Infrared rays: benefits and harms, effects on the human body. Infrared light - a workshop of invisible warm radiation

What is infrared radiation? The definition says that infrared rays are electromagnetic radiation that obeys optical laws and has the nature of visible light. Infrared rays have a spectral band between red visible light and shortwave radio emission. For the infrared region of the spectrum, there is a division into short-wave, medium-wave and long-wave. The heating effect of such rays is high. The abbreviation for infrared radiation is IR.

IR radiation

Manufacturers report different information about heating devices designed according to the principle of radiation in question. Some may indicate that the device is infrared, on the other - that it is long-wave or dark. In practice, all this applies to infrared radiation, long-wave heaters have the lowest temperature of the radiating surface, and waves are emitted in a larger mass in the long-wave spectrum zone. They also received the name dark, since at a temperature they do not give off light and do not shine, as in other cases. Medium-wave heaters have a higher surface temperature, and they are called gray. The short-wave device belongs to the light ones.

The optical characteristics of a substance in the infrared regions of the spectrum differ from the optical properties in ordinary everyday life. Heating devices that are used by a person every day give off infrared rays, but you cannot see them. The whole difference is in the wavelength, it varies. A conventional radiator gives off rays, this is how the heating in the room occurs. Waves of infrared radiation are present in human life in a natural way, the sun gives them exactly.

Infrared radiation belongs to the category of electromagnetic, that is, it cannot be seen with the eyes. The wavelength is in the range from 1 millimeter to 0.7 micrometer. The biggest source of infrared rays is the sun.

IR rays for heating

The presence of heating based on this technology allows you to get rid of the disadvantages of the convection system, which is associated with the circulation of air flow in the premises. Convection raises and carries dust, debris, creates a draft. If you put an electric infrared heater, it will work on the principle of sunlight, the effect will be like from solar heat in cool weather.

An infrared wave is a form of energy, it is a natural mechanism borrowed from nature. These rays are capable of heating not only objects, but also the air space itself. Waves penetrate the air layers and heat objects and living tissues. The localization of the source of the radiation under consideration is not so important, if the device is on the ceiling, the heating rays will reach the floor perfectly. It is important that infrared radiation allows you to keep the air moist, it does not dry it out, as other types of heating devices do. The performance of devices based on infrared radiation is extremely high.

Infrared radiation does not require large energy costs, so there is savings for domestic use of this development. IR beams are suitable for working in large spaces, the main thing is to choose the right beam length and set up the devices correctly.

The harm and benefits of infrared radiation

Long infrared rays falling on the skin cause a reaction of nerve receptors. This provides warmth. Therefore, in many sources, infrared radiation is called thermal. Most of the radiation is absorbed by the moisture contained in the upper layer of the human skin. Therefore, the temperature of the skin rises, and due to this, the whole body is heated.

There is an opinion that infrared radiation is harmful. This is not true.

Studies show that long-wave radiation is safe for the body, moreover, there are benefits from them.

They strengthen the immune system, stimulate regeneration and improve the condition of internal organs. These beams with a length of 9.6 microns are used in medical practice for therapeutic purposes.

Shortwave infrared radiation works differently. It penetrates deep into the tissues and warms the internal organs, bypassing the skin. If you irradiate the skin with such rays, the capillary network expands, the skin turns red, and signs of a burn may appear. Such rays are dangerous for the eyes, they lead to the formation of cataracts, disrupt the water-salt balance, and provoke convulsions.

Heatstroke is caused by shortwave radiation. If you raise the temperature of the brain at least a degree, then there are already signs of a blow or poisoning:

nausea;
frequent pulse;
darkening in the eyes.

If overheating occurs by two or more degrees, then meningitis develops, which is life-threatening.

The intensity of infrared radiation depends on several factors. The distance to the location of heat sources and the indicator of the temperature regime are important. Long-wave infrared radiation is important in life, and it is impossible to do without it. Harm can only be when the wavelength is wrong, and the time it affects a person is long.

How to protect a person from the harm of infrared radiation?

Not all infrared waves are harmful. You should be wary of shortwave infrared energy. Where is it found in everyday life? It is necessary to avoid bodies with a temperature above 100 degrees. This category includes steelmaking equipment, electric arc furnace. In production, employees wear specially designed uniforms, it has a protective screen.

