High ambient temperature and mortality: a review of epidemiologic studies from 2001 to 2008

Rupa Basu

doi:10.1186/1476-069x-8-40

Abstract

BackgroundThis review examines recent evidence on mortality from elevated ambient temperature for studies published from January 2001 to December 2008.MethodsPubMed was used to search for the following keywords: temperature, apparent temperature, heat, heat index, and mortality. The search was limited to the English language and epidemiologic studies. Studies that reported mortality counts or excess deaths following heat waves were excluded so that the focus remained on general ambient temperature and mortality in a variety of locations. Studies focusing on cold temperature effects were also excluded.ResultsThirty-six total studies were presented in three tables: 1) elevated ambient temperature and mortality; 2) air pollutants as confounders and/or effect modifiers of the elevated ambient temperature and mortality association; and 3) vulnerable subgroups of the elevated ambient temperature-mortality association. The evidence suggests that particulate matter with less than 10 um in aerodynamic diameter and ozone may confound the association, while ozone was an effect modifier in the warmer months in some locations. Nonetheless, the independent effect of temperature and mortality was withheld. Elevated temperature was associated with increased risk for those dying from cardiovascular, respiratory, cerebrovascular, and some specific cardiovascular diseases, such as ischemic heart disease, congestive heart failure, and myocardial infarction. Vulnerable subgroups also included: Black racial/ethnic group, women, those with lower socioeconomic status, and several age groups, particularly the elderly over 65 years of age as well as infants and young children.ConclusionMany of these outcomes and vulnerable subgroups have only been identified in recent studies and varied by location and study population. Thus, region-specific policies, especially in urban areas, are vital to the mitigation of heat-related deaths.

Highlights

This review examines recent evidence on mortality from elevated ambient temperature for studies published from January 2001 to December 2008
Many studies of temperature have been conducted in other disciplines such as climatology, they have received greater attention in epidemiology in the past few years
Many studies of ambient temperature and mortality did not account for air pollutants, and in the previous review [1], it was not clear from the few studies conducted whether air pollutants acted as confounders, effect modifiers, or both

Summary

Introduction

This review examines recent evidence on mortality from elevated ambient temperature for studies published from January 2001 to December 2008. In 2002, a comprehensive epidemiologic review by Basu and Samet [1] summarized the findings from studies examining mortality from elevated ambient temperature and heat waves. Environmental Health 2009, 8:40 http://www.ehjournal.net/content/8/1/40 conducted more recently on heat and mortality, the focus has been on methodological issues and approaches [2] and on climatology [3], leaving a number of important epidemiologic studies excluded. The actual association between ambient temperature and mortality can be observed, only after accounting for pollutants in the models with ambient temperature Demographic characteristics, such as poverty and age, can modify the severity of heat effects through various physiological and behavioral pathways. Certain subgroups may be vulnerable to heat effects, and identifying them for specific locations would be beneficial for targeting public health interventions

Results

Discussion

Conclusion