UNIVERSITY

Approved at a department meeting

Protocol No. ____from “____” __________2003

Educational and methodological manual

for students

Gomel, 2003

UDC 613.48 (075.8).

Organization of the work of the centralized laboratory of the Center for Hygiene and Epidemiology

(educational manual)

Compiled by: L.P. Mamchits, Gomel: State Medical University, 2003

Reviewers:

V.N. Bortnovsky - Head of the Department of General Hygiene, Ecology and Radiation Medicine

Approved at a meeting of the Scientific and Methodological Council of State Medical University, protocol No. dated 2003

The educational manual is intended for conducting practical classes on general hygiene in medical institutes at the medical and preventive faculty and compiled in accordance with the curriculum for the section

The materials presented in the manual meet the requirements of the qualification characteristics of graduates of the medical institute.

Gomel State

medical University,

MINISTRY OF HEALTH OF THE REPUBLIC OF BELARUS

GOMEL STATE MEDICAL

UNIVERSITY

Department of General Hygiene, Ecology and Radiation Medicine

TOPIC: HYGIENIC ASSESSMENT OF CLOTHING.

HYGIENIC METHODS FOR RESEARCHING MATERIALS FOR CLOTHING

Gomel, 2003

TOPIC: Hygienic assessment of clothing. Hygienic methods for studying clothing materials

Lesson time: 3 hours.

Motivational characteristics of the topic

Clothing serves to regulate the heat transfer of chalk and provides protection from adverse meteorological conditions, external pollution, and mechanical damage. Clothing remains one of the important means of human adaptation to environmental conditions. The properties of clothing largely depend on the properties of the fabrics.

As a result of the widespread introduction into everyday life of fabrics made from artificial and synthetic fibers, their combinations with natural fibers, new products have been created for the design of clothing.

Therefore, in the practical activities of the sanitary service, it is important to carry out a hygienic assessment of clothing.

The future hygienist must know the basic methods of hygienic assessment of clothing and methods for studying clothing materials.

Purpose of the lesson: study hygienic methods for studying clothing fabrics to develop recommendations for the use of fabrics for clothing for various purposes.

Tasks: master the methods and methods of hygienic examination of fabrics.

Requirements for the initial level of knowledge of students

To fully master the topic, the student must repeat from:

a) general chemistry - “Biogenic elements and their compounds as environmental factors.”

b) biophysics - “Thermodynamics, heat transfer”.

Test questions from related disciplines

1. The role of heat exchange processes between the body and the environment.

2. Methods for assessing a person’s functional state.

3. Clothing as an important means of human adaptation to environmental conditions.

4. Application of chemical research methods in clothing evaluation.

Test questions on the topic of the lesson

1. Hygienic importance of clothing for humans.

2. Basic hygienic requirements to the design, cut, thermal capacity, breathability and moisture permeability of clothing depending on its purpose.

3. Hygienic characteristics of fabrics made from synthetic fibers.

4. Hygienic requirements for individual parts of clothing (underwear, dresses, outerwear, hats).

5. Research methods and hygienic assessment of clothing fabrics. Hygienic examination of clothing.

Educational material on the topic:

Cloth - a product or a set of products worn by a person that has utilitarian and aesthetic functions. Assortment of clothing - clothing grouped into independent groups according to certain characteristics (purpose, materials, etc.)

Hygienic importance of clothing:

· to protect the skin from pollution and mechanical damage;

· protection from low temperatures, excessive radiation, precipitation and chemical damage;

· ensuring a comfortable thermal state by creating an optimal microclimate around the body;

· educational value of clothing: aesthetics, formation of taste.

Depending on the season, there may be summer, winter, demi-season, all-season clothing.

Depending on the age, clothes are allocated for a newborn, for children of the nursery group, preschool group, junior and senior school groups (junior - from 7 to 12.5 years old and boys, then 7 to 11.5 years old - for girls) clothes for children of the teenage group .

There are men's and women's clothing.

In connection with the various physiological characteristics of the body, the nature of the work performed and environmental conditions, household clothing is distinguished by purpose, casual, formal, home, work, industrial, special, national. Clothes can be mass-produced and custom-made, ready-made and semi-finished clothing.

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

The microclimate of the underwear space is the main parameter when choosing clothes, because... it determines a person’s thermal well-being.

Under clothing microclimate should be understood as a complex characteristic of the physical factors of the air adjacent to the surface of the skin. It is characterized by temperature, air humidity and CO 2 content. The temperature of the under-clothing space should be from 32-34 0 C, air temperature near the skin 24-32 0 C, humidity - 20-24%, carbon dioxide content - from 0.006 to 0.097%.

The properties of clothing largely depend on the properties of the fabrics. Fabrics must have thermal conductivity, sufficient breathability, hygroscopicity and moisture capacity, low gas absorption, and not have irritating properties. Fabrics must be soft, elastic, durable, and not change their hygienic properties during wear.

Depending on the purpose of the clothing, the requirements for fabrics are different. The weight of 1 m 2 of fabric is determined by dividing the weight of the sample by its area.

Breathability fabric depends on the number and volume of pores in the fabric, the nature of the fabric processing. At low air temperatures there should be minimal air permeability; for summer clothes, for example, there should be good air permeability in order to avoid overheating of the body. The air conductivity coefficient expresses the amount of air passing under constant pressure through a material at its natural thickness per unit of time (ml/cm 2 sec). Lowest air permeability region. ooooooooooo, canvas canvas, thick x 1 used fabric -< 50 л (м 2 С).

Hygroscopicity - the ability of tissues to absorb water in the form of water vapor from the air. The results are expressed in %, which characterize the ratio of the weight of the sample after testing to its constant weight obtained by drying.

Vapor permeability - calculated in mg/cm 3 hour, in relative % (reduction in the weight of cups of water covered with the test samples compared to an open vessel for a certain time (6 hours).

Thermal conductivity - the amount of heat per calorie passing in 1 s through 1 cm 2 of fabric when its thickness is 1 cm and the temperature difference on opposite surfaces is 1 0 C.

The thermal resistance of clothing was calculated using the formula:

Tk-To

R= ------------ - 0.15 m 2 deg/W

R- thermal resistance of clothing (shoes);

Tk- weighted average skin temperature;

That- t 0 outer surface of clothing

g- weighted average heat flux from the skin surface;

0.15 m 2 · deg/W - thermal resistance of air.

Skin temperature, heat flux density, is measured at the following points: forehead, hand, chest, thigh, lower leg, foot.

