Sanitary value of waters
Optimum speed of movement of air in summertime considers 1-4 km/s. In premises it is considered to be normal speed of movement of air, equal 0,2-0,4 km/s, the big speed causes unpleasant sensation of a draught, and smaller specifies in insufficient air exchange. In sports halls speed of movement of air, equal 0,5-0,6 km/s, and in hot shops - to 1-1,5 km/s is supposed.
Air Movement is characterised also by a direction which is defined by that part of horizon, whence air moves, and is designated by points (With - the north, JU - the south, In - the east, 3 - the West). The wind direction is considered at a lay-out and building of the occupied places. Thus it is necessary to know a direction of a wind dominating in given district. For this purpose consider all directions within year or a season, and on them build the schedule, luchivshy the wind rose name. Thus, a wind rose - a graphic representation of frequency of repeatability of winds. From fig. 1 it is visible, that in the given district a dominating direction of a wind northwest, and the most rare winds - southern, east and southeast. Hence, industrial region it is the most rational to arrange on southern, east or southeast suburb of settlement. Then the majority of days in a year industrial emissions will concern aside from settlement.
Pressure of air. The atmosphere surrounding the Earth, has certain weight: 1 m 3 dry air under standard conditions weighs 1294 Pressure of atmosphere which counterbalances a column of mercury in height of 760 mm at temperature 0 °s on a sea level and width 45 °, it is considered to be normal. Thus atmosphere presses on 1 sm 2 ^poverhnosti the Earth with force of 1 kg (more precisely 1,0333 kg), that is equal to pressure 1013,1 gpa.
Fluctuations of atmospheric pressure for days are insignificant (13-26 gpa) and are not reflected on health of the person. Similar changes in a complex with changes of other meteorological factors can make adverse impact only on meteosensitive people. Considerable pressure decline of air is marked, at liftings on height (work in the mountain areas located at height of 2500-3000 m, air flights, etc.) . Fall of atmospheric pressure causes high-rise meteorizm, caused by expansion of gases in pi-shchevom the channel that involves a number of functional frustration: high standing of a diaphragm, restriction of depth of breath, difficulty of inflow of blood to the right auricle, increase of arterial pressure. High-rise meteorizm aggravates action of oxygen insufficiency (in parallel decrease in atmospheric pressure decreases, and partsialnoe pressure of oxygen). Therefore at flights at the height exceeding 2500-3000 m, it is necessary to apply oxygen devices.
Sharp changes of atmospheric pressure at fast lifting or plane descent cause so sharp change of pressure of air in a cavity of an average ear and in okolonosovyh bosoms. Unpleasant sensations zalozhennosti in ears and a pain are observed first of all at those persons who in an acoustical pipe or okolonosovyh bosoms have the inflammatory processes interfering alignment of pressure of external air in these cavities.
Decrease partsialnogo pressure of oxygen at fall of atmospheric pressure serves as a principal cause of occurrence of high-rise illness. For it are characteristic a short wind, palpitation, dizziness, a nausea, the nasal bleeding, etc. High-rise illness can be shown at an ascension on mountains, at flights in planes. At the trained climbers, pilots, inhabitants of mountain districts of the phenomenon of high-rise illness haemoglobin maintenances, by increase of breath, etc. (kompensatornaja organism reaction) are observed seldom as their organism adapts to conditions of the lowered maintenance of oxygen in air kompensatornym quantity increase eritrotsitov.
As the Limit of height of lifting without application of special measures consider 5000 m. Stay at height of 7000-8000 m always conducts to heavy infringements, and the height of 9000 m is a limit above which without inhalation of oxygen the person cannot rise.
Conditions of the raised atmospheric pressure meet at diving works, in mines, at work in a caisson. At immersing in water on everyone 10,3м pressure increases approximately on 1013,1 gpa. It is known, that at normal atmospheric pressure in 100 ml of blood it is dissolved about 1,8 sm 3 nitrogen. At the raised pressure pressure of nitrogen in blood increases, and it arrives in a fabric. At slow transition from the raised pressure to normal nitrogen, owing to a difference partsialnogo pressure in alveolar air, passes from fabrics in blood and is deduced through lungs. However at fast dekompressii (pressure decrease) nitrogen has not time to be allocated through lungs, and in the form of gas vials remains in blood and fabrics, causing gas emboliju various bodies, development dekompressionnoj (kessonnoj) to illness. Therefore transition from the raised atmospheric pressure to the normal should be made gradually. Duration dekompressii is established depending on size of atmospheric pressure.
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