The physiological equivalent temperature (PET) Index and non-accidental and cardiovascular respiratory disease mortality in Ahvaz, Iran

Abstract

Background: Climate change may be associated with human morbidity and mortality through direct and indirect effects. Ahvaz is one of the hottest cities in the world. The aim of this study was to investigate the relation between Physiologically Equivalent Temperature (PET) and non-accidental, cardiovascular and respiratory disease mortality in Ahvaz, Iran. Methods: Distributed Lag Non-linear Models (DLNM) combined with quasi-Poisson regression were used to investigate the effect of PET on deaths. In this study the effect of time trend, air pollutants (NO2, SO2 and PM10), and weekdays were adjusted. Results: The results showed that in cold stress (the PET index, 1st percentile (2.7 CO) relative to 25th percentile (11.9 CO)) the risk of non-accidental mortality in men and the 65-74 year olds; and also total respiratory mortality, respiratory mortality in men, in people under 65 and the 65-74 year olds; significantly decreased in the cumulative lags of 0, 0-2, 0-6 and 0-13. In contrast, heat stress (the PET index, 99th percentile (44.9 CO) relative to 75th percentile (43.4 CO)) significantly increased the risk of total cardiovascular mortality (CVD), cardiovascular mortality in men and the elderly, ischemic heart disease and cerebrovascular disease mortality in lags 0 and 0-2. Conclusions: It seems that high PET values increase the risk of cardiovascular mortality, while low PET values have a protective effect on mortality, especially respiratory mortality in Ahvaz.