Personnel Working in Cold Stores
Working in a cold store means exposure to extreme cold and demands high physical and mental standards. Heat losses from the body must be minimized by proper clothing. In addition, working in a low temperature environment creates special effect on the human body, which must be counteracted by a special working routine and provisions for personal welfare. As for anybody else working in the food industry, the employees must undergo regular checks and maintain the necessary level of personal hygiene required for this industry.
Among the initial effects of exposure to low temperatures are numbness in the fingers and toes and reduction in dexterity. Muscular activity and increased metabolism would help to maintain the body temperature around 37°C.
Shivering is the principal mechanism of the body to momentarily increase its metabolism, but a shivering worker becomes ineffective, when the heat losses are greater than the heat generation, the body temperature will continue to fall and thus causes unsatisfactory physical response. It is usually considered that the metabolism will decrease by 12 percent for every 1°C decrease of the body temperature. The lungs begin to freeze at about -53°C. The human body will lose liquid through cold when exposed to low temperature. However, working in a low temperature environment is not hazardous to health, provided the worker is physically fit, i.e., submits himself to the necessary medical examination before employment and uses all the precautionary measures provided by the cold store properly.
The term clo was introduced in order to define the insulating quality of clothing assembly. By definition, one clo will provide thermal comfort to a man sitting in an ambient of 21 °C, 50 percent relative humidity and 0.1 m/s air velocity. A long suit corresponds roughly to one clo, a linen suit to 0.8 clo, and a woollen suit under which is a waistcoat, shirt and underclothes to 1.3-1.5. One clo is equal to 0.18 °C m2 h/kcal. In polar climates 3 clos generally are considered suitable for moderate activity in a -20C ambient with a low wind velocity. However, this relates to selected individuals and for similar conditions in a cold store a value of 4 clos may be considered necessary. The importance of correct clothing is shown in Table 25, which shows the relation between ambient activity and heat production.