The sun sends us light, heat and ultraviolet (UV) radiation. We are all exposed to ultraviolet radiation from the sun, as well as from artificial sources used in industry, trade and other sectors of the economy.
The area of ultraviolet radiation includes waves in the range of 100 - 400 nm and is conventionally divided into three groups:
- UV-A (UVA) (315-400 nm)
- UV-B (UVB) (280-315 nm)
- UV-C (UVC) (100-280 nm)
Influence of natural factors on the level of ultraviolet radiation:
Sun Height
The higher the sun is in the sky, the higher the level of ultraviolet radiation. Consequently, the level of ultraviolet radiation varies with the time of day and season. Outside the tropics, radiation is highest during the summer months when the sun is at its zenith around noon.Latitude
When approaching the equatorial regions, the degree of radiation increases.Cloudiness
The amount of UV radiation is higher in a cloudless sky, but even with clouds, the amount of UV radiation can be high. In this case, the scattered ultraviolet radiation is reflected by various surfaces, and therefore the overall level of ultraviolet radiation can be quite high.Height
With increasing altitude, the decreasing layer of the atmosphere absorbs ultraviolet radiation to a lesser extent. With an increase in altitude for every 1000 m, the level of ultraviolet radiation increases by 10% - 12%.Ozone
The ozone layer absorbs some of the ultraviolet radiation directed at earth surface... The thickness of the ozone layer changes throughout the year and even during the day.Reflection from the surface of the earth
Ultraviolet radiation reflected or scattered into varying degrees different surfaces, for example, clean snow can reflect up to 80% of UV radiation, dry coastal sand about 15%, sea foam about 25%.- More than 90% of UV radiation can penetrate through light clouds.
- Pure snow reflects up to 80% of UV radiation.
- UV radiation is increased by 4% for every 300 m ascent.
- People who work indoors are exposed to UV radiation 5-10 times less per year than people who work outdoors.
- In water at a depth of 0.5 m, the level of UV radiation is 40% of the level of UV radiation at the surface.
- We receive 60% of the total amount of UV radiation in the time interval from 10-00 to 14-00 h.
- The shade reduces UV radiation by 50% or more.
- White sand reflects up to 15% of UV radiation.
Health effects of ultraviolet radiation
A small amount of ultraviolet radiation is useful and necessary for the production of vitamin D. Ultraviolet radiation is also used to treat several conditions, including rickets, psoriasis, and eczema. Treatment is carried out under medical supervision, taking into account the benefit of the treatment and the risk of exposure to ultraviolet radiation.
However, prolonged human exposure to ultraviolet radiation can lead to acute and chronic damage to the skin, eyes and immune system.
A popular misconception is that only fair skinned populations should be concerned about excessive "sun exposure." Darker skin has a higher content of the protective pigment melanin. People with this type of skin have a lower incidence of skin cancer. However, skin cancer is also diagnosed in this population group, but often at a later and more dangerous stage.
The risk of damage to the eyes and immune system from UV radiation does not depend on skin type.
The most common acute injuries from overexposure to ultraviolet radiation are sunburn and sunburn, with prolonged exposure to ultraviolet radiation causes degenerative changes in cells and blood vessels, which leads to premature aging of the skin. Ultraviolet radiation can also cause acute eye damage.
Chronic lesions include skin cancer and cataracts.
There are 2-3 million cases of non-malignant skin cancer and 132,000 cases of skin melanoma each year. Non-malignant skin cancer can be removed surgically and is rarely fatal, malignant melanoma is one of the leading causes of death in light-skinned populations.
About 12 to 15 million people go blind each year due to catarct. Studies have shown that up to 20% of blindness cases can be caused or exacerbated by sun exposure, especially in India, Pakistan and other countries close to the equator.
There is also speculation that ultraviolet radiation may increase the risk of infectious diseases and limit the effectiveness of vaccinations.
However, despite all of the above, many people consider intense tanning to be normal. Children, adolescents and their parents perceive sunburn as an indicator of attractiveness and good health.
