Exposure to high temperatures is related to a large number of illness and deaths each year in the United States (1, 2). Because climate changes are likely to lead to more frequent and intense heat events, jurisdictions need to have tools available to help prepare for extreme heat and prevent heat-related illness and death.

Communities where people are most likely to feel the effects of heat on their health may need additional assistance preparing for and responding to heat events. The Heat and Health Index (HHI) can help those communities identify which factors may contribute to their vulnerability to heat and inform which interventions might decrease this vulnerability.

What is the Heat and Health Index?

The Heat and Health Index (HHI) is the first national tool to incorporate spatially granular heat-related illness and community characteristics data to measure extreme heat vulnerability and help communities prepare for warming temperatures in a changing climate.

The HHI delivers a single ranking for each ZIP code so that public health officials, city planners, policymakers and community members can identify and map areas that may be at increased risk of experiencing negative health outcomes, such as heat-related illness, from heat across the country. In addition to including historical heat-related illness data, the HHI incorporates data on pre-existing health conditions, sociodemographic factors, and natural and built environment characteristics, to assess vulnerability to extreme heat.

Communities at increased risk of negative health impacts from heat may need more assistance preparing for and responding to heat events. The HHI can help those communities identify which factors may be contributing to their vulnerability to heat and inform which interventions might decrease this vulnerability.

What data are included in the HHI?

The Heat and Health Index comprises four (4) modules:

1. A Historical Heat and Health Burden module which captures measures of previous experience with heat at the local level (ZCTA or ZIP code)

2. A Sensitivity module made of pre-existing health conditions that may increase risk of negative health outcomes when the individual with the condition is exposed to extreme heat

3. A Sociodemographic module encompassing social and demographic characteristics that increase exposure or sensitivity to heat or lessen one’s ability to cope with extreme heat

4. A Natural and Built Environment module which focuses on characteristics of the natural and built environment that increase exposure or sensitivity to heat or lessen one’s ability to cope with extreme heat

Publication date from document properties.

HHI-2024-Release-Technical-Documentation-508.pdf