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Concepts in Human Factors Engineering (Part 9 of 11)
Concepts in Human Factors Engineering (9): A Hot Workplace
By Dennis R Andrews PhD, PSP, CECD (ExpertPages member profile page)
The physical environment of the worker of is an important part of the workplace. The body attempts to cool itself by perspiring and exhaling. Clothing is an important part of a comfortable work environment but the environment must be controlled regardless of the outside climate. The law of thermodynamics states that heat flows from warmer to colder matter, which accounts for heat loss around doorways and windows. If the body deviates from the core temperature of approximately 99 degrees Fahrenheit/37 degrees Celsius, the safety and productivity of the work may suffer.
Clothing also determines the surface area of the exposed body. Obviously the more surface area exposed the faster the body will retain heat or lose heat depending upon the environment. Dehydration is an important concern when working strenuously in high temperatures and humidity. Dehydration in moderate or cool climates is not a great concern as compared with higher temperatures. As the body tries to regulate heat it does so by evaporation of perspiration on the surface of the skin. This perspiration causes loss of valuable water in the body. Dehydration can be quickly counteracted by drinking water. In very strenuous conditions adding salt may assist the body from excess salt loss and adding sugar may avoid or postpone fatigue. Either one of these losses can be hazardous if concentration is mandatory in a task such as working with machinery, serious or fatal injuries can occur. Plain water is usually best to drink since it would be relatively close in temperature with the body. Overheating of the body not only can cause stroke but can cause other problems before reaching this acute level. Overheating of the muscle tissue can cause fatigue and increase the metabolic rate, which would increase other functions of the body. Mental acuity is important and can suffer along with dexterity depending upon the environmental temperature and the body temperature.
Adjustments to create a comfortable and healthy work environment can be made if one knows what to do. To adjust radiated heat the adjacent surface or surfaces must be either cooled or warmed. If convection heat can be controlled through the movement of air such as air conditioning or forced hot air heating system. Adjusting the solids, such as walls etc., that come in contact with the skin of the worker controls conductive heat and evaporation is controlled through humidity or air movement. Much is talked about pertaining to wind chill factors basically this is a calculation to theoretically determine energy loss through the exposed skin from the environmental temperature and the velocity of the wind on the skin. Some think that wind chill is only important in bitterly cold climates. The body can lose heat through exposed skin in climates that are hot, warm or pleasant. Of course much less energy is lost through the exposed skin on a hot day compared to a bitterly cold day i.e. 200 kilojoules per meter squared per hour as opposed to 4900 kilojoules per meter squared per hour. The higher the heat loss the quicker the body can freeze. It should be said at this point that comfortable temperatures are as individual as the persons themselves. Some people are cold in winter even if the temperature is warmer than in the summer simply because of the lack of humidity.
In summary it is crucial to maintain the core body temperature at approximately 99 degrees. Any change up or down to the core temperature can result in injury or fatalities depending upon the work & task environment at the time. Heat is gained or lost through various methods such as radiation, convection, conduction and evaporation. All of these can be modified to make the work environment more pleasant, efficient and safe. The tolerance levels for individuals can be as varied as the individuals themselves consequently the health and stamina of the individual is an important function directly correlating to a productive and safe work environment. The environment is a combination of humidity, temperature, and air movement as well as the structures or walls.