New Map Shows the Highest Heat Risk Isn’t Always Where Temperatures Are Hottest
The CDC’s new Heat and Health Index looks at the vulnerability of 32,000 neighborhoods to extreme heat using demographic and health statistics
People in neighborhoods such as East Harlem, in upper Manhattan, are at more risk than those in the nearby Upper East Side during heat waves, a new CDC map shows.
Nisian Hughes/Getty Images
CLIMATEWIRE | The U.S. neighborhood facing the biggest health risks from extreme heat is not in Arizona, Texas or Florida.
It’s in Idaho.
That’s the conclusion of the Biden administration, which recently rated 32,000 communities for their heat vulnerability.
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An interactive map created by the Centers for Disease Control and Prevention rates each ZIP code in the mainland U.S. to identify areas “most likely to experience negative health outcomes from heat.”
But CDC’s Heat and Health Index shows that heat risk is about much more than temperatures.
Heat vulnerability varies sharply within cities and is affected by neighborhood characteristics such as asthma rates, income levels, tree cover and smog, rather than heat itself.
A low-income ZIP code in East Harlem, a Manhattan neighborhood in New York City, is twice as vulnerable to heat-related health problems as an adjacent ZIP code on the Upper East Side, which is one of the richest neighborhoods in the country, the index shows. The two ZIP codes are separated by East 96th Street, where a major subway line runs above ground and demographics change dramatically.
The ZIP codes have identical weather. But on every other measure used by CDC, the East Harlem area is worse off than its Upper East Side neighbor. The tracker measures 25 characteristics for each ZIP code.
“It is really analyzing unique local factors driving heat-related illness,” CDC epidemiologist Amy Lavery said. “We wanted a tool that jurisdictions could use to prepare for extreme heat and prevent heat-related illnesses and death.”
ZIP code 83203 in southeast Idaho has the highest heat-vulnerability score. Although its temperatures haven’t reached 90 degrees yet this year, the area is considered prone to heat danger because of social factors such as high rates of people without health insurance, a lack of public transportation and a relatively large population of people who don’t speak English.
The CDC tracker differs from a Federal Emergency Management Agency index that rates the vulnerability of the 73,000 census tracts in the U.S. to 18 natural hazards, including heat waves. It also differs from the Census Bureau’s Community Resilience Estimates for Heat, which rates census tracts based on 10 demographic conditions such as poverty and a lack of health insurance.
FEMA’s National Risk Index uses heat information, demographics and population to develop a score based on the projected number of annual heat-related deaths in each census tract.
But the indexes can follow similar patterns. In the two Manhattan ZIP codes, the census tracts in East Harlem have a slightly higher heat wave vulnerability than their Upper East Side neighbors.
“They’re two different tools that have two different things in them,” Lavery said.
Census tracts have roughly 4,500 residents on average. ZIP codes have an average of roughly 9,500 residents.
Both indexes use a variety of data to assess a community’s socioeconomic composition, which affects people’s ability to withstand extreme heat and other natural hazards. Neither uses the racial or ethnic makeup of communities.
The CDC acknowledged numerous limitations with the data it used to rate each ZIP code including the use of some “self-reported data” and of “modeled meteorological data that may not accurately reflect the true maximum air temperature in all locations.”
The CDC index excludes ZIP codes with fewer than 50 residents due to the unreliability of data for such a small population. But the index includes 5,650 ZIP codes with fewer than 500 people, which have large error margins for census data.
“It is one of the limitations when working with these types of data. When you have a smaller population, it can change the margin of error,” Lavery said.
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2024. E&E News provides essential news for energy and environment professionals.
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