Risk group
- Prolonged exposure to the sun during childhood increases the risk of later developing skin cancer and can seriously damage the eyes.
- All children under 15 have sensitive skin and eyes - protect them and set a good example for them yourself!
- Children under one year old should not be in direct sunlight!
- Parents, protect your children from the sun! Teach them on sunscreen and sun exposure!
Health effects of ozone depletion
Depletion of the ozone layer is likely to exacerbate the adverse effects of ultraviolet radiation, as stratospheric ozone is an effective absorber.
As the ozone layer decreases, the protective filter represented by the atmosphere decreases. Accordingly, the population and the environment are exposed to a higher degree of ultraviolet radiation, in particular UVB radiation, which has a great impact on the health of humans, animals, marine organisms and plant life.
Computational models predict that a 10% decrease in stratospheric ozone could cause an additional 300,000 non-malignant, 4,500 malignant skin cancers and 1.6 to 1.75 million cataracts each year.
GLOBAL SUNNY ULTRAVIOLET (UV) INDEX
Introduction
Since the 1970s, there has been an increase in the incidence of skin cancer among the fair-skinned population. This increase is associated with the habits of the population to stay "in the sun" under its ultraviolet component and the widespread opinion about the attractiveness and benefits of tanning.
Thus, there is an urgent need to raise awareness of the population about harmful effects ultraviolet radiation, which aims to change the habits of the population to prevent an increase in the incidence of skin cancer.
The Global UV Index is a simplified measure of the level of ultraviolet radiation at the Earth's surface and an indicator of potential skin hazard. It serves as a public awareness and warning tool for UV protective measures.
UFI was developed by the World Health Organization with the assistance of the United Nations Program on environment, World Meteorological Organization, International Commission on Non-Ionizing Radiation Protection, German Federal Office for Radiation Protection.
Since the first announcement in 1995, several international expert meetings have been held (Les Diablerets; Baltimore, 1996; Les Diablerets, 1997; Munich, 2000) to streamline public awareness of UVI and promote the use of UVR as a sun protection tool.
What is the Global Solar Ultraviolet Index?
The Global Solar UV Index (UVI, UV Index, UVI) characterizes the level of solar ultraviolet radiation at the Earth's surface. The UV index ranges from zero and above. Moreover, the higher the value of the UV index, the greater the potential danger to human skin and eyes, and the shorter the time required to cause harm to health.
The UV Index values correspond to the levels of UV exposure from the sun in the following categories:
Why is the UV index needed?
The UV Index is an important means of raising public awareness of the risk of excessive exposure to ultraviolet radiation and warns against the use of sunscreens. The level of ultraviolet radiation and therefore the UV index values vary throughout the day. Typically displayed is the maximum UV value observed in a 4-hour period around solar noon. Sunny afternoon lasts from 12 noon to 14 noon.
People, making plans for the day and deciding "what to get out", are usually guided by the weather forecast (or the view from the window) and especially the air temperature forecast.
Similar to the temperature scale, the UV Index indicates the level of ultraviolet radiation and the possible hazard of exposure to the sun.
By knowing the UV Index forecast, everyone can make health-promoting choices.
| Necessary protective measures depending on the value of the UV index | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No protection required | Protection required | Increased protection required | ||||||||||
| Stay out premises does not represent dangers |
At noon hours stay in the shadows! Wear clothes with long sleeves and a hat! Use sunscreen! |
Wait out the noon hours indoors! Stay in the shade outdoors! Be sure to wear clothes long sleeved hat, use sunscreen! |
||||||||||
Even for people with very sensitive light skin, the risk of harm to health is minimal with UV index values below 3, and under normal circumstances, the use of protective equipment is not required.
Protection is required at UV index values above 3, increased protective measures are required at UV index values of 8 and above. In this case, you must use all protective equipment:
- Limit sun exposure during midday hours.
- Stay in the shadows.