The weighted average skin temperature is calculated using the formula:

Ts.v.t.= 0.07T 0 forehead+ )0.5 T 0 breasts+ ),005 T 0 brushes + 0.18 T 0 hips +0.13 T 0 shin + 0.07T 0 feet.

A biothermal meter can be used to determine heat flows. Research using a heat meter is possible only in conditions where the main heat transfer from the body is carried out by radiation and convection.

A unit of thermal insulation is taken to be equal to 0.15 0 C m 2 /W or 1 ooooo i.e. a value that provides constant comfort to a sitting person whose heat production is 50 kcal/m 2 at T 0 air 21 0 C, relative humidity< 50 % и скорость движения воздуха 0,1м/с.

For a light dress, the thermal resistance value is 0.08 0 C m 2 /W,

for demisison clothing - 0.32 - 0.39 0 S m 2 /W,

for winter - 0.49 - 0.54 0 S m 2/W.

Objective studies of a person’s thermal state can be supplemented by a subjective assessment of their warmth

t 0 skin, C 0

28.0-29.0 cold

30-32.1 cool

32.2-33.2 comfort

33.3- 34.4 warm

34.5-35.5 very warm

35.6- 36.6 hot

The capillarity of materials is determined by their ability to absorb moisture from the surface of the skin. Determined by immersing 15 mm strips of material measuring 25 x 2.5 cm in tinted water and recording the height of the liquid rising through the capillaries of the material 3 t 1 hour/mm/hour. The degree of capillary rise of liquid is determined every 10 minutes.

The samples to be examined are kept for 24 hours in an unfolded form at an air temperature of 20±3 0 C and a relative humidity of 65±5%. Volumetric gravity is calculated by the formula by the ratio of weight and thickness (g/cm 3), porosity - by the ratio of volumetric gravity to specific (%) or the pore volume to the total volume of the sample.

P 0 · 10

D= ---------,

D- volumetric mass g/cm 2, R O- weight of 1 cm 2 fabric, J- fabric thickness,oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooolong it had a volumetric mass of 0.6 - 0.7 g/cm2, wool - 0.07 g/cm3 and below.

Fabrics made from artificial and synthetic fibers are now widely used. Chemical fibers are divided into artificial and synthetic. Artificial fibers - viscose, synthetic - lavsan, cashmilon, chlorine, vinyl, etc.

The positive properties of chemical fibers are high elasticity, wear resistance, antimicrobial properties, good breathability, high heat-shielding properties.

Negative properties include primarily:

The ability of tissues to accumulate electricity;

Low sorption properties;

May release harmful substances (monomers, etc.)

Increase the humidity of the underwear space.

The electrification capacity of polymer materials is determined by the strength of the electrostatic field without rubbing and when rubbing the surface of the sample and is expressed in KV/cm.

Measurements are carried out using existing instruments. An experimental and control sample is examined in laboratory conditions and in real use (test wear). If the charge value exceeds the permissible value by 1.5-2 times, then antistatic treatment cannot be considered effective.

Synthetic fibers - products obtained from monomers by chemical synthesis.

Man-made fibers- products obtained from natural materials or products of their transformation.

Hygienic safety of fibers - absence of migration from finished products into the environment (air, model environments) of monomers and other chemical ingredients of synthesis in quantities exceeding regulated values, as well as toxic, irritating, sensitizing, carcinogenic, mutagenic or other adverse effects on health when intended use.

Hygienic assessment of clothing made from synthetic fabrics, including natural sanitary-chemical studies, laboratory studies of physical properties, toxicological studies, physical studies in natural conditions, studying the reaction of human skin, mass experimental wear.

Clothing consists of several layers, each of them must fully meet its purpose.

Underwear (the first layer of clothing) should contribute to the normal functioning of the skin, cleanse the skin of microflora secretions and protect the dress from contamination. Linen has a direct impact on the temperature of the skin and the layer of air adjacent to it. Fabrics must be air- and vapor-permeable, hygroscopic, moisture-absorbing, soft, and elastic.

The best fabrics for linen are cotton, can be made of natural fur, linen, and for winter linen - wool. Wool underwear is worn over a layer of fine linen. As for synthetics, only viscose knitwear can be used.

A dress (the second layer of clothing) in the warm season should help transfer heat into the cold season - retain heat.

In summer, it is better to use cambric, chintz, and natural silk in light colors, which have good air and vapor permeability. Synthetic fibers are now widely used.

In winter, woolen and half-woolen fabrics and corduroy are used. Additions of viscose-lavsan yarn are allowed (up to 30%).

Woolen winter clothes should be aired once a week, brushed, and washed when dirty.

Outerwear is designed to retain heat and protect from precipitation. Warmth is retained by the still air under clothing and by the clothing's thermal permeability. To ensure low air mobility, outerwear can be windproof, slightly breathable and sufficiently sealed. A mandatory requirement is lightness and comfort of fit.

Clothing that meets the following requirements deserves a positive hygienic assessment:

1. Clothing should not be a source of odor or release of harmful chemical compounds that are hazardous to health.

2. The hygienically important physical properties of clothing (sorption, heat-protective, electrostatic, etc.) should ensure the optimal condition of the body.

3. The electrostatic field strength on the surface of products should be no higher than 0.3 sq/cm.

4. Each layer of clothing must meet its purpose.

5. Caring for all layers of clothing (washing, cleaning, dry cleaning) should ensure their complete sanitation.

6. Clothing must be chemically stable and meet all hygienic requirements.

7. Polymer shoe materials and products made from them should not have a specific odor or emit environment biologically active chemical substances, accumulate static electricity.

To conduct a hygienic assessment of textile materials and products made from them, the institution conducting the research must be provided with the following information:

1. Chemical and trade name of the fiber or material.

2. On the basis of which GOSTs, MRTUs and TUs the presented samples are manufactured.

3. Description of the technological process indicating the chemical compounds used.

The number of samples depends on the volume of research. To carry out the full scope of hygienic studies, it is necessary to submit:

a) for sanitary-chemical, toxicological and physiological studies - 8 m 2 of toxic material;

b) for physiological methods in natural conditions, the number of products should not be< 10;

c) in cases where the results of field studies play a decisive role (studying the influence of climatic conditions, individual sensitivity, etc.), it is necessary to provide field studies of 80-100 oooooooooooo;

4. Extract from the technical specifications indicating the physical and chemical properties of the starting ingredients and materials.

5. Production technology.

6. Name of the institution - manufacturer.

7. Description of methods for determining the initial volatile components of the material in air and water.

The hygienic assessment of clothing begins with sanitary and chemical studies.

