Ultraviolet radiation- form optical radiation, not visible to the human eye, characterized by a shorter length and higher energy of photons compared to light. Ultraviolet rays cover the spectrum between visible and x-ray radiation, in the wavelength range 400-10 nm. In this case, the radiation region in the range of 200-10 nm is called far or vacuum, and the region in the range of 400-200 nm is called near.
UV sources
1 Natural sources (stars, Sun, etc.)
Only the long-wave part of ultraviolet radiation from space objects (290-400 nm) is capable of reaching the Earth's surface. At the same time, short-wave radiation is completely absorbed by oxygen and other substances in the atmosphere at an altitude of 30-200 km from the earth's surface. UV radiation from stars in the wavelength range 90-20 nm is almost completely absorbed.
2. Artificial sources
Radiation from solids heated to a temperature of 3 thousand Kelvin includes a certain proportion of UV radiation, the intensity of which increases noticeably with increasing temperature.
A powerful source of UV radiation is gas-discharge plasma.
In various industries (food, chemical and other industries) and medicine, gas-discharge, xenon, mercury-quartz and other lamps are used, the cylinders of which are made of transparent materials - usually quartz. Significant UV radiation is emitted by electrons in the accelerator and special lasers in the nickel-like ion.
Basic properties of ultraviolet radiation
The practical use of ultraviolet is due to its basic properties:
— significant chemical activity (helps accelerate the flow of chemical and biological processes);
- bactericidal effect;
- the ability to cause luminescence of substances - glow with different colors of emitted light.
Research on modern equipment emission/absorption/reflection spectra in the UV range makes it possible to determine the electronic structure of atoms, molecules, and ions.
UV spectra of the Sun, stars and various nebulae make it possible to obtain reliable information about the processes occurring in these objects.
Also, ultraviolet radiation can disrupt and change chemical bonds in molecules, as a result, can occur various reactions(reduction, oxidation, polymerization, etc.), which serves as the basis for such a science as photochemistry.
UV radiation can destroy bacteria and microorganisms. Thus, ultraviolet lamps are widely used for disinfection in public places (medical institutions, kindergartens, subways, train stations, etc.).
Certain doses of UV radiation contribute to the formation of vitamin D, serotonin and other substances on the surface of human skin that affect the tone and activity of the body. Excessive exposure to ultraviolet radiation leads to burns and accelerates the aging process of the skin.
Ultraviolet radiation is also actively used in the cultural and entertainment sphere - to create a series of unique lighting effects in discos, stages of bars, theaters, etc.
Ultraviolet radiation (ultraviolet, UV, UV) - electromagnetic radiation, occupying the range between the violet boundary of visible radiation and x-ray radiation (380 - 10 nm, 7.9 1014 - 3 1016 Hertz).
The concept of ultraviolet rays was first encountered by an Indian philosopher of the 13th century in his work. The atmosphere of the Bhootakasha area he described contained violet rays that cannot be seen with the naked eye.
Soon after infrared radiation was discovered, the German physicist Johann Wilhelm Ritter began searching 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 faster when exposed to light decomposes under the influence of invisible radiation outside the violet region of the spectrum. Silver chloride white within a few minutes it darkens in the light. Different parts of the spectrum have different effects on the rate of darkening. This happens most quickly in front of the violet region of the spectrum. Many scientists, including Ritter, then agreed that light consists of three distinct components: an oxidative or thermal (infrared) component, an illuminant (visible light) component, and a reducing (ultraviolet) component. At that time, ultraviolet radiation was also called actinic radiation. Ideas about the unity of three different parts of the spectrum were first voiced only in 1842 in the works of Alexander Becquerel, Macedonio Melloni and others.
The electromagnetic spectrum of ultraviolet radiation can be divided into subgroups in various ways. The ISO standard for the definition of solar radiation (ISO-DIS-21348) gives the following definitions:
|
Name |
Abbreviation |
Wavelength in nanometers |
Amount of energy per photon |
|
Near |
400 nm - 300 nm |
3.10 - 4.13 eV |
|
|
Average |
300 nm - 200 nm |
4.13 - 6.20 eV |
|
|
Further |
200 nm - 122 nm |
6.20 - 10.2 eV |
|
|
Extreme |
121 nm - 10 nm |
10.2 - 124 eV |
|
|
Ultraviolet A, long wave range |
400 nm - 315 nm |
3.10 - 3.94 eV |
|
|
Ultraviolet B, midwave |
315 nm - 280 nm |
3.94 - 4.43 eV |
|
|
Ultraviolet C, shortwave |
280 nm - 100 nm |
4.43 - 12.4 eV |
The near ultraviolet range is often called “black light” because it is not recognized by the human eye, but when reflected from some materials, the spectrum moves into the visible region.