- Wear long sleeves.
- Wear a wide-brimmed hat to protect your eyes, face and neck.
- Protect your eyes with fitted glasses.
- Use a sunscreen with a sun protection factor (SPF) 15+. Do not use sunscreen to extend sun exposure.
- Protect your little ones: this is especially important.
Myths and reality
| MYTH | REALITY |
|---|---|
| Sunburn is good for you. | Sunburn is the body's defense against further damage from ultraviolet radiation. |
| Sunburn protects from the sun. | Dark tanning on fair skin is a limited protection equivalent to an SPF (sun protection factor) of approximately 4. |
| You won't tan on a cloudy day. | Up to 80% of the sun's ultraviolet radiation penetrates the cloud cover. Fog can increase UV radiation levels. |
| You will not tan while in the water. | Water provides minimal protection against UV radiation, and reflections from water can increase UV radiation levels. |
| Ultraviolet radiation is not dangerous in winter. | UV radiation is usually lower in the winter months, but the reflection from snow can double it, especially at higher altitudes. Be especially careful in early spring when the air temperature is low but the sun's UV radiation is strong. |
| Sunscreen is a remedy, I can increase the tanning time. | Sunscreen should not be used to prolong exposure to the sun, but to enhance UV protection. |
| You will not "burn out" if you take breaks during tanning. | Exposure to ultraviolet radiation tends to build up throughout the day. |
| You will not tan if the sun's warmth is imperceptible. | Sunburn is caused by ultraviolet radiation that cannot be felt. Feeling the warmth of the sun, we sense its infrared, not ultraviolet radiation. |
REMEMBER!
- Tanning does not stop UV radiation! Even if your skin is tanned, limit your exposure to the sun during the noon hours and apply sun protection measures.
- Limit tanning time! A sunburn is an indication that your skin has received an overdose of UV radiation! Protect your skin!
- Wear Sunglasses, wide-brimmed hat and protective clothing, use SPF 15+ sunscreen.
- Using sunscreen is not to lengthen your time in the sun, but to reduce your health risks from being in the sun.
- Taking certain medications and using perfumes and deodorants makes the skin more sensitive, causing severe sunburn.
- Exposure to the sun increases the risk of skin cancer, accelerates skin aging and damages the eyes. Protect yourself!
- Shade is one of the best protection against solar radiation. Try to stay in the shade during midday hours, when UV radiation is at its highest.
- Cloudiness in the sky does not prevent sunburn. Ultraviolet radiation penetrates the clouds.
- Remember that ultraviolet radiation, which cannot be seen or felt, causes harm to the skin and eyes - DO NOT BE FOLLOWED BY MODERATE TEMPERATURES!
- If you intend to be outdoors during the day, make sure you have sunscreen, a hat, and long sleeves.
- When staying on the slopes, don't forget that altitude and clear snow can double your UV radiation, don't forget your sunglasses and sunscreen! In the mountains, the level of ultraviolet radiation increases by about 10% every 1000 m.
- Sources of information:
1. Materials of the website of the World Health Organization (WHO).
http://www.who.int/uv/intersunprogramme/activities/uv_index/en/index.html
2. "Global Solar UV Index. A Practical Guide". "Global Solar UV Index. A Practical Guide.", WHO 2002
http://www.who.int/uv/publications/globalindex/en/index.html
The guidelines are recommended by the World Health Organization, the World Meteorological Organization, the United Nations Environment Program, and the International Commission on Non-Ionizing Radiation Protection.UV Index and Ozone Thickness Predictions provided.
Ultraviolet radiation in medicine is used in the optical range 180-380 nm (integral spectrum), which is subdivided into short-wavelength region (C or KUV) - 180-280 nm, medium-wavelength (B) - 280-315 nm and long-wavelength (A) - 315- 380 nm (FUV).
