New National Heat Index uses data from the U.S. Geological Survey

“Developed areas such as roads, buildings, sidewalks and rooftops absorb heat during the day and radiate it at night and into the next day,” said Jon Dewitz, a scientist with the U.S. Geological Survey’s Earth Observing System (EROS). LCD display module team.

“When you combine expanded development areas with longer periods of high temperatures, the heat index will rise. NLCD’s impervious surface calculations are a key baseline indicator for calculating and understanding the increased risk of heat stress to cities and vulnerable populations,” Dewitz added.

The NLCD is the nation’s definitive database for classifying the types of material that covers the nation’s land, including fields, forests, pastures, pavement, and other developed surfaces. Landsat satellite imagery is the basis for determining these categories. This information helps people who manage land and resources, as well as populations, in many ways.

Heat and Health Indexpeople can enter a ZIP code or select an area on a U.S. map to see how their community ranks in terms of percent vulnerability to heatwave impacts compared to the rest of the U.S. They can also see how their community ranks on four factors that influence the impacts of heatwaves.

One factor is the natural and built environment. It focuses on features of natural and built properties that increase human exposure or sensitivity to heat or reduce the body’s ability to cope with extreme heat. NLCD data provide information on land cover (the percentage of developed, waterproof surfaces) and land use (the percentage of land used for development).

“NLCD has provided calibrated impervious surface percentage models since 2001. These models measure developed area very accurately down to every 30-meter pixel,” Dewitz said.

The other three factors of the Heat and Health Index are:

• Historical heat and health burdens, and the heat that the community has previously experienced compared to the rest of the country.
• Sensitivity, considering the prevalence of six pre-existing conditions in the community that could increase the risk of heat effects for people with those conditions.
• Sociodemographics, comparing the community to the rest of the country on social and demographic characteristics that increase exposure or sensitivity to heat, or reduce people’s ability to cope with extreme heat.

The Heat and Health Index tool is designed to help identify areas most vulnerable to extreme heat and to help individuals and communities make informed decisions to prepare for and prevent negative health impacts caused by heat.