Topic 3
Hygienic normatives of air physical properties as one of the preventive measures directions of unfavorable microclimate influence on human being.
unfavorable- heating or cooling Overheating(hyperthermia) Acture form: Heat stroke Sun stroke Convulsion disease Chronic form: Chronic overheating Infrared cataract Overcooling(hypothermia) Local cooling: Frostbite Local inflammation Catarrhal disease General cooling: Acute hypothermia Chronic hypothermia Prevention of meteopathic reactions 1.Institutional arrangements: accounting risk groups of meteopaty, medical weather forecasts, advance warning about weather changes, etc. 2. Hardening of organism( the complex one): air, water and the sun. 3. Bland way of life (limit of loads, restful sleep, positive emotions, and for patients - bed rest, removing of physical treatments, massage, operations). 4. Drug prevention: (regula antiregression course in worsenings season, periodic preventive measures on the unfavorable days, taking sedatives, antihypertensives, antipsychotics, etc.) There are three types of reactions to the weather: A. Change the physiological reactions of the organism within its adaptive range - pulse, blood pressure, respiration, thermoregulation, health, neuro-sensory processes, etc. B. Seasonal exacerbation of disease, especially a cold nature, with their maximum in autumn and spring seasons (influenza, acute respiratory infections, respiratory diseases, etc.), acute gastric ulcer, hypertension and coronary heart disease. The influence of weather on the vector-specific infection (gnats, mosquitoes, flies, mites, rodents, etc.) and determine their seasonality in humans. C. Meteopathic states, which are sometimes difficult to differentiate, for the occurrence of which requires a certain disposition of the body, ie meteolability. Most often prone to meteopathic of patients with chronic cardiovascular disease (60%), musculoskeletal disorders, mental illnesses, the elderly cohort. In healthy people meteorological dependence response to abrupt weather changes are manifested in the form of headaches, phantom pain, anxiety, appetite loss, headache, ia speeded heart rate, insomnia, etc. The first group is the scientific substantiation of hygienic standards for the microclimate of premises for different purposes. So, for residential areas in the cold season the following standards are set: air temperature 18-20 ° C, humidity 30-60%, air velocity of 0.1-0.2 m / s, temperature of the wall ± 2 ° C compared to the rated air temperature. The second group of measures is the impact on the environment in order to bring microclimate to optimal hygienic requirements or, in extreme cases, to levels that do not produce adverse effects on health and efficiency. These measures include the heating, ventilation, air conditioning, sun protection measures (visors, curtains, etc.), elimination of the causes overheating in the production (changing technology, heat insulation and so on. P.), The normalization of conditions in the workplace (air shower, screen et al.). The third group consists of measures aimed at the human: the selection of clothing (including electrically heated), hardening, rational mode of work and rest, good nutrition and drinking regime (special drinks, salty carbonated water, etc.). The fourth group includes medical and preventive measures: medical screening for employment, periodic medical examinations in order to identify individuals with health problems caused by the uncomfortable climate, health education for the prevention of overheating or overcooling and others.
Devices and methods of air pressure measuring.
Air is a tangible material substance and as a result has mass. Any instrument that measures air pressure is called a barometer. The most common type of barometers used in homes is the aneroid barometer Inside this instrument is a small, flexible metal capsule called an aneroid cell. In the construction of the device, a partial vacuum is created inside the capsule so that small changes in outside air pressure cause the capsule to expand or contract. Mercurial barometer used in meteorology to measure atmospheric pressure. Siphon barometer Cistern barometer
Air physical properties, their hygienic meaning. The definition of «microclimate» and factors which influence its formation. The classification of microclimate.
