Room Moisture

Room Moisture. Moisture in living quarters, i.e., excessive humidity of their air, can depend either on organic causes (from the building itself) or from the exploitation of the dwelling. Organic causes: 1) In bricklaying with binding mortar and wetting of bricks, 10-20% of water is introduced per volume of the wall, and with the hydraulic water of the mortar even up to 12-25%; moving into a building that has not dried sufficiently causes dampness of the walls; 2) With high thermal conductivity of wall materials and small wall thickness, the temperature on the inner surface of the wall falls below the dew point, which causes condensation of water vapor and dampness of the wall; 3) Wetting and dampness of walls of insufficient thickness from prolonged slanting rains, as well as from rain penetration through the roof or from downspouts; 4) Introduction of hygroscopic salts into the walls with contaminated water: calcium chloride and magnesium chloride, niter, etc.; 5) A foundation reaching the level of standing groundwater, by the law of capillarity, can cause dampness of basement and lower floor walls. Exploitation causes: 1) A person on average exhales 1,400 grams of water vapor per day, therefore overpopulation of a dwelling with insufficient ventilation causes dampness of the walls; 2) Household processes of residents (cooking, washing and drying laundry, etc.) can also cause excess moisture in the dwelling and its dampness; 3) Low temperature of an insufficiently heated dwelling leads to an increase in relative humidity and hence to dampness of the walls. The air of damp rooms has not only high humidity, often reaching maximum levels, but also an unpleasant smell (musty) with various, sometimes very harmful (arsenic) chemical impurities, depending on the decomposition processes that arise under the influence of molds and bacteria, which develop abundantly in damp dwellings, in walls, inter-wall spaces, wallpaper (see), on household items and clothing of residents. Due to the filling of pores of wall materials with water, walls in damp dwellings become more thermally conductive and sound-conductive and less air-permeable, which reduces natural ventilation of dwellings. This further worsens the composition of the air, and cooling of the walls occurs, which become like a reserve reservoir for water vapor from the air, settling on the walls when the temperature drops, and when the temperature rises, re-entering the air of the dwelling. The walls of damp dwellings deteriorate: 1) In wooden walls, molds and fungi easily develop, and various types of house fungus are especially dangerous (see); 2) Plaster is covered with mold spots and peels off; 3) Wallpaper changes color, becomes moldy and peels away from the wall. Air with high humidity acts both directly on a person living in a damp dwelling and through their clothing, which becomes damp; as a result, a person experiences chilliness at normal room temperature and the thermal balance of the body is disrupted. This leads to an increase in general morbidity and mortality among residents of damp apartments, including from infectious diseases (bacteria survive longer in damp dwellings), as well as the development of a number of diseases (muscular rheumatism, neuralgia, catarrhs of the respiratory tract, inflammation of the kidneys) and worsening of the course of some diseases (tuberculosis and anemia). External signs of dampness in dwellings are: 1) Mold spots on the wall, 2) Cracked and peeling plaster, 3) Peeling, discolored wallpaper, 4) A wall that feels cold to the touch, 5) A dull sound (from filling of pores with water) when tapping the wall, 6) Sometimes a wet wall, 7) Mold on items in the apartment, 8) Musty, specific smell. Excess moisture in the air is accurately determined by psychrometers and hygrometers, and the water content in walls by various methods based on direct or indirect determination of water in various wall materials. The most common methods are drying with heated air without Na₂O and CO₂, distillation of water with media lighter or heavier than water, obtaining acetylene by the carbide method (Korff-Petersen), and extracting water from plaster with alcohol (MarkГ). Housing-sanitary legislation, based on the desirable norm in a dwelling-35-65% relative humidity, requires: 1) Use for construction of wood with moisture not more than 20% and occupancy of plastered buildings from the inside with plaster moisture not more than 2%, i.e., not earlier than 10 months after laying brick buildings; 2) Wall thickness ensuring overall thermal resistance of at least 1.3-1.1-0.9-0.7 for four climate zones of the USSR; 3) Proper maintenance of roofs and downspouts; 4) Use of clean water for laying; 5) Drainage of soil and insulating linings in the foundation (see Dwelling and Building Materials); 6) Prevention of overpopulation of dwellings; 7) Prohibition of washing and drying laundry in apartments; 8) Sufficient firing of stoves with ventilation. Some of these measures are also measures to combat dampness (items 3, 5, 6, 7 and 8); to increase thermal resistance, walls are insulated with thermal insulation materials, to eliminate hygroscopicity they are covered with waterproof plaster (see Building Materials). Moisture in storage premises (warehouses, storerooms) is usually of constructional origin and causes an increase in moisture in stored products (salt, sugar, flour, cookies, etc.), acquisition of a musty taste (milk, butter, flour, cereals, etc.), development of mold in the product itself (butter, cheese, bread) and on the surface (sausage, vegetables) and accelerates spoilage processes of various products. The fight against moisture in storage premises is carried out in the same way as in dwellings, but it is also necessary to allocate strongly hygroscopic products, such as salt, that maintain air humidity, to special storerooms. However, for storage of some products (meat, cheese), high air humidity (i.e., small saturation deficit) is desirable, usually combined with low temperature (ice cellars, refrigerators), to avoid significant drying of products. Moisture in work premises depends almost exclusively on production processes and is encountered in many industries where boiling occurs in boilers and a large amount of steam enters the air (pickling shops, textile and dyeing factories, leather and sugar factories, laundries, etc.); sometimes humidity is necessary for the production process (spinning mills). Water vapor saturates the air, forming fogs, the floor is often wet. High humidity and especially fogs contribute to injuries, worsening lighting and causing earlier fatigue, leading to reduced labor productivity and increased scrap. Workers in damp workshops get sick with the same diseases as in damp dwellings, and in damp and hot workshops also with heart diseases, gastrointestinal diseases and anemias. The fight against moisture in work premises consists of the following: 1) Changing production processes, for example replacing live steam for heating jiggers with dead steam, replacing hot pickling with cold; 2) Mechanization of the process (pouring acid and water into pickling vats, loading and unloading pickled materials); 3) Possible sealing of equipment with local exhaust (pickling vats, troughs for sizing); 4) Isolation of such processes in separate premises; 5) Installation of supply-exhaust ventilation with heating of supply air to reduce relative humidity. Elimination and removal of excess moisture reduce injuries and scrap, increase labor productivity (by 12-16%), and reduce morbidity. Individual protective measures for workers against moisture consist of wearing waterproof clothing, aprons (canvas, rubberized, rubber), waterproof footwear and gloves; to improve the well-being of workers in hot and humid workshops, air is moved by electric fans.