Heat-Waves And Mortality - An Examination Of The Impacts Of Extreme Heat On Health In Northwestern India

Abstract

Purpose—Many studies have linked weather to mortality, and the role of such critical factors as regional variation, susceptible populations, and acclimatization has been studied in developed countries. However, the relationship between temperature and mortality in developing countries is far less characterized. Methods—We applied time-series models to 5 urban communities in Northwestern India, allowing a nonlinear relationship between temperature and mortality by using a 5-year dataset. Heat waves were modeled with varying intensity and duration. Different heat wave definitions were applied to explore variations in risk between commonly used heat wave definitions from prior research as compared with definitions applied by the Indian Government to declare heat wave events. Results—Heat-related mortality was most associated mortality with a short lag (same day). There was a 15% increase in mortality on days designated as a heat wave compared to non-heat wave days (using a heat wave definition of temperatures =97th quantile on consecutive days). Mortality risk increased with the intensity (overall temperature) or duration of heat waves, and high mortality risk was exhibited in heat waves occurring later in the hot season. Conclusions—Average temperatures are relatively high during summer months in India as compared with countries in North American and Europe. Comparison with health estimates generated from studies in those developed country settings indicates that mortality risks during heat waves in India may be more extreme. Findings indicate a substantial public health burden from heat waves in India, but further studies in a variety of settings (urban, rural, different climate zones) are needed, especially to better understand sensitive subpopulations.