Air temperature is a measure of how hot or cold the air is. It is the most commonly measured weather parameter. More specifically, temperature describes the kinetic energy, or energy of motion, of the gases that make up air. As gas molecules move more quickly, air temperature increases. Air temperature affects the growth and reproduction of plants and animals, with warmer temperatures promoting biological growth. Air temperature also affects nearly all other weather parameters. For instance air temperature affects: the rate of evaporation relative humidity wind speed and direction precipitation patterns and types, such as whether it will rain, snow, or sleet. Air environments refer, in addition to ambient air, to the industrial, occupational air (indoor and outdoor), non-industrial occupational indoor air (household, study halls, shops, theatres, and medical faci- lities) and the air inside the means of transport (cars, trains, planes). The microclimate refers to all the physical factors of air (tempe- rature, humidyti, air currents heat radiation) which influence the heat exchange between the body and the environment. Such physical pro- perties as atmospheric pressure, radiation and air electricity are micro- climate factors but they to not determine microclimate factors, they do not have a direct influence on the human thermal sensations.
The methodology of definition air speed movement with a help of anemometers and catathermometers. Kinds of anemometers and catathermometers.
Airflow, or air flow, is the movement of air. ... Air behaves in a fluid manner, meaning particles naturally flow from areas of higher pressure to those where the pressure is lower. Atmospheric air pressure is directly related to altitude, temperature, and composition. An anemometer is a device used for measuring wind speed and direction.Anemometer is a device used for measuring wind speed, and is a common weather station instrument. The term is derived from the Greek word anemos, which means "wind", and is used to describe any wind speed measurement instrument used in meteorology. Cup anemometers.It consisted of four hemispherical cups mounted on horizontal arms, which were fixed on a vertical shaft. The air flow past the cups in any horizontal direction, turned the shaft at a rate that was proportional to the wind speed. The refore, the number of the turns of the shaft within a certain periode of time produced a value proportional to the average wind speed for a wide range of speeds Vane anemometers. The other form of mechanical velocity anemometer is the vane anemometer. It may be described as a windmill or a propeller anemometer. Vane anemometer thus combines a propeller and a tail on the same axis to obtain accurate and precise wind speed and direction measu- rements by the same instrument. Hot Wire anemometers - for this, a very thin and electrically heated wire is used, which is cooled as wind flows past. This type of anemometer allows experts to obtain a relationship between the flow speed and resistance of the wire. Laser Doppler anemometers catathermometer, katathermometer 1. An alcohol thermometer, with a dry bulb and a wet bulb, which measures how quickly air is cooling; and so, permitting an estimate of evaporation of moisture from the body. 2. A device consisting of two thermometers, one a dry bulb and the other a wet bulb. Both are heated to 110°F (43.3°C) and the time required for each thermometer to fall from 100° to 90°F (37.8° to 32.2°C) is noted. The dry bulb gives the cooling power by radiation and convection, the wet bulb by radiation, convection, and evaporation. From this, the temperature as it affects the body can be deduced; or it is a measure of the heat content of the environment that takes into account air movement as well as temperature.
The heat loss ways and heat relative density (in %), excreting by the organism in conditions of comfortable microclimate.
Because of that interestingly will learn how the heat is lost by skin. Appear, that skin loses a heat by three ways: •by radiation, •taking and •on evaporation of sweat moisture. Major part of heat loses through the skin and mucous, other part goes on heating of food, water and breathes air. Through the skin loses main heat mass
The definition of absolute, maximum and relative air humidity. The principle of psychrometry. Devices and methods using for measuring the absolute air humidity with a help of psychrometer. The calculation of the absolute air humidity.
Determination of the air humidity using psychrometers The absolute and relative air humidity is determined using the August stationary psychrometer. The reservoir of the psychrometer is filled with water. One of the device's thermometers is wrapped with the fabric. The fabric is put down into the water so that the reservoir is located about 3 cm above the water surface. After this the psychrometer is hanged onto the support at the determination point. The wet and dry thermometer data are taken 8-10 minutes later. The absolute humidity is calculated using the Regnault formula: А = f - a · (t - t1) · B, where, А - the air absolute humidity at the current temperature in Hg mm; f - maximum pressure of water vapour at the wet thermometer's temperature (see the table of saturated water vapours, table 3); а - psychrometric coefficient is 0.0011 for enclosed spaces; t - temperature of the dry thermometer; t1 - temperature of the wet thermometer; В - barometric pressure during the humidity determination, Hg mm. Absolute Humidity - The density of water vapor (mass of water vapor in a volume of air). ... Specific Humidity- The mass of water vapor per unit mass of air. Absolute humidity is the measure of water vapor (moisture) in the air, regardless of temperature. It is expressed as grams of moisture per cubic meter of air (g/m3). Relative humidity also measures water vapor but RELATIVE to the temperature of the air. It is expressed as the amount of water vapor in the air as a percentage of the total amount that could be held at its current temperature. Warm air can hold far more moisture than cold air meaning that the relative humidity of cold air would be far higher than warm air if their absolute humidity levels were equal.
