I remember disinfection with UV lamps from childhood - in the kindergarten, sanatorium and even in the summer camp there were somewhat frightening structures that glowed with a beautiful purple light in the dark and from which the educators drove us away. So what exactly is ultraviolet radiation and why does a person need it?
Perhaps the first question to be answered is what ultraviolet rays are and how they work. This is usually referred to as electromagnetic radiation, which is in the range between visible and X-ray radiation. Ultraviolet is characterized by a wavelength from 10 to 400 nanometers.
It was discovered back in the 19th century, and this happened thanks to the discovery of infrared radiation. Having discovered the IR spectrum, in 1801 I.V. Ritter drew attention to the opposite end of the light spectrum during experiments with silver chloride. And then several scientists at once came to the conclusion about the heterogeneity of the ultraviolet.
Today it is divided into three groups:
- UV-A radiation - near ultraviolet;
- UV-B - medium;
- UV-C - far.
This division is largely due to the impact of rays on a person. The natural and main source of ultraviolet radiation on Earth is the Sun. In fact, it is from this radiation that we are saved by sunscreens. At the same time, far ultraviolet is completely absorbed by the Earth's atmosphere, and UV-A just reaches the surface, causing a pleasant tan. And on average, 10% of UV-B provokes those same sunburns, and can also lead to the formation of mutations and skin diseases.
Artificial sources of ultraviolet are created and used in medicine, agriculture, cosmetology and various sanitary institutions. Generation of ultraviolet radiation is possible in several ways: by temperature (incandescent lamps), by the movement of gases (gas lamps) or metal vapors (mercury lamps). At the same time, the power of such sources varies from a few watts, usually small mobile radiators, to a kilowatt. The latter are mounted in volumetric stationary installations. The areas of application of UV rays are due to their properties: the ability to accelerate chemical and biological processes, the bactericidal effect and the luminescence of certain substances.
Ultraviolet is widely used to solve a variety of problems. In cosmetology, the use of artificial UV radiation is used primarily for tanning. Solariums produce rather mild UV-A according to the introduced standards, and the share of UV-B in tanning lamps is no more than 5%. Modern psychologists recommend solariums for the treatment of "winter depression", which is mainly caused by vitamin D deficiency, as it is formed under the influence of UV rays. Also, UV lamps are used in manicure, since it is in this spectrum that especially resistant gel polishes, shellac and the like dry out.
Ultraviolet lamps are used to create photographs in non-standard situations, for example, to capture space objects that are invisible with a conventional telescope.
Ultraviolet is widely used in expert activities. With its help, the authenticity of the paintings is checked, since fresher paints and varnishes in such rays look darker, which means that the real age of the work can be established. Forensics also use UV rays to detect traces of blood on objects. In addition, UV light is widely used to develop hidden seals, security features and document authentication threads, as well as in the lighting design of shows, restaurant signs or decorations.
In healthcare facilities, ultraviolet lamps are used to sterilize surgical instruments. In addition, air disinfection using UV rays is still widespread. There are several types of such equipment.
So called high and low pressure mercury lamps, as well as xenon flash lamps. The bulb of such a lamp is made of quartz glass. The main advantage of germicidal lamps is their long service life and instantaneous ability to work. Approximately 60% of their rays are in the bactericidal spectrum. Mercury lamps are quite dangerous in operation; in case of accidental damage to the housing, thorough cleaning and demercurization of the room is necessary. Xenon lamps are less dangerous if damaged and have a higher bactericidal activity. Also bactericidal lamps are divided into ozone and ozone-free. The former are characterized by the presence in their spectrum of a wave with a length of 185 nanometers, which interacts with oxygen in the air and turns it into ozone. High concentrations of ozone are dangerous for humans, and the use of such lamps is strictly limited in time and is recommended only in a ventilated area. All this led to the creation of ozone-free lamps, the bulb of which is coated with a special coating that does not transmit a wave of 185 nm to the outside.
Regardless of the type, bactericidal lamps have common drawbacks: they work in complex and expensive equipment, the average life of the emitter is 1.5 years, and the lamps themselves, after burnout, must be stored packed in a separate room and disposed of in a special way in accordance with current regulations.