For the far and extreme range, the term "vacuum" (VUV) is often used, due to the fact that waves in this range are strongly absorbed by the Earth's atmosphere.
The biological effects of ultraviolet radiation in the three spectral regions are significantly different, so biologists sometimes identify the following ranges as the most important in their work:
Near ultraviolet, UV-A rays (UVA, 315-400 nm)
UV-B rays (UVB, 280-315 nm)
Far ultraviolet, UV-C rays (UVC, 100-280 nm)
Almost all UVC and approximately 90% of UVB are absorbed by ozone, as well as water vapor, oxygen and carbon dioxide as they pass through sunlight through the earth's atmosphere. Radiation from the UVA range is rather weakly absorbed by the atmosphere. Therefore, the radiation reaching the Earth's surface largely contains near-ultraviolet UVA and a small proportion - UVB.
Somewhat later, in the works of (O. G. Gazenko, Yu. E. Nefedov, E. A. Shepelev, S. N. Zaloguev, N. E. Panferova, I. V. Anisimova), this specific effect of radiation was confirmed in space medicine . Preventive UV irradiation was introduced into space flight practice along with the 1989 Methodological Instructions (MU) “Preventive ultraviolet irradiation of people (using artificial sources of UV radiation).” Both documents are a reliable basis for further improvement of UV prevention.
Exposure of the skin to ultraviolet radiation in excess of the skin's natural protective ability to tan results in burns.
Long-term exposure to ultraviolet radiation can contribute to the development of melanoma and premature aging.
Ultraviolet radiation is imperceptible to the human eye, but with intense irradiation it causes typical radiation damage (retinal burn).
Natural springs
The main source of ultraviolet radiation on Earth is the Sun. The ratio of UV-A to UV-B radiation intensity, the total amount of ultraviolet rays reaching the Earth's surface, depends on the following factors:
on the concentration of atmospheric ozone above the earth's surface (see ozone holes)
from the height of the Sun above the horizon
from altitude above sea level
from atmospheric dispersion
on the state of the cloud cover
on the degree of reflection of UV rays from the surface (water, soil)
Thanks to the creation and improvement of artificial sources of UV radiation, which went in parallel with the development of electrical sources of visible light, today specialists working with UV radiation in medicine, preventive, sanitary and hygienic institutions, agriculture, etc., are provided with significantly greater opportunities than with using natural UV radiation.
There are a number of lasers operating in the ultraviolet region. The laser produces high-intensity coherent radiation. However, the ultraviolet region is difficult for laser generation, so there are no sources as powerful here as in the visible and infrared ranges. Ultraviolet lasers find their application in mass spectrometry, laser microdissection, biotechnology and other scientific research.
Many polymers used in consumer products degrade when exposed to UV light. To prevent degradation, special substances that can absorb UV are added to such polymers, which is especially important in cases where the product is directly exposed to sunlight. The problem manifests itself in color fading, surface tarnishing, cracking, and sometimes complete destruction of the product itself. The rate of destruction increases with increasing exposure time and intensity of sunlight.
The described effect is known as UV aging and is one of the types of aging of polymers. Sensitive polymers include thermoplastics such as polypropylene, polyethylene, polymethyl methacrylate (plexiglass), as well as special fibers such as aramid fiber. UV absorption leads to destruction of the polymer chain and loss of strength at a number of points in the structure. The effect of UV on polymers is used in nanotechnology, transplantology, X-ray lithography and other fields to modify the properties (roughness, hydrophobicity) of the surface of polymers. For example, the smoothing effect of vacuum ultraviolet (VUV) light on the surface of polymethyl methacrylate is known.
Application: Disinfection with ultraviolet (UV) radiation, Sterilization of air and hard surfaces, Disinfection of drinking water, Chemical analysis, UV spectrometry, Mineral analysis, Qualitative chromatographic analysis, Insect catching, Artificial tanning and “Mountain sun”, restoration.
