Chapter 6 BASIC PRINCIPLES FOR DESIGNING SPECIAL CLOTHING AND EVALUATION OF ITS QUALITY

Special clothing that provides protection against hazardous and harmful production factors must meet ergonomic, operational and aesthetic requirements. In practice, we often have to deal with the contradictions of these requirements.

The creation of special clothing that meets all of the listed requirements consists of five main stages:

1) analysis of technical requirements and study of working conditions of workers;

2) selection of materials that best suit specific production conditions (exposure to harmful and hazardous production factors, meteorological conditions);

3) development of clothing design, taking into account the dynamics of workers, localization of the impact of a harmful or hazardous production factor and meteorological conditions;

4) assessment of special clothing in laboratory and production conditions;

5) development of normative and technical documentation for the mass or serial production of special clothing.

The quality of special clothing for workers in specific professions is largely determined by the knowledge of working conditions. Upon studying the working conditions of workers, first of all, they pay attention to the following: the nature of production factors and the degree of their influence (over the entire surface or in local areas); the severity of the work performed; characteristic movements; meteorological conditions (air temperature and humidity, wind speed); work and rest regime; standard service life (in accordance with the norms of free distribution of overalls, safety footwear and safety devices); aesthetic requirements (color scheme, compliance with the industrial interior of the enterprise).

Taking into account all these factors, special clothing is being developed. For example, in accordance with the meteorological data, the intensity of physical work, the time spent in the workplace, materials are selected and a design of clothing is developed that provides normal conditions for human heat transfer in production. In accordance with the nature of production factors and human movements, materials are selected and a design of clothing is developed that provides the necessary protection against these factors and freedom of movement. The selected materials and design also determine the wearing period of special clothing and the person's ability to work.

Materials are chosen so that they best meet the protective, operational and ergonomic requirements. To do this, in laboratory conditions, along with protective properties, such indicators as strength, abrasion resistance, rigidity, air permeability, moisture permeability, weight, etc. are determined.

The design of special clothing is developed taking into account the movements of workers, the properties of materials and the requirements for this type of clothing. At this stage, the change in the size of individual sections of the human figure is determined, depending on the nature of the movements during work. The analysis of the movements of workers in various industries showed that when performing the basic (characteristic) movements, the values ​​of the leading dimensional characteristics of the human figure change significantly.

Based on the dynamic increase in measurements during the design of products, a general allowance for free fitting is established and its distribution over the main structural sections. At the same time, the properties of the selected materials are taken into account: rigidity, drape, weight, which to a large extent determine the ergonomic properties of workwear. Much attention has been paid to improving these properties of workwear in recent years. Naturally, any workwear to some extent restricts a person's movements. However, in any case, it should not have undesirable effects on the human body, since this is associated with a decrease in the level of performance. At the same time, clothes, in turn, undergo a number of changes: while moving, they slide relative to the human body until the increasing forces of tangential resistance force the clothes to stretch, bend or shrink. Deforming, clothes act with varying force on parts of a person's body (presses on his body). Therefore, it is necessary to create such a design of workwear that would enable the worker to carry out a variety of movements with the greatest scope with a minimum expenditure of physical energy.

The degree of ergonomic perfection is assessed according to the following complex indicators: anthropometric, hygienic, physiological, psychophysiological, psychological.

The anthropometric indicator of the quality of workwear characterizes its compliance with the size and shape of the human body. The hygienic indicator evaluates the ability of a product to remove or retain heat, remove moisture and other waste products of the body from the underwear space.

The physiological indicator characterizes the thermal state of the body in overalls, compliance with the power and energy capabilities of a person. In particular, the materials from which the overalls are made must have the lowest possible flexural rigidity and maximum elasticity so that efforts to overcome the resistance of the clothing do not cause increased human fatigue.

Psychophysiological indicator of the quality of workwear (Evaluates its compliance with the peculiarities of the functioning of the human sensory organs: visual, auditory, tactile, olfactory, kinestatic (muscular), etc. For example, clothes with a hood or helmet should not reduce the hearing threshold of a person or reduce his field of vision For a number of professions (hunters, security guards, etc.) it is not allowed to use materials that emit a rustle, creak when moving.

The use of materials with a high surface reflection coefficient (for example, metallized) can lead to a deterioration in visual acuity, the throughput of the visual analyzer, etc.

The psychological indicator characterizes the convenience of using individual elements of workwear, the convenience of putting it on and taking it off, the correspondence of the color of the product to the possibilities of human color vision. With this in mind, when designing workwear, the convenience of using pockets and other structural elements for placing the necessary objects of labor is assessed. For a number of professions (for example, firefighters working in "hot shops", etc.), the design of workwear should be such as to ensure that it can be quickly removed if necessary. The color of the material from which the overalls are to be made should not have an irritating effect on the human psyche. At the same time, in a number of cases, the color of clothing or its individual parts should be such that, in emergency situations, it would be possible to detect a person in a short time.

To assess the ergonomic properties of workwear, TsNIISHP has developed and uses anthropodynamic stands for various types of products, a microclimate chamber, various medical devices, etc. gloves).

When ergonomic indicators are obtained that do not correspond to those of the best samples, changes are made to the design. An example of this is the development of workwear for welders. Such clothing is known to be made from materials of increased surface density, thickness and rigidity to provide protection against sparks and molten metal splashes. As it turned out during the research, the developed classical design of the set-in sleeve exposes the welder's hand to a significant load (over 5 N). In order to identify the possibility of reducing this load, studies were carried out on jackets made of materials of different surface density, rigidity and_ sleeve design.

As a result of these studies, it was found that the least effort on the welder's arm is provided by a jacket made of soft fabric (of the phenylone-ZN type) with a sleeve, the design of which corresponds to the main working position of the worker's hand (the articular angle between the shoulder and forearm is 120 °).

Research carried out in TsNIISHP with the use of modern mathematical apparatus made it possible to identify the optimal values ​​of the design parameters of another type of workwear - overalls:

The basic design of the overalls, developed on the basis of the optimal values ​​of the design parameters, has passed production tests and received positive opinions from consumers.

Ensuring the ergonomic requirements for workwear is possible not only due to optimal design parameters, but also due to the necessary structural elements. The main of these structural elements are folds and elastic inserts. Their introduction into the design allows to reduce the increase in free fit without reducing the ergonomic level while improving the aesthetic properties (Fig. 6.1). The depth of the folds and the size of elastic inserts should be determined depending on the dynamic growth of dimensional characteristics; those parts of the body where inserts or folds are provided when performing certain movements by the worker. Table 6.2 shows the ergonomic indicators of overalls of various design solutions.

As you can see from the table. 6.2, jumpsuits with elasticated inserts and pleats in the back are more ergonomic improvements, as evidenced by the data

physiological and hygienic assessment of these products, carried out in a "microclimatic chamber with specified meteorological conditions: temperature, humidity, wind speed, etc.