Consist of a lamp, reflectors and other auxiliary elements. Such devices are of two types - open and closed, depending on whether UV rays pass out or not. Open emit ultraviolet, enhanced by reflectors, into the space around, capturing almost the entire room at once, if installed on the ceiling or wall. It is strictly forbidden to treat the premises with such an irradiator in the presence of people.
Closed irradiators work on the principle of a recirculator, inside which a lamp is installed, and the fan draws air into the device and releases the already irradiated air to the outside. They are placed on the walls at a height of at least 2 m from the floor. They can be used in the presence of people, but long-term exposure is not recommended by the manufacturer, as part of the UV rays can pass out.
Among the shortcomings of such devices, one can note immunity to mold spores, as well as all the difficulties of recycling lamps and strict regulations for use, depending on the type of emitter.
Germicidal installations
A group of irradiators combined into one device used in one room is called a bactericidal installation. Usually they are quite large and are characterized by high power consumption. Air treatment with bactericidal installations is carried out strictly in the absence of people in the room and is monitored according to the Commissioning Certificate and the Registration and Control Log. It is used only in medical and hygienic institutions for disinfection of both air and water.
Disadvantages of ultraviolet air disinfection
In addition to those already listed, the use of UV emitters has other disadvantages. First of all, ultraviolet itself is dangerous for the human body, it can not only cause skin burns, but also affect the functioning of the cardiovascular system, it is dangerous for the retina. In addition, it can cause the appearance of ozone, and with it the unpleasant symptoms inherent in this gas: irritation of the respiratory tract, stimulation of atherosclerosis, exacerbation of allergies.
The effectiveness of UV lamps is quite controversial: the inactivation of pathogens in the air by permitted doses of ultraviolet radiation occurs only when these pests are static. If microorganisms move, interact with dust and air, then the required radiation dose increases by 4 times, which a conventional UV lamp cannot create. Therefore, the efficiency of the irradiator is calculated separately, taking into account all the parameters, and it is extremely difficult to choose the right ones for influencing all types of microorganisms at once.
Penetration of UV rays is relatively shallow, and even if the immobile viruses are under a layer of dust, the upper layers protect the lower ones by reflecting ultraviolet from themselves. So, after cleaning, disinfection must be carried out again.
UV irradiators cannot filter the air, they only fight microorganisms, keeping all mechanical pollutants and allergens in their original form.
On the body.
ultraviolet radiation.
Ultraviolet radiation is part of solar radiation with a wavelength of 10 to 400 nm.
Ultraviolet rays with a wavelength of 10 to 290 nm do not reach the earth's surface. The properties of ultraviolet radiation with different wavelengths are not the same. The shortest waves (from 10 to 200 nm) in their action approach ionizing radiation. This area was named ozonating. The energy of ultraviolet radiation with a wavelength of 200 to 400 nm is not sufficient to excite atoms; photochemical reactions.
For us, the part of the spectrum from 200 to 400 nm is of the greatest importance. This area is divided into
region C - from 200 to 280 nm
area B - from 280 to 320 nm
region A- from 320 to 400 nm
Region C called bactericidal. The predominant effect of ultraviolet radiation in this area is a bactericidal effect, which is widely used to disinfect water, air, and so on. Areas B and A also have a bactericidal effect, but to a much lesser extent.
Region B called erythema, because under the influence of ultraviolet radiation of this area, erythema occurs. In area B is also very pronounced vitamin action. The most powerful vitamin-forming effect has a region with a long wavelength from 265 to 315 nm.
Region A was named tan. Under the influence of ultraviolet radiation of this area, a tan occurs - the formation of melanin, which is a protective reaction of the body.
The role of UVI very large. It increases the tone of the body, mental and physical performance, resistance to infections, stimulates the activity of the endocrine glands, hematopoiesis.
Under the action of ultraviolet radiation, vitamin D, histamine, tissue hormones, and pigments are formed.