Ultraviolet radiation specifically affects living cells without affecting chemical composition water and air, which distinguishes it exceptionally favorably from all chemical methods disinfection and disinfection of water.
Achievements recent years in lighting and electrical engineering, they can ensure a high degree of reliability of water disinfection with ultraviolet rays.
What kind of radiation is this
Ultraviolet radiation, ultraviolet rays, UV radiation, electromagnetic radiation invisible to the eye, occupying the spectral region between visible and X-ray radiation within the wavelength range of 400-10 nm. The entire region of UV radiation is conventionally divided into near (400-200 nm) and far, or vacuum (200-10 nm); last name due to the fact that the UV radiation of this area is strongly absorbed by the air and is studied using vacuum spectral instruments.
Natural sources of UV radiation are the Sun, stars, nebulae and other space objects. However, only the long-wave part of UV radiation - 290 nm - reaches the earth's surface. Shorter wavelength UV radiation is absorbed by ozone, oxygen and other components of the atmosphere at an altitude of 30-200 km from the Earth's surface, which plays a large role in atmospheric processes.
Artificial sources of UV radiation. For various applications of UV radiation, the industry produces mercury, hydrogen, xenon and other gas-discharge lamps, the windows of which (or the entire bulb) are made of materials transparent to UV radiation (usually quartz). Any high-temperature plasma (plasma of electric sparks and arcs, plasma formed when focusing powerful laser radiation in gases or on the surface of solids, etc.) is powerful source UV radiation.
Despite the fact that ultraviolet radiation is given to us by nature itself, it is unsafe
There are three types of ultraviolet: “A”; "B"; "WITH". The ozone layer prevents Ultraviolet C from reaching the earth's surface. Light in the ultraviolet “A” spectrum has a wavelength from 320 to 400 nm, light in the ultraviolet “B” spectrum has a wavelength from 290 to 320 nm. UV radiation has sufficient energy to affect chemical bonds, including in living cells.
The energy from the ultraviolet component of sunlight causes damage to microorganisms at the cellular and genetic levels, the same damage done to humans, but it is limited to the skin and eyes. Sunburn is caused by exposure to ultraviolet B rays. Ultraviolet “A” penetrates much deeper than ultraviolet “B” and contributes to premature aging of the skin. In addition, exposure to ultraviolet A and B leads to skin cancer.
From the history of ultraviolet rays
The bactericidal effect of ultraviolet rays was discovered about 100 years ago. The first laboratory tests of UVR in the 1920s were so promising that complete eradication of airborne infections seemed possible in the very near future. UVI has been widely used since the 1930s and was first used in 1936 to sterilize the air in a surgical operating room. In 1937, the first use of UVR in the ventilation system of an American school impressively reduced the incidence of measles and other infections among students. Then it seemed that a wonderful remedy had been found to combat airborne infections. However, further study of UVR and its dangerous side effects has seriously limited its use in the presence of people.
The penetration power of ultraviolet rays is small and they travel only in a straight line, i.e. In any workroom, many shaded areas are formed that are not subject to bactericidal treatment. As you move away from the source of ultraviolet radiation, its biocidal action decreases sharply. The action of the rays is limited to the surface of the irradiated object, and its purity is of great importance.
Bactericidal effect of ultraviolet light
The disinfecting effect of UV radiation is mainly due to photochemical reactions, which result in irreversible DNA damage. In addition to DNA, ultraviolet radiation also affects other cell structures, in particular RNA and cell membranes. Ultraviolet light, as a high-precision weapon, specifically affects living cells without affecting the chemical composition of the environment, which is the case for chemical disinfectants. The latter property distinguishes it extremely favorably from all chemical methods of disinfection.
Application of ultraviolet
Ultraviolet is currently used in various areas: medical institutions (hospitals, clinics, hospitals); Food Industry(foods, drinks); pharmaceutical industry; veterinary medicine; for disinfection of drinking, recycled and waste water.
Modern advances in lighting and electrical engineering have provided the conditions for the creation of large UV disinfection complexes. The widespread introduction of UV technology into municipal and industrial water supply systems makes it possible to ensure effective disinfection (disinfection) of both drinking water before being supplied to the municipal water supply network and Wastewater before their release into water bodies. This eliminates the use of toxic chlorine and significantly increases the reliability and safety of water supply and sewerage systems in general.