The goal is:

1) detection of possible release of harmful substances into contacting media;

2) study of the intensity and dynamics of their migration;

3) predicting the degree of their adverse effect on the body.

The sanitary and climatic assessment provides for:

Organoleptic studies of model environments - air and extracts (smell, taste and taste) in contact with fiber;

Studying the degree of migration from fiber to air and model liquids of chemical substances using integral methods (oxidability, bromination, pH of extracts);

Determination of residual quantities of initial synthesis products, additive technology.

In order to determine the migration of chemicals into the air, the samples under study are placed in closed containers - desiccators, from which, after certain exposures, air samples are taken using an electric aspirator device, taking into account 6-10 times the air exchange of the container. Exposure duration is usually 3 days.

Analysis of the air in contact with the test samples must be carried out immediately after production, after 1, 3, 6 months of storage under conditions of free access to air. Temperature conditions are determined by the operating conditions of this type of clothing.

The determining role of hygienic requirements for clothing 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, it is necessary to highlight four main hygienic functions that must be provided in the clothing used by a person:

1) protection from mechanical, chemical and biological influences;

2) protection from unfavorable climatic elements;

3) keeping the human body clean;

4) ensuring the normal functioning of the body.

The first function is decisive for the special one,

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

In accordance with Labor Code The Republic of Belarus (Article 230) provides for the provision of workers with personal protective equipment, including special clothing. This takes into account work with harmful, dangerous working conditions (exposure to toxic fumes, radiation, acids, alkalis, metal splashes, etc.), as well as work associated with pollution or carried out in unfavorable temperature conditions. At the same time, the procedure and standards for the free issuance of personal protective equipment to employees are determined by the Government of the Republic of Belarus.

The second function requires protecting 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 areas and the need to take them into account when creating clothing.

Currently, the following division of the CIS territory into climatic zones is accepted:

Zone I - a territory with a climate that requires high-quality fur clothing and insulated shoes;

Zone II - a territory with a climate that requires normal, but always heat-protective natural materials, fur clothes and insulated shoes;

Zone III - a territory with a climate that requires mainly warm clothing and a variety of footwear;

Zone IV - a territory with a climate that requires more clothing and footwear to protect against dampness and precipitation;

Zone V - a territory with a climate that requires increased attention to clothing and footwear for protection human body from overheating.

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

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

1) protecting a person from excessive heat transfer;

2) compliance of the thermal insulation properties of clothing with human physical activity and climatic conditions in which it is expected 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 slight cooling is acceptable, which stimulates physical activity, reduces fatigue and promotes hardening of the body.

Since clothing to protect against the cold is different, great importance have the properties of individual materials that make up the product design package. In this case, it is extremely important to take into account the expected operating conditions and the heterogeneity of heat flows in individual areas of the human body.

Relative specific heat fluxes in different parts of the human body, W/m2

	Physical activity	Part of the body
			torso
	Rest (standing)
Room	Rest (standing) Walking
Winter coveralls	Rest (standing)
Winter coat	Rest (standing) Walking

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

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

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

At wind speeds of up to 2 m/s, the air permeability of the bag is in the range of 0-60 dm 3 / (m 2 s) practically does not affect its thermal insulation properties. At higher wind speeds, the influence of the air permeability index on the thermal resistance of clothing material packages 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 toiletries, etc.

The fourth function is aimed at the optimal functioning of the body in the person-product-environment system. IN in general terms the implementation of this function is manifested in ensuring three indicators of the underclothing (between the human body and clothing) microclimate within optimal limits: 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 divided into two areas:

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

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

Hygienic requirements for clothing are differentiated depending on its purpose and operating conditions. IN general view they boil down to this:

1) the heat-protective properties of clothing must correspond to human activity and the environmental conditions in which it is used. Therefore, this property of clothing must be regulated;

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

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

4) clothes should be soft and light;

5) the design of clothing should allow a person to perform various movements, be easy to put on and take off, and not restrict 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 made from them:

♦ chemical stability of materials and substances;

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

♦ clothing made from synthetic materials should not be toxic or cause irritation skin.

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

For characteristics static electricity arising on materials, the sign of the appearing charges matters. Thus, most chemical fibers, with the exception of viscose, are negatively electrified.

The most important factor on which the ability of materials to accumulate charges depends is chemical nature fibers Thus, 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 treatment 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 classified as environmental factors that are not indifferent to human health. There is evidence of the potential for negative effects of static electricity. Persons exposed to a static electric field sometimes complain of a deterioration in their general health, headaches, sleep disturbances, and pain in the heart area.

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, the 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 a constant human body temperature (up to 37 °C). The temperature range of the organism's existence 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 based on the selection of rational clothing can active human activity and a constant rate of metabolic processes in the body be achieved.

In the person-product system, the most important properties are those that ensure cleanliness of the skin, underwear, and the product itself. Water, carbon dioxide, salts, and fatty substances are released 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), which softens the surface of the skin and protects it from drying out, wetting, and the penetration of microbes. When you sweat, water and salts are removed from the body. On average, all sweat glands (there are several million of them) 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 released per week. Therefore, clothing, especially underwear, must absorb them, thereby ensuring cleansing of the skin from the boundary layer and retaining secretions until the product is cleaned. Naturally, the product itself becomes contaminated.

Structure of substances contaminating laundry

Requirements in in this case look twofold and contradictory. On the one hand, it is necessary to clean the skin, which is only possible by absorbing secretions; on the other hand, contamination of the product is undesirable. High contamination dramatically changes a number of properties of clothing made from fabrics, especially knitted products. Thus, underwear contaminated with liquid and dense skin secretions are 20% less breathable, their weight increases on average by 10%, thickness by 25%, ash content by 4 times, and thermal conductivity also increases. All this worsens a person’s comfortable condition, complicates gas exchange with the external environment, promotes the development of microorganisms, and worsens appearance, leads to an increase in labor and economic costs for operating the product (washing, cleaning).

The skin also participates in gas exchange. In a calm state, skin respiration (oxygen absorption and carbon dioxide release) accounts for about 1% of the total gas exchange. During the day, about 4.5 liters of carbon dioxide are released through the surface of the skin and 1.9 liters of oxygen enters. An increase in air temperature and heavy physical work increase the intensity of gas exchange through the skin several times, bringing it to 10% of pulmonary gas exchange. The work of physiologists has shown that when there is more than 0.07% carbon dioxide in the under-clothes space, gas exchange through the skin, and, consequently, a person’s well-being deteriorates. Carbon dioxide concentrations greater than 0.1% cause fainting. If the partial pressure of nitrogen under clothing is higher than in the environment, then it is absorbed into the blood, which is unsafe for the body. Therefore, it is necessary to provide ventilation of the underwear space in clothing.