Hygienic norms of temperature, relative humidity and air speed movement indoors
In hygienic practice it is accepted to normalize relative humidity due to the fact that by its value it is possible to judge about the impact of humidity and other environmental factors on heat exchange in human. It is believed that the optimal value of relative humidity is in the range of 30-60%, and its permissible level is 65-75%. To describe the character of humidity the following values are used: - absolute humidity - water vapor pressure, found in the air at the time of measurement, expressed in mmHg, or the amount of water vapor, contained at the time of measurement in 1 m3 of the air, in grams; - maximum humidity - water vapor pressure at complete moisture saturation of the air at the given temperature in mm Hg, or the amount of water vapor, contained in 1 m3 of the air at the time of saturation at the same temperature; - relative humidity - the ratio of maximum and absolute humidity, expressed as a percentage; - saturation deficit (physical deficiency) - the difference between maximum and absolute humidity; - dew point - the temperature at which the air is maximally saturated with water vapor; the absolute humidity value is equal to the maximum value. Modern electronic thermohygrometers and psychrometers, hygrometers, and a hygrograph are used to determine air humidity indoors.
The methodology of air temperature measuring indoors. Devices and methods using for measuring.
The devices for the air humidity determination (a - August psychrometer; b - Assmann psychrometer; c - hygrometer) The psychrometer operation is based on the fact that the rate of the water evaporation from the surface of dampened psychrometer's reservoir is proportional to the air dryness . The drier the air - the lower is the wet thermometer's result in comparison to the dry thermometer due to the latent evaporation. Measurement of air temperature Instruments: − Common thermometrs are used to determine the thermal values between - 30°C and 300°C and alcohol themometers-between - 70°C and 120°C. − Ordinary thermometers are: room thermometer, bathroom ther- mometer, laboratory thermometer, etc. special thermometers are: medical thermometer, skin thermometer, maximum and minimum thermometer, the thermograph. − The medical thermometer measures thermal values between 35- 42°C, and the skin thermomenter between 20-40°C. The smalles changes in the themal environment are recorded by skin temperature, which is a highly sensitive physiological indicator. − Maximum and Minimum thermometers (Six-Bellani) show the maximum and minimum temperature in a given period of time. − The thermograph records the air temperature, the resulting diagram being called a thermogram.
Physiological mechanism of heat exchange and thermoregulation as factors in the warm-blooded organism thermal status: heat production and loss.
When the environment is not thermoneutral, the body uses four mechanisms of heat exchange to maintain homeostasis: conduction, convection, radiation, and evaporation. Each of these mechanisms relies on the property of heat to flow from a higher concentration to a lower concentration; therefore, each of the mechanisms of heat exchange varies in rate according to the temperature and conditions of the environment. Conduction is the transfer of heat by two objects that are in direct contact with one another. It occurs when the skin comes in contact with a cold or warm object. Convection is the transfer of heat to the air surrounding the skin. The warmed air rises away from the body and is replaced by cooler air that is subsequently heated. Radiation is the transfer of heat via infrared waves. This occurs between any two objects when their temperatures differ. A radiator can warm a room via radiant heat. On a sunny day, the radiation from the sun warms the skin. Evaporation is the transfer of heat by the evaporation of water. Because it takes a great deal of energy for a water molecule to change from a liquid to a gas, evaporating water (in the form of sweat) takes with it a great deal of energy from the skin.
The definition of «wind rose», its hygienic meaning and the methodology of scheming.
a diagram with radiating lines showing the frequency and strength of winds from each direction affecting a specific place