Lack of ultraviolet radiation adversely affects the body and can lead to:
1. Rickets in children
2. Decreased overall immunological reactivity
3. Decreased mental and physical performance
4. Increasing incidence
5. Violation of calcium metabolism (due to lack of vitamin D) - osteoporosis, osteomalacia, caries
However, one should not forget about the negative effect of ultraviolet radiation, which has recently received close attention.
Negative effect of overexposure:
1. Exacerbation of a number of chronic diseases. Therefore, sunbathing cannot be recommended for diseases such as tuberculosis, rheumatism, gastric and duodenal ulcers, cardiovascular diseases, all types of tumor processes.
2. The role of ultraviolet radiation in development has been proven skin cancer, in particular melanoma
3. Possibly the occurrence of a deficit some aromatic amino acids - tyrosine, phenylalanine, as well as vitamin C and vitamin PP, which are involved in the synthesis of melanin
4. The amount is increasing peroxide compounds, which leads to excess consumption of protein and iron and the formation of radiomimetics - compounds with mutagenic activity.
5. Possible occurrence photochemical burn in the case when the protective pigment does not have time to form. A photochemical burn is characterized by fever, headache, and malaise.
6. With excessive exposure to ultraviolet radiation, photophthalmia - conjunctivitis, accompanied by redness, a feeling of sand in the eyes, burning, lacrimation, photophobia, sometimes temporary loss of vision. Photophthalmia is possible not only under the action of direct, but also reflected and scattered light and can be observed in climbers, skiers, electric welders, in photariums, operating rooms. In industrial conditions (for example, welders), if the cornea is damaged by intense ultraviolet radiation, cataracts may develop.
7. Photosensitivity - hypersensitivity to the action of ultraviolet radiation, which manifests itself in photoallergic reactions such as urticaria, dermatitis, eczema. For the occurrence of photosensitivity, as a rule, the presence of both exogenous and endogenous factors is necessary. Endogenous factors include diseases of the thyroid, pancreas, liver, enzymopathies leading to the accumulation of porphyrins, fatty acids, bilirubin. Exogenous factors - various chemical agents - tar, asphalt, creosote oil, fuels and lubricants, dyes (acridine, creosote).
Infrared radiation.
Infrared radiation is part of solar radiation in the wavelength range from 670 to 3400 nm.
Infrared learning has primarily a thermal effect. In addition, a number of biological effects have now been established.
The thermal effect is determined primarily by the long wave. longwave part of the infrared radiation (more than 1400 nm) is retained by the surface layers of the skin, due to which they are heated, a burning sensation appears. Due to this effect, the long-wavelength part of the radiation is called "scorching rays".At sufficient radiation intensity, erythema and burns are possible.
shortwave part of the radiation penetrates the tissues to a depth of about 3 cm, as a result of which it can cause heating of the tissues, including the meninges. It is the influence of short-wave infrared radiation that causes such a phenomenon as sunstroke. In addition, it causes overheating and clouding of the lens, which leads to the development of cataracts.
General reactions in response to the action of infrared radiation, they are characterized by hyperemia, an increase in gas exchange, an increase in the excretory function of the kidneys, and a change in the functional state of the nervous system.
Theoretically, the question How are infrared rays different from ultraviolet rays?' could be of interest to anyone. After all, both those and other rays are part of the solar spectrum - and we are exposed to the Sun every day. In practice, it is most often asked by those who are going to purchase devices known as infrared heaters, and would like to make sure that such devices are absolutely safe for human health.
How infrared rays differ from ultraviolet rays in terms of physics
As you know, in addition to the seven visible colors of the spectrum beyond its limits, there are radiation invisible to the eye. In addition to infrared and ultraviolet, these include x-rays, gamma rays and microwaves. 
Infrared and UV rays are similar in one thing: they both belong to that part of the spectrum that is not visible to the naked eye of a person. But this is where their similarity ends.
Infrared radiation
Infrared rays were found outside the red border, between the long and short wavelengths of this part of the spectrum. It is worth noting that almost half of the solar radiation is infrared radiation. The main characteristic of these rays, invisible to the eye, is strong thermal energy: all heated bodies continuously radiate it.
