Federal State Budgetary Educational Institution of Higher Education «Irkutsk State Medical University» of the Ministry of Healthcare of the Russian Federation Department of General Hygiene R. S. Мanueva HYGIENIC ASSESSMENT OF MICROCLIMATE Study guide Irkutsk ISMU 2019 УДК 613.646(075.8)=111 ББК 51.218я73 М24 Recommended by the CCMС of FSBEI HE ISMU MOH Russia as a study guide for foreign students, mastering educational programs of higher education by the educational program of the specialty of General Medicine (Protocol № 2 of 18.12.2019) Author: R. S. Мanuevа – Candidate of Medical Sciences, Associate Professor, Department of General Hygiene, FSBEI HE ISMU MOH Russia Translator: O. V. Antipina – Candidate of Philological Sciences, Associate Professor, Department of Foreign Languages with Latin and «Russian for Foreigners» Programs, FSBEI HE ISMU MOH Russia Reviewers: L. P. Ignatieva – Doctor of Biological Sciences, Professor, Head of the Department of Specialized Hygienic Disciplines, FSBEI HE ISMU MOH Russia S.V. Makarov – Candidate of Medical Sciences, Associate Professor, Department Public Health and Healthcare, FSBEI HE ISMU MOH Russia Manueva, R. S. М24 Hygienic assessment of microclimate : study guide / R. S. Manueva ; FSBEI HE ISMU MOH Russia, Department of General Hygiene. – Irkutsk : ISMU, 2019. – 54 p. The study guide contains information on the physiological and hygienic significance of the microclimate, methods for assessing the microclimate of rooms. The basic hygienic requirements for microclimate indicators in premises for various purposes are presented: residential, industrial, medical organizations. In order to assimilate the material studied and self-control, situational tasks, theoretical questions, and test tasks are also included. This edition can be used by foreign students mastering educational programs for specialists in General Medicine, in the course of studying Hygiene as an academic discipline. УДК 613.646(075.8)=111 ББК 51.218я73 © Manueva R. S., 2019 © FSBEI HE ISMU MOH Russia, 2019 2 CONTENTS ABBREVIATIONS 4 INTRODUCTION 5 1. HYGIENIC VALUE OF THE MICROCLIMATE 6 2. WEATHER AND CLIMATE. THEIR INFLUENCE ON THE HUMAN 14 ORGANISM 3. HYGIENIC ASSESSMENT OF THE MICROCLIMATE 21 3.1. Determination of barometrical pressure 22 3.2. Determination of air temperature 23 3.3. Determination of humidity 24 3.4. Determination of air mobility 27 4. PREVENTATIVE MEASURES 30 5. HYGIENIC VALUE OF MOBILITY OF AIR 32 QUESTIONS 35 SAMPLE TASKS 35 TEST 38 SOLUTION PATTERNS 41 KEYS 43 RECOMMENDED LITERATURE 44 GLOSSARY 45 APPENDIX 48 3 ABBREVIATIONS BP – blood pressure HR – heart rate GPA – hectopascal ICD – International Classification of Diseases CVS – cardiovascular system CNS – central nervous system WHO – World Health Organization 4 INTRODUCTION The microclimate of the premises is the most important physical environmental factor, on which the state and performance of people largely depends. In practical conditions, situations often arise related to the need for people to stay in rooms with adverse microclimatic conditions. In this regard, the tasks of hygienic research of the basic laws of microclimate formation, adaptation of the organism, ways to accelerate or facilitate this process, hygienic assessment of the microclimate as the basis for predicting the state and performance of people are always relevant. As a result of studying the topic, the student should know the concept of microclimate and its physiological and hygienic significance, the main ways of heat transfer, their dependence on microclimate parameters, methods for assessing the microclimate of rooms, hygienic requirements for microclimate indicators in rooms for various purposes. To be able to give a hygienic assessment of all microclimate parameters in accordance with hygienic standards and draw up a sanitary conclusion about the microclimate in the room. To give recommendations to the public on improving health in an uncomfortable microclimate. As a result, they should handle a hygienic assessment of all microclimate parameters. 5 1. HYGIENIC VALUE OF THE MICROCLIMATE The human body has perfect mechanisms of thermoregulation – physical and chemical, which allow it to adapt to various temperature conditions and for a short time to suffer significant temperature fluctuations for health damage. In accordance with the external temperature, both the heat generation mechanism and the mechanism regulating its loss come into effect. Chemical thermoregulation – the production of heat by the body due to oxidative processes. The body’s heat production at rest is for a “standard person” (weight 70 kg, height 170 cm, body surface 1.8 m2) up to 293 kJ per hour, with light physical work – up to 628, moderate – up to 1256, heavy – 1256–2093 and more. Metabolic heat is a kind of excretion and must be continuously removed from the body. Physical thermoregulation provides an increase or decrease in heat transfer. At a high external temperature, the skin vessels expand, the secretion of water by the sweat glands increases, the temperature of