In an objective assessment of the functional state of the human body, dressed in the test clothes, the following indicators are used: wrist muscle strength and muscle endurance before and after the experiment; dynamics of heart rate immediately after the end of work; recovery of the pulse after the end of the periods of work during the experiment; the degree of fatigue of a person according to the change in the index of working capacity when performing a step test; an indicator of the thermal state of a person; temperature of the skin and body; energy consumption; moisture loss.

Overalls of various designs have a significant impact on the physiological indicators of the functional "state of the human body. The most informative physiological criteria that determine the degree of influence of the product design on the general functional state of the body are the dynamics of heart contractions during the performance of work and the dynamics of their recovery after the end of work. These indicators correlate well with the subjective feelings of the subjects.

The hygienic indicator of the quality of workwear is the most important ergonomic criterion. The ergonomic perfection of workwear can be judged by hemodynamic parameters (heart rate, blood pressure), working capacity, the state of the central nervous system, and criteria for the thermal state. For example, the comfort of jackets with sleeves of different cut can be judged by the heart rate (Table 6.3).

For light and medium work, from an ergonomic point of view, the sleeve cut with a gusset is the most perfect.

The dependence of the heart rate of a person in overalls on its weight is clearly visible from the data given in table. 6.4.

The level of ergonomic perfection of workwear can also be judged by the state of the motor analyzer, which is determined by assessing the time of performing movements by a person and the accuracy of coordination of these movements.

So, when assessing the convenience of the design of two types of trousers using this indicator, it was found that in subjects in trousers, which they rated as more comfortable, the degree of coordination after 1.5 hours of work changed by 18.9%, and as uncomfortable - by 28. 3%.

In the ergonomic assessment of the quality of workwear construction, methods are used to determine muscle strength and endurance of the right and left hands before and after the experiment. For example, a subject wearing a jacket with an increase in free fit in the chest area of ​​5 cm and with raglan sleeves showed a significant decrease in muscle strength of the hand (up to 30%) after physical exertion, and in the case of an increase in free fit in the chest area

11 cm, all other things being equal, changes in muscle strength are not observed.

Dependence of heart rate on the weight of workwear

The pressure of clothing on the human body is one of the most important indicators that determine the level of its ergonomic perfection. This indicator may be different depending on the purpose of the products. So, for trousers like jeans it is 150-170 kPa, for overalls for special purposes - 70 kPa. It should be borne in mind that "overalls" exerting pressure on the human body during operation should not cause irritation of the skin, bumps, abrasions.

As we know, in recent years, the production of synthetic threads and fibers, and, consequently, materials from them, has been growing all over the world. Synthetic fiber materials have many positive properties: durability, dimensional stability, ease of maintenance and a high level of aesthetic properties. However, the use of these hydrophobic materials has an adverse effect on the microclimate under clothing, causing discomfort from electrical discharges, skin irritation, and rapid contamination. In addition, some man-made fibers have insufficient chemical stability. A significant disadvantage of hydrophobic chemical fibers is their high electrification, which negatively affects human well-being.

In this regard, a problem has arisen related to the elucidation of the effect of the fibrous composition of materials on the microclimate under clothing and the determination of the optimal mixture of synthetic and natural fibers. The latter allows you to combine the positive properties of fibers and compensate for their disadvantages.

In the practice of making workwear, the following ratio of synthetic (polyamide - PA, polyester - PE) and natural (in particular, cotton) all-cotton is most often used: 50% PA + 50% Cotton; 50% PE + 50% Cotton; 65% PA + 35% reinforced concrete; 65% PE + 35% Cotton, etc.

Another direction associated with improving the hygienic properties of synthetic fibers is their chemical and physical modification, which contributes to a change in hygroscopicity, antistaticity, air permeability, heat and moisture conductivity.

The trend of replacing natural fibers with synthetic ones in the manufacture of materials for workwear opens up wide opportunities for ensuring a high protective effect. However, the hygienic properties of such materials are significantly inferior to natural ones, which is associated with the hydrophobicity of synthetic fibers, their high thermal conductivity. Therefore, replacing natural fibers with synthetic ones leads to a deterioration in the hygienic properties of clothing due to a violation, first of all, of the body's heat exchange.

The deterioration of the hygienic properties of clothing made of synthetic materials increases with a change in a person's physical activity, under uncomfortable microclimatic environmental conditions, which leads to a decrease in a person's working capacity.

Gorodinsky S.M. and other researchers found that with an optimal thermal state for 1 hour of performing work of average severity, a person's working capacity decreases by 2.2-3.8%, with an admissible thermal state - by 5-8.1%, at a limiting level thermal state - by 9.6-11.2%. Under conditions of thermal stress on the body, a person's ability to coordinate movements also changes. Therefore, it is necessary to find such combinations of hydrophilic (natural) and hydrophobic (synthetic) fibers, which would include the positive properties of both components, and materials from them would have a minimal effect on the thermal state of a person.

In TsNIISHP, studies were carried out to establish hygienic regulation of the permissible investment of synthetic fibers in a different range of materials for workwear. These studies are based on an assessment of the thermal and functional state of a person during the operation of clothing made from materials with various physical and hygienic properties. The experience of using workwear made from the same materials has shown that the thermal state of a person differs significantly depending on meteorological conditions and the level of physical activity.

Based on the prospects for the development of materials for workwear in table. 6 5 is a list of those materials from which samples of workwear were made. In accordance with the method of physiological and hygienic assessment of the quality level used in TsNIISHP, comparative studies of workwear samples made of materials of various fibrous composition were carried out.

When using clothes both from natural fibers and from a mixture with the attachment of synthetic fibers to normal

conditions when performing work of light and medium severity categories, there was no significant difference in the increase in the tension of the functional systems of the human body. Some deterioration of the thermal state of a person is observed only when performing work with a high level of energy consumption in products made of mixed fabrics with an investment of more than 50% of polyester fiber.

The most significant difference was obtained in the study of overalls made of mixed fabrics (with an investment of more than 50% synthetic fibers), operated in a moderately heating microclimate at an ambient temperature of 30 ± 5 ° C and performing physical work of varying severity. This can be clearly seen when comparing the indicators of a person's condition, characterizing the rate of moisture loss. The efficiency of moisture evaporation determines the moisture-conducting function of clothing and the rationality of its design.

So, in the case of light physical activity at an air temperature of 30 ... 35 ° C in gowns made of mixed fabrics with an investment of 70% of the mass of polyester fibers, the rate of moisture loss increases by 48.5% compared to similar conditions when using gowns made of natural fibers.

A comparative analysis of the indicators of the functional state of the neuromuscular system of a person performing light work in overalls made of 100% cotton and mixed materials with more than 50% polyester fiber invested in them indicates a decrease in the coefficient of muscle endurance (0.88-0.96 in suits made of cotton and 0.8-0.82 in suits from a blend with an investment of 67% polyester fiber).

