In the process of activity, a person is under the influence of certain meteorological conditions or microclimate. The main indicators of the microclimate are temperature, relative humidity, air velocity. The intensity of thermal radiation from various heated surfaces has a significant effect on the parameters of the microclimate and the state of the human body.

Relative humidity is the ratio of the actual amount of water vapor in the air at a given temperature to the amount of water vapor that saturates the air at that temperature.

If there are various sources of heat in the room, the temperature of which exceeds the temperature of the human body, then the heat from them spontaneously passes to the less heated body, i.e. person. There are three ways of heat propagation: heat conduction, convection, thermal radiation.

Thermal conductivity - heat transfer due to the random thermal movement of microparticles (atoms, molecules, electrons).

Convection is the transfer of heat due to the movement and mixing of macroscopic volumes of a gas or liquid.

Thermal radiation is the process of propagation of electromagnetic oscillations with different wavelengths, caused by the thermal motion of atoms or molecules of the radiating body. In real conditions, heat is transferred in a combined way. A person is constantly in a state of thermal interaction with the environment. For normal flow physiological processes in the human body, it is required to maintain an almost constant body temperature. The body's ability to maintain a constant temperature is called thermoregulation (removal of the generated heat into the surrounding space).

The effect of ambient temperature on the human body is primarily with the narrowing and expansion of the blood vessels of the skin. Under the influence of low temperatures, the vessels narrow, as a result of which the blood flow to the body surface slows down and the heat transfer from the body surface decreases due to convection and radiation. The opposite picture is observed at high temperatures.

High humidity complicates heat exchange between the human body and the external environment due to a decrease in moisture evaporation from the skin surface, and low humidity leads to drying out of the mucous membranes of the respiratory tract. The movement of air improves heat transfer between the body and the external environment.

A constant deviation from the normal parameters of the microclimate leads to overheating or hypothermia of the human body and the negative consequences associated with them: profuse sweating, increased heart rate and respiration, dizziness, convulsions, heatstroke.

In the regulatory documents, the concepts of optimal and permissible microclimate parameters are introduced.

Radiation: first aid

Radiation is an integral part of the environment. It enters the environment from natural sources created by man (nuclear power plants, nuclear weapons tests). Natural sources of radiation include: cosmic radiation, radioactive rocks, radioactive chemicals, and elements found in food and water. Scientists call all types of natural radiation the term "background radiation".

Other forms of radiation enter nature as a result of human activities. People receive different doses of radiation during medical and dental x-rays.

Radioactivity and accompanying radiation existed in the Universe all the time. Radioactive materials are part of the Earth, and even a person is slightly radioactive, because any living tissue contains trace amounts of radioactive substances. The most unpleasant property of radioactive radiation is its effect on the tissues of a living organism; therefore, measuring instruments are needed that would give operational information.

The peculiarity of ionizing radiation is that a person will begin to feel its effect only after some time has passed. Different types of radiation are accompanied by the release of different amounts of energy and have different penetrating ability, so they have a different effect on the tissues of a living organism.

Alpha radiation is trapped, for example, by a sheet of paper and practically unable to penetrate the outer layer of the skin. Therefore, it does not pose a danger until the radioactive substances emitting alpha particles enter the body through an open wound, with food, water or air, then they become extremely dangerous.

The beta particle has a greater penetrating ability: it penetrates into the tissues of the body to a depth of 1-2 cm or more, depending on the amount of energy. The penetrating power of gamma radiation is very high, it spreads at the speed of light: it can only be stopped by a thick lead or concrete slab.

You can take protective measures, but it is almost impossible to completely get rid of the effects of radiation. The level of radiation on Earth is different.

If the sources of ionizing radiation are inhaled, drinking water or food, then such radiation is called internal.

Of all natural sources of radiation, the greatest danger is radon - a heavy gas without taste, smell and, at the same time, invisible: with its daughter products. Radon is released from the earth's crust everywhere, but a person receives the main radiation from radon when he is in a closed, unventilated room. Radon concentrates indoors only when they are sufficiently isolated from the external environment. Sealing the premises for the purpose of insulation only aggravates the matter, since it makes it even more difficult for the radioactive gas to leave the room.

The most common building materials - wood, brick and concrete - emit relatively little radon. Granite, pumice, and alumina products are much more radioactive. Another source of radon intake in living quarters is water and natural gas. Water from deep wells or artesian wells contains a lot of radon. When boiling or cooking hot dishes, radon is almost completely volatilized. A great danger is the ingress of water vapor with a high content of radon into the lungs along with the inhaled air in the bathroom or steam room.

Other sources of radiation, unfortunately, are created by man himself. Artificial radionucleids, beams of neurons and charged particles created with the help of nuclear reactors and accelerators are sources of artificial radiation. They are called technogenic sources of ionizing radiation.

