamin D, etc.) enter the bloodstream and cause those general changes in the body that occur during irradiation.
Thus, the processes developing in the irradiated area lead in a neurohumoral way to the development of a general reaction of the organism. This reaction is determined mainly by the state of the higher regulatory divisions of the central nervous system, which, as you know, can change under the influence of various factors.
It is impossible to talk about the biological effect of ultraviolet radiation in general, regardless of the wavelength. Short-wave ultraviolet radiation causes denaturation of protein substances, long-wave - photolytic decay. The specific action of different sections of the spectrum of ultraviolet radiation is revealed mainly in the initial stage.
Application of ultraviolet radiation
The wide biological effect of ultraviolet rays makes it possible to use them in certain doses for preventive and therapeutic purposes.
For ultraviolet irradiation, sunlight is used, as well as artificial sources of irradiation: mercury-quartz and argon-mercury-quartz lamps. The emission spectrum of mercury-quartz lamps is characterized by the presence of shorter ultraviolet rays than in the solar spectrum.
Ultraviolet irradiation can be general or local. The dosage of procedures is carried out according to the principle of biodoses.
Currently, ultraviolet irradiation is widely used, primarily for the prevention of various diseases. For this purpose, ultraviolet irradiation is used to improve the human environment and change its reactivity (primarily to increase its immunobiological properties).
With the help of special bactericidal lamps, air can be sterilized in medical institutions and residential premises, sterilization of milk, water, etc. Ultraviolet irradiation is widely used to prevent rickets, influenza, in order to generally strengthen the body in medical and children's institutions, schools, gyms , fotaria at coal mines, when training athletes, for acclimatization to the conditions of the north, when working in hot shops (ultraviolet irradiation gives a greater effect in combination with infrared radiation).
Ultraviolet rays are especially widely used for irradiating children. First of all, such exposure is shown to weakened, often ill children living in the northern and middle latitudes. At the same time, the general condition of children improves, sleep increases, weight increases, morbidity decreases, the frequency of catarrhal phenomena and the duration of diseases decrease. Improves overall physical development, normalizes blood, vascular permeability.
Ultraviolet irradiation of miners in fotaria, which are organized in large numbers at mining enterprises, has also become widespread. With systematic mass exposure of miners employed in underground work, there is an improvement in well-being, an increase in working capacity, a decrease in fatigue, a decrease in morbidity with temporary disability. After irradiation of miners, the percentage of hemoglobin increases, monocytosis appears, the number of cases of influenza decreases, the incidence of the musculoskeletal system, the peripheral nervous system decreases, pustular skin diseases, catarrhs of the upper respiratory tract and tonsillitis are less common, and the readings of vital capacity and lungs improve.
The use of ultraviolet radiation in medicine
The use of ultraviolet rays for therapeutic purposes is based mainly on the anti-inflammatory, anti-neuralgic and desensitizing effects of this type of radiant energy.
In combination with other therapeutic measures, ultraviolet irradiation is carried out:
1) in the treatment of rickets;
2) after suffering infectious diseases;
3) in case of tuberculosis diseases of bones, joints, lymph nodes;
4) with fibrous pulmonary tuberculosis without phenomena indicating activation of the process;
5) in diseases of the peripheral nervous system, muscles and joints;
6) with skin diseases;
7) with burns and frostbite;
8) with purulent complications of wounds;
9) with resorption of infiltrates;
10) in order to accelerate regenerative processes in case of injuries of bones and soft tissues.
Contraindications to radiation are:
1) malignant neoplasms (since radiation accelerates their growth);
2) severe exhaustion;
3) increased function of the thyroid gland;
4) severe cardiovascular diseases;
5) active pulmonary tuberculosis;
6) kidney disease;
7) pronounced changes in the central nervous system.
It should be remembered that obtaining pigmentation, especially in the short term, should not be the goal of treatment. In some cases, a good therapeutic effect is observed with weak pigmentation.