Physical and physiological action ultraviolet radiation
Penetrates into biological tissues to a depth of 0.1-1 mm, is absorbed by molecules of nucleic acids, proteins and lipids, has sufficient photon energy to break covalent bonds, electronic excitation, dissociation and ionization of molecules (photoelectric effect), which leads to the formation of free radicals, ions, peroxides (photochemical effect), i.e. there is a sequential transformation of the energy of electromagnetic waves into chemical energy.
The mechanism of action of UV radiation - biophysical, humoral and neuro-reflex:
Change in the electronic structure of atoms and molecules, ionic conjuncture, electrical properties cells;
- inactivation, denaturation and coagulation of protein;
- photolysis - the breakdown of complex protein structures - the release of histamine, acetylcholine, biogenic amines;
- photooxidation - intensification of oxidative reactions in tissues;
- photosynthesis - reparative synthesis in nucleic acids, elimination of damage in DNA;
- photoisomerization - internal rearrangement of atoms in a molecule, substances acquire new chemical and biological properties (provitamin - D2, D3),
- photosensitivity;
- erythema, with FUF it develops 1.5-2 hours, with FUF - 4-24 hours;
- pigmentation;
- thermoregulation.
Ultraviolet radiation affects functional state various bodies and human systems:
Leather;
- central and peripheral nervous system;
- the autonomic nervous system;
- the cardiovascular system;
- blood system;
- hypothalamus-pituitary-adrenal glands;
- endocrine system;
- all types of metabolism, mineral metabolism;
- respiratory organs, respiratory center.
The curative effect of ultraviolet radiation
The reaction from organs and systems depends on the wavelength, dose and method of exposure to UV radiation.
Local irradiation:
Anti-inflammatory (A, B, C);
- bactericidal (C);
- pain reliever (A, B, C);
- epithelizing, regenerating (A, B)
General exposure:
Stimulating immune response (A, B, C);
- desensitizing (A, B, C);
- regulation of the vitamin balance "D", "C" and metabolic processes(A, B).
Indications for UFO therapy:
Acute, subacute and chronic inflammatory process;
- trauma to soft tissues and bones;
- wound;
- skin diseases;
- burns and frostbite;
- trophic ulcer;
- rickets;
- diseases of the musculoskeletal system, joints, rheumatism;
- infectious diseases - influenza, whooping cough, erysipelas;
- pain syndrome, neuralgia, neuritis;
- bronchial asthma;
- ENT diseases - tonsillitis, otitis media, allergic rhinitis, pharyngitis, laryngitis;
- compensation for solar deficiency, increasing the stamina and endurance of the body.
Indications for ultraviolet irradiation in dentistry
Diseases of the oral mucosa;
- periodontal disease;
- dental diseases - non-carious diseases, caries, pulpitis, periodontitis;
- inflammatory diseases maxillofacial area;
- TMJ diseases;
- facial pain.
Contraindications to UFO therapy:
Malignant neoplasms
- predisposition to bleeding,
- active tuberculosis,
- functional kidney failure,
- hypertension stage III,
- severe forms atherosclerosis.
- thyrotoxicosis.
Ultraviolet devices:
Integral sources using DRT (arc mercury tubular) lamps of various power:
ORK-21M (DRT-375) - local and general exposure
- OKN-11M (DRT-230) - local irradiation
- Lighthouse OKB-ZO (DRT-1000) and OKM-9 (DRT-375) - group and general irradiation
- ON-7 and UGN-1 (DRT-230). OUN-250 and OUN-500 (DRT-400) - local irradiation
- OUP-2 (DRT-120) - otolaryngology, ophthalmology, dentistry.
Selective short-wavelength (180-280 nm) use arc bactericidal lamps (DB) in the mode of a glow electric discharge in a mixture of mercury vapor with argon. Lamps of three types: DB-15, DB-30-1, DB-60.
Irradiators are produced:
Wall (OBN)
- ceiling (OBP)
- on a tripod (OBSh) and mobile (OBP)
- local (BOD) with a lamp DRB-8, BOP-4, OKUF-5M
- for blood irradiation (AUFOK) - MD-73M "Isolde" (with a lamp low pressure LB-8).
