[The evaluation of the individual thermal load in work activity with uneven energy expenditure]

It is often very difficult to quantify the potential thermal stress in jobs characterized by sudden variations of energy expenditure and thermal overload for time periods of short duration. Heart rate varies rapidly with the changes of energy expenditure and thermal load and the application of the mathematical model, proposed by Givoni and Goldmann for prediction of heart rate response to work in hot environments, to values of the physiological parameter, continuously measured during the periods of work and rest, allows the calculation of the two components of the HSI stress index (Er, Emax) from which to derive safe times of exposure. In this study practical applications of the theoretical method are verified in the control of the potential thermal stress of workers engaged in the carbon coke production. In that job the variability of thermal conditions make unfeasible a complete and whole evaluation of thermal overload only based on the measure of the microclimatic environmental parameters.