Ultraviolet water disinfection
One of the urgent tasks in the disinfection of drinking water, as well as industrial and domestic wastewater after their clarification (biological purification) is the use of technology that does not use chemical reagents, i.e. technology that does not lead to the formation of toxic compounds during the disinfection process (as in the case of chlorine compounds and ozonation) while simultaneously completely destroying pathogenic microflora.
There are three sections of the ultraviolet radiation spectrum, which have different biological effects. Ultraviolet radiation with a wavelength of 390-315 nm has a weak biological effect. UV rays in the range of 315-280 nm have an antirachitic effect, and ultraviolet radiation with a wavelength of 280-200 nm has the ability to kill microorganisms.
Ultraviolet rays with a wavelength of 220-280 have a detrimental effect on bacteria, with the maximum bactericidal effect corresponding to a wavelength of 264 nm. This circumstance is used in bactericidal installations designed to disinfect mainly groundwater. The source of ultraviolet rays is a mercury-argon or mercury-quartz lamp, installed in a quartz case in the center of the metal case. The cover protects the lamp from contact with water, but allows ultraviolet rays to pass through. Disinfection occurs during the flow of water in the space between the body and the cover with direct exposure to ultraviolet rays on microbes.
The bactericidal effect is assessed in units called bacts (b). To ensure the bactericidal effect of ultraviolet irradiation, approximately 50 μb min/cm2 is sufficient. UV irradiation is the most promising method of water disinfection with high efficiency against pathogenic microorganisms, which does not lead to the formation of harmful by-products, which sometimes causes ozonation.
UV irradiation is ideal for disinfecting artesian waters
The view that groundwater is considered free of microbial contaminants as a result of water filtration through the soil is not entirely correct. Research has shown that groundwater is free of large microorganisms, such as protozoa or helminths, but smaller microorganisms, such as viruses, can penetrate the soil into underground water sources. Even if bacteria are not found in the water, disinfection equipment should serve as a barrier against seasonal or emergency contamination.
UV irradiation should be used to ensure water disinfection before standard quality according to microbiological indicators, while the required doses are selected based on the required reduction in the concentration of pathogenic and indicator microorganisms.
UV irradiation does not form reaction by-products; its dose can be increased to values that ensure epidemiological safety for both bacteria and viruses. It is known that UV radiation acts on viruses much more effectively than chlorine, so the use of ultraviolet radiation in the preparation of drinking water allows, in particular, to largely solve the problem of removing hepatitis A viruses, which is not always solved with traditional chlorination technology.
The use of UV irradiation as disinfection is recommended for water that has already been purified for color, turbidity and iron content. The effect of water disinfection is controlled by determining total number bacteria in 1 cm3 of water and the number of indicator bacteria of the E. coli group in 1 liter of water after its disinfection.
Today, flow-type UV lamps are widely used. The main element of this installation is a block of irradiators consisting of UV-spectrum lamps in an amount determined by the required productivity for treated water. Inside the lamp has a cavity for flow. Contact with UV rays occurs through special windows inside the lamp. The body of the installation is made of metal, which protects against the penetration of rays into the environment.
Water supplied to the installation must meet the following requirements:
- total iron content – no more than 0.3 mg/l, manganese – 0.1 mg/l;
- hydrogen sulfide content – no more than 0.05 mg/l;
- turbidity – no more than 2 mg/l for kaolin;
- color – no more than 35 degrees.
The ultraviolet disinfection method has the following advantages over oxidative disinfection methods (chlorination, ozonation):
- UV irradiation is lethal to most aquatic bacteria, viruses, spores and protozoa. It destroys the causative agents of infectious diseases such as typhoid, cholera, dysentery, viral hepatitis, polio, etc. The use of ultraviolet light allows for more effective disinfection than chlorination, especially in relation to viruses;
- disinfection with ultraviolet light occurs due to photochemical reactions inside microorganisms, therefore, changes in the characteristics of water have a much smaller impact on its effectiveness than when disinfecting with chemical reagents. In particular, the effect of ultraviolet radiation on microorganisms is not affected by water pH and temperature;
- toxic and mutagenic compounds that have a negative impact on the biocenosis of water bodies are not detected in water treated with ultraviolet radiation;
- unlike oxidative technologies, there are no negative effects in case of overdose. This makes it possible to significantly simplify control over the disinfection process and not carry out tests to determine the residual concentration of the disinfectant in the water;
- disinfection time under UV irradiation is 1-10 seconds in flow mode, so there is no need to create contact containers;
- Recent achievements in lighting and electrical engineering make it possible to ensure a high degree of reliability of UV complexes. Modern UV lamps and ballasts for them are mass-produced and have a long service life;
- Disinfection with ultraviolet radiation is characterized by lower operating costs than with chlorination and, especially, ozonation. This is due to relatively low energy costs (3-5 times less than with ozonation); no need for expensive reagents: liquid chlorine, sodium or calcium hypochlorite, as well as no need for dechlorination reagents;
- there is no need to create warehouses of toxic chlorine-containing reagents that require compliance with special technical and environmental safety measures, which increases the reliability of water supply and sewerage systems in general;
- ultraviolet equipment is compact, requires minimal space, its implementation is possible in existing technological processes treatment facilities without stopping them, with minimal volumes of construction and installation work.