The negative effect of ultraviolet radiation
Prolonged and intense ultraviolet irradiation can have an adverse effect on the body and cause pathological changes. With significant exposure, fatigue, headaches, drowsiness, memory impairment, irritability, palpitations, and loss of appetite are noted. Excessive exposure can cause hypercalcemia, hemolysis, growth retardation and decreased resistance to infection. With strong exposure, burns and dermatitis develop (burning and itching of the skin, diffuse erythema, swelling). At the same time, there is an increase in body temperature, headache, weakness. Burns and dermatitis that occur under the influence of solar radiation are associated mainly with the influence of ultraviolet rays. People working outdoors under the influence of solar radiation may develop long-term and severe dermatitis. It is necessary to remember about the possibility of the transition of the described dermatitis into cancer.
Depending on the depth of penetration of the rays of different parts of the solar spectrum, changes in the eyes may develop. Under the influence of infrared and visible rays, acute retinitis occurs. The so-called glassblower's cataract, which develops as a result of prolonged absorption of infrared rays by the lens, is well known. Clouding of the lens occurs slowly, mainly among workers in hot shops with work experience of 20-25 years or more. Currently, professional cataracts in hot shops are rare due to a significant improvement in working conditions. The cornea and conjunctiva react mainly to ultraviolet rays. These rays (especially with a wavelength of less than 320 mμ.) cause in some cases an eye disease known as photophthalmia or electrophthalmia. This disease is most common in electric welders. In such cases, acute keratoconjunctivitis is often observed, which usually occurs 6-8 hours after work, often at night.
With electrophthalmia, hyperemia and swelling of the mucosa, blepharospasm, photophobia, and lacrimation are noted. Corneal lesions are often found. The duration of the acute period of the disease is 1-2 days. Photophthalmia sometimes occurs in people working outdoors in bright sunlight in wide snow-covered spaces in the form of so-called snow blindness. Treatment of photophthalmia is to stay in the dark, the use of novocaine and cold lotions.
UV protection
To protect the eyes from the adverse effects of ultraviolet rays in the workplace, they use shields or helmets with special dark glasses, goggles, and to protect the rest of the body and those around them, they use insulating screens, portable screens, and overalls.
ultraviolet light is a type of electromagnetic radiation that causes black light posters to glow, and is responsible for summer tanning and sunburn. However, too much exposure to UV radiation damages living tissue.
Electromagnetic radiation comes from the sun and is transmitted in waves or particles at different wavelengths and frequencies. This wide range of wavelengths is known as the electromagnetic (EM) spectrum. The spectrum is usually divided into seven regions in order of decreasing wavelength and increasing energy and frequency. Common designations are radio waves, microwaves, infrared (IR), visible, ultraviolet (UV), x-rays, and gamma rays.
Ultraviolet (UV) light falls within the EM spectrum between visible light and X-rays. It has frequencies from about 8×1014 to 3×1016 cycles per second or hertz (Hz) and wavelengths from about 380 nanometers (1.5×10-5 inches) to about 10 nm (4×10-7 inches). According to "Ultraviolet Radiation" by W.S. Navy, UV is usually divided into three subranges:
- UVA or near UV (315-400nm)
- UVB or Medium UV (280-315nm)
- UVC, or far UV (180-280nm)
Ultraviolet light has enough energy to break chemical bonds. Because of their higher energies, UV photons can cause ionization, a process in which they break away from atoms. The resulting vacancy affects the chemical properties of atoms and causes them to form or break chemical bonds that they would not otherwise have. This may be useful for chemical processing, or it may damage materials and living tissues. This damage can be beneficial, for example, on disinfecting surfaces, but it can also be harmful, especially to the skin and eyes, which are most adversely affected by ultraviolet radiation.
Much of the natural light with ultraviolet rays is found from the sun. However, only about 10 percent of sunlight is ultraviolet radiation, and only about a third of that enters the atmosphere when it reaches the ground. Of the sunlight, 95% reaches the equator, and 5% is ultraviolet. No measurable UVC from solar radiation reaches the Earth's surface because ozone, molecular oxygen and water vapor in the upper atmosphere completely absorb the shortest UV wavelengths. However, "broad-spectrum ultraviolet radiation is the strongest and most damaging to living things," according to the 13th NTP Report on Carcinogens.