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

Children's bodies are in a state of constant growth and development, bone differs in flexibility and elasticity, muscles are poorly developed. Muscle mass in relation to body weight is 27.2% in an 8-year-old child, and 44.2% in an 18-year-old boy.

Children's muscles are richer in water, but poorer in proteins, fats, and inorganic substances, as a result of which they become tired more quickly in children than in adults.

Children have thinner, more delicate skin compared to adults. They have a less perfect thermoregulation apparatus: heat transfer is increased due to changes (with age) in the relationship between the surface of the body and its mass. In an adult, per 1 kg of mass there is 221 cm 2 of body surface, in children 15 years old - 378 cm 2, in children 10 years old - 423 cm 2, in a child 6 years old - 456 cm 2, in a newborn - 707 cm 2. The 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 external temperature.

Blood circulation in children also occurs faster. So, in an adult, 1/3, and in children, 1/2 or even 2/3 of the total blood flows through the thickness of the skin. 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 he produces is given off by evaporation of water vapor released through the skin. Children spend most of their time on the move, and the level of heat production increases by 2-4 times, so the amount of evaporating moisture is very significant. At high air temperatures, active sweating begins and almost all excess heat is removed from the body by evaporation of fluid from the surface of the body.

In children younger age all physiological systems that maintain a constant temperature of the internal environment and maintain thermal balance are underdeveloped. Changes in unfavorable meteorological factors affect a child’s body more sharply than on an adult’s body.

Clothing protects the human body from unfavorable environmental conditions and, above all, ensures optimal thermal condition. Hygienic requirements for clothing are developed taking into account climatic (or microclimatic) conditions and the nature of human activity.

The hygienic characteristics of clothing as a whole depend largely on the quality of the materials used in its manufacture. When carrying out a hygienic examination of fabrics intended for the manufacture of children's clothing, the nature of the fibers and the structure of the fabric are determined (a description of the structure of the fabric is given - knitted, woven, etc.), the weight of the fabric, volumetric weight and thickness, air permeability, vapor permeability, hygroscopicity, maximum and minimal water retention, wettability, capillarity. All clothing research is carried out on both unwashed and washed materials.

When carrying out experimental wear of clothing, its physicochemical and chemical properties are repeatedly examined (2-4 times), and indicators characterizing the thermal state of children and their heat sensation are systematically recorded.

When evaluating fabrics and clothing using polymeric materials, laboratory studies are carried out using special methods to establish that clothing is not a source of release of harmful chemical compounds that are potentially hazardous to health, and its properties such as sorption, electrostatic, etc. do not reduce the optimal condition body. In particular, the electrostatic field strength on the surface of products should not exceed 0.3 kV/cm2.

Particularly important in the hygienic assessment of clothing are physiological and hygienic studies conducted in natural conditions and aimed at studying the functional indicators of the child’s body. In such conditions, the heat-protective properties of clothing are studied.

Currently, control over the release of new samples of children's clothing is based on the following regulatory documents: “Hygienic requirements for children’s clothing” (guidelines), M., 1981 and “Guidelines for the hygienic assessment of clothing and footwear made of polymeric materials” No. 1353 -76, M., 1977. The study is carried out according to the following scheme:

1. Basic hygienic requirements for children's clothing.

2. Features of sanitary supervision over the production of children's clothing using chemical materials.

3. Determination of the thermal resistance of clothing.

Assessment of laboratory research data on physical and mechanical parameters characterizing fabrics and fabric “packages” Assessment of the heat-protective properties of children's clothing. When assessing the heat-protective properties of clothing, you can use observation of some general reactions of the body. This is the determination of the amount of energy expenditure, the amount of sweat produced, counting the pulse rate, breathing, etc. When considering the heat-protective properties of clothing, a subjective assessment of these properties is also important - a verbal report of well-being. However, the most complete picture of the thermal insulation properties of clothing is provided by studying the body’s energy consumption, changing the value of skin temperatures and studying the heat flux density.

It should be emphasized that the study of a child’s thermal state is necessary when solving a number of hygienic problems: standardizing the microclimatic parameters of various premises, studying working conditions, medical monitoring physical education and hardening and hygienic standardization of the heat-protective properties of clothing.

The amount of heat lost by radiation and convection per unit time is proposed to be called heat flow.

The heat flux per unit surface area is called the heat flux density.

The thermal protective ability of clothing should be called its ability to reduce the density of heat flux. Heat flow reacts very clearly to changes in the environment and the heat-protective properties of clothing. Knowing the amount of heat transfer, as well as the weighted average temperature of the skin and meteorological environmental factors, it is possible to calculate the resistance that this clothing provides to heat transfer from the body under certain conditions, i.e., a quantitative assessment of the thermal properties of clothing is possible.

It is known that the cooling rate of a heated body is proportional to the temperature difference between the body and the environment and the size of the body surface. When determining the heat-protective properties of clothing, the formula is used for calculation (A. Barton, G. M. Kondratyev):

I 0 =-------------------Iв

where I 0 is the thermal resistance of clothing; Iв - thermal air resistance of the under-clothes space; T - weighted average body surface temperature; t B -

Ambient temperature; H - weighted average value of heat flux density in kcal/m 2 -hour

The conversion factor to SI units (W/m2) is 0.86.

Thermal resistance of clothing (10) is directly proportional to the temperature gradient of the surface of the skin and air and inversely proportional to the heat flux density. The total thermal resistance 1sum consists of the thermal resistance of the clothing itself L, and the air resistance of the under-clothing space 1B and is expressed in the following units: °C-m2-hour/kcal or in SI units - °C m2/W.

The most modern devices that make it possible to measure the magnitude of heat flows, as well as the surface temperature of individual parts of the body, are biothermal meters - devices designed to study the thermal state of a person. It is used to measure body surface temperature (skin temperature) in degrees Celsius, in the range from 16 to 40 ° C, and heat flow from the body surface.

The bioheat meter consists of 2 parts: a set of 6 combined “thermocouple - heat meter” sensors and a potentiometer recording device, specially calibrated for measuring small EMF and obtaining in degrees Celsius or kilocalories. The sensors are connected to the potentiometer via a special connector. Each sensor is a box measuring 20X20X40 mm made of organic glass, inside of which a thermocouple and a thermopile made of copper-constatan junctions are placed. The thermocouple is designed to measure skin temperature, the thermopile is designed to measure heat flow. All heat measuring sensors (thermopiles) are pre-calibrated.

