Objective  To observe the effect of working in high temperature environment on the blood viscosity of workers in the electric power industry.

  Methods  A total of 134 workers in an electric power transmission and transformation company were studied, and they were divided into three groups according to their work characteristics: electricians working both in high temperature environment and at high altitude(n=48);electricians working at high altitude(n=40) and workers only working in high temperature environmental(n=46). 5 mL of elbow vein blood was collected on an empty stomach to detect the blood viscosity.

  Results  The plasma viscosity, whole blood low shear reduced viscosity, whole blood medium shear reduced viscosity, whole blood high shear reduced viscosity, erythrocyte deformation index and electrophoresis index of these workers were within the normal range. The difference of abnormal rate of whole blood viscosity under different shear rates among three groups was statistically significant(P < 0.05), and the abnormal rate of electricians working at high altitude was the lowest. There were significant differences of whole blood viscosity under different shears among three groups (P < 0.05), and electricians working at high altitude had a lowest value. There were no significant differences of plasma viscosity and hematocrit among three groups(P > 0.05). There were significant differences of whole blood reduced viscosity under different shears among three groups(P < 0.05), and electricians working at high altitude had the lowest value(P < 0.05). The differences of erythrocyte deformation index and electrophoresis index among three groups were statistically significant (P < 0.05), and electricians working at high altitude had the highest value.

  Conclusions  Heat stress may cause the increase of the whole blood viscosity and whole blood reduced viscosity of the workers, increase the aggregation of red blood cells, decrease the deformability, and change the rheological properties. It has not been found that electricians and high altitude work have synergistic effects on the changes of hemorheological properties caused by high temperature.