Commentary: Responding to hazardous heat: think climate not weather

In this issue, Sunet al. report on heat waves and mortality in 130 Chinese counties from 2013 –15.1 Heat waves are defined as ≥2 days with average temperatures ≥99th percentile for the location. Distinctive features of the study are: the number of study sites, the consistency of data collections and reporting, and the attention paid to confounding and modifying factors. Major findings are: surprisingly similar effect s in different climatic zones (about 16% increase in non-accidental deaths, 22% increase in cardiovascular mortality); greater impacts following the first heat wave of the season than later events; and no sign of an effect of heat wave duration. In this instance there were no sites in the coldest pa rt of the country, and few in the tropics or on the Chinese high plateau, so the analysis was not a strong test of spatial variability; others have found considerable heterogeneity in the relation between heat waves and mortality.2 It is well-established that early heat waves tend to be the most dangerous, although this does depend on severity —the catastrophic heat wave in Europe in July 2003 was the seventh of the summer. Other studies of heat intensity and duration report that daily temperatures dominate, but duration is not unimportant, especially when heat continues for ≥4 days.3
Source: International Journal of Epidemiology - Category: Epidemiology Source Type: research