[Effect of long-term work in hot microclimate on various physiological parameters in metallurgists].

The study was carried out in 20 per cent of the total number of workers repairing furnaces. Thermal load of workers exceeded the permissible values of heat stress indices (HSI, P4SR, WBGT). Body temperature and pulse rate in workers, taken at the workplaces, confirmed the high thermal load. In the laboratory there were measured: VO2 max., VC, FEV1 blood pressure (RR) and hemoglobin level (Hb). It was stated that VO2 max. in the consecutive class intervals of age decreased not because of work in heat stress but due to ageing. VO2 max. amounted, in those aged 56--60, to 68 per cent, in comparison with those aged 18--25 years. VD, FEV4 and RR were within the physiological limits. Hb level was lower in all age groups as compared to physiological values. The analysis of workers' age structure indicated that only those with high physical capacity and acclimatization abilities were able to remain in the occupation and reach pensionable age (60 years). The work in heat stress itself causes natural selection of workers. On the basis of the study it was concluded that the pensionable age for workers exposed to heat stress should be lowered.