The sensors of the device are attached to the child’s body with elastic bands according to the measurement points and secured. The sensor connector is led out through all layers of clothing. Thus, measurements can be repeated for different types of activities.

Both the weighted average skin temperature and the weighted average heat flux density are determined taking into account the relative size of the body surface areas on which the device sensors are located. To do this, the value of the heat flow (device readings) must be multiplied by the surface coefficient, which determines the proportion of a given surface (head, torso, etc.) relative to the total surface of the body.

To determine the weighted average value of heat flow, measurements are taken at 9-11 points on the skin surface.

Hg is the heat flux density of the head surface; surface coefficient 0.06; the sensor is attached to the middle of the forehead;

Npt - heat flux density of the front surface of the body (neck, chest, abdomen); surface coefficient 0.2; the sensor is attached on the chest near the nipple, on the stomach - near the navel;

Нзт - heat flux density of the rear surface of the body; surface coefficient 0.18; the sensor is mounted on the back on the right under the shoulder blade, on the lower back - to the left of the spine;

Нп - heat flux density of the shoulder surface; surface coefficient 0.035; the sensor is mounted on the outer surface of the left shoulder;

Npr - heat flux density of the forearm surface; surface coefficient 0.025; the sensor is mounted in the middle outer surface right forearm;

Hk - heat flux density of the brush; surface coefficient 0.0225; the sensor is attached to the dorsum of the hand;

But is the heat flux density of the thigh; surface coefficient 0.1025; the sensor is attached to the outer surface of the right thigh;

Hgl - heat flux density of the lower leg; surface coefficient 0.0625; The sensor is attached to the outer surface of the left shin.

Note - heat flux density of the foot; surface coefficient 0.0325; The sensor is attached to the dorsum of the foot.

Chapter 6. BASIC PRINCIPLES OF DESIGNING SPECIAL CLOTHING AND ASSESSING ITS QUALITY

Special clothing that provides protection from hazardous and harmful production factors must meet ergonomic, operational and aesthetic requirements. In practice, one often encounters contradictions between these requirements.

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

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

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

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

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

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

The quality of special clothing for workers in specific professions is largely determined by knowledge of working conditions. When studying the working conditions of workers, first of all, pay attention to the following: the nature of production factors and the degree of their impact (over the entire surface or in local areas); the severity of the work performed; characteristic movements; meteorological conditions (temperature and humidity, wind speed); work and rest schedule; standard service life (in accordance with the standards for the free issuance of workwear, safety shoes and safety equipment); aesthetic requirements (color scheme, compliance with the industrial interior of the enterprise).

Taking into account all these factors, special clothing is developed. For example, in accordance with meteorological data, the intensity of physical work, and the time spent at the workplace, materials are selected and a clothing design is developed that provides normal conditions for human heat exchange in production. In accordance with the nature of production factors and human movements, materials are selected and a clothing design is developed that provides the necessary protection from these factors and freedom of movement. The selected materials and design also determine the wear time of special clothing and a person’s performance.

Materials are selected in such a way that they best meet the protective, operational and ergonomic requirements. To do this, in laboratory conditions, along with protective properties, indicators such 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 areas of the human figure is determined depending on the nature of movements during work. An analysis of the movements of workers in various industries showed that when performing basic (characteristic) movements, the values ​​of the leading dimensional features of the human figure change significantly.

Based on the dynamic increase in measurements when designing products, a general allowance for loose fitting and its distribution over the main structural sections are established. At the same time, the properties of the selected materials are taken into account: rigidity, drapability, weight, which to a large extent determine the ergonomic properties of workwear. Improving these properties of workwear in last years much attention is paid. Naturally, any protective clothing to some extent limits 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. In this case, the clothing, in turn, undergoes a number of changes: as it moves, it slides relative to the human body until increasing tangential resistance forces cause the clothing to stretch, bend or shrink. When deformed, clothing acts with varying force on parts of the human body (presses on his body). Therefore, it is necessary to create such a design of workwear that would enable the worker to carry out various movements with the greatest scope with minimal expenditure of physical energy.

The degree of ergonomic perfection is assessed by 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 strength and energy capabilities of a person. In particular, the materials from which workwear is made must have the minimum possible bending rigidity and maximum elasticity so that efforts to overcome the resistance of clothing do not cause increased human fatigue.

Psychophysiological indicator of the quality of workwear (Evaluates its compliance with the peculiarities of the functioning of human senses: visual, auditory, tactile, olfactory, kinestatic (muscular), etc. For example, clothing with a hood or helmet should not reduce a person’s hearing threshold or reduce his field of vision For a number of professions (hunters, security guards, etc.), the use of materials that produce rustling or creaking noises when moving is not allowed.The increased mass of the product and its uneven distribution over the surface of the human body cause a feeling of pressure, abrasion of the skin, etc.

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

The psychological indicator characterizes the ease of use of individual elements of workwear, the ease of putting it on and taking it off, and the correspondence of the color of the product to the capabilities of a person’s color vision. Taking this into account, when designing workwear, the ease of use of pockets and other structural elements for placing the necessary work items 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 quick removal if necessary. The color of the material from which the workwear should 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 must be such that in emergency situations it will be possible to detect a person in a short time.

To assess the ergonomic properties of workwear, the TsNIISHP has developed and uses anthropodynamic stands for various types of products, a microclimatic chamber, various medical devices, etc. At the anthropodynamic stands, comprehensive studies of different types of workwear (jackets, trousers, overalls) and hand protection equipment (mittens, gloves)

If 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, as is known, is made from materials of increased surface density, thickness and rigidity to provide protection to workers from sparks and splashes of molten metal. As it turned out during the study, the developed classic design of the set-in sleeve exposes the welder’s hand to a significant load (over 5 N). To identify the possibility of reducing this load, studies were carried out on jackets, manufactured materials of different surface density, stiffness and sleeve design.

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

Research carried out at TsNIISHP using 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 design parameters, has passed production tests and received positive feedback 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 such structural elements include folds and elastic inserts. Their introduction into the design makes it possible to reduce the allowance for a loose fit without reducing the ergonomic level while simultaneously improving aesthetic properties (Fig. 6.1). The depth of the folds and the size of the elastic inserts should be determined depending on the dynamic increase in dimensional characteristics; those areas of the body where inserts or folds are provided when workers perform certain movements. In table 6.2 shows the ergonomic indicators of overalls of various design solutions.