Similar data were obtained during the operation of overalls made of materials with an investment of synthetic fibers of more than 50%, operating with an energy consumption of 220 W (average physical activity). For example, when up to 70% of synthetic fibers are invested in mixed materials, the rate of increase in body temperature increases, which causes an increase in the accumulation of heat in the body by an average of 30-40% in comparison with overalls made of materials with 50% of synthetic fibers. At the same time, when investing up to 70% of synthetic fibers, the moisture evaporation efficiency decreases by 14.3%.

When more than 67% of synthetic fibers are invested in materials, the indicators of a suitable microclimate and indicators characterizing the tension of nervous processes deteriorate. At the same time, an increase in the air permeability of blended fabrics with an investment of 50% of synthetic fibers over 60-80 dm3 / (m2-s) does not affect the improvement of the indicators of the thermal and functional state of workers.

The results of the physiological and hygienic assessment of overalls used when performing hard physical work

energy consumption 300 W), show that when working in overalls made of a material with an investment of synthetic fibers of 67%, the rate of heat accumulation increases by 44% in comparison with products made from 100% cotton. Consequently, the stress of the thermoregulatory system, and hence fatigue, will increase by almost 1.5 times in those working in suits made of these mixed fabrics.

An analysis of the indicators of a suitable microclimate also indicates that when using blended fabrics with an investment of synthetic fibers of more than 50%, there is a sharper increase in the temperature of the comfortable air in the back and chest area than when using overalls made of 100% cotton.

Physiological and hygienic studies carried out at TsNIISHP found that in workwear made of mixed fabrics with an investment of more than 50% of synthetic fibers, the air temperature and relative humidity under the clothes do not decrease during periods of rest, which increases the rate of human fatigue.

Thus, on the basis of the studies carried out at TsNIISHP, it was concluded that the use of blended fabrics for the manufacture of overalls must be differentiated depending on the share of synthetic fibers, the level of energy consumption and climatic conditions.

Correct use of these materials will ensure the best hygienic, performance and aesthetic properties of the workwear.

Indicators of the functional state of a person in special clothing when performing light, medium and hard work are presented in table. 5, 6, 7 applications.

A source: Collection of information and normative materials "Working conditions at geological survey"

Editor and compiler Grigory Luchansky

Moscow, FGUNPP "Aerogeology", 2004

Due to the various physiological characteristics of the body, the nature of the work performed and the environmental conditions, several types of clothing are distinguished:

Household clothing made taking into account seasonal and climatic characteristics (winter, summer, clothing for middle latitudes, north, south);

Children's clothing, which, with a low weight, loose fit and made from soft fabrics, provides high heat protection in the cold season and does not lead to overheating in summer;

Professional clothing, designed taking into account working conditions, protecting a person from the effects of occupational hazards. There are many types of professional clothing; it is an indispensable element of the worker's personal protective equipment. Clothing is often critical in reducing the impact of an unfavorable occupational factor on the body;

Sportswear designed for various sports. At present, the design of sportswear is of great importance, especially in high-speed sports, where the weakening of the friction of air flows against the athlete's body contributes to the improvement of sports results. In addition, fabrics for sportswear should be elastic, with good hygroscopicity and breathability;

Special cut military clothing from a specific range of fabrics. The hygienic requirements for the fabrics and cut of military clothing are especially high, since the military clothing is his home. Fabrics should have good hygroscopicity, air permeability, retain heat well, dry quickly when wet, be durable, dust-resistant, easy to wash. When worn, the fabric should not discolor and deform. Even a completely wet set of clothes for a soldier should not weigh more than 7 kg, otherwise heavy clothes will reduce performance. Distinguish between casual, ceremonial and work military clothing. In addition, there are sets of seasonal clothing. The cut of military clothing is different and depends on the type of troops (clothing of sailors, infantrymen, paratroopers). Ceremonial clothes have various finishing details that give the costume solemnity and elegance;

Hospital clothing, consisting primarily of linen, pajamas, and a dressing gown. Such clothes should be lightweight, well cleaned of dirt, easy to disinfect, they are usually made from cotton fabrics. The cut and appearance of hospital gowns require further improvement. Currently, it is possible to manufacture disposable hospital clothes from special paper.

Clothing fabrics are made from plant, animal and artificial fibers. Clothing in general consists of several layers and has different thicknesses. Average clothing thickness varies with the season. For example, summer clothes are 3.3-3.4 mm thick, autumn clothes are 5.6-6.0 mm thick, and winter clothes are from 12 to 26 mm thick. The weight of men's summer clothing is 2.5-3 kg, winter clothing is 6-7 kg.

Regardless of the type, purpose, cut and shape, clothes must correspond to weather conditions, the state of the body and the work performed, weigh no more than 10% of a person's body weight, have a cut that does not impede blood circulation, does not restrict breathing and movements and does not cause displacement of internal organs, it is easy to clean from dust and dirt, be durable.

Clothing plays an important role in the processes of heat exchange between the body and the environment. It provides such a microclimate, which in various environmental conditions allows the body to remain in a normal thermal regime. The microclimate of the suitable space is the main parameter when choosing a suit, since, ultimately, the suitable microclimate largely determines the thermal well-being of a person.

A suitable microclimate should be understood as a complex characteristic of the physical factors of the air layer adjacent to the skin surface and directly affecting the physiological state of a person. This individual microenvironment is in a particularly close interaction with the organism, changes under the influence of its vital activity and, in turn, continuously influences the organism; the state of thermoregulation of the body depends on the characteristics of a suitable microclimate.

A suitable microclimate is characterized by temperature, air humidity and carbon dioxide content.

The temperature of the underwear space ranges from 30.5 to 34.6 ° C and the ambient temperature is 9-22 ° C. In temperate climates, the temperature of the clothing space decreases with distance from the body, and at high ambient temperatures, it decreases as it approaches the body due to the heating of the surface of the clothing by the sun's rays.

The relative humidity of the air under the conditions of the middle climatic zone is usually less than the humidity of the ambient air and rises as the air temperature rises. So, for example, at an ambient temperature of 17 ° C, the humidity of the underwear air is about 60%, when the temperature of the ambient air rises to 24 ° C, the air humidity in the underwear space decreases to 40%. When the ambient temperature rises to 30-32 ° C, when a person is actively sweating, the humidity of the available air increases to 90-95%.

The air of the underwear space contains about 1.5-2.3% carbon dioxide, its source is the skin. At an ambient temperature of 24-25 ° C, 255 mg of carbon dioxide is released into the underwear space in 1 hour. In contaminated clothing on the surface of the skin, especially when moistened and the temperature rises, there is an intensive decomposition of sweat and organic matter with a significant increase in the carbon dioxide content in the air of the clothing space. If in a dress made of chintz or satin of a loose fit, the content of carbon dioxide in the air of the underwear space does not exceed 0.7%, then in narrow and tight clothes made of the same fabrics the amount of carbon dioxide reaches 0.9%, and in warm clothes consisting of 3-4 layers, it increases to 1.6%.