Selective long-wavelength (310-320 nm) use fluorescent erythemal lamps (LE), with a power of 15-30 W from uveol glass with an internal phosphor coating:
Wall-mounted irradiators (OE)
- suspended reflected distribution (OEE)
- mobile (OEP).
Beacon irradiators (EOKS-2000) with an arc xenon lamp (DKS TB-2000).
An ultraviolet irradiator on a tripod (ОУШ1) with a fluorescent lamp (LE153), a large ultraviolet lighthouse irradiator (OMU), an ultraviolet desktop irradiator (OUN-2).
Low-pressure gas-discharge lamp LUF-153 in UUD-1 and UDD-2L devices for Puva and therapy, in an OUK-1 UV irradiator for extremities, for an OUG-1 head and in EOD-10, EGD-5 irradiators. Installations for general and local irradiation are produced abroad: Puva, Psolylux, Psorymox, Valdman.
Technique and methodology of UFO therapy
General exposure
Carried out according to one of the schemes:
Basic (from 1/4 to 3 biodoses, adding 1/4)
- slow (from 1/8 to 2 biodoses, adding 1/8 each)
- accelerated (from 1/2 to 4 biodose. adding 1/2).
Local irradiation
Irradiation of the lesion site, fields, reflexogenic zones, staged or by zones, extrafocal. fractional.
Features of irradiation with erythemal doses:
One area of the skin can be irradiated no more than 5 times, and the mucous membrane - no more than 6-8 times. Repeated irradiation of the same skin area is possible only after the extinction of erythema. The subsequent dose of radiation is increased by 1 / 2-1 biodose. When treating with UV rays, light-protective glasses are used for the patient and the medical staff.
Dosage
Dosing of UV irradiation is carried out by determining the biodose, biodose is the minimum amount of UV radiation sufficient to obtain the weakest threshold erythema on the skin for least time, with a fixed distance from the feed (20 - 100 cm). Determination of the biodose is carried out with the BD-2 biodosimeter.
Distinguish between doses ultraviolet radiation:
Suberythemal (less than 1 biodose)
- erythemal small (1-2 biodoses)
- medium (3-4 biodoses)
- large (5-6 biodoses)
- hypererythemal (7-8 biodoses)
- massive (over 8 biodoses).
In order to disinfect the air:
Indirect radiation for 20-60 minutes, in the presence of people,
- direct radiation for 30-40 minutes, in the absence of people.
Ultraviolet radiation Prepared by a student of grade 11 Yumaev Vyacheslav
Ultraviolet radiation - electromagnetic radiation invisible to the eye, occupying the area between the lower limit of the visible spectrum and upper bound X-ray radiation. The wavelength of UV radiation is between 100 and 400 nm (1 nm = 10 m). According to the classification of the International Commission on Illumination (CIE), the UV spectrum is divided into three ranges: UV-A - long wave (315 - 400 nm.) UV-B - medium wave (280 - 315 nm.) UV-C - short wave (100 - 280 nm.) The entire UV region is conventionally divided into: - near (400-200 nm); - distant or vacuum (200-10 nm).
Properties: High chemical activity, invisible, high penetrating ability, kills microorganisms, in small doses has a beneficial effect on the human body: sunburn, UV rays initiate the formation of vitamin D, which is necessary for the absorption of calcium by the body and ensuring the normal development of the bone skeleton, ultraviolet light is active affects the synthesis of hormones responsible for the daily biological rhythm; but in large doses it has a negative biological effect: changes in the development of cells and metabolism, an effect on the eyes.
UV radiation spectrum: linear (atoms, ions and light molecules); consists of stripes (heavy molecules); Continuous spectrum (arises during deceleration and recombination of electrons).