As can be seen from table. 6.2, overalls with elastic inserts and with folds on the back are more advanced from an ergonomic point of view, which is confirmed 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.

At objective assessment the functional state of the human body dressed in the clothing being tested, the following indicators are used: hand muscle strength and muscle endurance before and after the experiment; dynamics of heart rate immediately after finishing work; restoration of heart rate after the end of periods of work during the experiment; the degree of human fatigue based on changes in the performance index when performing a step test; an indicator of a person’s thermal state; skin and body temperature; energy consumption; moisture loss.

Jumpsuits 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 work and the dynamics of their recovery after work. These indicators correlate well with the subjective feelings of the subjects.

The hygienic quality indicator of workwear is the most important ergonomic criterion. The ergonomic perfection of workwear can be judged by hemodynamic indicators (heart rate, blood pressure), performance, state of the central nervous system, thermal state criteria. For example, the comfort of jackets with sleeves of various cuts can be judged by heart rate (Table 6.3).

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

The dependence of the heart rate of a person in protective clothing 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, determined by assessing the time a person performs movements and the accuracy of coordination of these movements.

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

When ergonomically assessing the quality of workwear design, methods are used to determine muscle strength and endurance of the right and left arms before and after the experiment. Thus, a subject wearing a jacket with a loose-fitting increase of 5 cm in the chest area and with raglan sleeves, there is a significant decrease in the muscle strength of the hand (up to 30%) after physical exercise, and in the case of a loose-fitting increase

11 cm, other things being equal, no changes in muscle strength are observed.

Dependence of heart rate on the weight of workwear

Workwear	Pulse, beats per minute, after physical work for, min
	1	2	3
Sample 1 weighing X kg	132	120	114
Sample 2 weighing (dg+2) kg	141	135	129

The pressure of clothing on the human body is one of the most important indicators, determining the level of its ergonomic perfection. This indicator may vary depending on the intended product. So, for trousers such as jeans it is 150-170 kPa, for special-purpose overalls it is 70 kPa. At the same time, it must be borne in mind that special clothing, while exerting pressure on the human body during operation, should not cause skin irritation, rashes, or abrasions.

As we know, in recent years the production of synthetic threads and fibers, and consequently, materials made from them, has been growing all over the world. Materials made from synthetic fibers have many positive properties: durability, dimensional stability, ease of maintenance and high level 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, rapid contamination. In addition, some chemical fibers are characterized by insufficient chemical stability. A significant disadvantage of hydrophobic chemical fibers is their high electrification ability, which negatively affects human well-being.

In this regard, a problem arose related to elucidating the influence of the fibrous composition of materials on the microclimate under clothing and determining the optimal mixture of synthetic and natural fibers. The latter allows you to combine the positive properties of fibers and compensate for their shortcomings.

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

Another direction related to improving the hygienic properties of synthetic fibers is their chemical and physical modification, which contributes to changes in hygroscopicity, antistatic properties, 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 due to the hydrophobicity of synthetic fibers and their high thermal conductivity. Therefore, replacing natural fibers with synthetic ones leads to a deterioration in the hygienic properties of clothing due to a disruption, first of all, of the body’s heat metabolism.

The deterioration of the hygienic properties of clothing made of synthetic materials increases with changes in human physical activity, under uncomfortable microclimatic environmental conditions, which leads to a decrease in human performance.

S. M. Gorodinsky and other researchers have established that with an optimal thermal state, in 1 hour of performing work of moderate severity, a person’s performance decreases by 2.2-3.8%, with an acceptable thermal state - by 5-8.1%, with a maximum 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 that would include the positive properties of both components, and materials from them would have minimal impact on the thermal state of a person.

Research has been carried out at TsNIISHP to establish hygienic regulations for the permissible inclusion of synthetic fibers in a various range of materials for workwear. These studies are based on assessing the thermal and functional state of a person during the use of clothing made from materials with different physical and hygienic properties. Experience in using workwear made from the same materials has shown that a person’s thermal state varies 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 provides a list of the materials from which samples of workwear were made. In accordance with the methodology of physiological and hygienic assessment of the quality level used at the Central Scientific Research Institute of Shipping, comparative studies were carried out on samples of workwear made from materials of different fibrous compositions.

When using clothing both from natural fibers and from a mixture with the inclusion of synthetic fibers in normal

conditions when performing work of light and moderate severity categories, no significant difference in the increase in stress of the functional systems of the human body was revealed. A slight deterioration in a person’s thermal state is observed only when performing work with a high level of energy consumption in products made from mixed fabrics containing more than 50% polyester fiber.

The most significant difference was obtained in the study of workwear made from mixed fabrics (with the input of “synthetic fibers more than 50%), used in conditions of a moderately heating microclimate at an ambient temperature of 30±5°C and performing physical work of varying severity. This is clearly seen when comparing indicators of a person’s condition that characterize the rate of moisture loss. The efficiency of moisture evaporation determines the moisture-conducting function of clothing and the rationality of its design.

Thus, in the case of light physical activity at an air temperature of 30...35°C, in gowns made of mixed fabrics with 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 workwear 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 made from a mixture containing 67% polyester fiber).

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

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

Results of physiological and hygienic assessment of workwear used when performing heavy physical work

energy consumption of 300 W), show that when working in workwear made of material containing 67% synthetic fibers, the rate of heat accumulation increases by 44% compared to products made from 100% cotton. Consequently, for those working in suits made from the specified mixed fabrics, the tension in the thermoregulatory system will increase almost 1.5 times, and therefore fatigue.

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

Physiological and hygienic studies carried out at the Central Scientific Research Institute of Shymbols have established that in workwear made of mixed fabrics containing more than 50% synthetic fibers, the air temperature and relative humidity under clothing do not decrease during rest periods, which increases the rate of human fatigue.

Thus, based on the research carried out at the Central Scientific Research Institute of Shipping, it was concluded that the use of mixed fabrics for the manufacture of workwear 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, operational and aesthetic properties of workwear.

Indicators of the functional state of a person in special clothing when performing light, moderate and heavy work are presented in Table. 5, 6, 7 applications.

General hygiene: lecture notes Yuri Yurievich Eliseev

Clothing hygiene

Clothing hygiene

Important integral part personal hygiene is clothing hygiene.

According to F. F. Erisman, clothing is a kind of ring of protection from unfavorable natural conditions, mechanical influences, protects the body surface from contamination, excessive solar radiation, other unfavorable factors in the domestic and work environment.