Emergencies such as the Chernobyl accident can have an uncontrolled impact on humans

High doses of radiation pose a deadly threat to humans. The resulting dose of 500 rem or more will kill almost anyone within a few weeks. A dose of 100 rem can lead to severe radiation sickness. Radiation contributes to an increase in cancers and causes various defects in the fetus.

Scientists say that a person receives an average annual dose of 150-200 millirems of radiation. Most of the radiation (about 80 millirems) comes from natural sources of radiation or from medical examinations (about 90 millirems). The radiation received as a result of scientific research is 1 millirem, from the operation of nuclear installations - 4-5, from the use of household appliances - 4-5 millirem. The dose of radiation in the air is measured in X-rays, and the dose absorbed by living tissues is measured in rad. To assess the intensity of contamination of the area, the concept of "radiation dose rate" has been introduced. EE is measured in roentgens (R), milliroentgens (mR), microrengenes (μR) per hour. From the moment of contamination of the territory, with each sevenfold increase in time, the level of radiation decreases 10 times. If after an hour the level of radiation on the ground was 100 R / h, then after 7 hours it will be equal to 10 R / h, and after 49 hours - 1 R / h.

Human labor activity always takes place in certain meteorological conditions, which are determined by a combination of air temperature, air speed and relative humidity, barometric pressure and thermal radiation from heated surfaces. If labor takes place indoors, then these indicators in aggregate (with the exception of barometric pressure) are usually called the microclimate of the industrial premises.

According to the definition given in GOST, the microclimate of industrial premises is the climate of the internal environment of these premises, which is determined by the combinations of temperature, humidity and air velocity acting on the human body, as well as the temperature of the surrounding surfaces.

If the work is carried out in open areas, then the meteorological conditions are determined by the climatic zone and the season of the year. However, in this case, a certain microclimate is created in the working area.

All life processes in the human body are accompanied by the formation of heat, the amount of which varies from 4 ... 6 kJ / min (at rest) to 33 ... 42 kJ / min (with very hard work).

Microclimate parameters can vary over a very wide range, while a necessary condition for human life is to maintain a constant body temperature.

With favorable combinations of microclimate parameters, a person experiences a state of thermal comfort, which is an important condition for high labor productivity and prevention of diseases.

When the meteorological parameters deviate from the optimal ones in the human body to maintain a constant body temperature, various processes begin to occur, aimed at regulating heat production and heat transfer. This ability of the human body to maintain a constant body temperature, despite significant changes in the meteorological conditions of the external environment and its own heat production, is called thermoregulation.

At air temperatures ranging from 15 to 25 ° C, the body's heat production is at an approximately constant level (zone of indifference). As the air temperature decreases, heat production increases primarily for

account of muscle activity (a manifestation of which is, for example, tremors) and increased metabolism. As the air temperature rises, heat transfer processes intensify. The return of heat by the human body to the external environment occurs in three main ways (paths): convection, radiation and evaporation. The prevalence of one or another heat transfer process depends on the ambient temperature and a number of other conditions. At a temperature of about 20 ° C, when a person does not experience any unpleasant sensations associated with the microclimate, heat transfer by convection is 25 ... 30%, radiation - 45%, evaporation - 20 ... 25%. With changes in temperature, humidity, air speed, nature of the work performed, these ratios change significantly. At an air temperature of 30 ° C, the release of heat by evaporation becomes equal to the total release of heat by radiation and convection. At an air temperature of more than 36 ° C, heat transfer occurs completely due to evaporation.

When 1 g of water evaporates, the body loses about 2.5 kJ of heat. Evaporation occurs mainly from the skin surface and to a much lesser extent through the respiratory tract (10 ... 20%).

Under normal conditions, with sweat, the body loses about 0.6 liters of fluid per day. With hard physical work at an air temperature of more than 30 ° C, the amount of fluid lost by the body can reach 10 ... 12 liters. With intense sweating, if the sweat does not have time to evaporate, it is excreted in the form of drops. In this case, moisture on the skin not only does not contribute to the release of heat, but, on the contrary, prevents this. Such sweating leads only to the loss of water and salts, but does not fulfill the main function of increasing the release of heat.

A significant deviation of the microclimate of the working area from the optimal one can cause a number of physiological disorders in the body of workers, lead to a sharp decrease in efficiency, even to occupational diseases.

Overheating. At an air temperature of more than 30 ° C and significant thermal radiation from heated surfaces, a violation of the body's thermoregulation occurs, which can lead to overheating of the body, especially if the loss of sweat per shift approaches 5 liters. There is growing weakness headache, tinnitus, distortion of color perception (coloring everything in red or green), nausea, vomiting, body temperature rises. Breathing and pulse become more frequent, blood pressure first rises, then falls. In severe cases, heat occurs, and when working outdoors, sunstroke. A seizure disorder is possible, which is a consequence of a violation of the water-salt balance and is characterized by weakness, headache, sharp cramps, mainly in the limbs. At present, such severe forms of overheating are practically not encountered in industrial conditions. With prolonged exposure to heat radiation, professional cataracts can develop.