the skin rises, and as a result of this, the heat transfer from the body surface increases; at low temperature, the skin vessels narrow, the blood moves to the internal organs, the skin cools and therefore the difference between the temperature of the skin and air becomes smaller, the heat transfer decreases. Normal vital activity and a high efficiency of the human being are only possible if there is a balance between heat production and its impact on the environment. Heat exchange depends on microclimate conditions. Most of all, microclimate conditions influence physical thermoregulation 6 by reducing or increasing the surface body temperature. They indirectly affect chemical thermoregulation, reducing or increasing the intensity of metabolic processes in the body (heat production). To keep the body temperature constant, the heat in the body gained must be equal to heat lost from the body surface. There are several ways of heat transfer: 1) radiation of heat towards the colder surfaces and objects; 2) evaporation of moisture through perspiration; 3) convection – heating the layer of air adjacent to the surface of the body, followed by its displacement; 4) conduction – heat conduction due to the difference in temperature of the body surface and the contacting surfaces with him. In normal conditions (room temperature 18 ° C man loses about 85% of the heat through the skin, and 15% of the heat for heating food intake, drinking, and the inhaled air for evaporation of water in the lungs. Of the 85% of the heat given off by the skin, about 45% lost by radiation, 30% – holding, and 10% – due to the evaporation of moisture from the skin surface. These ratios vary considerably depending on microclimate conditions. 1. Radiation 45–50%, as a result of the difference between temperature of the surrounding and body temperature. 2. Evaporation 10 %, the amount of heat lost by evaporation depends on the air velocity and relative humidity. 3. Convention 15%, the air temperature and air velocity are the two factors treat loss of temperature by convection. 4. Conduction 30%, the heat loss by convection is directly 7 proportional to the difference between skin temperature and the air temperature. The heat balance provides thermal comfort of human. The heat balance ensures the temperature constancy of the organism (36,1–37,2°С) and thermal equilibrium with the environment. It is achieved by the ratio of heat production and heat output of the body. Heat production occurs during the oxidation of nutrients, the reduction of skeletal muscle. The drier the air the more water vapor it can absorb. If the humidity in the air is high, there is a corresponding reduction in cooling power. If air temperature is between 24–37°C, heat loss by radiation and convection falls but evaporation loss increases. High temperature with high relative humidity decreases the evaporation through the skin, and cause over heat of the body. Low temperature with high relative humidity causes coolness of the body. The high air velocity cause increases the heat loss by evaporation, and convention. The loss of heat by radiation according to the Stefan-Boltzmann law depends on the difference between the temperature of the skin of the human body and the radiation temperature. The radiation balance is positive when a person receives more heat radiation from walls or other objects located at a distance from him than he gives them. A similar situation is often in hot shops and contributes to overheating. In an open atmosphere, heat loss by radiation depends on solar radiation, soil temperature and building walls. Temperature, humidity and air velocity do not affect heat loss by radiation. Heat loss is carried out by contact of the human body with the surrounding air – convection or with objects (floor, wall) – conduction. 8 Most of the heat is lost by convection. Loss of heat by convection is directly proportional to the difference between skin temperature and air temperature - the larger the difference, the greater the heat transfer. If the air temperature rises, then the heat loss by convection decreases, and at a temperature of 35–36° C it stops. Loss of heat by convection also increases with increasing speed of air movement, but air having a high speed of movement does not have time to heat up in the body and therefore slightly enhances heat transfer. At the same time, acting on baroreceptors, it has an irritating effect. Therefore, in hot shops, where artificially created blowing is used to increase heat transfer, air velocities exceeding 2–3 m / s are not used. Loss of heat by evaporation depends on the amount of moisture (sweat) that evaporates from the surface of the body. When 1 g of moisture is evaporated, the body loses 2.43 kJ of heat (latent heat of evaporation). At room temperature, about 0.5 l of moisture per day evaporates from the surface of human skin, with which about 1200 kJ is released. With increasing temperature of air and walls, heat loss by radiation and convection decreases, a person sweats and heat loss by evaporation sharply increases.