Effects of targeted interventions on heat-related deaths among Maricopa County's homeless population, Phoenix, Arizona, 2006-2010

Background:

The average July daytime temperature in Maricopa County, (MC) is 107.0°F, and can peak at 116.0°F. Because exposure makes the homeless extremely vulnerable to heat-associated death, specially-targeted interventions toward the homeless were implemented in 2006, including cooling stations, water distribution, shelters, and coordination among agencies.

Method:

To determine the proportion of heat-related deaths among the homeless from 2006-2010, Maricopa County Department of Public Health (MCDPH) analyzed death certificates with environmental heat exposure as an underlying or contributing cause. MCDPH calculated the annual proportion of heat-related deaths among homeless persons and the relative risk of heat related death for homeless persons compared to non-homeless persons. A homeless case is defined as having, after investigation, a homeless shelter, street intersection, or unknown location as an address.

Results:

MCDPH identified 336 total heat-related deaths. Of those, 64 (20%) were homeless with a relative risk of 151 for homelessness; average years of potential life lost was 22.81 per homeless decedent, versus 16.77 per general decedent.

In 2006, 24 (28%) of heat-related deaths were homeless. Homeless heat-related deaths decreased to 4 (8%) in 2007 and 2008 and subsequently increased to 15 (20%) in 2009. This represents a 220% increase from 2008 in homeless deaths compared with 45% in the general population. In 2010, there were 17 (21%) homeless heat-related deaths.

Discussion: Homeless individuals are disproportionately at risk for heat-related death in MC. Our results suggest that targeted interventions were effective in reducing heat-related deaths in the homeless, although other factors must be considered.