But even if such painful conditions do not arise, overheating of the body greatly affects the condition nervous system and human performance. Studies, for example, have established that by the end of a 5-hour stay in an area with an air temperature of about 31 ° C and a humidity of 80 ... 90%; working capacity is reduced by 62%. The muscular strength of the arms is significantly reduced (by 30 ... 50%), the endurance to static effort decreases, the ability to fine coordination of movements deteriorates approximately 2 times. Labor productivity decreases in proportion to the deterioration of meteorological conditions.

Cooling.

Long-term and strong exposure to low temperatures can cause various adverse changes in the human body. Local and general cooling of the body is the cause of many diseases: myositis, neuritis, radiculitis, etc., as well as colds. Any degree of cooling is characterized by a decrease in the heart rate and the development of inhibition processes in the cerebral cortex, which leads to a decrease in performance. In severe cases, exposure to low temperatures can lead to frostbite and even death.

Air humidity is determined by the content of water vapor in it. Distinguish between absolute, maximum and relative humidity. Absolute humidity (A) is the mass of water vapor contained at a given moment in a certain volume of air, maximum (M) is the maximum possible content of water vapor in the air at a given temperature (saturation state). Relative humidity (V) is determined by the ratio of the absolute humidity Ak to the maximum MI, expressed as a percentage:

Physiologically optimal is relative humidity in the range of 40 ... 60%. Increased air humidity (more than 75 ... 85%) in combination with low temperatures has a significant cooling effect, and in combination with high temperatures contributes to overheating of the body. A relative humidity of less than 25% is also unfavorable for humans, as it leads to drying out of the mucous membranes and a decrease in the protective activity of the ciliated epithelium of the upper respiratory tract.

Air mobility. A person begins to feel the movement of air at its speed of about 0.1 m / s. Light movement of air at normal temperatures contributes to good health, blowing off the overheated layer of air that envelops a person. At the same time, the high speed of air movement, especially at low temperatures, causes an increase in heat loss by convection and evaporation and leads to a strong cooling of the body. Strong air movement is particularly detrimental when working outdoors in winter conditions.

A person feels the influence of microclimate parameters in a complex manner. The introduction of the so-called effective and effectively equivalent temperatures is based on this. Effectivetemperature characterizes the sensation of a person while being exposed to temperature and air movement.

Effectively equivalentthe temperature also takes into account the humidity of the air. A nomogram for finding the effective-equivalent temperature and comfort zone was constructed empirically (fig. 7).

Thermal radiation is characteristic of any body whose temperature is above absolute zero.

The thermal effect of irradiation on the human body depends on the wavelength and intensity of the radiation flux, the size of the irradiated area of \u200b\u200bthe body, the duration of the irradiation, the angle of incidence of the rays, and the type of person's clothing. The greatest penetrating power is possessed by red rays of the visible spectrum and short infrared rays with a wavelength of 0.78 ... 1.4 microns, which are poorly retained by the skin and penetrate deeply into biological tissues, causing an increase in their temperature, for example, prolonged exposure to such rays of the eyes - leads clouding of the lens (professional cataract). Infrared radiation also causes various biochemical and functional changes in the human body.

In industrial conditions, thermal radiation occurs in the wavelength range from 100 nm to 500 μm. In hot shops, this is mainly infrared radiation with a wavelength of up to 10 microns. The intensity of irradiation of workers in hot shops varies widely: from a few tenths to 5.0 ... 7.0 kW / m 2. At an irradiation intensity of more than 5.0 kW / m 2

Figure: 7. Nomogram for determining the effective temperature and comfort zone

within 2 ... 5 minutes a person feels a very strong thermal effect. The intensity of thermal irradiation at a distance of 1 m from the heat source on the hearth sites of blast furnaces and open-hearth furnaces reaches 11.6 kW / m 2 with open valves.

The level of heat radiation intensity permissible for a person at workplaces is 0.35 kW / m 2 (GOST 12.4.123 - 83 "Occupational safety standards. Means of protection against infrared radiation. Classification. General technical requirements").

Meteorological conditions (microclimate) are characterized by parameters:

2.1. Air temperature, 0 С;

2.2. Relative humidity;

2.3. Air speed, m / s;

2.4 Intensity of thermal radiation (exposure of workers), W / m 2

2.5. The temperature of the surfaces of the enclosing structures (room walls, floor,

ceiling, windows).

Air temperature -this is a parameter characterizing its thermal state and is determined by the kinetic energy of motion of gas molecules.