Radiation of this type is divided into three regions according to such a parameter as wavelength:
- from 0.75 to 1.5 microns - near area;
- from 1.5 to 5.6 microns - medium;
- from 5.6 to 100 microns - far.
It must be understood that infrared radiation is not a product of all kinds of modern technical devices, for example, infrared heaters. This is a factor of the natural environment, which constantly acts on a person. Our body continuously absorbs and emits infrared rays.
Ultraviolet radiation
The existence of rays beyond the violet end of the spectrum was proved in 1801. The range of ultraviolet rays emitted by the Sun is from 400 to 20 nm, but only a small part of the short-wave spectrum reaches the earth's surface - up to 290 nm.
Scientists believe that ultraviolet radiation plays a significant role in the formation of the first organic compounds on Earth. However, the impact of this radiation is also negative, leading to the decay of organic substances.
When answering a question, How is infrared radiation different from ultraviolet radiation?, it is necessary to consider the impact on the human body. And here the main difference lies in the fact that the effect of infrared rays is limited mainly to thermal effects, while ultraviolet rays can also have a photochemical effect.
UV radiation is actively absorbed by nucleic acids, resulting in changes in the most important indicators of cell vital activity - the ability to grow and divide. It is DNA damage that is the main component of the mechanism of exposure to ultraviolet rays on organisms.
The main organ of our body that is affected by ultraviolet radiation is the skin. It is known that thanks to UV rays, the process of formation of vitamin D, which is necessary for the normal absorption of calcium, is triggered, and serotonin and melatonin are also synthesized - important hormones that affect circadian rhythms and human mood.
Exposure to IR and UV radiation on the skin
When a person is exposed to sunlight, infrared, ultraviolet rays also affect the surface of his body. But the result of this impact will be different:
- IR rays cause a rush of blood to the surface layers of the skin, an increase in its temperature and redness (caloric erythema). This effect disappears as soon as the effect of irradiation stops.
- Exposure to UV radiation has a latent period and may appear several hours after exposure. The duration of ultraviolet erythema ranges from 10 hours to 3-4 days. The skin turns red, may peel off, then its color becomes darker (tan).
It has been proven that excessive exposure to ultraviolet radiation can lead to the occurrence of malignant skin diseases. At the same time, in certain doses, UV radiation is beneficial for the body, which allows it to be used for prevention and treatment, as well as for the destruction of bacteria in indoor air.
Is infrared radiation safe?
People's fears in relation to such a type of device as infrared heaters are quite understandable. In modern society, a stable tendency has already formed with a fair amount of fear to treat many types of radiation: radiation, X-rays, etc.
For ordinary consumers who are going to purchase devices based on the use of infrared radiation, the most important thing to know is the following: infrared rays are completely safe for human health. This is what needs to be emphasized when considering How are infrared rays different from ultraviolet rays?.
Studies have proven that long-wave infrared radiation is not only useful for our body - it is absolutely necessary for it. With a lack of infrared rays, the body's immunity suffers, and the effect of its accelerated aging is also manifested. 
The positive impact of infrared radiation is no longer in doubt and manifests itself in various aspects.
A significant part of non-ionizing electromagnetic radiation is radio waves and oscillations of the optical range (infrared, visible, ultraviolet radiation). Depending on the place and conditions of exposure to electromagnetic radiation of radio frequencies, four types of exposure are distinguished: professional, non-professional, domestic and for medical purposes, and according to the nature of exposure - general and local.
Infrared radiation is a part of the electromagnetic radiation with a wavelength of 780 to 1000 microns, the energy of which, when absorbed by a substance, causes a thermal effect. Short-wave radiation is the most active, since it has the highest photon energy, is able to penetrate deeply into the tissues of the body and is intensively absorbed by the water contained in the tissues. In humans, the organs most affected by infrared radiation are the skin and organs of vision.
Visible radiation at high energy levels can also be hazardous to the skin and eyes.
