environmental stresses and strains in an extreme situation the repair of electrometallurgy furnaces whenever continuous casting furnace breaks down the emergency intervention necessary to repair it has to be carried out under exceptional environmental conditions caused mainly by heat as the furnace must be stopped for the shortest possible time in this study we aimed to evaluate the stresses and strains to which boilermakers are subjected during the replacement of an electrode element of a 20 mw furnace the thermal stress was evaluated by the wet bulb globe temperature wbgt index co2 was measured continuously at the furnace periphery and sporadically in the center of the furnace using an electrochemical method while co was also measured in both areas using drger tubes dusts were sampled by a cpm3 andersen particle fractionating sampler and a cip10 personal sampler the strain was evaluated by continuous ecg recording with an aclan ifc 85 breathing performance was assessed with an hi 298 microspirometer and blood oxygen saturation was evaluated using a biox oximeter thermal stresses are extreme wbgt was 55 degrees c in the furnace center and 34 degrees c in the furnace periphery in spite of the ventilation the reduction in heat during the 6 h of the intervention was negligible and did not provide sufficient cooling the analysis of gases and dusts were of minor interest although the mean co level at the furnace periphery was 40 ppm with a peak level of 140 ppm in furnace center co2 and so2 levels did not exceed tlvtwa and tlvstel valuesabstract truncated at 250 words