Discovery of UV radiation: Near UV radiation was discovered in 1801 by the German scientist N. Ritter and the English scientist W. Wollaston on the photochemical effect of this radiation on silver chloride. Vacuum UV radiation was discovered by the German scientist W. Schumann using a vacuum spectrograph with a fluorite prism built by him and gelatin-free photographic plates. He was able to register short-wave radiation up to 130 nm. N. Ritter W. Wollaston
Features of UV radiation Up to 90% of this radiation is absorbed by atmospheric ozone. With every increase in altitude of 1000 m, the UV level increases by 12%
Application: Medicine: the use of UV - radiation in medicine is associated with the fact that it has bactericidal, mutagenic, therapeutic (therapeutic), antimitotic, prophylactic actions, disinfection; laser biomedicine Show business: Lighting, light effects
Cosmetology: In cosmetology, ultraviolet irradiation is widely used in tanning salons to obtain an even, beautiful tan. Deficiency of UV rays leads to vitamin deficiency, decreased immunity, poor performance nervous system, the appearance of mental instability. Ultraviolet radiation has a significant effect on phosphorus-calcium metabolism, stimulates the formation of vitamin D and improves all metabolic processes in the body.
Food industry: Disinfection of water, air, premises, containers and packaging with UV radiation. It should be emphasized that the use of UV as physical factor exposure to microorganisms can ensure the decontamination of the environment to a very high degree, for example, up to 99.9%.
Forensic Science: Scientists have developed technology to detect the slightest dose explosives. The device for detecting traces of explosives uses the finest thread (it is two thousand times thinner than a human hair), which glows under the influence of ultraviolet radiation, but any contact with explosives: trinitrotoluene or other explosives used in bombs, stops its glow. The device detects the presence of explosives in the air, in water, on the fabric and on the skin of suspects in a crime. Using invisible UV inks for protection bank cards and banknotes from counterfeiting. Images, design elements invisible in normal light are applied to the card, or the entire card is made glowing in UV rays.
Sources of UV radiation: emitted by all solid bodies with t> 1000 С, as well as by luminous mercury vapors; stars (including the sun); laser installations; gas-discharge lamps with quartz tubes (quartz lamps), mercury; mercury rectifiers
UV protection: Application of sun screens: - chemical ( chemical substances and cover creams); - physical (various obstacles reflecting, absorbing or scattering rays). Special clothing (for example, made from poplin). To protect the eyes in industrial conditions, light filters (goggles, helmets) made of dark green glass are used. Flint glass (glass containing lead oxide) with a thickness of 2 mm provides full protection against UV radiation of all wavelengths.
Thank you for your attention!
UV radiation is electromagnetic waves that are invisible human eye... It occupies a spectral position between visible and X-ray radiation. The interval of ultraviolet radiation is usually divided into near, middle and far (vacuum).
Biologists have made such a division of UV light in order to better see the difference in the effect of beams of different lengths on a person.
- Near ultraviolet is commonly referred to as UV-A,
- medium - UV-B,
- far - UV-C.
Ultraviolet radiation comes from the sun and the atmosphere of our planet Earth protects us from the powerful effects of ultraviolet rays... The sun is one of the few natural UV emitters. In this case, the far ultraviolet UV-C is almost completely blocked by the Earth's atmosphere. Those 10% of long-wave ultraviolet rays reach us in the form of the sun. Accordingly, the ultraviolet that hits the planet is mainly UV-A, and in small amounts UV-B.
One of the main properties of ultraviolet radiation is its chemical activity, due to which UV radiation produces great effect on the human body... The most dangerous for our body is considered to be short-wave ultraviolet light. Despite the fact that our planet protects us as much as possible from exposure to ultraviolet rays, if you do not follow some precautions, you can still suffer from them. Sources of shortwave type of radiation are welding machines and ultraviolet lamps.
The positive properties of ultraviolet radiation
Only in the XX century, studies began to be carried out that proved positive effect of UV radiation on the human body... The result of these studies was the identification of the following useful properties: strengthening of human immunity, activation defense mechanisms, improved blood circulation, vasodilation, increased vascular permeability, increased secretion of a number of hormones.