Sunburn is a reaction to exposure to harmful rays. Essentially, tanning is due to the body's natural defense mechanism, which consists of a pigment called melanin, which is produced by cells in the skin called melanocytes. Melanin absorbs ultraviolet light and scatters it as heat. When the body senses sun damage, it sends melanin to surrounding cells and tries to protect them from further damage. The pigment causes the skin to darken.
“Melanin is a natural sunscreen,” an assistant professor of dermatology at Tufts University School of Medicine said in a 2013 interview. However, constant exposure to ultraviolet light can overwhelm the body's defenses. When this happens, a toxic reaction occurs, leading to sunburn. UV light can damage DNA in body cells. The body senses this destruction and floods the area with blood to aid in the healing process. Painful inflammation also occurs. Usually during the afternoon, due to overexhaustion in the sun, the characteristic red-lobster appearance of sunburn begins to become known and felt.
Sometimes cells with DNA mutated by sunlight turn into problem cells that don't die but continue to spread like cancer. "UV light causes random damage during the DNA repair process, so that cells acquire the ability to avoid death," Zhuang said.
The result is skin cancer, the most common form of cancer. People who get sunburn are at a significantly higher risk. According to the Skin Cancer Foundation, the risk of a deadly form of skin cancer called melanoma doubles for those who have had five or more sunburns.
A number of artificial sources have been developed to produce ultraviolet light. According to the Society for Health Physics, "Man-made sources include tanning booths, black lights, vulcanizing lamps, germicidal lamps, mercury lamps, halogen lamps, high-intensity discharge lamps, fluorescent and incandescent lamps, and some types of lasers."
One of the most common ways to produce ultraviolet light is to pass an electric current through vaporized mercury or some other gas. This type of lamp is commonly used in tanning booths and for surface disinfection. Lamps are also used in black lamps, which cause fluorescent dyes and dyes. Light emitting diodes (LEDs), lasers and arc lamps are also available as ultraviolet sources in various wavelengths for industrial, medical and research applications.
Many substances, including minerals, plants, fungi and microbes, as well as organic and inorganic chemicals, can absorb ultraviolet light. Absorption causes the electrons in the material to jump to a higher energy level. These electrons can then return to a lower energy level in a series of smaller steps, releasing some of their absorbed energy as visible light - fluorescence. Materials used as pigments in paint or dye that exhibit such fluorescence become brighter under sunlight because they absorb invisible ultraviolet light and re-emit it at visible wavelengths. For this reason, they are commonly used for signs, life jackets, and other applications where high visibility is important.
Fluorescence can also be used to detect and identify certain minerals and organic materials. Fluorescent probes allow researchers to detect specific components of complex biomolecular assemblies, such as living cells, with exquisite sensitivity and selectivity.
In fluorescent lamps used for lighting, 254 nm ultraviolet light is produced along with blue light, which is emitted when an electric current is passed through mercury vapor. This ultraviolet radiation is invisible, but contains more energy than the visible light emitted. The energy of ultraviolet light is absorbed by the fluorescent coating inside the fluorescent lamp and emitted as visible light. Similar tubes without the same fluorescent coating emit ultraviolet light, which can be used to disinfect surfaces, since the ionizing effect of UV radiation can kill most bacteria.
In addition to the sun, there are numerous celestial sources of ultraviolet light. In space, very large young stars shine most of their light at ultraviolet wavelengths, according to NASA. Since the Earth's atmosphere blocks most ultraviolet light, especially at shorter wavelengths, observations are made using high-altitude balloons and orbiting telescopes equipped with specialized image sensors and filters for observing in the UV region of the EM spectrum.
According to Robert Patterson, professor of astronomy at the University of Missouri, most observations are made using charge-coupled devices (CCDs), detectors designed to be sensitive to short-wavelength photons. These observations can determine the surface temperatures of the hottest stars and reveal the presence of intermediate gas clouds between Earth and quasars.
