Temperature and Humidity Effects on Hospital Morbidity in Darwin, Australia

Abstract

Background: Many studies have explored the relationship between temperature and health in the context of a changing climate, but few have considered the effects of humidity, particularly in tropical locations, on human health and well-being. To investigate this potential relationship, this study assessed the main and interacting effects of daily temperature and humidity on hospital admission rates for selected heat-relevant diagnoses in Darwin, Australia. Methods: Univariate and bivariate Poisson generalized linear models were used to find statistically significant predictors and the admission rates within bins of predictors were compared to explore nonlinear effects. Findings: The analysis indicated that nighttime humidity was the most statistically significant predictor ('P' < 0.001), followed by daytime temperature and average daily humidity ('P' < 0.05). There was no evidence of a significant interaction between them or other predictors. The nighttime humidity effect appeared to be strongly nonlinear: Hot days appeared to have higher admission rates when they were preceded by high nighttime humidity. Conclusions: From this analysis, we suggest that heat-health policies in tropical regions similar to Darwin need to accommodate the effects of temperature and humidity at different times of day.

Keywords

• admissions
• heat stress
• hyperthermia
• sleep disruption
• tropical