The properties of clothes are largely dependent on the properties of fabrics. Fabrics must have thermal conductivity according to climatic conditions, sufficient air permeability, hygroscopicity and moisture capacity, low gas absorption, and not have irritating properties. Fabrics should be soft, elastic and at the same time durable, not change their hygienic properties during wear.

Depending on the purpose of the garment, the requirements for the fabrics are different.

Hygienic requirements for linen fabrics

(according to R.A. Dellu et al., 1979)

For example, good breathability is important for summer clothes, on the contrary, clothes for working in the wind at low air temperatures should have a minimum breathability. Good absorption of water vapor is a necessary property of linen fabrics, completely unacceptable for the clothes of people working in an atmosphere of high humidity or with constant wetting of clothes with water (workers of dye shops, sailors, fishermen, etc.).

In the hygienic assessment of clothing fabrics, their relation to air, water, thermal properties and the ability to retain or transmit ultraviolet rays are examined.

The breathability of fabrics is of great importance for the ventilation of the underwear space. It depends on the number and volume of pores in the tissue, the nature of the tissue processing.

Air-tight clothing makes it difficult to ventilate the underwear space, which is quickly saturated with water vapor, which disrupts the evaporation of sweat and creates the prerequisites for overheating a person.

It is very important that the fabrics maintain sufficient air permeability even when wet, i.e. after being wet with rain or wet from sweat. Wet clothing makes it difficult for outside air to access the surface of the body, moisture and carbon dioxide accumulate in the underwear space, which reduces the protective and thermal properties of the skin.

An important indicator of the hygienic properties of fabrics is their relation to water. Water in tissues can be in the form of vapor or in a liquid-droplet state. In the first case, they talk about hygroscopicity, in the second - about the moisture capacity of tissues.

Hygroscopicity means the ability of tissues to absorb water in the form of water vapor from the air - to absorb vaporous secretions from human skin. The hygroscopicity of tissues is different. If the hygroscopicity of linen is taken as a unit, then the hygroscopicity of chintz will be 0.97, cloth - 1.59, silk - 1.37, suede - 3.13.

Wet clothes quickly take away heat from the body and thus create the preconditions for hypothermia. In this case, the evaporation time is important. So, flannel and cloth evaporate water more slowly, which means that the heat transfer of woolen clothes due to evaporation will be less than silk or linen. In this regard, wet clothes made of silk, chintz or linen, even at a sufficiently high air temperature, cause a feeling of chilliness. Wearing a flannel or woolen garment over it will significantly soften these sensations.

Thermal properties of fabrics are of great importance. Heat loss through clothing is determined by the heat-conducting properties of the fabric, and also depends on the saturation of the fabric with moisture. The degree of influence of clothing fabrics on total heat loss is an indicator of its thermal properties. This assessment is carried out by determining the thermal conductivity of tissues.

Thermal conductivity is understood as the amount of heat in calories passing in 1 s through 1 cm2 of tissue with a thickness of 1 cm and a temperature difference of 1 ° C on opposite surfaces. The thermal conductivity of the fabric depends on the size of the pores in the material, and it is not so much the large gaps between the fibers that matter, but the small ones - the so-called capillary pores. The thermal conductivity of a worn or repeatedly washed fabric increases, as there are fewer capillary pores, the number of larger gaps increases.

Due to the different humidity in the surrounding air, the pores of the clothes contain more or less water. This changes the thermal conductivity, since a wet cloth conducts heat better than a dry one. When completely wet, the thermal conductivity of wool increases by 100%, silk by 40% and cotton fabrics by 16%.

Of significant importance is the relation of tissues to radiant energy, the ability to retain, transmit and reflect both the integral flux of solar radiation and the biologically most active infrared and ultraviolet rays. The absorption of visible and heat rays by tissues largely depends on their color, and not on the material. Any non-dyed fabric absorbs visible light equally, but dark fabrics absorb more heat than light fabrics.

In hot climates, it is better to make linen from dyed cotton fabrics (red, green), which provide the best retention of sunlight and the least access of heat to the skin.

One of the essential features of fabrics is their permeability to ultraviolet rays. It is important as an element of the prevention of ultraviolet deficiency, which often occurs in residents of large industrial cities with intense air pollution. Of particular importance is the transparency of materials in relation to ultraviolet rays for residents of northern regions, where an increase in the area of ​​open parts of the body is not always possible due to the harsh climatic conditions.

The ability of materials to transmit ultraviolet rays was not the same. Of synthetic fabrics, nylon and nylon are the most permeable to ultraviolet rays - they transmit 50-70% of ultraviolet rays. Fabrics made of acetate fibers (0.1-1.8%) transmit ultraviolet rays much worse. Dense fabrics - wool, satin transmit ultraviolet rays poorly, and chintz and cambric are much better.

Silk fabrics of rare weaving, both undyed (white) and dyed in light colors (yellow, light green, blue), are more transparent to ultraviolet rays than materials with a higher specific density, thickness, as well as dark and saturated colors (black, lilac , Red).

Ultraviolet rays passed through tissues based on polymers retain their biological properties and, above all, antirachitic activity, as well as a stimulating effect on the phagocytic function of blood leukocytes. There is also a high bactericidal efficacy against Escherichia coli and Staphylococcus aureus. Irradiation with ultraviolet rays through nylon fabrics after 5 minutes leads to the death of 97.0 - 99.9% of bacteria.

Under the influence of wear, the fabric of the garment changes its properties due to wear and tear.

Contamination of clothes occurs from the inside (liquid and gaseous waste products of the skin) and from the outside (from the introduction of dust and stains). Distinguish between mechanical (dust, dirt), chemical (gases) and bacterial contamination of clothing.

A certain role is played by the gas absorption of tissues. This property is of particular importance in industrial and field conditions. The amount of gas absorption depends on their concentration and tissue moisture. Wool absorbs more gases than cotton and releases them more slowly. Sometimes the amount of gases adsorbed by tissues is so great that if they are released back, they can cause poisoning (aniline). The ability of tissues to absorb gases (vapors) from the air also depends on the structure of the tissue and the nature of its processing.

Clothing fabrics contaminated with dust, secretions from the nasopharynx, fumes may contain pathogenic pathogens - mycobacterium tuberculosis, microorganisms of the typhoid-paratyphoid group, streptococci, staphylococci. Linen and woolen clothes are especially heavily soiled, the large thickness of which, looseness and relatively rare washing contribute to the accumulation of microorganisms.

Contaminated clothing can transmit typhoid fever, dysentery and other infections. The danger of such transmission is determined by the duration of the survival of microorganisms on the tissue. Due to the epidemic danger of contaminated clothing, it must be disinfected.

Dyes used in fabric finishing may contain toxic impurities. Cases of skin irritation with severe inflammation when wearing clothes containing residual amounts of arsenic compounds, cases of eczema of the facial skin with severe itching when wearing theater costumes, the parts of which were painted with fuchsin with toxic impurities, are described. Such phenomena are currently extremely rare, they are not excluded when using fabrics dyed with synthetic dyes or made from a variety of chemical fibers.