Ultraviolet radiation, like infrared, is part of the electromagnetic radiation with a wavelength of 200 to 400 nm. Natural solar ultraviolet radiation is vital, has a beneficial stimulating effect on the body.
Radiation from artificial sources can cause acute and chronic occupational injuries. The most vulnerable organs are the eyes. Acute eye lesions are called electrophthalmia. Getting on the skin, ultraviolet radiation can cause acute inflammation, swelling of the skin. The temperature may rise, chills, headache.
Laser radiation is a special type of electromagnetic radiation generated in the wave range of 0.1-1000 microns. It differs from other types of radiation in monochromaticity (strictly one wavelength), coherence (all radiation sources emit electromagnetic waves in one phase) and sharp beam directivity. Acts on various organs selectively. Local damage is associated with irradiation of the eyes, skin damage. The general effect can lead to various functional disorders of the human body (nervous and cardiovascular systems, blood pressure, etc.)
2. Collective means of protection (types, methods of application)
Protecting the population and productive forces of the country from weapons of mass destruction, as well as in case of natural disasters, industrial accidents is the most important task of the Office for Civil Defense and Emergencies.
Collective protective equipment - means of protection, structurally and functionally associated with the production process, production equipment, premises, building, structure, production site.
Collective means of protection are divided into: protective, safety, braking devices, automatic control and signaling devices, remote control, safety signs.
Protective devices are designed to prevent accidental entry of a person into the danger zone. These devices are used to isolate moving parts of machines, processing areas of machine tools, presses, impact elements of machines from the working area. Devices are divided into stationary, mobile and portable. They can be made in the form of protective covers, visors, barriers, screens; both solid and mesh. They are made from metal, plastic, wood.
Stationary fences must be strong enough and withstand any loads arising from the destructive actions of objects and the disruption of workpieces, etc. Portable fences in most cases are used as temporary.
Safety devices are used to automatically turn off machines and equipment in case of deviation from the normal mode of operation or when a person enters the danger zone. These devices can be blocking and restrictive. Blocking devices according to the principle of operation are: electromechanical, photoelectric, electromagnetic, radiation, mechanical. Limiting devices are components of machines and mechanisms that are destroyed or fail when overloaded.
Braking devices are widely used, which can be divided into shoe, disc, conical and wedge. Most types of production equipment use shoe and disc brakes. Brake systems can be manual, foot, semi-automatic and automatic.
To ensure the safe and reliable operation of the equipment, information, warning, emergency automatic control and signaling devices are very important. Control devices are devices for measuring pressures, temperatures, static and dynamic loads that characterize the operation of machines and equipment. When monitoring devices are combined with alarm systems, their effectiveness is significantly increased. Alarm systems are: sound, light, color, sign, combined.
Various technical measures are used to protect against electric shock. These are small stresses; electrical separation of the network; control and prevention of insulation damage; protection against accidental contact with live parts; protective grounding; protective shutdown; personal protective equipment.
Ultraviolet radiation belongs to the invisible optical spectrum. The natural source of ultraviolet radiation is the sun, which accounts for approximately 5% of the solar radiation flux density - this is a vital factor that has a beneficial stimulating effect on a living organism.
Artificial sources of ultraviolet radiation (electric arc during electric welding, electric smelting, plasma torches, etc.) can cause damage to the skin and vision. Acute eye lesions (electrophthalmia) are acute conjunctivitis. The disease is manifested by the sensation of a foreign body or sand in the eyes, photophobia, lacrimation. Chronic diseases include chronic conjunctivitis, cataracts. Skin lesions occur in the form of acute dermatitis, sometimes with the formation of edema and blisters. There may be general toxic effects with fever, chills, headaches. Hyperpigmentation and peeling develop on the skin after intense irradiation. Prolonged exposure to ultraviolet radiation leads to "aging" of the skin, the likelihood of developing malignant neoplasms.
Hygienic regulation of ultraviolet radiation is carried out according to SN 4557-88, which establish the permissible radiation flux density depending on the wavelength, provided that the organs of vision and skin are protected.