The most useful infrared heating tool was the Russian stove, the heat from it was healing and beneficial. However, now no one uses such devices. Infrared heaters have firmly entered into use, and infrared waves are widely used in industry.

If the heat-releasing coil in the infrared device is protected by a heat insulator, then the radiation will be soft and long-wavelength, and this is safe. If the device has an open heating element, then the infrared radiation will be hard, short-wave, and this is dangerous to health.

In order to understand the design of the device, you need to study the technical data sheet. There will be information about the infrared rays used in a particular case. Pay attention to the wavelength.

Infrared radiation is not always unambiguously harmful, only open sources emit danger, short rays and a long stay under them.

You should protect your eyes from the source of waves, if discomfort occurs, get out of the influence of IR rays. If unusual dryness appears on the skin, it means that the rays dry the lipid layer, and this is very good.

Infrared radiation in useful ranges is used as a treatment, physiotherapy methods are based on working with beams and electrodes. However, all exposure is carried out under the supervision of specialists; it is not worth treating yourself with infrared devices. The time of action should be strictly determined by medical indications, it is necessary to proceed from the goals and objectives of treatment.

It is believed that infrared radiation is unfavorable for systematic exposure to young children, so it is advisable to carefully choose heating devices for the bedroom and children's rooms. You will need the help of specialists to set up a safe and effective infrared grid in an apartment or house.

It is not necessary to refuse modern technologies because of prejudices out of ignorance.

Infrared radiation is a type of electromagnetic radiation that borders on the red part of the visible light spectrum on one side and microwaves on the other. Wavelength - from 0.74 to 1000-2000 micrometers. Infrared waves are also called "thermal". Based on the wavelength, they are classified into three groups:

shortwave (0.74-2.5 micrometers);

medium wave (longer than 2.5, shorter than 50 micrometers);

longwave (more than 50 micrometers).

Sources of infrared radiation

On our planet, infrared radiation is by no means uncommon. Almost any heat is the effect of exposure to infrared rays. It doesn't matter what it is: sunlight, the heat of our bodies, or the heat coming from heating appliances.

The infrared part of the electromagnetic radiation does not heat the space, but directly the object itself. It is on this principle that the work of infrared lamps is built. And the Sun heats the Earth in the same way.

Impact on living organisms

At the moment, science does not know the confirmed facts of the negative impact of infrared rays on the human body. Unless due to too intense radiation, the mucous membrane of the eyes can be damaged.

But we can talk about the benefits for a very long time. Back in 1996, scientists from the US, Japan and Holland confirmed a number of positive medical facts. Thermal Radiation:

destroys some types of hepatitis virus;

inhibits and slows down the growth of cancer cells;

has the ability to neutralize harmful electromagnetic fields and radiation. Including radioactive;

helps diabetics produce insulin;

can help with dystrophy;

improving the condition of the body with psoriasis.

Under the state of health improves, the internal organs begin to work more efficiently. Muscle nutrition is increased, the strength of the immune system is greatly increased. It is a well-known fact that in the absence of infrared radiation, the body ages noticeably faster.

Infrared rays are also called "rays of life". It was under their influence that life was born.

The use of infrared rays in human life

Infrared light is used no less widely than it is common. Perhaps it will be very difficult to find at least one area of the national economy where the infrared part of electromagnetic waves has not found application. We list the most famous areas of application:

warfare. The homing of missile warheads or night vision devices are all the result of the use of infrared radiation;

thermography is widely used in science to determine the overheated or supercooled parts of the object under study. Infrared images are also widely used in astronomy, along with other types of electromagnetic waves;

household heaters. Unlike convectors, such devices use radiant energy to heat all objects in the room. And already further, interior items give off heat to the surrounding air;

data transmission and remote control. Yes, all remotes for TVs, tape recorders and air conditioners use infrared rays;

disinfection in the food industry

the medicine. Treatment and prevention of many different types of diseases.

Infrared rays are a relatively small part of electromagnetic radiation. Being a natural way of heat transfer, not a single life process on our planet can do without it.

Light is the key to the existence of living organisms on Earth. There are a huge number of processes that can occur due to the influence of infrared radiation. In addition, it is used for medicinal purposes. Since the 20th century, light therapy has become a significant component of traditional medicine.