As a result of the widespread introduction of polymeric materials into everyday life, including fabrics made of artificial and synthetic fibers, as well as their combinations with natural fibers, fundamentally new products for the design of clothing were created.

Scheme of research on the hygienic assessment of clothing made of synthetic materials (according to K.A. Rapport, 1971).

Chemical fibers are divided into artificial and synthetic. Artificial fibers are represented by cellulose and its acetate, viscose and triacetate esters. Synthetic fibers are lavsan, cashmilon, chlorin, vinyl, etc.

In terms of physicochemical and physicomechanical properties, chemical fibers are significantly superior to natural ones.

Synthetic fibers are highly elastic, have significant resistance to repeated deformations, and are resistant to abrasion. Unlike natural chemical fibers, they are resistant to acids, alkalis, oxidants and other reagents, as well as to mold and moths.

Chemical fiber fabrics have antimicrobial properties. So, microorganisms survive on chlorine underwear during experimental wear much less than on underwear made from natural fabrics. New fibers have been created that inhibit the growth of staphylococcal flora and Escherichia coli.

Fabrics made of chemical fibers also have higher breathability than materials made from natural fibers of the same structure. The air permeability of lavsan, nylon and chlorin fabrics is higher than that of cotton.

Physiological and hygienic studies with experimental wear confirmed the high heat-shielding properties of clothing made of synthetic fibers - orlon, nitron, polyvinyl chloride, lavsan.

In addition to heat-shielding properties, the sorption qualities of clothing made of chemical fibers are of great importance.

Along with the high hygienic properties of synthetic fiber fabrics, some of their negative qualities should be noted. First of all, this refers to the ability of fabrics made of polymeric materials to accumulate static electricity. At the same time, the high electrical charge of polyvinyl chloride fibers is used to create medical linen.

Low sorption properties limit the use of most synthetic fibers for the manufacture of linen.

The lipophilic properties of nylon fibers also determine the ability of such fabrics to retain odors and poorly wash. Washing with conventional means reduces the bacterial contamination of nylon stockings by only 10%, and on stockings made of natural fibers after a similar procedure, it was only 40-25% of the introduced microflora.

For the hygienic evaluation of garments made from man-made fabrics, the chemical stability of the textile materials is extremely important. Polymeric materials can give off some harmful substances (uncured monomers and other precursors of synthesis). In addition, solvents, stabilizers, heat carriers, anti-electrostatic drugs and other substances used in the processes of obtaining, forming, finishing fibers and fabrics can migrate into air and water from the polymer mass.

In clothes made of synthetic fabrics, an area of ​​high humidity is formed in the underwear space, in such clothes overheating quickly sets in, especially in summer. Perspiration that does not have time to evaporate builds up on the skin, and rubbing clothes can cause abrasions and irritation. In winter, when the relative humidity in the room is low, static electricity makes itself felt. It causes a tingling sensation, clothes stick to the body. At the same time, the rhythm of heart contractions changes, there is a tendency to vasospasm, changes in blood pressure, fatigue develops, and a headache occurs. Static electricity also affects the properties of the fabric - it attracts dust and microflora to itself. The hygienic properties of such fabric are sharply reduced. In our country, strict hygienic control over the quality of synthetic materials for clothing and footwear is carried out. Samples of such tissues are subjected to complex research in the relevant research laboratories.

In the hygienic assessment of chemically stable tissues, toxicological studies are carried out using specific and sensitive tests. Direct contact of clothing with skin makes it necessary to study the reaction of the skin of laboratory animals to exposure to aqueous extracts from tissue samples. This study aims to identify local irritant and sensitizing effects. Skin reactions to tissue extracts preclude the use of the tissue under study. The final stage of toxicological studies is the study of the skin-resorptive effect, since some substances (for example, organophosphorus compounds) have a general toxic effect when they come into contact with the skin without a local skin reaction. Only in the absence of local irritating, sensitizing and skin-resorptive action of aqueous extracts from tissues in laboratory animals, observations on human volunteers are carried out. This is carried out either by the method of "patchwork" tests, or an experimental wearing of a product made of the tissue under investigation is carried out. At least one case of a skin reaction in humans provides a basis for the deviation of the tissue under study from widespread adoption. In the absence of a skin reaction, toxicological studies continue in the direction of the action of aqueous extracts from tissues on the immune and genetic responses of animals. For example, when studying formaldehyde-containing impregnations for clothing, no toxic effect was detected using skin tests, biochemical and morphological studies, but immunological and genetic methods revealed the effect of low concentrations of formaldehyde and dimethylformamide released from clothing. Thus, in the hygienic assessment of new fabrics and clothing made of it, the results of sanitary-chemical and toxicological studies are of decisive importance.

Based on the data obtained, recommendations for the use of fabrics for clothing are developed and formalized in the form of hygienic standards and rules.

Currently, fabrics are made from blended fibers, which allows you to combine the advantages of natural and synthetic materials.

Mixtures of fibers of various natures increase the heat-shielding properties of clothing, reduce hydrophobicity and electrostaticity, improve sorption properties, i.e. allow fabrics with favorable hygienic properties to be obtained. Improving the heat-shielding properties of chemical fibers of the same type is also possible by giving the fiber bulk, changing weaving, creating openwork, etc.

Recently, a porous plastic based on polyurethane foam has been successfully used as a heater for winter clothing. This material is chemically stable, has a low bulk density and high porosity, and pronounced heat-insulating properties. However, its high moisture content and poor fit hinder its use. Physiological studies of various clothing options in the Far North and the middle climatic zone have shown the feasibility of using polyurethane foam, especially in combination with windproof and water-repellent materials (raincoat fabric, Bologna). The use of polyurethane foam in winter clothes for children can reduce the weight of clothes by 30-40%, which is essential for children of primary school and preschool age.

Polyvinyl chloride fibers are used to make medicinal linen. Toxicological studies on laboratory animals and observations during experimental wearing did not reveal any adverse effects. These fabrics have high heat-shielding properties, good air and vapor permeability, low moisture capacity and hygroscopicity. The high electrification of these tissues gives a physiotherapeutic effect ("dry" heat). However, these fabrics do not withstand frequent washings, quickly deteriorate from hot water, which precludes their use in hospitals. PVC fiber linen can be recommended in conditions of cooling during work and sports activities (outdoors in winter).

The quality of the used workwear and other PPE

When assessing the quality, the assortment of the issued overalls and other PPE was studied, their compliance was established depending on the operation in various types of exploration work and the presence of harmful production and unfavorable factors.

The main disadvantages and comments on the standard overalls of geologists are reflected in the topographies.

General remarks about summer and winter workwear are as follows:

Low protective and operational qualities of the fabrics and materials used;

Imperfect design;

Lack of overalls care.

It was found that overalls in most cases do not withstand the normalized wearing periods and do not provide protection for workers from the effects of harmful production and unfavorable factors.

The nature of contamination and destruction of the overalls of core drillers, percussion-rope and deep drilling indicate the need to develop rational types of overalls for these occupations.