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, commerce and other sectors of the economy.
The ultraviolet radiation region includes waves in the range of 100 – 400 nm and is conventionally divided into three groups:
- UV-A (UVA) (315–400 nm)
- UVB (280–315 nm)
- UV-C (UVC) (100–280 nm)
The influence of natural factors on the level of ultraviolet radiation:
Height of the Sun
The higher the sun is in the sky, the higher the level of ultraviolet radiation. Consequently, the level of ultraviolet radiation varies depending on the time of day and season. Outside the tropics, the highest degree of radiation is observed in the summer months when the sun is at its zenith around noon.Latitude
As you approach the equatorial regions, the degree of radiation increases.Cloudiness
The degree of ultraviolet radiation is higher in clear skies, but even in the presence of clouds the degree of ultraviolet radiation can be high. In this case, ultraviolet radiation, scattered, is reflected by various surfaces, and therefore the overall level of ultraviolet radiation can be quite high.Height
As altitude increases, 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 part of the ultraviolet radiation aimed at earth's surface. The thickness of the ozone layer changes throughout the year and even throughout the day.Reflection from the Earth's surface
Ultraviolet radiation is reflected or scattered to varying degrees by different surfaces, e.g. pure snow can reflect up to 80% of ultraviolet radiation, dry coastal sand about 15%, sea foam about 25%.- More than 90% of UV radiation can penetrate through light cloud cover.
- Clean snow reflects up to 80% of UV radiation.
- UV radiation increases by 4% for every 300 m rise.
- People who work indoors are exposed to 5-10 times less UV radiation 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 period from 10-00 to 14-00 hours.
- Shade reduces UV radiation levels by 50% or more.
- White sand reflects up to 15% of UV radiation.
Effects of ultraviolet radiation on health
Small amounts of ultraviolet radiation are beneficial and necessary for the production of vitamin D. Ultraviolet radiation is also used to treat several diseases, including rickets, psoriasis and eczema. Treatment is carried out under medical supervision, taking into account the benefits of treatment and the risks of exposure to ultraviolet radiation.
However, long-term exposure to ultraviolet radiation in humans can lead to acute and chronic damage to the skin, eyes and immune system.
A popular misconception is that only fair-skinned people should be concerned about excessive "sun exposure." Darker skin has higher levels of the protective pigment melanin. People with such skin have a lower incidence of skin cancer. However, skin cancer is also diagnosed in this population, but often at a later and more dangerous stage.
The risk of damage to the eyes and immune system from ultraviolet radiation does not depend on skin type.
The most well-known acute lesions resulting from excessive exposure to ultraviolet radiation are sunburn and tanning; with prolonged exposure, 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.
Every year there are 2-3 million cases of non-malignant skin cancer and 132,000 cases of skin melanoma. While non-malignant skin cancer can be removed surgically and is rarely fatal, malignant melanoma is one of the leading causes of death in the fair-skinned population.
Each year, approximately 12 to 15 million people go blind due to cataracts. Studies have shown that up to 20% of blindness may be caused or worsened 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 consider intense tanning to be normal. Children, teenagers and their parents perceive tanning as an indicator of attractiveness and good health.
Risk group
- Prolonged sun exposure during childhood increases the risk of developing skin cancer later and can cause serious damage to the eyes.
- All children under 15 have sensitive skin and eyes - protect them and set a good example for them!
- Children under one year old should not be exposed to direct sunlight!