Features of radiation

Phototherapy is a special section in physiotherapy that studies the effects of a light wave on the human body. It was noted that the waves have a different range, so they affect the human body in different ways. It is important to note that radiation has the largest penetration depth. As for the surface effect, ultraviolet has it.

The infrared spectrum (radiation spectrum) has a corresponding wavelength, namely 780 nm. up to 10000 nm. As for physiotherapy, a wavelength is used to treat a person, which ranges in the spectrum from 780 nm. up to 1400 nm. This range of infrared radiation is considered the norm for therapy. In simple terms, the appropriate wavelength is applied, namely a shorter one, capable of penetrating three centimeters into the skin. In addition, the special energy of the quantum, the frequency of radiation, is taken into account.

According to many studies, it has been found that light, radio waves, infrared rays, are of the same nature, since these are varieties of electromagnetic waves that surround people everywhere. These waves power televisions, mobile phones and radios. In simple words, waves allow a person to see the world around them.

The infrared spectrum has a corresponding frequency, the wavelength of which is 7-14 microns, which has a unique effect on the human body. This part of the spectrum corresponds to the radiation of the human body.

As for the objects of the quantum, the molecules do not have the ability to oscillate arbitrarily. Each quantum molecule has a certain set of energy, radiation frequencies, which are stored at the moment of oscillation. However, it is worth considering that air molecules are equipped with a wide range of such frequencies, so the atmosphere is able to absorb radiation in a variety of spectra.

Radiation sources

The sun is the main source of IR.

Thanks to him, objects can be heated to a specific temperature. As a result, thermal energy is emitted in the spectrum of these waves. Then the energy reaches the objects. The process of transferring thermal energy is carried out from objects with a high temperature to a lower one. In this situation, the objects have different radiating properties that depend on several bodies.

Sources of infrared radiation are everywhere, equipped with elements such as LEDs. All modern televisions are equipped with remote controls, as it operates in the appropriate frequency of the infrared spectrum. They include LEDs. Various sources of infrared radiation can be seen in industrial production, for example: in the drying of paint surfaces.

The most prominent representative of an artificial source in Russia was Russian stoves. Almost all people have experienced the influence of such a stove, and also appreciated its benefits. That is why such radiation can be felt from a heated stove or a heating radiator. At present, infrared heaters are very popular. They have a list of advantages compared to the convection option, as they are more economical.

Coefficient value

In the infrared spectrum, there are several varieties of the coefficient, namely:

radiation;
reflection coefficient;
throughput ratio.

So, the emissivity is the ability of objects to radiate the frequency of radiation, as well as the energy of the quantum. May vary according to the material and its properties, as well as temperature. The coefficient has such a maximum cure = 1, but in a real situation it is always less. As for the low ability of radiation, then it is endowed with elements that have a shiny surface, as well as metals. The coefficient depends on temperature indicators.

The reflectance factor gives an indication of the ability of the materials to reflect the frequency of examinations. Depends on the type of materials, properties and temperature indicators. Basically, reflection is present on polished and smooth surfaces.

Transmittance measures the ability of objects to conduct infrared radiation through itself. Such a coefficient directly depends on the thickness and type of material. It is important to note that most of the materials do not have such a factor.

Use in medicine

Light treatment with infrared radiation has become quite popular in the modern world. The use of infrared radiation in medicine is due to the fact that the technique has healing properties. Due to this, there is a beneficial effect on the human body. Thermal influence forms a body in tissues, regenerates tissues and stimulates reparation, accelerates physicochemical reactions.

In addition, the body experiences significant improvements, as the following processes occur:

acceleration of blood flow;
vasodilation;
production of biologically active substances;
muscle relaxation;
great mood;
comfortable state;
good dream;
pressure reduction;
removal of physical, psycho-emotional overstrain and so on.

The visible effect of the treatment occurs within a few procedures. In addition to the noted functions, the infrared spectrum has an anti-inflammatory effect on the human body, helps fight infection, stimulates and strengthens the immune system.

Such therapy in medicine has the following properties:

biostimulating;
anti-inflammatory;
detoxification;
improved blood flow;
awakening of the secondary functions of the body.

Infrared light radiation, or rather its treatment, has a visible benefit for the human body.

Therapeutic techniques

Therapy is of two types, namely - general, local. With regard to local exposure, the treatment is carried out on a specific part of the patient's body. During general therapy, the use of light therapy is designed for the entire body.