Treatment of cancer with ultraviolet light
While exposure to ultraviolet light can lead to skin cancer, some skin conditions can be treated with ultraviolet light. In a procedure called psoralin ultraviolet (PUVA) treatment, patients take medication or apply lotion to make their skin sensitive to light. Then ultraviolet light shines on the skin. PUVA is used to treat lymphoma, eczema, psoriasis, and vitiligo.
It may seem counterintuitive to treat skin cancer with the same cause that caused it, but PUVA may be beneficial due to the effect of UV light on skin cell production. This slows down growth, which plays an important role in the development of the disease.
The key to the origin of life?
Recent research suggests that ultraviolet light may have played a key role in the origin of life on Earth, especially in the origin of RNA. In a 2017 article in the Astrophysics Journal, the authors of the study note that red dwarf stars cannot emit enough ultraviolet light to start the biological processes necessary to form the ribonucleic acid necessary for all life forms on Earth. The study also suggests that this finding could help in the search for life elsewhere in the universe.
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
- ISO 21348 Process for Determining Solar Irradiances. Archived from the original on June 23, 2012.
- Bobukh, Evgeny On the vision of animals. Archived from the original on November 7, 2012. Retrieved November 6, 2012.
- Soviet Encyclopedia
- V. K. Popov // UFN. - 1985. - T. 147. - S. 587-604.
- 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.
- A. G. Molchanov Lasers in the vacuum ultraviolet and X-ray regions of the spectrum // UFN. - 1972. - T. 106. - S. 165-173.
- V. V. Fadeev Ultraviolet lasers based on organic scintillators // UFN. - 1970. - T. 101. - S. 79-80.
- Ultraviolet laser // Scientific network nature.web.ru
- Laser Twinkles in Rare Color (Russian), Science Daily(Dec. 21, 2010). Retrieved 22 December 2010.
- R. V. Lapshin, A. P. Alekhin, A. G. Kirilenko, S. L. Odintsov, V. A. Krotkov (2010). "Smoothing of Nano-Roughnesses of Polymethyl Methacrylate Surface by Vacuum Ultraviolet" (PDF). Surface. X-ray, synchrotron and neutron studies(MAIK)(1): 5-16.
The energy of the Sun is electromagnetic waves, which are divided into several parts of the spectrum:
- x-rays - with the shortest wavelength (below 2 nm);
- the wavelength of ultraviolet radiation is from 2 to 400 nm;
- the visible part of the light that is captured by the eye of humans and animals (400-750 nm);
- warm oxidizing (over 750 nm).
Each part finds its application and is of great importance in the life of the planet and all its biomass. We will consider what rays are in the range from 2 to 400 nm, where they are used and what role they play in people's lives.
History of the discovery of UV radiation
The first mentions date back to the 13th century in the descriptions of a philosopher from India. He wrote about the invisible violet light that he discovered. However, the technical capabilities of that time were clearly not enough to confirm this experimentally and study it in detail.
It was possible five centuries later, a physicist from Germany, Ritter. It was he who conducted experiments on silver chloride on its decay under the influence of electromagnetic radiation. The scientist saw that this process was faster not in that region of the world, which had already been discovered by that time and was called infrared, but in the opposite one. It turned out that this is a new area, still not explored.
Thus, in 1842, ultraviolet radiation was discovered, the properties and application of which subsequently underwent a thorough analysis and study by various scientists. A great contribution to this was made by such people as: Alexander Becquerel, Warsawer, Danzig, Macedonio Melloni, Frank, Parfenov, Galanin and others.
general characteristics
What is the application of which today is so widespread in various branches of human activity? Firstly, it should be noted that this light appears only at very high temperatures from 1500 to 2000 0 C. It is in this range that UV reaches its peak activity in terms of exposure.
By physical nature, this is an electromagnetic wave, the length of which varies over a fairly wide range - from 10 (sometimes from 2) to 400 nm. The entire range of this radiation is conditionally divided into two areas:
- near spectrum. It reaches the Earth through the atmosphere and the ozone layer from the Sun. Wavelength - 380-200 nm.