The microclimate has a significant impact on the general condition and performance of a person, since he is constantly in a state of heat exchange with the environment. The normal course of physiological processes in the human body is possible only when the heat released from the surface of the human body is discharged into the surrounding air, provided its quantitative temperature indicator is within the range below the normal body temperature of a healthy person (+ 36 ... 37 0 С, the average medical indicator is 36.6 0 С).

Optimal climatic conditions are characterized by the body's heat balance equation, in which heat transfer from the human body is equal to heat generation, due to which the body temperature remains within normal limits. The heat balance equation can be represented by the expression:

Q to \u003d Q from + Q is + Qv, (1)

Where Q to- Total heat transfer from the body to the environment (J, W);

Q -Heat transfer by radiation (J, W);

Q - Heat transfer as a result of sweat evaporation (J, W);

Q- Heat transfer during air exhalation (J, W).

The conditions for the impact of microclimatic factors on the human body are determined by thermal stability and thermoregulation. Thermal stability is determined directly by the thermoregulation of the organism.

Thermal stability- a parameter of a person's thermal well-being, which determines the body's ability to recover by maintaining its thermal balance.

Thermoregulation- this is the body's ability to maintain body temperature within certain constant limits (close to 36.6 0 С) when external conditions and the severity of the work performed change. Thermoregulation is carried out by establishing optimal equilibrium thermal ratios by reducing the level of metabolism with the threat of overheating or cooling the body ( chemical thermoregulation), as well as heat transfer to the environment ( physical thermoregulation). Disturbance of heat transfer aggravates the impact on a person of material (harmful substances) and energy production factors (infrasound, noise, ultrasound.

Heat emission control processes can be carried out according to four principal mechanisms:

1. thermoregulation by changing the intensity of blood circulation- consists in the body's regulation of blood supply from internal organs to the surface of the body due to the expansion or narrowing of the subcutaneous blood vessels:

2. biochemical thermoregulation- consists in changing the intensity of oxidative biochemical reactions occurring in the human body:

3. thermoregulation by changing the intensity of sweating - consists in changing the amount of evaporated moisture (sweat), leading to evaporative cooling of the human body:

4. total thermoregulation carried out by all of these mechanisms.

The work environment can be further characterized by radiation, the electrical state of the air surrounding the workplace.

In hot shops or when working in the cold, the so-called thermal load of the environment is additionally taken into account, which is characterized either by increased thermal radiation or by exposure to low or negative temperatures.

For high-altitude flights, in addition to the parameters, barometric pressure, radiation and air ionization are taken into account.

The deviation of the values \u200b\u200bof the listed factors from the standard values \u200b\u200bcan affect both the characteristics of the technological process and the quality of products and work performed (high air humidity when gluing parts worsens the quality of joints, etc.). In addition, elevated temperatures are dangerous for electrical cables and wires due to changes in the properties of their insulation, and in combination with high humidity in the production environment, it can cause a short circuit in electrical circuits and be considered a hazardous production factor.

Factors affecting the microclimate can be divided into 2 groups: unregulated (a complex of climate-forming factors in a given area) and regulated (features and quality of construction of buildings and structures, the frequency of air exchange, the number of people in the premises, and others).

The factors of the second group are of decisive importance to maintain the parameters of the air environment in the working zones.

2.1.1 Influence of changes in the temperature of the external environment on the thermal well-being of a person

Thermal well-being of a person, or heat balance, in the “human-environment” system depends on the temperature of the environment, air mobility and relative humidity, atmospheric pressure, temperature of surrounding objects and the intensity of physical activity of the body.

An increase in the air temperature in the production room contributes to an increase in heat transfer due to evaporation, as well as due to the intensity of blood circulation, since at elevated temperatures a person's blood vessels expand, then heat loss due to heat conduction, convection and heating of exhaled air decreases.

A decrease in temperature and an increase in air speed contribute to an increase in convective heat transfer and the process of heat transfer during sweat evaporation, which can lead to hypothermia of the body. When the air temperature rises, the opposite occurs.

Studies have established that at an air temperature of more than 30C, a person's performance begins to decline. Maximum temperatures have been determined for humans, depending on the duration of their exposure and the protective equipment used. The maximum temperature of inhaled air at which a person is able to breathe for several minutes without special protective equipment is about 116C

Human tolerance to temperature, as well as his heat perception, largely depends on the humidity and speed of the surrounding air. The higher the relative humidity, the less sweat evaporates per unit of time and the faster the body overheats. A particularly unfavorable effect on the thermal well-being of a person is exerted by high humidity at tOC \u003d 30C, since in this case almost all of the heat released is released into the environment when sweat evaporates. When the humidity rises, sweat does not evaporate, but drips down from the surface of the skin. There is a so-called "torrential" sweat flow, exhausting the body and not providing the necessary heat transfer.