- Parents, protect your children from the sun! Teach them about sunscreen use and sun exposure!
Health effects of ozone depletion
Depletion of the ozone layer is likely to increase the adverse effects of ultraviolet radiation, since stratospheric ozone is an effective absorber of ultraviolet radiation.
As the ozone layer decreases, the protective filter provided by the atmosphere decreases. Accordingly, the population and the environment are exposed to more high degree ultraviolet radiation, especially UVB radiation, which has a major impact on the health of people, animals, marine organisms and plant life.
Computational models predict that a 10% decrease in stratospheric ozone could cause an additional 300,000 non-cancerous skin cancers, 4,500 malignant skin cancers, and 1.6 to 1.75 million cases of cataracts annually.
GLOBAL SOLAR ULTRAVIOLET (UV) INDEX
Introduction
Since the 1970s, there has been an increase in the incidence of skin cancer among fair-skinned people. This increase is associated with the population's habits of being “in the sun” under its ultraviolet component and the generally accepted opinion about the attractiveness and benefits of tanning.
Thus, there is an urgent need to increase public awareness about the harmful effects of ultraviolet radiation, with the goal of changing the habits of the population to prevent the trend of increasing cases of skin cancer.
The Global Ultraviolet Index is a simplified measure of the level of ultraviolet radiation on the Earth's surface and an indicator of potential skin hazards. It serves as a means of raising public awareness and warning of the need to take protective measures against exposure to ultraviolet radiation.
The UVI was developed by the World Health Organization with the assistance of the United Nations Human Rights Program 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 education about UVR and promote the use of UVR as a means of sun protection.
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 takes values from zero and above. Moreover, the higher the UV index value, the greater the potential danger to human skin and eyes and the shorter the time required to cause harm to health.
UV index values correspond to levels of exposure to ultraviolet radiation from the sun in the following categories:
Why do you need an ultraviolet index?
The UV Index is an important means of raising public awareness of the risks of excessive exposure to ultraviolet radiation and warning of the need for sunscreen use. The level of ultraviolet radiation and, therefore, the UV index values vary throughout the day. Usually the maximum value of ultraviolet radiation observed in a 4-hour period around solar noon is shown. Sunny noon lasts from 12 noon to 2 pm.
When people make plans for the day and decide “what to go out in,” they 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 shows the level of ultraviolet radiation and the possible danger of exposure to the sun.
Knowing the UV index forecast can help everyone make healthy choices.
| Required protective measures depending on the UV index value | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| No protection required | Protection required | Increased protection required | ||||||||||
| Stay out premises doesn't represent dangers |
At noon stay in the shadows! Wear clothes with long sleeves and a hat! Use sunscreen! |
Wait out the midday hours indoors! Stay in the shade outdoors! Be sure to wear clothes long sleeves, hat, use sunscreen! |
||||||||||
Even for people with very sensitive fair skin, the risk of harm to health is minimal at UV index values below 3 and under normal circumstances the use of protective products is not required.
Protection is required for UV index values above 3, increased protective measures are required for UV index values of 8 and above. In this case, you need to use all protective equipment:
- Limit exposure to the sun 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 sunscreen with a sun protection factor (SPF) of 15+. Do not use sunscreen to extend your sun exposure.
- Protect your little ones: This is especially important.
Myths and reality
| MYTH | REALITY |
|---|---|
| Sun tanning is beneficial. | Tanning is the body's defense against further damage from ultraviolet radiation. |
| A tan protects you from the sun. | A dark tan on fair skin provides 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 cloud cover. Fog can increase ultraviolet radiation levels. |
| You won't get tanned while in the water. | Water provides minimal protection from ultraviolet radiation, and reflection from water can increase the level of ultraviolet radiation. |
| Ultraviolet radiation is not dangerous in winter. | UV radiation levels are generally lower during the winter months, but reflection from snow can double them, especially at altitudes. Be especially careful in early spring when temperatures are low but the sun's UV radiation is strong. |
| Sunscreen is a means of protection, I can increase the tanning time. | Sunscreen should not be used to prolong the time spent in the sun, but to enhance protection from ultraviolet radiation. |
| You won't get burned if you take breaks while tanning. | Exposure to ultraviolet radiation tends to accumulate throughout the day. |
| You won't tan if the sun's heat is imperceptible. | Sun tanning is caused by ultraviolet radiation, which cannot be felt. When we feel the heat of the Sun, we feel its infrared, not ultraviolet, radiation. |
REMEMBER!