- Far (vacuum). It is actively absorbed by ozone, air oxygen, atmospheric components. It is possible to explore only with special vacuum devices, for which it got its name. Wavelength - 200-2 nm.
There is a classification of species that have ultraviolet radiation. Properties and application finds each of them.
- Near.
- Further.
- Extreme.
- Average.
- Vacuum.
- Long wavelength black light (UV-A).
- Shortwave germicidal (UV-C).
- Medium wave UV-B.
Each species has its own wavelength of ultraviolet radiation, but they are all within the general limits already indicated earlier.
UV-A, or the so-called black light, is interesting. The fact is that this spectrum has a wavelength of 400-315 nm. This is on the border with visible light, which the human eye is able to capture. Therefore, such radiation, passing through certain objects or tissues, is able to move into the region of visible violet light, and people distinguish it as black, dark blue or dark purple.
The spectra produced by ultraviolet radiation sources can be of three types:
- ruled;
- continuous;
- molecular (band).
The first are characteristic of atoms, ions, gases. The second group is for recombination, bremsstrahlung radiation. Sources of the third type are most often encountered in the study of rarefied molecular gases.
Sources of ultraviolet radiation
The main sources of UV rays fall into three broad categories:
- natural or natural;
- artificial, man-made;
- laser.
The first group includes the only type of concentrator and emitter - the Sun. It is the celestial body that gives the most powerful charge of this type of waves, which are able to pass through and reach the surface of the Earth. However, not in its entirety. Scientists put forward the theory that life on Earth originated only when the ozone screen began to protect it from excessive penetration of harmful UV radiation in high concentrations.
It was during this period that protein molecules, nucleic acids and ATP became able to exist. Until today, the ozone layer enters into close interaction with the bulk of UV-A, UV-B and UV-C, neutralizing them and preventing them from passing through. Therefore, protection from ultraviolet radiation of the entire planet is exclusively his merit.
What determines the concentration of ultraviolet radiation that reaches the Earth? There are several main factors:
- ozone holes;
- height above sea level;
- solstice height;
- atmospheric dispersion;
- the degree of reflection of rays from earth's natural surfaces;
- cloud vapor state.
The range of ultraviolet radiation penetrating the Earth from the Sun ranges from 200 to 400 nm.
The following sources are artificial. These include all those devices, devices, technical means that were designed by man to obtain the desired spectrum of light with given wavelength parameters. This was done in order to obtain ultraviolet radiation, the use of which can be extremely useful in various fields of activity. Artificial sources include:
- Erythema lamps that have the ability to activate the synthesis of vitamin D in the skin. This prevents and cures rickets.
- Devices for solariums, in which people get not only a beautiful natural tan, but are also treated for diseases that occur when there is a lack of open sunlight (the so-called winter depression).
- Attractant lamps that allow you to fight insects indoors safely for humans.
- Mercury-quartz devices.
- Excilamp.
- Luminous devices.
- Xenon lamps.
- gas discharge devices.
- High temperature plasma.
- Synchrotron radiation in accelerators.
Another type of source is lasers. Their work is based on the generation of various gases - both inert and not. Sources can be:
- nitrogen;
- argon;
- neon;
- xenon;
- organic scintillators;
- crystals.
More recently, about 4 years ago, a free electron laser was invented. The length of ultraviolet radiation in it is equal to that observed in vacuum conditions. UV laser suppliers are used in biotechnology, microbiological research, mass spectrometry and so on.
Biological effects on organisms
The effect of ultraviolet radiation on living beings is twofold. On the one hand, with its deficiency, diseases can occur. This became clear only at the beginning of the last century. Artificial irradiation with special UV-A in the required norms is capable of:
- activate the immune system;
- cause the formation of important vasodilating compounds (histamine, for example);
- strengthen the musculoskeletal system;
- improve lung function, increase the intensity of gas exchange;
- affect the speed and quality of metabolism;
- increase the tone of the body by activating the production of hormones;
- increase the permeability of the walls of blood vessels on the skin.
