Heat exposure standards and women's work: equitable or debatable?

Although there is an abundant literature on the health effects of occupational heat exposure, very few authors have addressed the question of the effects of heat stress on women workers. Knowledge about the effects of work in hot environments is mainly derived from the study of "heavy" muscular activity and current heat exposure standards are based on an energy criterion according to metabolic load. Metabolic load does not reflect cardiac strain associated with sedentary, repetitive work, involving static effort. The research presented here was conducted in an industrial laundry with 11 women mangle operators exposed to moderate heat stress during the summer months and whose work activity is classified as light on the basis of energy expenditure. Physiological and symptomatological responses, work activity and ambient temperature were assessed over 3 complete work days in summer and in winter. Recorded and perceived temperature, discomfort, feelings of fatigue and symptoms of thermal stress were significantly higher in summer than in winter. Symptoms of drowsiness and musculo-skeletal aches were reported equally in both seasons. Heart rate was high in both seasons, as were calculated indices of cardiac strain. Recommended limits for cardiac strain were surpassed significantly more often in summer than in winter. It is suggested that threshold levels should be redefined to include the prevention of cardiac strain resulting from cumulative effects of heat stress and sedentary, repetitive activity, typical of many women's job with low energy requirement.