Standard industry norms for the free issuance of overalls, special footwear and safety devices for workers of geological exploration enterprises and organizations provide for: leather boots, rubber boots, tarpaulin boots and felt boots. Taking into account the location of the studied areas with IV and special belts, the normalized period of wearing for boots and rubber boots is 18, tarpaulin boots - 27, felt boots - 24 months.

It was found that the issued safety footwear does not withstand the standardized terms of wearing. The actual service life of rubber boots is 6-8 months, tarpaulin boots - from 2 to 6 months, felt boots - 6-8 months. The main reasons for the premature wear of safety footwear are: harsh operating conditions, insufficiently high quality of the materials and workmanship used. However, it should be noted that in most cases the reason for the destruction of safety footwear is its misuse, improper storage and lack of proper care during operation.

Kirz boots fail mainly due to a violation of the attachment of the sole to the upper of the shoe and the rapid wear of the sole when working on rocky and rocky ground.

One of the most rational types of special footwear for geologists can be considered geological yuft boots (TU RSFSR 6300-73). They are more consistent with working conditions and generally received a positive assessment of the workers.

However, as evidenced by the materials and reviews of workers collected in exploration expeditions, the leather sole of the boots must be replaced with a wear-resistant microporous rubber, which is most convenient for operation in mountainous conditions.

Felted shoes are operated without galoshes, therefore they quickly fail due to wear of the sole, as well as large shrinkage after getting wet and dry.

In the process of research on expeditions, it was found that the most common type of special footwear among workers of the main professions is rubber boots, less often tarpaulin boots are used, and workers prefer rubber shaped fishing boots (they are not provided for in the standard industry norms). The presence of elongated tops in these boots, which provide convenience when performing work related to dousing with drilling fluid and water, as well as during work and transitions in wet places, make this type of footwear the most rational in carrying out geological exploration.

The question of the quality of the means of protection for the hands of geologists is serious.

Standard industry standards provide for combined gloves for a period of 1 or 2 months and tarpaulins - for 1 month. In all the types of work studied, none of the specified types of mittens can withstand the terms of wearing. Depending on the nature of the work performed, the actual terms of wearing mittens, for various professions of workers, range from 1 shift to 15-20 days.

Along with the low operational properties of mittens, it should be noted that they lack protective ability against the effects of various harmful production factors. They do not protect workers' hands from drilling mud, water and oil products.

In winter, workers use fur gloves, putting them on under canvas or combined. This combination creates inconvenience in work and does not protect hands from production hazards.

It is necessary to point out the low quality of the manufacture of gloves and, first of all, the use of fragile threads. Most mittens fail due to the rapid destruction of the seams.

Short periods of operation of mittens entail additional issuance of them to workers, and, accordingly, overspending of expedition material resources for their purchase.

This situation indicates the need to develop rational types of hand protection for geologists.

In the system of preventive measures aimed at ensuring safe working conditions and reducing occupational poisoning and diseases, personal protective equipment (PPE) of workers in production plays an important role. Their use becomes necessary in cases where difficulties arise in ensuring the safety of technological processes and production equipment with existing technical means and the conditions for contact of workers with factors harmful to health.

In everyday work, personal protective equipment is most often used as one of the links in the general complex of preventive measures, while during emergency, repair and other occasional work, they become one of the main measures to ensure the safe performance of work.

The need to use PPE is regulated by the fundamental standards of the State Standardization System (SSS) and the Occupational Safety Standards System (SSBT). According to these regulatory documents, all newly developed and revised standards for production processes and equipment, materials and substances must include specific requirements for protective equipment for workers. In addition, the SSBT system has an independent classification grouping of standards for protective equipment for workers. In our country, specialized organizations and enterprises are engaged in the development, production, evaluation and supply of PPE. As a result of the existing system of control over the development and production of PPE by state and trade union bodies, most modern domestic PPE are characterized by high protective and operational properties that provide reliable protection against all kinds of hazardous and harmful production factors. The use of self-made PPE designs that have not passed certain stages of development, examination and implementation is strictly prohibited.

The effectiveness of the use of PPE is determined by the following basic requirements: the correct choice of a specific brand of PPE, the maintenance of PPE in good condition, the training of personnel in the rules for using PPE in accordance with the operating instructions during the entire period of their use.

The purpose of using PPE is to reduce to permissible values ​​or completely prevent the possible influence of harmful production factors on the body. In contrast to collective protective equipment, PPE is directly on the person, therefore, the requirements for a minimum negative impact on the functional state and performance of the person are imposed on them. Individual protective equipment for workers, depending on the purpose, are divided into the following classes: insulating suits; respiratory protection equipment; special clothing; special footwear; hand protection; head protection means; face protection means; eye protection; hearing protection; safety devices; protective dermatological agents.

The main purpose of the workwear is to provide reliable protection of the human body from various production factors while maintaining a normal functional state and working capacity. In recent years, the requirements for the aesthetic performance of workwear have increased.

All types of overalls are subdivided into groups and subgroups according to their protective properties. So, for example, there is workwear for protection against heat radiation, sparks and splashes of molten metal and scale; from oil, mechanical damage (abrasion) and low temperatures, etc. The protective, operational and hygienic properties of workwear primarily depend on the materials from which they are made, therefore, special requirements are imposed on the quality of fabrics. To achieve the required properties, when sewing workwear, cotton, linen, woolen, silk and synthetic fabrics are used, as well as fabrics with film coatings and made from a mixture of natural and synthetic fibers. To give fabrics certain protective properties, they are impregnated with various compounds (waterproof, water-repellent, heat-resistant, fire-resistant, oil-resistant, acid-resistant, acid-repellent or light-resistant combined impregnation). Film-coated materials are generally designed to protect against hazardous and noxious liquid substances. Recently, the widespread use of materials with a metallized coating, which are intended to protect against infrared radiation, has begun. As a basis for applying a metallized layer, semi-linen, asbestos, synthetic fabrics, as well as fiberglass fabrics are used. Ensuring the protective properties of workwear depends not only on the properties of the materials used, but also on its design. Therefore, when creating workwear, they are guided by certain requirements that take into account the whole range of indicators of its quality and purpose. These indicators are divided into general for all groups and subgroups of overalls and specialized, characterizing the protective properties of a particular group or subgroup in accordance with its purpose. General indicators of the quality of workwear mainly characterize its operational, hygienic and aesthetic properties. These include the strength and rigidity of the seam, the wear life and the time of continuous use; compliance of fabrics, materials and construction with working conditions; resistance to washing, artistic and aesthetic indicators, etc.