Currently, the concept of a clothing package includes the following main components: underwear (1st layer), suits and dresses (2nd layer), outerwear (3rd layer).

According to the purpose and nature of use, clothing is distinguished between household, professional (working clothing), sports, military, hospital, ritual, etc.

Everyday clothing must meet the following basic hygiene requirements:

1) provide an optimal microclimate under clothing and promote thermal comfort;

2) do not impede breathing, blood circulation and movement, do not displace or squeeze internal organs, do not disrupt the functions of the musculoskeletal system;

3) be strong enough, easy to clean from external and internal contaminants;

5) have a relatively small mass (up to 8-10% of a person’s body weight).

The most important indicator of the quality of clothing and its hygienic properties is the microclimate under clothing. At an ambient temperature of 18-22 °C, the following parameters of the underwear microclimate are recommended: air temperature - 32.5-34.5 °C, relative humidity - 55-60%.

The hygienic properties of clothing depend on a combination of a number of factors. The main ones are the type of fabric, the nature of its manufacture, and the cut of the clothing. Various fibers are used to make fabric - natural, chemical, artificial and synthetic. Natural fibers can be organic (plant, animal) and inorganic. Plant (cellulosic) organic fibers include cotton, flax, sisal, jute, hemp and others; organic fibers of animal origin (protein) include wool and silk. Inorganic (mineral) fibers, such as asbestos, may be used to make some types of workwear.

In recent years, chemical fibers, which are also divided into organic and inorganic, have become increasingly important. Main fiber group chemical origin constitute organic. They can be artificial and synthetic. Artificial fibers include viscose, acetate, triacetate, casein, etc. They are obtained by chemical processing of cellulose and other raw materials of natural origin.

Synthetic fibers are obtained by chemical synthesis from oil, coal, gas and other organic raw materials. Based on their origin and chemical structure, heterocidal and carbocidal synthetic fibers are distinguished. Heterocides include polyamide (nylon, perlon, xylon, etc.), polyester (lavsan, terylene, dacron), polyurethane, carbicides include polyvinyl chloride (chlorin, vinol), polyvinyl alcohol (vinylon, kuralon), polyacrylonitrile (nitron, orlon ).

The hygienic advantages or disadvantages of certain fabrics primarily depend on the physicochemical properties of the original fibers. The most important hygienic values ​​of these properties are air and vapor permeability, moisture capacity, hygroscopicity, and thermal conductivity.

Air permeability characterizes the ability of a fabric to pass air through its pores, which determines the ventilation of the underwear space and the convection transfer of heat from the surface of the body. The breathability of a fabric depends on its structure, porosity, thickness and degree of moisture. Breathability is closely related to the fabric's ability to absorb water. The faster the pores of a fabric fill with moisture, the less breathable it becomes. When determining the degree of air permeability, a pressure of 49 Pa (5 mm water column) is considered standard.

The air permeability of household fabrics ranges from 2 to 60,000 l/m2 at a pressure of 1 mm of water. Art. According to the degree of breathability, windproof fabrics are distinguished (air permeability 3.57-25 l/m2) with low, medium, high and very high air permeability (more than 1250.1 l/m2).

Vapor permeability characterizes the ability of a fabric to pass water vapor through its pores. Absolute vapor permeability is characterized by the amount of water vapor (mg) passing through 2 cm 2 of fabric within 1 hour at a temperature of 20 ° C and a relative humidity of 60%. Relative vapor permeability is the percentage ratio of the amount of water vapor passing through the fabric to the amount of water evaporating from an open vessel. For different fabrics this figure varies from 15 to 60%.

Evaporation of sweat from the surface of the body is one of the main ways of heat transfer. Under conditions of thermal comfort, 40-50 g of moisture evaporates from the surface of the skin within 1 hour. Sweat production of more than 150 g/h is associated with thermal discomfort. Such discomfort also occurs when the steam pressure in the underwear space is above 2 GPa. Therefore, good vapor permeability of the fabric is one of the factors in ensuring thermal comfort.

Removal of moisture through clothing is possible by diffusion of water vapor, evaporation from the surface of moistened clothing, or evaporation of sweat condensation from layers of this clothing. The most preferred way to remove moisture is the diffusion of water vapor (other ways increase thermal conductivity, reduce air permeability, and reduce porosity).

One of the most hygienically important properties of fabric is its hygroscopicity, which characterizes the ability of fabric fibers to absorb water vapor from the air and from the surface of the body and retain it under certain conditions. Wool fabrics have the greatest hygroscopicity (20% or more), which allows them to maintain high heat-protective properties even when moistened. Synthetic fabrics have minimal hygroscopicity. An important characteristic of fabrics (especially used for the manufacture of linen, shirts and dresses, and towels) is their ability to absorb droplet-liquid moisture. This ability is assessed by tissue capillarity. The highest capillarity is for cotton and linen fabrics (110-120 mm/h or more).

Under normal temperature and humidity conditions, cotton fabrics retain 7-9%, linen - 9-11%, wool - 12-16%, acetate - 4-5%, viscose - 11-13%, nylon - 2-4%, lavsan – 1%, chlorine – less than 0.1% moisture.

The thermal protective properties of a fabric are determined by its thermal conductivity, which depends on its porosity, thickness, the nature of the weave of fibers, etc. The thermal conductivity of fabrics characterizes thermal resistance, to determine which it is necessary to measure the amount of heat flow and skin temperature. The density of the thermal cover is determined by the amount of heat lost from a unit of body surface per unit of time, by convection and radiation with a temperature gradient on the outer and inner surface of the tissue equal to 1 °C, and is expressed in W/m2.

As a unit of the heat-protective ability of fabric (the ability to reduce the density of heat flow), the value clo (from the English clothes - “clothing”) is adopted, which characterizes the thermal insulation of indoor clothing equal to 0.18 ° C m / 2 h / kcal. One unit of clo provides a state of thermal comfort if the heat generation of a quietly sitting person is approximately 50 kcal/m 2 h, and the surrounding microclimate is characterized by an air temperature of 21 ° C, a relative humidity of 50%, and an air speed of 0.1 m/s.

Wet fabric has a high heat capacity and therefore absorbs heat from the body much faster, contributing to its cooling and hypothermia.

In addition to those listed, fabric properties such as the ability to pass through are of great hygienic importance. ultraviolet radiation, reflect visible radiation, the time of evaporation of moisture from the surface of the body. The degree of transparency of synthetic fabrics for UV radiation is 70%; for other fabrics this value is much less (0.1-0.2%).