The procedure is carried out twice a day, the duration of the session varies between 15-30 minutes. The general treatment course contains at least five to twenty procedures. Make sure you have infrared protection for the face area ready. Special glasses, cotton wool or cardboard pads are intended for the eyes. After the session, the skin is covered with erythema, namely, redness with blurred boundaries. The erythema disappears an hour after the procedure.

Indications and contraindications for treatment

IC has the main indications for use in medicine:

diseases of ENT organs;
neuralgia and neuritis;
diseases affecting the musculoskeletal system;
pathology of the eyes and joints;
inflammatory processes;
wounds;
burns, ulcers, dermatoses and scars;
bronchial asthma;
cystitis;
urolithiasis;
osteochondrosis;
cholecystitis without stones;
arthritis;
gastroduodenitis in a chronic form;
pneumonia.

Light treatment has positive results. In addition to the therapeutic effect, IR can be dangerous for the human body. This is due to the fact that there are certain contraindications, not observing which can be harmful to health.

If there are the following ailments, then such treatment will be harmful:

period of pregnancy;
blood diseases;
individual intolerance;
chronic diseases in the acute stage;
purulent processes;
active tuberculosis;
predisposition to bleeding;
neoplasms.

These contraindications should be taken into account so as not to harm your own health. Too much radiation intensity can cause great harm.

As for the harm of IR in medicine and at work, a burn and severe reddening of the skin can occur. In some cases, people have developed tumors on the face, as they have been in contact with this radiation for a long time. Significant damage from infrared radiation can result in dermatitis, and there is also heat stroke.

Infrared rays are quite dangerous for the eyes, especially in the range up to 1.5 microns. Prolonged exposure has significant harm, as photophobia, cataracts, vision problems appear. Long-term influence of IR is very dangerous not only for people, but for plants. Using optical devices, you can try to correct the problem with vision.

Impact on plants

Everyone knows that IR have a beneficial effect on the growth and development of plants. For example, if you equip a greenhouse with an infrared heater, you can see a stunning result. Heating is carried out in the infrared spectrum, where a certain frequency is observed, and the wave is equal to 50,000 nm. up to 2,000,000 nm.

There are quite interesting facts according to which you can find out that all plants, living organisms, are influenced by sunlight. The radiation of the sun has a specific range, consisting of 290 nm. – 3000 nm. In simple words, radiant energy plays an important role in the life of every plant.

Given interesting and informative facts, it can be determined that plants need light and solar energy, since they are responsible for the formation of chlorophyll and chloroplasts. The speed of light affects stretching, the origin of cells and growth processes, the timing of fruiting and flowering.

The specifics of the microwave oven

Household microwave ovens are equipped with microwaves that are slightly lower than gamma and x-rays. Such furnaces are capable of provoking an ionizing effect that poses a danger to human health. Microwaves are located in the gap between infrared and radio waves, so such furnaces cannot ionize molecules, atoms. Functional microwave ovens do not affect people, as they are absorbed into food, generating heat.

Microwave ovens cannot emit radioactive particles, therefore they do not have a radioactive effect on food and living organisms. That is why you should not worry that microwave ovens can harm your health!

In various spheres of life, a person uses infrared rays. The benefits and harms of radiation depend on the wavelength and time of exposure.

In everyday life, a person is constantly exposed to infrared radiation (IR radiation). Its natural source is the sun. Artificial include electric heating elements and incandescent lamps, any heated or red-hot bodies. This type of radiation is used in heaters, heating systems, night vision devices, remote controls. The principle of operation of medical equipment for physiotherapy is based on infrared radiation. What are infrared rays? What are the benefits and harms of this type of radiation?

What is IR radiation

IR radiation is electromagnetic radiation, a form of energy that heats objects and is adjacent to the red spectrum of visible light. The human eye does not see in this spectrum, but we feel this energy as heat. In other words, people perceive infrared radiation from heated objects with their skin as a sensation of warmth.

Infrared rays are short-wave, medium-wave and long-wave. The wavelengths emitted by a heated object depend on the heating temperature. The higher it is, the shorter the wavelength and the more intense the radiation.