Insufficient air humidity can also be unfavorable for humans due to intensive evaporation of moisture from the mucous membranes, their drying out and cracking, and then contamination with pathogens. Therefore, when people stay in closed rooms for a long time, it is recommended to limit the relative humidity within 3070 percent.

Together with sweat, the body loses a significant amount of mineral salts (up to 1%, including 0.40.6% NaCl). Under unfavorable conditions, the loss of fluid can reach 810 liters per shift and it contains up to 60 g of sodium chloride (in total, about 140 g of NaCl in the body). The loss of salt deprives the blood of the ability to retain water and leads to disruption of the cardiovascular system. At high air temperatures, carbohydrates and fats are easily consumed, proteins are destroyed. It is considered acceptable for a person to reduce his weight by 23% by evaporation of moisture - dehydration of the body. Dehydration by 6% entails mental impairment, decreased visual acuity; evaporation of moisture by 1520% is fatal.

To restore the water balance, people working in hot shops are equipped with vending machines with salted (about 0.5% NaCl) carbonated drinking water at the rate of 45 liters per person per shift. In many factories, a protein-vitamin drink is used for these purposes. In hot climatic conditions it is recommended to drink chilled drinking water or green tea.

Prolonged exposure to high temperatures, especially in combination with high humidity, can lead to overheating of the body above the permissible level - hyperthermia. A condition in which the body temperature rises to 3839C. Hyperthermia (heatstroke) is accompanied by headache, dizziness, general weakness, distortion of color perception, dry mouth, nausea, vomiting, and profuse sweating. Pulse and respiration are quickened, the content of nitrogen and lactic acid in the blood increases. In this case, there is pallor, cyanosis, the pupils are dilated, at times there are convulsions, loss of consciousness.

Production processes carried out at a low temperature, high mobility and air humidity can cause hypothermia of the body - hypothermia. With prolonged exposure to cold, breathing becomes irregular, carbohydrate metabolism changes. The increase in metabolic processes with a decrease in temperature by 1C is about 10%, and with intense cooling it can increase 3 times compared with the level of basic metabolism. The appearance of muscle tremors, in which external work is not performed, and all the energy is converted into heat, can delay the decrease in the temperature of the internal organs for some time. Cold injuries result from low temperatures.

2.1.2 Atmosphere pressure

Atmospheric pressure has a significant impact on the breathing process and human well-being. The main respiratory organ of a person, through which gas exchange with the environment is carried out, is the tracheobronchial tree and a large number of pulmonary vesicles (alveoli), the walls of which are permeated with a dense network of capillary vessels. The total surface of an adult's alveoli is 90150m3. Through the walls of the alveoli, oxygen enters the bloodstream to nourish the tissues of the body.

The intensity of oxygen diffusion into the blood is determined by the partial pressure (p) of oxygen in the alveolar air.

The most successful diffusion of oxygen into the blood occurs at a partial pressure of oxygen (?) Within 95120 mm Hg. A change in partial pressure outside these limits leads to difficulty breathing and an increased load on the cardiovascular system. At an altitude of 23 km (p \u003d 70 mm Hg), blood oxygen saturation decreases to such an extent that it increases the activity of the heart and lungs. Long-term stay of a person in this zone does not affect his health, and it is called a zone of sufficient compensation. From a height of 4 km (p \u003d 60 mm Hg), oxygen diffusion from the lungs into the blood decreases to such an extent that, despite the high oxygen content (21%), oxygen starvation - hypoxia can occur. The main signs of hypoxia are headache, dizziness, delayed reaction, disruption of the normal functioning of the organs of hearing and vision, metabolic disorders.

The satisfactory state of health of a person when breathing air is maintained up to an altitude of about 4 km, with pure oxygen (100%) up to an altitude of 12 km. During long flights on aircraft at an altitude of more than 4 km, either oxygen masks, or space suits, or cabins are used. If the sealing is broken, the pressure in the cab drops sharply. Often this process proceeds quickly, which has the character of a kind of explosion and is called explosive decompression. The effect of explosive decompression on the body depends on the initial value and the rate of pressure decrease.

In general, the slower the rate of depressurization, the easier it is tolerated. Decrease in pressure by 385 mm. rt. Art. for 0.4 s a person suffers without any consequences. However, the new pressure that occurs as a result of decompression can lead to high-altitude flatulence and high-altitude emphysema. High-altitude flatulence is an expansion of gases present in free body cavities (at an altitude of 12 km, the volume of the stomach and intestinal tract increases 5 times). Altitude emphysema, or altitude pain, is the transition of a gas from a dissolved state to a gaseous state.

During the period of compression (pressure increase) and stay at elevated pressure, the body is saturated with nitrogen through the blood. Full saturation of the body with nitrogen occurs after 4 hours of stay in conditions of high pressure.