If UV-A enters the human body in sufficient quantities, then it does not develop diseases such as winter depression or light starvation, and the risk of developing rickets is also significantly reduced.
The effect of ultraviolet radiation on the body is of the following types:
- bactericidal;
- anti-inflammatory;
- regenerating;
- painkiller.
These properties largely explain the widespread use of UV in medical institutions of any type.
However, in addition to the above advantages, there are also negative aspects. There are a number of diseases and ailments that can be acquired if you do not get enough or, on the contrary, take the considered waves in excess.
- Skin cancer. This is the most dangerous exposure to ultraviolet radiation. Melanoma can form with excessive influence of waves from any source - both natural and man-made. This is especially true for lovers of tanning in the solarium. In everything, measure and caution are necessary.
- Destructive effect on the retina of the eyeballs. In other words, a cataract, pterygium, or sheath burn may develop. The harmful excessive effects of UV on the eyes have been proven by scientists for a long time and confirmed by experimental data. Therefore, when working with such sources, you should observe. On the street, you can protect yourself with the help of dark glasses. However, in this case, you should be wary of fakes, because if the glasses are not equipped with UV-repellent filters, then the destructive effect will be even stronger.
- Burns on the skin. In the summer, they can be earned if you expose yourself to UV for a long time uncontrollably. In winter, you can get them because of the peculiarity of the snow to reflect these waves almost completely. Therefore, irradiation occurs both from the side of the Sun and from the side of snow.
- Aging. If people are exposed to UV for a long time, then they begin to show signs of skin aging very early: lethargy, wrinkles, sagging. This is due to the fact that the protective barrier functions of the integument are weakened and violated.
- Impact with consequences over time. They consist in manifestations of negative influences not at a young age, but closer to old age.
All of these results are consequences of misdosing UV, ie. they occur when the use of ultraviolet radiation is carried out irrationally, incorrectly, and without observing safety measures.
Ultraviolet radiation: application
The main areas of use are based on the properties of the substance. This is also true for spectral wave radiation. So, the main characteristics of UV, on which its application is based, are:
- high level chemical activity;
- bactericidal effect on organisms;
- the ability to cause the glow of various substances in different shades visible to the human eye (luminescence).
This allows wide use of ultraviolet radiation. Application is possible in:
- spectrometric analyses;
- astronomical research;
- medicine;
- sterilization;
- disinfection of drinking water;
- photolithography;
- analytical study of minerals;
- UV filters;
- for catching insects;
- to get rid of bacteria and viruses.
Each of these areas uses a specific type of UV with its own spectrum and wavelength. Recently, this type of radiation has been actively used in physical and chemical research (determination of the electronic configuration of atoms, the crystal structure of molecules and various compounds, work with ions, analysis of physical transformations on various space objects).
There is another feature of the effect of UV on substances. Some polymeric materials are capable of decomposing under the influence of an intense constant source of these waves. For example, such as:
- polyethylene of any pressure;
- polypropylene;
- polymethyl methacrylate or organic glass.
What is the impact? Products made from these materials lose color, crack, fade, and eventually collapse. Therefore, they are called sensitive polymers. This feature of carbon chain degradation under solar illumination conditions is actively used in nanotechnologies, X-ray lithography, transplantology, and other fields. This is done mainly to smooth out the surface roughness of the products.
Spectrometry is a major field of analytical chemistry that specializes in identifying compounds and their composition by their ability to absorb UV light of a specific wavelength. It turns out that the spectra are unique for each substance, so they can be classified according to the results of spectrometry.
Also, the use of ultraviolet germicidal radiation is carried out to attract and destroy insects. The action is based on the ability of the insect's eye to capture short-wave spectra invisible to humans. Therefore, animals fly to the source, where they are destroyed.
Use in solariums - special installations of vertical and horizontal type, in which the human body is exposed to UV-A. This is done to activate the production of melanin in the skin, giving it a darker color, smoothness. In addition, inflammation is dried and harmful bacteria on the surface of the integument are destroyed. Particular attention should be paid to protecting the eyes and sensitive areas.
medical field
The use of ultraviolet radiation in medicine is also based on its ability to destroy living organisms invisible to the eye - bacteria and viruses, and on the features that occur in the body during competent lighting with artificial or natural radiation.