For the first time, the biological effect of this type of radiation was studied on the example of cell cultures, plants, and animals. It was found that under the influence of IR rays, the development of microflora is suppressed, metabolic processes are improved due to the activation of blood flow. It has been proven that this radiation improves blood circulation and has an analgesic and anti-inflammatory effect. It is noted that under the influence of infrared radiation, patients after surgery are easier to tolerate postoperative pain, and their wounds heal faster. It has been established that infrared radiation enhances nonspecific immunity, which reduces the effect of pesticides and gamma radiation, and also accelerates the process of recovery from influenza. IR rays stimulate the excretion of cholesterol, toxins, toxins and other harmful substances from the body through sweat and urine.

Benefits of infrared rays

Due to these properties, infrared radiation is widely used in medicine. But the use of infrared radiation with a wide spectrum of action can lead to overheating of the body and reddening of the skin. At the same time, long-wave radiation does not have a negative effect, therefore, long-wave devices or emitters with a selective wavelength are more common in everyday life and medicine.

Exposure to long-wave infrared rays contributes to the following processes in the body:

Normalization of blood pressure by stimulating blood circulation
Improvement of cerebral circulation and memory
Cleansing the body of toxins, salts of heavy metals
Normalization of hormonal levels
Stopping the spread of harmful germs and fungi
Restoration of water-salt balance
Pain relief and anti-inflammatory effect
Strengthening the immune system.

The therapeutic effect of infrared rays can be used for the following diseases and conditions:

bronchial asthma and exacerbation of chronic bronchitis
focal pneumonia in resolution stage
chronic gastroduodenitis
hypermotor dyskinesia of the digestive system
chronic acalculous cholecystitis
osteochondrosis of the spine with neurological manifestations
rheumatoid arthritis in remission
exacerbation of deforming osteoarthritis of the hip and knee joints
obliterating atherosclerosis of the vessels of the legs, neuropathy of the peripheral nerves of the legs
exacerbation of chronic cystitis
urolithiasis disease
exacerbation of chronic prostatitis with impaired potency
infectious, alcoholic, diabetic polyneuropathy of the legs
chronic adnexitis and ovarian dysfunction
withdrawal syndrome

Heating with infrared radiation helps to strengthen the immune system, inhibits the growth of bacteria in the environment and in the human body, improves skin condition by increasing blood circulation in it. Air ionization is the prevention of exacerbations of allergies.

When infrared radiation can harm

First of all, you need to take into account the existing contraindications before using infrared rays for medicinal purposes. Harm from their use can be in the following cases:

Acute purulent diseases
Bleeding
Acute inflammatory diseases leading to decompensation of organs and systems
Systemic blood diseases
Malignant neoplasms

In addition, excessive exposure to broad-spectrum infrared rays causes severe reddening of the skin and may cause burns. There are known cases of the appearance of a tumor on the face of metallurgical workers as a result of prolonged exposure to this type of radiation. There have also been cases of dermatitis and heatstroke.

Infra-red rays, especially in the range of 0.76 - 1.5 microns (shortwave region) are dangerous to the eyes. Prolonged and prolonged exposure to radiation is fraught with the development of cataracts, photophobia and other visual impairments. For this reason, it is undesirable to be exposed to short-wave heaters for a long time. The closer a person is to such a heater, the less time he spends near this device should be. It should be noted that this type of heater is designed for street or local heating. Long-wave IR heaters are used for heating residential and industrial premises intended for long-term stay of people.

Infrared radiation. Discovery of infrared radiation

Definition 1

Under infrared radiation(IR) refers to a form of energy or a method of heating in which heat from one body is transferred to another body.

A person in the course of his life is constantly under the influence of infrared radiation and is able to feel this energy as heat coming from an object. Received infrared radiation human skin, the eyes do not see in this spectrum.

natural source high temperature is our luminary. The heating temperature is associated with the wavelength of infrared rays, which are short-wave, medium-wave, long-wave.

Short Wavelength has a high temperature and intense radiation. As early as $1,800 an English astronomer W. Herschel made observations of the sun. Being engaged in the study of the luminary, he was looking for a way that would reduce the heating of the instrument with which these studies were carried out. At one of the stages of his work, the scientist discovered that after a saturated in red located " maximum heat". The study was the beginning of the study infrared radiation.

If earlier sources infrared radiation in the laboratory served as hot bodies or electrical discharges in gases, today created modern sources infrared radiation with a frequency that can be adjusted or fixed. They are based on solid-state and molecular gas lasers.

