Heat is the No. 1 weather-related killer in the United States, but it might be even more of a problem than we thought. A new report from NPR and Boston University suggests that the average number of heat-related deaths in North Carolina each year is almost 18 times what the U.S. Centers for Disease Control and Prevention have recorded.
NPR partnered with researchers at Boston University to better understand how rising temperatures are taking a toll on public health. They built a statistical model that ingested temperature readings — maximum daily temperature averaged at the weekly level. They used that model to estimate heat-related deaths.
The CDC data showed an average of about 19 heat-related deaths in North Carolina a year. NPR’s modeling based on climate data estimated 330.
The CDC only monitors heat deaths when doctors, coroners and medical examiners mention heat on the death certificate.
In South Carolina, Georgia, Tennessee and other Southeastern states, the model also estimated death totals many times the federal statistic.
The model also zooms in on the county level. 24 people on average die from heat in Mecklenburg County every year, according to the report. 20 in Wake County.
North Carolina uses the same standard as other states when it comes to determining the main cause of death: the International Classification of Diseases. The World Health Organization updates these codes every 10 years, adopting the most recent classification in 2019; however, the United States continues to use the 10th revision, which it adopted in 1999.
There are three codes relating to heat deaths, which correspond to “Exposure to Excessive Natural Heat,” “Heatstroke and Sunstroke,” and “Environmental Hyperthermia of Newborn.” According to the N.C. Department of Health and Human Services, this should include cases in which heat was reported as a “contributing cause of death,” as long as the death investigators include heat data in their report.
Some counties in other states have modified their heat reporting protocol to capture more heat-related deaths. During the warmer months, death investigators note the room temperature at the time of death. They also look for access to air-conditioning, even checking whether the person could pay their electric bills at the time of death. As a result, the CDC count is actually higher than the model estimates in places like Maricopa County in Arizona.
These numbers suggest counties are underreporting total heat-related deaths and underestimating the country’s #1 weather-related killer. But current data makes it hard to infer how heat deaths are trending in the United States. As global surface and oceanic temperatures continue to rise, many states are experiencing more risky heat days and higher humidity — two things that hinder our body’s ability to self-regulate.