- Tanning does not stop ultraviolet radiation! Even if your skin is tanned, limit sun exposure to midday hours and use sun protection measures.
- Limit your sunbathing time! A tan is an indication that your skin has received an overdose of ultraviolet radiation! Protect your skin!
- Wear sunglasses, a wide-brimmed hat, protective clothing, and SPF 15+ sunscreen.
- Using sunscreen is not a means of extending your time in the sun, but of reducing the health risks of being in the sun.
- Taking certain medications, as well as using perfumes and deodorants, make the skin more sensitive, causing severe sunburn.
- Exposure to the sun increases the risk of developing skin cancer, accelerates skin aging and damages the eyes. Protect yourself!
- Shadow is one of the best means protection from solar radiation. Try to stay in the shade during the midday hours, when UV radiation is highest.
- Cloudy skies do not prevent sunburn. Ultraviolet radiation penetrates clouds.
- Remember that damage to the skin and eyes is caused by ultraviolet radiation, which cannot be seen or felt - DO NOT BE FOOLED BY MODERATE TEMPERATURES!
- If you expect to be outdoors during the day, be sure to wear sunscreen, a hat, and long sleeves.
- When on the ski slopes, don't forget that altitude and clear snow can double your UV radiation, don't forget sunglasses and sunscreen! In the mountains, the level of ultraviolet radiation increases by approximately 10% every 1000 m.
- Information sources:
1. Materials from 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. 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 Programme, and the International Commission on Non-Ionizing Radiation Protection.Forecast of UV index and ozone layer thickness provided.
Ultraviolet radiation Prepared by 11th grade student Yumaev Vyacheslav
Ultraviolet radiation is electromagnetic radiation invisible to the eye, occupying the region between the lower limit of the visible spectrum and the upper limit of x-ray radiation. The wavelength of UV radiation ranges from 100 to 400 nm (1 nm = 10 m). According to the classification of the International Commission on Illumination (CIE), the UV radiation spectrum is divided into three ranges: UV-A - long wavelength (315 - 400 nm) UV-B - medium wavelength (280 - 315 nm) UV-C - short wavelength (100 - 280 nm.) The entire UVR 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: tanning, UV rays initiate the process of formation of vitamin D, which is necessary for the body to absorb calcium and ensure normal development of the bone skeleton, ultraviolet radiation is active influences the synthesis of hormones responsible for the daily biological rhythm; but in large doses it has negative biological effects: changes in cell development and metabolism, effects on the eyes.
UV radiation spectrum: line (atoms, ions and light molecules); consists of stripes (heavy molecules); Continuous spectrum (occurs during inhibition 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 based 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 and gelatin-free photographic plates that he built. He was able to detect 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. For every 1000m increase in altitude, UV levels increase by 12%
Application: Medicine: the use of UV radiation in medicine is due to the fact that it has bactericidal, mutagenic, therapeutic (medicinal), antimitotic, preventive effects, disinfection; laser biomedicine Show business: Lighting, lighting effects
Cosmetology: In cosmetology, ultraviolet irradiation is widely used in solariums to obtain an even, beautiful tan. A deficiency of UV rays leads to vitamin deficiency, decreased immunity, and 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 ultraviolet radiation as a physical factor influencing microorganisms can ensure disinfection of the living environment to a very high degree, for example up to 99.9%.
Forensics: Scientists have developed technology that can detect the smallest doses of explosives. The device for detecting traces of explosives uses a very thin 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 fabric and on the skin of crime suspects. Using invisible UV inks for protection bank cards and banknotes from counterfeiting. Images and design elements invisible in normal light are applied to the card, or the entire card is made to glow in UV rays.
UV radiation sources: emitted by all solids, for which t >1000 C, as well as luminous mercury vapor; stars (including the Sun); laser installations; gas-discharge lamps with quartz tubes (quartz lamps), mercury; mercury rectifiers
Protection from UV radiation: Application of sun screens: - chemical ( chemical substances and covering creams); - physical (various barriers that reflect, absorb or scatter rays). Special clothing (for example, made from poplin). To protect eyes in industrial conditions, light filters (glasses, helmets) made of dark green glass are used. Full protection from UV of all wavelengths is provided by flint glass (glass containing lead oxide) 2 mm thick.
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