HEAT STRESS HEAT STRESS WHAT IS HEAT STRESS ? WHAT ARE THE CAUSES OF HEAT STRESS? HOW DOES IT AFFECT ME? WHO ARE PRONE TO HEAT STRESS? HOW TO ASSESS HOT ENVIRONMENT? HOW TO PREVENT/CONTROL HEAT STRESS? FACTORS INFLUENCES HEAT STRESS AirTemperature Humidity -prevention of evaporation Movement of air Radiant temperature - exposure to sun Clothings Physical activities HOT ENVIRONMENTS Gold, iron and steel foundries. Manufacture of bricks, ceramics, glass, rubber and chemicals. Boiler maintenance. Bakeries. Laundries. Kitchens. Outdoor operations etc. THERMO REGULATION BODY PRODUCES HEAT - must be dispatched if body temperature is not to change. BLOOD FLOW INCREASED TO SKIN. SWEAT GLANDS - evaporation of sweat. ACCLIMATISATION. HEAT STRESS DISORDERS SAFETY PROBLEMS - Lowered alertness & poor coordination/task performance HEALTH PROBLEMS Heat rash (skin wet). Fainting (unacclimatised and stand up or stand still). Heat cramps ( loss of salt from heavy sweating). Heat exhaustion (skin moist, feels faint or sick). Heat stroke ( skin dry, high temperature, confused or unconscious ). RISK TO HEAT STRESS MEDICALLY UNFIT OVERWEIGHT SUFFER FROM HEART DISEASE ALCOHOL ABUSE NOT ACCLIMATIZED ASSESSMENT OF HOT ENVIRONMENT WBGT (wet bulb globe temperature)-ISO 7243. Outdoors : WBGT = 0.7 nwb + 0.2 Tg + 0.1 Ta. Indoors : WGBT = 0.7 nwb + 0.3 Tg. Underestimates effect of environments of low evaporative capacity resulting from low air movement and high humidity. Limited information about severity of stress and cause. SWEAT RATE - ISO 7933 Detail analysis of hot environment CALCULATION INCLUDES THE FOLLOWING VARIABLES :- Duration in minutes. Air temperature. Globe temperature. Wet bulb temperature (psychometric). Air velocity. Metabolic rate. External work. Mean radiant temperature. Calculated from globe temp, air temp, air velocity. REQUIRED SWEAT RATE COMPUTER PROGRAMME IN STANDARD HELP TO DETERMINE: Exposure times.- excessive core temp or water loss Rest duration to remove possibility of risk. If modifications are necessary, eg lighter load, shield from radiation, increase ventilation, modify clothing, drying the air, etc. If close monitoring is necessary, eg record heart rate. If a medical evaluation is necessary - workers exposed to heat stress required a comprehensive medical evaluation. SAFE SYSTEMS OF WORK WORK ORGANISATION Work in cool part of day. Reduce physical effort. Shorter exposure. Acclimatise workers. System for report heat-related discomfort. WORK ENVIRONMENT Erect temporary / permanent cover. Breaks in cool areas / creates cool environment Barriers, screens. SAFE SYSTEMS OF WORK COOL DRINKING WATER Frequent drinking of cool water. CLOTHING Loose reflective clothing & light coloured HEALTH Medical examinations.
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