One of the main general requirements for workwear, regardless of its protective properties, is to ensure the normal thermal state of a person. Clothing creates a certain microclimate around the body, which depends, on the one hand, on human heat release, and on the other, on the meteorological parameters of the external environment and the properties of clothing (its design, physicochemical properties of materials, etc.). The indicators of the microclimate of the under-clothing space are its humidity and air temperature, as well as the content of carbon dioxide in it. In conditions of thermal comfort, the relative humidity under the clothing is 35 - 60%. This indicator can be used to judge the ability of clothing to transfer moisture from the surface of the body to the environment. The increased humidity of the air under the clothing space has an unfavorable effect both in conditions of high and low temperatures. The increased humidity of the underwear space when working in conditions of high dustiness or gas contamination contributes to irritation of the skin and increases the rate of entry of harmful substances through the skin. The air temperature of the underwear space is a function of a person's physical activity, therefore, the optimal values ​​of this indicator are different depending on the intensity of work. So, for a person who is in a state of relative rest, the temperature in the trunk region is comfortable, equal to 30 - 32 ° С, and with heavy physical work - 15 ° С. In this regard, when assessing the hygienic properties of clothing in terms of the air temperature of the underwear space, it is necessary to take into account the physical activity of a person and the environmental conditions. For example, when working in a cooling environment, a large drop in air temperature directly under the outerwear indicates its insufficient thermal resistance, and when working in windy conditions, high air permeability.

Specialized quality indicators characterize the protective properties of workwear. These include the following: resistance of the product to its parts to rupture (for overalls from mechanical stress and general industrial pollution); thermal conductivity, air permeability and vapor permeability (for workwear against high and low temperatures); protection factor and decontamination ability (for workwear against radioactive substances); lead equivalent (for workwear against X-rays); electrical resistance and protection factor (for workwear against electrostatic charges, electromagnetic and electric fields); dustproof and dustproof (for dustproof workwear); acid resistance (for workwear against acids), alkali resistance (for workwear against alkalis), etc. These requirements are achieved by using workwear in the model, in addition to appropriate materials, using various structural elements. So, when designing overalls for operation in conditions of changing environmental parameters, it is envisaged to use multi-layer insulation that is fastened to the main fabric, insulated linen, insulating gaskets and various ventilation devices. This allows you to adjust the thermal resistance of the garment by changing the thickness of the insulation depending on the ambient temperature. Wind protection is provided by special valves along the zipper line of the jacket and trousers, a hood, earmuffs, and structural elements that protect the face. Overalls for protection against harmful liquid factors should have a minimum number of seams, as well as protective valves along the lines of fasteners and pockets, its cut should not prevent liquids from draining. Structural elements that provide protection against dust-like harmful factors, microorganisms include all kinds of additional cuffs, valves, belts, capes, etc. materials resistant to the action of these substances. One of the ways to improve the heat exchange of a person, and therefore his well-being, is the introduction of special elements into the design to ensure air ventilation in the underwear space. These include various fly-off yokes in the back and shelves, openings of various shapes at the bottom of the armholes of the sleeves, at the top or along the entire length of the crotch seams, etc.

The decisive role of hygienic requirements for clothes and their adequate properties is due to the fact that it covers about 80% of the surface of the human body, performing important functions of his life (hygiene - from the Greek hygieinos - healthy).

In this regard, four main functions of a hygienic nature should be distinguished, which must be ensured in clothing used by a person:

1) protection against mechanical, chemical and biological influences;

2) protection from adverse climatic elements;

3) keeping the human body clean;

4) ensuring the normal functioning of the body.

The first function is defining for a special,

as well as sportswear. This does not exclude the need to provide this function in other classes of clothing.

In accordance with the Labor Code of the Republic of Belarus (Art. 230), it is envisaged to provide employees with personal protective equipment, including special clothing. At the same time, work with harmful, hazardous working conditions (exposure to poisonous vapors, radiation, acids, alkalis, metal splashes, etc.), as well as work related to pollution or carried out in unfavorable temperature conditions, are taken into account. At the same time, the procedure and norms for the free issuance of personal protective equipment to employees are determined by the Government of the Republic of Belarus.

The second function requires the protection of a person from various natural influences: low and high temperatures, precipitation, dust, wind, solar radiation, etc. This function is due to differences in the climatic conditions of individual regions and the need to take them into account when creating clothes.

Currently, the following division of the CIS territory by climatic zones has been adopted:

Zone I - an area with a climate that requires high-quality fur clothing and insulated footwear;

Zone II - an area with a climate that requires normal, but always made from heat-shielding natural materials, fur clothing and insulated footwear;

Zone III - an area with a climate that requires mostly warm clothing and a variety of shoes;

Zone IV - an area with a climate that requires more clothing and footwear to protect against moisture and precipitation;

Zone V is an area with a climate that requires increased attention to clothing and footwear to protect the human body from overheating.

For most areas, a special place from the variety of requirements is given to protection against low temperatures.

Analysis of the work carried out by various researchers allowed prof. R.F. Afanasyeva to formulate the requirements for clothing for protection from the cold. The most important of these are:

1) protecting a person from excessive heat transfer;

2) the conformity of the thermal insulation properties of clothing to physical activity of a person and the climatic conditions in which it is supposed to be used;

3) the inner layers of clothing should absorb sweat well and easily release moisture. Clothing should not interfere with the removal of moisture from the underwear space;

4) clothing should not cause overheating of the human body. A little cooling is acceptable, which stimulates physical activity, reduces fatigue and helps to harden the body.

Since clothing for protection from the cold is different, the properties of the individual materials that make up the product design package are of great importance. In this case, it is extremely important to take into account the expected operating conditions, the inhomogeneity of heat fluxes in certain areas of the human body.

Relative specific heat fluxes in different parts of the human body, W / m 2

It is important to take into account that heat flows are not associated with the surface of the human body, but are due to the peculiarities of their functioning.

The ratio of the area of ​​body parts to the total surface of the human body,%

With an increase in the speed of the wind flow and the air permeability of the package of clothing materials, the intensity of cooling of a person increases.

At a wind speed of up to 2 m / s, the air permeability of the package in the range of 0-60 dm 3 / (m 2 s) practically does not affect its thermal insulation properties. At a higher wind speed, the effect of the air permeability index on the thermal resistance of clothing bags is significant, especially with a wind of 8-10 m / s.

The third function is most important for products that come into contact with the human body: underwear, hosiery, hats, women's toilet accessories, etc.

The fourth function is aimed at the optimal functioning of the body in the human-product-environment system. In general terms, the implementation of this function is manifested in the provision of three indicators of a suitable (between the human body and clothing) microclimate in the optimal range: temperature - 28-32 ° C; humidity - 35-55%; carbon dioxide content - 0.04-0.06%.

The above functions from the standpoint of the physiology of the body and hygienic requirements for clothing can be subdivided in two directions:

1) protection of the body from adverse environmental factors - the effects of low and high temperatures, changes in solar radiation, wind, precipitation, mechanical influences;

2) creating the necessary conditions for the normal functioning of the body; maintaining a constant body temperature; removal of metabolic products - water vapor, carbon dioxide, salts; obstacle to the penetration of dust, dirt, microorganisms from the outside.

