The risk of heat exhaustion at a deep underground metalliferous mine in relation to body-mass index and predicted Vo(2)max

The risk of heat exhaustion at a deep underground metalliferous mine was as sessed in relation to the body-mass index (BMI) and predicted maximal oxyge n uptake ((V) over dot O(2)max) of miners, using case- control methodology. Sixty-five cases of acute heat exhaustion and 119 controls were studied. H eat exhaustion cases had a significantly higher BMI than controls (P=0.006) . The odds ratios increased with BMI. For a BMI of 32.00-36.99, compared to a BMI of less than 27.00 the odds ratio was 3.63 (95% confidence interval, 1.42-9.36). (V) over dot O(2)max was not significantly lower in cases than controls. The odds ratios for heat exhaustion increased with decreasing (V ) over dot O(2)max, but not significantly. The sample size provided 80% pow er of detecting an odds ratio of 2.5 or greater. Deep underground miners sh ould be advised to maintain a BMI of 24-27. Selection of miners on the basi s of BMI should not be used as an alternative to satisfactory engineering c ontrols such as ventilation and refrigeration.