When working in conditions of excessive pressure, ventilation rates are reduced due to a slight decrease in the respiratory rate and pulse. Prolonged exposure to excess pressure (about 700 kPa) leads to the toxic effect of some gases that make up the inhaled air. It manifests itself in impaired coordination of movements, excitement or depression, hallucinations, impaired memory, visual and hearing impairment.

During decompression, due to a drop in the partial pressure in the alveolar air, desaturation (release) of nitrogen from the tissues occurs, which is carried out through the blood and then the lungs. If decompression is carried out forcibly, nitrogen bubbles are formed in the blood and other liquid media, which cause gas embolism (blockage of blood vessels by gases) and, as its manifestation, decompression sickness. The severity of decompression sickness is determined by the massiveness of vascular occlusion and their localization. Hypothermia or overheating of the body contributes to the development of decompression sickness. A decrease in temperature leads to vasoconstriction, a slowdown in blood flow, which slows down the removal of nitrogen from tissues and the desaturation process. At high temperatures, blood thickens and slows down its movement.

2.1.3 Air humidity

Air humidity is determined by the content of water vapor in it and is measured in absmonetary and relative units. It is characterized by absolute, maximum and relative humidity, as well as saturation deficit.

Absolute humidity - the elasticity of water vapor in the air at the considered moment, expressed in millimeters of mercury or the amount of water vapor in grams contained in 1 m3 of air at the time of the study.

Maximum humidity - the elasticity of water vapor when the air is completely saturated with moisture at a certain temperature or the amount of water vapor in grams contained in 1m3 of air at the same temperature.

Relative humidity is the ratio of the absolute and maximum humidity values, expressed as a percentage.

Saturation deficit (physiological) - the difference between the values \u200b\u200bof air humidity at a temperature of 37C (human body temperature) and absolute at the time of the study. It indicates how many grams of water 1m3 of exhaled air can extract from the human body.

Saturation deficit refers to one of the wet environmental parameters, as it characterizes two parameters at once - humidity and temperature. The higher the saturation deficit, the drier and warmer, and vice versa.

An important characteristic of air humidity is such a concept as dew point.

Dew point characterized by the temperature at which the air becomes saturated with water parameters, turning into a droplet-liquid state - the appearance of dew. The dew point is determined by the absolute humidity. Knowing the dew point, you can graphically determine the partial pressure of water vapor, and therefore the relative humidity.

The hygienic value of air humidity is determined by the effect on the heat exchange of the organism.

The meteorological conditions of industrial premises (microclimate) have a great influence on the well-being of a person and on his labor productivity.

To perform various types of work, a person needs energy, which is released in his body in the processes of redox decomposition of carbohydrates, proteins, fats and other organic compounds contained in food ..

The released energy is partially spent on doing useful work, and partially (up to 60%) is dissipated in the form of heat in living tissues, heating the human body.

At the same time, thanks to the mechanism of thermoregulation, the body temperature is maintained at 36.6 ° C. Thermoregulation is carried out in three ways: 1) by changing the rate of oxidative reactions; 2) a change in the intensity of blood circulation; 3) a change in the intensity of sweating. The first method regulates the release of heat, the second and third methods - heat removal. The permissible deviations of the human body temperature from normal are very insignificant. The maximum temperature of internal organs that a person can withstand is 43 ° C, the minimum is plus 25 ° C.

To ensure the normal functioning of the body, it is necessary that all the heat released into the environment, and the changes in the microclimate parameters are within the zone of comfortable working conditions. If comfortable working conditions are violated, increased fatigue is observed, labor productivity decreases, overheating or hypothermia of the body is possible, and in especially severe cases loss of consciousness and even death occurs.

The removal of heat from the human body to the environment Q is carried out by convection Q convection as a result of heating the air that washes the human body, infrared radiation to the surrounding surfaces with a lower temperature Q rad, evaporation of moisture from the skin surface (sweat) and upper respiratory tract Q isp. Comfortable conditions are ensured by observing the thermal balance:

Q \u003d Q conv + Q uiz + Q isp

Under normal temperature and a low air velocity in a room, a person at rest loses heat: as a result of convection - about 30%, radiation - 45%, evaporation -25%. This ratio can change, since the process of heat release depends on many factors. The intensity of convective heat transfer is determined by the temperature environment, mobility and moisture content of the air. Radiation of heat from the human body to surrounding surfaces can occur only if the temperature of these surfaces is lower than the temperature of the surface of clothing and open parts of the body. At high temperatures of surrounding surfaces, the process of heat transfer by radiation goes in the opposite direction - from heated surfaces to a person. The amount of heat removed by evaporation of sweat depends on temperature, humidity and air speed, as well as on the intensity of physical activity.