The main indications for UV treatment can be summarized in several points:
- All types of inflammatory processes, open wounds, suppuration and open seams.
- With injuries of tissues, bones.
- For burns, frostbite and skin diseases.
- With respiratory ailments, tuberculosis, bronchial asthma.
- With the emergence and development of various types of infectious diseases.
- With ailments accompanied by severe pain, neuralgia.
- Diseases of the throat and nasal cavity.
- Rickets and trophic
- Dental diseases.
- Regulation of blood pressure, normalization of the heart.
- The development of cancerous tumors.
- Atherosclerosis, kidney failure and some other conditions.
All these diseases can have very serious consequences for the body. Therefore, treatment and prevention using UV is a real medical discovery that saves thousands and millions of human lives, preserving and restoring their health.
Another option for using UV from a medical and biological point of view is the disinfection of premises, the sterilization of work surfaces and tools. The action is based on the ability of UV to inhibit the development and replication of DNA molecules, which leads to their extinction. Bacteria, fungi, protozoa and viruses are killed.
The main problem when using such radiation for sterilization and disinfection of a room is the area of illumination. After all, organisms are destroyed only with the direct impact of direct waves. Everything that remains outside continues to exist.
Analytical work with minerals
The ability to induce luminescence in substances makes it possible to use UV to analyze the qualitative composition of minerals and valuable rocks. In this regard, precious, semi-precious and ornamental stones are very interesting. What kind of shades they do not give when irradiated with cathode waves! Malakhov, the famous geologist, wrote about this very interestingly. His work tells about observations of the glow of the color palette, which minerals can give in different sources of radiation.
So, for example, topaz, which has a beautiful saturated blue color in the visible spectrum, glows bright green when irradiated, and emerald - red. Pearls cannot give any particular color at all and shimmers with many colors. The resulting spectacle is simply fantastic.
If the composition of the studied rock contains uranium impurities, then the highlight will show a green color. Melite impurities give a blue, and morganite - a lilac or pale purple hue.
Use in filters
For use in filters, ultraviolet germicidal radiation is also used. The types of such structures can be different:
- hard;
- gaseous;
- liquid.
Such devices are mainly used in the chemical industry, in particular, in chromatography. With their help, it is possible to conduct a qualitative analysis of the composition of a substance and identify it by belonging to a particular class of organic compounds.
Drinking water treatment
Disinfection by ultraviolet radiation of drinking water is one of the most modern and high-quality methods of its purification from biological impurities. The advantages of this method are:
- reliability;
- efficiency;
- the absence of foreign products in the water;
- safety;
- profitability;
- preservation of the organoleptic properties of water.
That is why today this method of disinfection keeps pace with traditional chlorination. The action is based on the same features - the destruction of the DNA of harmful living organisms in the composition of water. Use UV with a wavelength of about 260 nm.
In addition to direct impact on pests, ultraviolet light is also used to destroy the remains of chemical compounds that are used to soften and purify water: such as, for example, chlorine or chloramine.
black light lamp
Such devices are equipped with special emitters capable of producing waves of great length, close to visible. However, they still remain indistinguishable to the human eye. Such lamps are used as devices that read secret signs from UV: for example, in passports, documents, banknotes, and so on. That is, such marks can be distinguished only under the action of a certain spectrum. Thus, the principle of operation of currency detectors, devices for checking the naturalness of banknotes is built.
Restoration and determination of the authenticity of the painting
And in this area finds application UV. Each artist used white, containing different heavy metals in each epochal period of time. Thanks to irradiation, it is possible to obtain so-called underpaintings, which provide information about the authenticity of the painting, as well as about the specific technique, manner of painting of each artist.
In addition, the lacquer film on the surface of products belongs to sensitive polymers. Therefore, it is capable of aging under the influence of light. This allows you to determine the age of compositions and masterpieces of the artistic world.