AT near infrared(about $ 1.3 $ microns) for registration of radiation use special photographic plates.

AT far infrared radiation is registered bolometers are detectors that are sensitive to infrared heat.

infrared waves have different length, so their penetrating power will also be different.

longwave rays coming from the sun, for example, calmly pass through the earth's atmosphere while not heating it up. Penetrating through solids, they increase their temperature, so for all life on the planet it is of great importance far radiation.

Interestingly, in constant compensatory make-up need all living bodies, which also radiate the same spectrum of heat. In the absence of such replenishment, the temperature of the living body drops, which makes it vulnerable to various infections. This additional make-up in the form of infrared radiation, according to scientists, rather helpful than harmful.

Remark 1

Experts have conducted numerous animal experiments that have shown that infrared rays suppress the growth of cancer cells, destroy a number of viruses, neutralize the destructive effect of electromagnetic waves. long-wave infrared rays increase the amount of insulin produced by the body, and neutralize the effects of radioactive exposure.

Application of infrared radiation

Infrared radiation is widely used both in everyday life and in various fields of human activity.

Its main areas of application are:

thermography. IR radiation allows you to determine the temperature of objects that are at some distance. Thermal imaging is widely used in industrial and military applications, and its cameras can detect IR and produce an image of that radiation. Thanks to thermographic cameras, without any illumination, you can "see" everything that is nearby, because all heated objects emit IR.

Tracking. IR tracking is used when pointing missiles into which a device called " thermal finders". As a result of the fact that the engines of machines and mechanisms, and the person himself radiate heat, they will be clearly visible in the infrared range, and from here rockets can easily find the direction of flight.

Heating. How does an infrared heat source raise the temperature and have a beneficial effect on human health, for example, infrared saunas about which there is a lot of talk today. They are used in the treatment of hypertension, heart failure, rheumatoid arthritis.

Meteorology. The height of the clouds, the temperature of the surface of the water and the earth is determined from satellites that make infrared images. In such images, cold clouds are colored white, while warm clouds are colored gray. The hot surface of the earth is painted black or gray.

Astronomy. When observing celestial objects, astronomers use special infrared telescopes. Thanks to these telescopes, scientists determine protostars before they emit visible light, distinguish between cool objects, and observe the nuclei of galaxies.

Art. And here infrared radiation has found application. Art historians, thanks to infrared reflectograms, see the lower layers of the paintings, the sketches of the artist. This device helps to distinguish the original from the copy, errors of restoration work. With it, old written documents are studied.

The medicine. The healing properties of IR therapy are widely known. Heated clay, sand, salt have long been considered healing and beneficial to the human body. IR help treat fractures, improve metabolism in the body, fight obesity, promote wound healing, improve blood circulation, and have a beneficial effect on joints and muscles.

In addition, the therapeutic effect is used for diseases:

Chronic bronchitis and bronchial asthma;
pneumonia;
Chronic cholecystitis and its exacerbation;
Prostatitis with impaired potency;
rheumatoid arthritis;
For diseases of the urinary tract, etc.

In order to use infrared rays for medicinal purposes, contraindications must be taken into account.

They can bring great harm:

When a person has purulent diseases;
Hidden bleeding;
blood diseases;
Neoplasms and, above all, malignant;
Inflammatory diseases, most often acute.

Shortwave IR negatively affect the human brain tissue, as a result of which there is " sunstroke". The damage in this case is obvious. A person experiences a headache, pulse and breathing become quickened, it gets dark in the eyes, loss of consciousness is possible. With further irradiation, the body does not withstand - swelling of the tissues and membranes of the brain occurs, symptoms of encephalitis and meningitis appear. short waves particularly severe harm is done to human eyes, the cardiovascular system.

Remark 2

Thus, it turns out that the benefits of IR exposure to the body, despite the negative aspects, are significant.

Infrared protection

To reduce the harm caused by IR and protect against it, standards of IR radiation that are safe for humans have been developed.

Basic protection measures:

Outdated technologies must be replaced with modern ones, which will reduce the radiation intensity of the source;
The use of screens made of metal meshes and chains, asbestos lining of open furnace openings;
Mandatory personal protection and, above all, eye glasses with light filters;
Body protection with linen or semi-linen overalls;
Rational mode of work and rest;
Compulsory medical and preventive measures for employees.

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