A person has the greatest efficiency if the air temperature is in the range of 16-25 ° C. Due to the mechanism of thermoregulation, the human body responds to a change in the temperature of the surrounding air by narrowing or expanding the blood vessels located at the surface of the body. With a decrease in temperature, blood vessels narrow, blood flow to the surface decreases and, accordingly, the removal of heat by convection and radiation decreases. The opposite picture is observed when the ambient air temperature rises: blood vessels expand, blood flow increases and, accordingly, heat transfer to the environment increases. However, at a temperature of the order of 30 - 33 ° C, close to the temperature of the human body, heat removal by convection and radiation practically stops, and most of the heat is removed by evaporation of sweat from the skin surface. Under these conditions, the body loses a lot of moisture, and with it salt (up to 30-40 g per day). This is potentially very dangerous and therefore steps must be taken to compensate for these losses.

For example, in hot shops, workers receive salted (up to 0.5%) carbonated water.

Big influence Humidity and air velocity affect human well-being and related thermoregulation processes.

Relative air humidity φ is expressed as a percentage and is the ratio of the actual content (g / m 3) of water vapor in the air (D) to the maximum possible moisture content at a given temperature (Dо):

or the ratio of absolute humidity P n(partial pressure of water vapor in air, Pa) to the maximum possible P maxunder given conditions (vapor pressure)

(Partial pressure is the pressure of a component of an ideal gas mixture, which it would exert if it occupied one volume of the entire mixture).

The removal of heat during sweating directly depends on the humidity of the air, since heat is removed only if the sweat released evaporates from the surface of the body. With increased humidity (φ\u003e 85%), sweat evaporation decreases until it stops completely at φ \u003d 100%, when sweat drips from the surface of the body in drops. Such a violation of heat dissipation can lead to overheating of the body.

Reduced air humidity (φ< 20 %), наоборот, сопровождается не только быстрым испарением пота, но и усиленным испарением влаги со слизистых оболочек дыхательных путей. При этом наблюдается их пересыхание, растрескивание и даже загрязнение болезнетворными микроорганизмами. Сам же процесс дыхания может сопровождаться болевыми ощущениями. Нормальная величина относительной влажности 30-60 %.

Air speed indoors noticeably affects the well-being of a person. In warm rooms at low air velocities, heat removal by convection (as a result of the washing of heat by the air flow) is very difficult and overheating of the human body can be observed. An increase in air speed contributes to an increase in heat transfer, and this has a beneficial effect on the state of the body. However, at high speeds of air movement, drafts are created, which lead to colds both at high and at low temperatures in the room.

Indoor air speed is set depending on the season and some other factors. So, for example, for rooms without significant heat release, the air speed in winter is set in the range of 0.3-0.5 m / s, and in summer time - 0.5-1 m / s.

In hot shops (rooms with an air temperature of more than 30 ° C), the so-called air shower. In this case, a stream of humidified air is directed to the worker, the speed of which can reach up to 3.5 m / s.

Has a significant impact on human life atmosphere pressure ... Under natural conditions, at the surface of the Earth, atmospheric pressure can fluctuate between 680-810 mm Hg. Art., but practically the vital activity of the absolute majority of the population takes place in a narrower pressure range: from 720 to 770 mm Hg. Art. Atmospheric pressure rapidly decreases with increasing altitude: at an altitude of 5 km it is 405, and at an altitude of 10 km - 168 mm Hg. Art. For a person, a decrease in pressure is potentially dangerous, and the danger is both the decrease in pressure itself and the rate of its change (with a sharp decrease in pressure, painful sensations arise).

With a decrease in pressure, the supply of oxygen to the human body during breathing worsens, but up to an altitude of 4 km, a person maintains satisfactory health and performance due to an increase in the load on the lungs and cardiovascular system. Starting from an altitude of 4 km, the supply of oxygen decreases so much that oxygen starvation can occur - hypoxia... Therefore, when at high altitudes, oxygen devices are used, and in aviation and astronautics - space suits. In addition, cabins are sealed in aircraft. In some cases, such as when diving or tunneling in water-saturated soils, the workers are under increased pressure. Since the solubility of gases in liquids increases with increasing pressure, the blood and lymph of the workers are saturated with nitrogen. This creates the potential danger of the so-called " decompression sickness ", which develops when there is a rapid decrease in pressure. In this case, nitrogen is released at a high rate and the blood "boils", as it were. The resulting nitrogen bubbles clog up small and medium-sized blood vessels, and this process is accompanied by sharp painful sensations ("gas embolism"). The disturbances in the vital functions of the body can be so serious that they sometimes lead to death. To avoid dangerous consequences, pressure reduction is carried out slowly, over many days, so that excess nitrogen is removed naturally when breathing through the lungs.

