Surveillance system for deaths associated with environmental heat exposure, Phoenix, Arizona, 2006-2010

Background: In July 2005, during a month with three heat warnings and temperatures reaching 1160F, Maricopa County (MC) reported 32 heat-associated deaths, 29 of them occurring over 14 consecutive days. Beginning in 2006, Maricopa County Department of Public Health (MCDPH) implemented a surveillance system for heat-associated deaths, that although labor intensive, proved effective over the following five years.

Method: The sources of data are three: 1) Weekly reports from the Office of the Medical Examiner (OME) on suspected heat-associated deaths, including information on circumstances surrounding the death; 2) Daily electronic reports from hospital infection control preventionists and emergency departments covering heat associated illnesses; and 3) Daily multiple-causes-of-death analyses by MCDPH, using the Arizona electronic death registration system (EDRS) and identifying heat associated deaths by code and text searches. MCDPH epidemiologists manually review each report, classifying it as either “heat caused” (caused directly by environmental heat exposure) or “heat related” (caused by some other disease or condition with environmental heat exposure as a contributor), according to the circumstances at time of death. The resulting electronic database includes seventy variables for 336 deaths associated with environmental heat exposure from 2006 to 2010. Quarterly, data analyses are reviewed by a consortium of agencies providing population services to minimize environmental heat exposure.

Results: These data have helped design and evaluate intervention strategies, guide population education efforts, and inform policy decisions.

Conclusion: The surveillance system has proven its utility to policy makers and service agencies in MC.