Another property of ultraviolet radiation is its ability change carbohydrate and protein metabolism
substances of a person. UV rays can also affect the ventilation of the lungs - the frequency and rhythm of breathing, increased gas exchange, the level of oxygen consumption. Functioning is also improved. endocrine system, vitamin D is formed in the body, which strengthens the human musculoskeletal system.
The use of ultraviolet radiation in medicine
Ultraviolet is often used in medicine. Despite the fact that in some cases, ultraviolet rays can have a bad effect on the human body, with correct use they can also be useful.
Medical institutions have long come up with useful application artificial ultraviolet light. There are various emitters that can help a person with ultraviolet rays deal with various diseases
... They are also divided into those that emit long, medium and short wavelengths. Each of them applies in a specific case. Thus, long-wavelength radiation is suitable for the treatment of the respiratory tract, for damage to the osteoarticular apparatus, as well as in the case of various skin injuries. We can also see long-wave radiation in tanning salons.
Treatment has a slightly different function. medium wave ultraviolet... It is prescribed mainly to people suffering from immunodeficiency, metabolic disorders. It is also used in the treatment of disorders of the musculoskeletal system, has an analgesic effect.
Shortwave radiation it is also used in the treatment of skin diseases, in diseases of the ears, nose, in case of damage to the respiratory tract, in diabetes mellitus, in case of damage to the heart valves.
In addition to various devices emitting artificial ultraviolet light, which are used in mass medicine, there are also ultraviolet lasers with a more targeted action. These lasers are used, for example, in eye microsurgery. Such lasers are also used for scientific research.
The use of ultraviolet radiation in other areas
In addition to medicine, ultraviolet radiation is used in many other areas, significantly improving our lives. So, ultraviolet is excellent disinfectant, and is used, among other things, for the treatment of various objects, water, indoor air. Ultraviolet and in the printing industry: it is with the help of ultraviolet radiation that various seals and stamps are produced, paints and varnishes are dried, banknotes are protected from counterfeiting. In addition to its useful properties, with the correct supply, ultraviolet light can create beauty: it is used for various lighting effects (most often this happens at discos and at performances). UV rays also help in finding fires.
One of the negative consequences ultraviolet exposure on the human body is electrophthalmia... This term is called the defeat of the human organ of vision, in which the cornea of the eye burns and swells, and a cutting pain appears in the eyes. This disease can occur if a person looks at the rays of the sun without a special protective device ( sunglasses) or stays in a snowy area in sunny weather, with very bright light. Also, electrophthalmia can be earned by quartzing rooms.
Negative consequences can be achieved due to the long, intense exposure to ultraviolet rays on the body. There can be a lot of such consequences, up to the development various pathologies... The main symptoms of over-exposure are
The consequences of strong radiation are as follows: hypercalcemia, growth retardation, hemolysis, deterioration of immunity, various burns and skin diseases. Most exposed to excessive radiation are people who constantly work outdoors, as well as those who constantly work with devices that emit artificial ultraviolet light.
Unlike UV emitters used in medicine, tanning salons are more dangerous for a person. Visiting tanning salons is not controlled by anyone other than the person himself. People who often visit tanning salons in order to achieve a beautiful tan often neglect the negative effects of UV radiation, despite the fact that frequent visits to tanning salons can even be fatal.
The acquisition of a darker skin color occurs due to the fact that our body fights against the traumatic effects of UV radiation on it, and produces a coloring pigment called melanin. And if the redness of the skin is a temporary defect that passes over time, then freckles appearing on the body, age spots that occur as a result of the proliferation of epithelial cells - persistent skin damage.
Ultraviolet, penetrating deep into skin, can alter skin cells at the genetic level and lead to ultraviolet mutagenesis... One of the complications of this mutagenesis is melanoma - a tumor of the skin. It is she who is able to lead a person to death.