The main hygienic advantage of fabrics made from natural fibers is their high hygroscopicity and good air conductivity. That is why cotton and linen fabrics are used to make linen and linen products. The hygienic advantages of woolen fabrics are especially great - their porosity is 75-85%, they have high hygroscopicity.

Viscose, acetate and triacetate fabrics, obtained by chemical processing of wood cellulose, are characterized by a high ability to sorb water vapor on their surface; they have high moisture absorption. However, viscose fabrics are characterized by prolonged evaporation, which causes significant heat loss from the surface of the skin and can lead to hypothermia.

Acetate fabrics are similar in properties to viscose. However, their hygroscopicity and moisture capacity are significantly lower than those of viscose, and when they are worn, electrostatic charges are formed.

Synthetic fabrics have attracted particular attention from hygienists in recent years. Currently, more than 50% of clothing types are made using them. These fabrics have a number of advantages: they have good mechanical strength, are resistant to abrasion, chemical and biological factors, have antibacterial properties, elasticity, etc. The disadvantages include low hygroscopicity and, as a result, sweat is not absorbed by the fibers, but accumulates in air pores, impairing air exchange and the heat-protective properties of the fabric. At high temperature The environment creates conditions for overheating of the body, and when it is low, for hypothermia. Synthetic fabrics have 20-30 times less ability to absorb water than woolen fabrics. The higher the moisture permeability of the fabric, the worse its heat-protective properties. In addition, synthetic fabrics are capable of retaining unpleasant odors and are less washable than natural ones. Destruction of fiber components due to their chemical instability and migration of chlorine compounds and other substances into the environment and underwear space are possible. Migration, for example, of formaldehyde-containing substances continues for several months and can create a concentration several times higher than the maximum permissible concentration for atmospheric air. This can lead to skin resorptive, irritant and allergenic effects.

Electrostatic voltage when wearing clothes made of synthetic fabrics can be up to 4-5 kV/cm, with a norm of no more than 250-300 V/cm. Synthetic fabrics should not be used for underwear of newborns, toddlers, preschoolers and younger children. school age. When making rompers and tights, it is allowed to add no more than 20% synthetic and acetate fibers.

Basic hygienic requirements for fabrics of various origins are presented in Table 6.

Table 6. Hygienic requirements for various types fabrics.

Hygiene requirements for various components of a clothing package

The components of a clothing package perform different functions, which is why the hygienic requirements for the fabrics from which they are made are different.

The first layer of the clothing package is underwear. The main physiological and hygienic purpose of this layer is the absorption of sweat and other skin secretions, good ventilation between the skin and underwear. Therefore, the fabrics from which underwear is made must be highly hygroscopic, hydrophilic, air- and vapor-permeable. Natural fabrics best meet these requirements. The second layer of clothing (suits, dresses) should ensure the creation of an optimal microclimate under clothing, help remove fumes and air from the laundry and correspond to the nature of the work performed. From a hygienic point of view, the most important requirement for the second layer of clothing is its high vapor permeability. For the manufacture of suits and other types of second layer, you can use both natural and synthetic fabrics. The most appropriate are mixed fabrics (for example, lavsan mixed with wool), which have improved sorption properties, reduced electrification, high vapor permeability, low thermal conductivity, combined with good performance and appearance.

The main functional purpose of the third layer (outerwear) is protection from cold, wind, and adverse weather conditions. Fabrics for this layer must have low thermal conductivity, high wind resistance, moisture resistance (low hygroscopicity), and abrasion resistance. Natural or synthetic furs meet these requirements. It is advisable to use combinations of different fabrics (for example, combine a top wind- and moisture-proof layer made of synthetic fabric with a heat-insulating lining made of a mixture of artificial and natural fur and wool). Recommended standards for some material indicators for various layers of clothing are presented in table No. 7

Chlorine staple fiber was previously widely used for the manufacture of medicinal knitted underwear. Chlorine underwear has good heat-protective properties and, due to the so-called triboelectric effect (accumulation of an electrostatic charge on the surface of the material as a result of its friction against the skin), has a beneficial effect on patients with rheumatism and radiculitis. This linen is highly hygroscopic and at the same time air and vapor permeable. The disadvantage of chlorine linen is its instability to washing at high temperatures. In this regard, medical underwear made from polyvinyl chloride has an advantage.

Antimicrobial underwear has been developed and is being used. Preparations of the nitrofuran series can be used as bactericidal agents for antimicrobial linen.

Additional requirements apply to children's clothing. Due to a less perfect mechanism of thermoregulation, a significantly larger specific ratio of the size of the body surface to a unit of its mass in children than in adults, more intense peripheral blood circulation (a large mass of blood flows in the peripheral capillaries), they are more easily cooled in the cold season and overheated in the summer. Therefore, children's clothing should have higher thermal insulation properties in winter and promote heat transfer in summer. It is important that the clothing is not bulky, does not interfere with movement, and does not cause disturbances in musculoskeletal tissues and ligaments. Children's clothing should have a minimum number of scars and seams, and the cut should be loose.

Differences in natural and climatic conditions in Russia also determine hygienic requirements for clothing. 16 zones with different requirements for the heat-protective properties of clothing have been identified. So, for example, for the zone of mixed and deciduous forests middle zone In the European part of Russia, a comfortable state in the summer is provided by clothing with thermal protection of 0.1-1.5 Clo, in winter - 3-5 Clo, depending on the nature and severity of the work.

This text is an introductory fragment. From the book Sexual Psychopathy author Richard von Krafft-Ebing

From the book General Hygiene author Yuri Yuryevich Eliseev

From the book Oddities of our body - 2 by Stephen Juan

From the book Child Health and common sense his relatives author Evgeny Olegovich Komarovsky

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From the book Health for All author Herbert McGolfin Shelton

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From the book Secrets of Eastern Healers author Victor Fedorovich Vostokov

From the book Back and Spine Health. Encyclopedia author Olga Nikolaevna Rodionova

From the book Getting Rid of Cellulite in 48 Hours: The Newest Method author Olga Sergeevna Chernogaeva

From the book Treatment of Leg Diseases and varicose veins veins author Evgenia Mikhailovna Sbitneva

From book Onion peel. Treatment for 100 diseases author Anastasia Prikhodko

From the book Treatment with Soda author Andrey Kutuzov

From the book Protect Your Body. Optimal methods of cleansing, strengthening and healing author Svetlana Vasilievna Baranova