The hygienic requirements for clothing are differentiated depending on its purpose and operating conditions. In general terms, they boil down to the following:

1) the heat-shielding properties of clothing must correspond to human activities and the conditions of the external environment in which it is used. Therefore, this property of clothing must be regulated;

2) the air permeability of clothing and its individual parts must also correspond to the operating conditions and be adjustable;

3) the inner layers of clothing should be hygroscopic and easy to dry, the clothing should not interfere with the removal of moisture emitted by human skin;

4) clothes should be soft and light;

5) the design of clothing should allow a person to perform various movements, easily dress and take off, not impede movement and blood circulation.

The modern period is characterized by the widespread use of chemical materials in the manufacture of garments. They have a number of specific properties. Therefore, a number of additional requirements are imposed on clothing from them:

♦ chemical stability of materials and substances;

♦ the degree of electrification should not exceed the established sanitary standards;

♦ clothes made of synthetic materials should not be toxic, not irritate the skin.

Of particular importance in ensuring the safety of clothing are the level and nature of its electrification, i.e. the formation of electrostatic charges due to contact friction.

To characterize the static electricity generated on materials, the sign of the charges appearing matters. So, most chemical fibers, with the exception of viscose, are electrified negatively.

The most important factor affecting the ability of materials to store charges is the chemical nature of the fibers. So, synthetic fibers, as a rule, have a higher degree of electrification than artificial ones based on cellulose. Natural fibers of plant origin are much less electrified. But at present, fabrics, knitted fabrics and products made from them cannot be considered non-electrifying, since the presence of chemical fibers and additional chemical processing in them contribute to the accumulation of minor charges on their surfaces.

Observations lead to the conclusion that static electricity, along with electromagnetic radiation, ionizing radiation, noise and vibration, can and should be attributed to environmental factors that are not indifferent to human health. There is evidence of potential negative effects of static electricity. Persons exposed to a static electric field sometimes complain of a deterioration in general health, headache, sleep disturbance, pain in the heart.

The manifestation of the considered functions ensures the normal state of the human body. It should be borne in mind that the basis of life is metabolism. In the process, his body receives and assimilates nutrients and oxygen, and also consumes energy and releases excess heat and other waste products into the environment.

It is important to ensure the constancy of the human body temperature (up to 37 ° C). The temperature range for the existence of an organism is narrow. Heating the body to 42-43 ° C and cooling to 24-25 ° C can be fatal. Only by maintaining a constant body temperature on the basis of the selection of rational clothing is an active human activity and a constant rate of metabolic processes in the body achieved.

In the human-product system, the most important properties are those that ensure the purity of the skin, clothing space, as well as the product itself. The release of water, carbon dioxide, salts, fatty substances occurs through the skin. On the skin of an adult, there are about 300 thousand sebaceous glands, which secrete sebum (from 100 to 300 g per week), softening the surface of the skin and protecting it from drying out, wetting, and penetration of microbes. When sweat is excreted, water and salts are excreted from the body. On average, all sweat glands (there are several million) secrete from 0.5 to 1 liter of sweat per day in a temperate climate, in a hot zone - up to 450 g per hour; during physical work and walking, the amount of sweat can increase to 10 liters per day. From the surface of the skin, from 40 to 90 g of small scales of the superficial stratum corneum are also secreted per week. Therefore, clothes, especially linen products, must absorb them, thereby ensuring that the skin is cleaned from the boundary layer, and retains secretions until the product is cleaned. Naturally, the product itself is contaminated in this case.

The structure of laundry pollutants

The requirements in this case look ambiguous and contradictory. On the one hand, it is necessary to cleanse the skin, which is possible only by absorbing the secretions, on the other hand, the product's contamination is undesirable. High contamination dramatically changes a number of properties of fabrics, especially knitwear. So, linen products contaminated with liquid and dense secretions of the skin are 20% worse permeable to air, their weight on average increases by 10%, thickness - by 25%, ash content - 4-fold, and thermal conductivity also increases. All this worsens the comfortable state of a person, complicates gas exchange with the external environment, promotes the development of microorganisms, worsens the appearance, leads to an increase in labor and economic costs for operating the product (washing, cleaning).

The skin is also involved in gas metabolism.In a calm state, skin respiration (absorption of oxygen and release of carbon dioxide) accounts for about 1% of the total gas exchange. During the day, about 4.5 liters of carbon dioxide are released through the skin surface and 1.9 liters of oxygen are supplied. An increase in air temperature and hard physical work increase the intensity of gas exchange through the skin several times, bringing it to 10% of pulmonary gas exchange. The works of physiologists have shown that when the content in the underwear space is more than 0.07% of carbon dioxide, gas exchange through the skin, and, consequently, a person's well-being deteriorates. A carbon dioxide concentration of more than 0.1% causes fainting. If the partial pressure of nitrogen under clothing is higher than in the environment, then it is absorbed into the bloodstream, which is unsafe for the body. Therefore, it is necessary to provide for ventilation of the underwear space in clothes.

It should be especially noted that the functioning of the child's body has significant differences. Taking them into account is one of the important tasks of ensuring hygienic requirements for clothing.

The body of children is in a state of constant growth and development, bone tissue is flexible and elastic, muscles are poorly developed. Muscle mass in relation to body weight is 27.2% in an 8-year-old child, and 44.2% in 18-year-old boys.

Muscles of children are richer in water, but poorer in proteins, fats, inorganic substances, as a result of which their fatigue occurs faster in a child than in adults.

Children have thinner, more delicate skin than adults. They have a less perfect apparatus for heat regulation: heat transfer is increased due to changes (with age) in the relationship between the surface of the body and its mass. In an adult, there is 221 cm 2 of body surface per 1 kg of weight, in children of 15 years old - 378 cm 2, in children of 10 years old - 423 cm 2, in a child 6 years old - 456 cm 2, in a newborn - 707 cm 2. Rapid cooling of children also occurs due to the thin epithelium and a significant amount of blood flowing in the thickness of the skin (as a result of a more developed network of capillaries). Therefore, the skin of children, to a much lesser extent than that of an adult, protects the body from fluctuations in the temperature of the external environment.

The blood circulation in children is also faster. So, in an adult, 1/3 of the entire mass of blood flows in the thickness of the skin, and in children 1/2 or even 2/3 of the entire mass of blood. As a result, the blood flow time in children accelerates: in an adult it is 22 s, in a 14-year-old teenager - 18 s, in a 3-year-old child - 15 s.

The skin also plays a huge role in the body's heat exchange with the environment. It is known that in a person at rest, even at a relatively low air temperature (10-18 ° C), about 1/5 of the heat produced by him is given off by evaporation of water vapor released through the skin. Children are in motion most of the time, while the level of heat production increases by 2-4 times, so the amount of evaporated moisture they have is very significant. At a high air temperature, active sweating begins and almost all excess heat is removed from the body by evaporation of fluid from the surface of the body.

In young children, all physiological systems that maintain a constant temperature of the internal environment and maintain a thermal balance are insufficiently developed. Changes in unfavorable meteorological factors in a child's body are reflected more sharply than in an adult's body.