To create normal meteorological conditions in industrial premises, the following measures are taken:

mechanization and automation of heavy and labor-intensive work, which frees workers from performing heavy physical activity, accompanied by a significant release of heat in the human body;

remote control of heat-emitting processes and devices, which makes it possible to exclude the presence of workers in the zone of intense heat radiation;

removal of equipment with significant heat release to open areas; when installing such equipment in closed rooms, it is necessary, if possible, to exclude the direction of radiant energy to workplaces;

thermal insulation of hot surfaces; the thermal insulation is calculated so that the temperature of the outer surface of the heat-emitting equipment does not exceed 45 ° C;

installation of heat-shielding screens (heat-reflecting, heat-absorbing and heat-removing);

air curtains or air shower;

installation of various ventilation and air conditioning systems;

device in rooms with unfavorable temperature conditions of special places for short-term rest; in cold workshops these are heated rooms, in hot workshops - rooms to which cooled air is supplied.

Introduction

Studies have shown that a person spends 80% of his own life indoors. Of these eighty percent, he spends 40% at the workplace. And much depends on the conditions in which any of us have to work. The air of office buildings and industrial premises contains numerous bacteria, viruses, dust particles, harmful organic compoundssuch as carbon monoxide molecules and many other substances that adversely affect the health of workers. According to statistics, 30% of office workers suffer from increased irritability of the retina, 25% experience systematic headaches, and 20% have difficulty with the respiratory tract.

The relevance of the topic is that the microclimate has an extremely important role on the state and well-being of a person, on his performance, and the requirements for heating, ventilation and air conditioning directly affect human health and productivity.

The influence of meteorological conditions on the body

Meteorological conditions, or the microclimate of industrial premises, are made up of the air temperature in the room, the humidity of the air and its mobility. The parameters of the microclimate of industrial premises depend on the thermophysical characteristics of the technological process, climate, season of the year.

The industrial microclimate, as a rule, is characterized by great variability, horizontal and vertical unevenness, a variety of combinations of temperature and humidity of air movement and radiation intensity. This diversity is determined by the peculiarities of production technology, climatic features of the area, the configuration of buildings, the organization of air exchange with external atmosphere, heating and ventilation conditions.

By the nature of the impact of the microclimate on the working industrial premises can be: with a predominant cooling effect and with a relatively neutral (not causing significant changes in thermoregulation) microclimate effect.

Meteorological conditions for the working area of \u200b\u200bindustrial premises are regulated by GOST 12.1.005-88 "General sanitary and hygienic requirements for the air in the working area" and Sanitary standards for the microclimate of industrial premises (SN 4088-86). In the working area, the microclimate parameters must be provided that correspond to the optimal and permissible values.

GOST 12.1.005 establishes optimal and permissible microclimatic conditions. With a long and systematic stay of a person in optimal microclimatic conditions, the normal functional and thermal state of the body is preserved without stressing the mechanisms of thermoregulation. At the same time, thermal comfort is felt (a state of satisfaction with the external environment), high level performance. Such conditions are preferred in the workplace.

To create favorable working conditions that meet the physiological needs of the human body, sanitary standards establish the optimal and permissible meteorological conditions in the working area of \u200b\u200bthe premises.

The regulation of the microclimate in the working premises is carried out in accordance with the sanitary rules and regulations set forth in SanPiN 2.2.4.548-96 " Hygiene requirements to the microclimate of industrial premises ".

A person can tolerate air temperature fluctuations in a very wide range from - 40 - 50 o and below to +100 o and above. The human body adapts to such a wide range of fluctuations in ambient temperatures by regulating heat production and heat transfer from the human body. This process is called thermoregulation.

As a result of the normal vital activity of the body, heat is constantly generated in it and its return, that is, heat exchange. Heat is generated by oxidative processes, of which two-thirds falls on oxidative processes in the muscles. Heat is released in three ways: convection, radiation and sweat evaporation. Under normal meteorological conditions of the environment (air temperature about 20 o C) convection gives off about 30%, radiation - about 45% and evaporation of sweat - about 25% of the heat.

At low ambient temperatures in the body, oxidative processes intensify, internal heat production increases, due to which a constant body temperature is maintained. In the cold, people try to move or work more, since muscle work leads to increased oxidative processes and an increase in heat production. The tremors that appear when a person is in the cold for a long time is nothing more than small twitching of muscles, which is also accompanied by an increase in oxidative processes and, consequently, an increase in heat production.

Despite the fact that the human body, due to thermoregulation, can adapt to a very wide range of temperature fluctuations, its normal physiological state remains only up to a certain level. The upper limit of normal thermoregulation in complete rest lies in the range of 38 - 40 o C with a relative humidity of about 30%. With physical exertion or high humidity, this limit decreases.

Thermoregulation in unfavorable meteorological conditions, as a rule, is accompanied by the stress of certain organs and systems, which is expressed in a change in their physiological functions. In particular, when exposed to high temperatures, an increase in body temperature is noted, which indicates some violation of thermoregulation. The degree of temperature rise, as a rule, depends on the ambient temperature and on the duration of its effect on the body. During physical work in conditions of high temperatures, the body temperature rises more than under similar conditions at rest.