In order to avoid the negative effects of exposure to UV rays, need to provide yourself with some protection... At various enterprises working with devices emitting artificial ultraviolet light, it is necessary to use overalls, helmets, shields, insulating screens, goggles, and a portable screen. People who are not involved in the activities of such enterprises need to limit themselves to excessive visits to tanning salons and long exposure to the open sun, to use sunscreens, sprays or lotions in the summer, and to wear sunglasses and closed clothing made from natural fabrics.
There are also Negative consequences from lack of UV radiation... Prolonged absence of UVR can lead to a disease called "light starvation". Its main symptoms are very similar to those of excessive exposure to ultraviolet radiation. With this disease, a person's immunity decreases, metabolism is disturbed, fatigue, irritability, etc. appear.
The concept of ultraviolet rays was first encountered by a 13th century Indian philosopher in his work. The atmosphere of the area he described Bhootakasha contains violet rays that cannot be seen with the naked eye.
Soon after infrared radiation was discovered, 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, decomposed by light, was faster decomposes under the influence of invisible radiation outside the violet region of the spectrum. Silver chloride white darkens in the light within a few minutes. Different parts of the spectrum have different effects on the rate of darkening. This occurs most rapidly in front of the violet region of the spectrum. It was then that many scientists, including Ritter, agreed that light is made up 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. Ideas about the unity of the three different parts spectra were first announced 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 the irradiation of a substance with monochromatic UV radiation, the wavelength of which changes over time. The substance absorbs UV radiation at different wavelengths to varying degrees. The graph, the ordinate of which is the amount of transmitted or reflected radiation, and the abscissa is the wavelength, forms a spectrum. Spectra are unique for each substance, which 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 light, 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. AA Malakhov in his book "Interestingly about geology" (M., "Molodaya gvardiya", 1969, 240 p.) Tells about it this way: “The cathode, ultraviolet, and X-rays cause an unusual glow of minerals. In the world of dead stone, those minerals that light up and shine most brightly, which, once in the ultraviolet light zone, tell about the smallest impurities of uranium or manganese included in the composition of the rock. Many other minerals, which do not contain any impurities, flash with a strange "unearthly" color. I spent the whole day in the laboratory, where I observed the luminescent glow of minerals. Plain colorless calcite was colored wonderfully under the influence of various light sources. The cathode rays made the crystal ruby red; in ultraviolet light, it lit up with 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 connected, the fluorite turned violet, 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 matter by the color of the glow and the retention index.
Catching insects
Ultraviolet radiation is often used to catch insects by 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, in the shortwave part of the spectrum: insects do not see what humans perceive as red, but they see soft ultraviolet light.
Artificial tan and "Mountain sun"
At certain dosages, artificial tanning improves the condition and appearance of human skin, promotes the formation of vitamin D. Currently, photoaria are popular, which are often called solariums in everyday life.
Ultraviolet in restoration
One of the experts' main tools is ultraviolet, X-ray and infrared radiation. Ultraviolet rays allow you to determine the aging of the varnish film - a fresher varnish looks darker in ultraviolet light. In the light of a large laboratory ultraviolet lamp, the restored areas and artisanally rewritten signatures show through darker spots. X-rays are trapped by the heaviest elements. In the human body it is bone, and in the picture - whitewash. In most cases, white is based on lead, in the 19th century zinc began to be used, and in the 20th century - titanium. All of these are heavy metals. Ultimately, on film, we get an image of a whitewash underpainting. Underpainting is the artist's individual "handwriting", an element of his own unique technique. To analyze the underpainting, the bases of the radiographs of the paintings of the great masters are used. Also, these pictures are used to recognize the authenticity of the painting.
Notes (edit)
- ISO 21348 Process for Determining Solar Irradiances. Archived from the original on June 23, 2012.
- Bobukh, Eugene About the eyesight 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 high repetition mode // Ukrainian physics journal... - 1977. - T. 22. - No. 1. - S. 157-158.
- A. G. Molchanov