Permissible exposure intensity of workers at
unprotected areas of the skin surface no more than 0.2 m 2 (face,
neck, hands) with a total duration of exposure to radiation of 50% of the work shift and the duration of a single exposure
over 5 minutes should not exceed 10 W / m 2 for the region of 400-280 nm and
0.01 W / m 2 - for the region of 315-280 nm.
When using special clothing and face protection
and hands that do not transmit radiation, the permissible intensity
exposure should not exceed 1 W/m 2 .
The main methods of protection against ultraviolet radiation include screens, personal protective equipment (clothing, glasses), protective creams.
Infrared radiation represents the invisible part of the optical electromagnetic spectrum, the energy of which, when absorbed in a biological tissue, causes a thermal effect. Sources of infrared radiation can be melting furnaces, molten metal, heated parts and blanks, various types of welding, etc.
The most affected organs are the skin and organs of vision. In case of acute skin irradiation, burns, a sharp expansion of capillaries, increased skin pigmentation are possible; with chronic exposure, changes in pigmentation can be persistent, for example, an erythema-like (red) complexion in glass workers, steel workers.
When exposed to vision, clouding and burns of the cornea, infrared cataracts can be noted.
Infrared radiation also affects metabolic processes in the myocardium, water and electrolyte balance, the state of the upper respiratory tract (the development of chronic laryngitis, rhinitis, sinusitis), and can cause heat stroke.
Rationing of infrared radiation is carried out according to the intensity of permissible integral radiation fluxes, taking into account the spectral composition, the size of the irradiated area, the protective properties of overalls for the duration of action in accordance with GOST 12.1.005-88 and Sanitary Rules and Norms SN 2.2.4.548-96 "Hygienic requirements for the microclimate of production premises."
The intensity of thermal exposure of workers from heated surfaces of technological equipment, lighting fixtures, insolation at permanent and non-permanent workplaces should not exceed 35 W / m 2 when irradiating 50% of the body surface or more, 70 W / m 2 - with the size of the irradiated surface from 25 to 50% and 100 W / m 2 - with irradiation of no more than 25% of the body surface.
The intensity of thermal exposure of workers from open sources (heated metal, glass, “open” flame, etc.) should not exceed 140 W / m 2, while more than 25% of the body surface should not be exposed to radiation and it is mandatory to use personal protective equipment, including including face and eye protection.
The permissible intensity of exposure to permanent and non-permanent places is given in Table. 4.20.
Table 4.20.
Permissible exposure intensity
The main measures to reduce the risk of exposure to infrared radiation on humans include: reducing the intensity of the radiation source; technical protective equipment; time protection, use of personal protective equipment, therapeutic and preventive measures.
Technical protective equipment is divided into enclosing, heat-reflecting, heat-removing and heat-insulating screens; equipment sealing; means of ventilation; means of automatic remote control and monitoring; alarm.
When protecting with time, in order to avoid excessive general overheating and local damage (burn), the duration of periods of continuous infrared irradiation of a person and pauses between them is regulated (Table 4.21. according to R 2.2.755-99).
Table 4.21.
Dependence of continuous irradiation on its intensity.
Questions to 4.4.3.
- Describe the natural sources of the electromagnetic field.
- Give a classification of anthropogenic electromagnetic fields.
3. Tell us about the effect of an electromagnetic field on a person.
4. What is the regulation of electromagnetic fields.
5. What are the permissible levels of exposure to electromagnetic fields in the workplace.
6. List the main measures to protect workers from the adverse effects of electromagnetic fields.
7. What screens are used to protect against electromagnetic fields.
8. What personal protective equipment is used and how their effectiveness is determined.
9. Describe the types of ionizing radiation.
10. What doses characterize the effect of ionizing radiation.
11. What is the effect of ionizing radiation on a person.
12. What is the regulation of ionizing radiation.
13. Tell us the procedure for ensuring safety when working with ionizing radiation.
14. Give the concept of laser radiation.
15. Describe its impact on humans and methods of protection.
16. Give the concept of ultraviolet radiation, its effects on humans and methods of protection.
17. Give the concept of infrared radiation, its effects on humans and methods of protection.
