Lee Su-jin: 245-Death Gap in Heat Statistics Calls for Better Reporting

Between 2021 and 2025, South Korea’s official heat-related death figures showed a discrepancy of 245 deaths depending on the data source, according to records released to National Assembly member Lee Su-jin. Data from the Korea Disease Control and Prevention Agency (KDCA) reported 124 heat-related deaths, while the National Data Agency’s vital statistics recorded 369 deaths over the same five-year period, World Disability Love News reported.

Discrepancies in Five-Year Heat Mortality Data

The gap between the two agencies’ statistics has widened annually. In 2021, the KDCA recorded 20 deaths compared to 42 in the National Data Agency’s statistics. By 2024, the KDCA reported 34 deaths, while the National Data Agency recorded 108. In 2025, the figures stood at 29 and 100, respectively. Over the five-year span, the National Data Agency’s total count was nearly three times higher than the KDCA’s emergency room surveillance data.

Methodological Differences in Reporting

The variance stems from how each agency tracks heat-related health outcomes. The KDCA utilizes an emergency room surveillance system that monitors reports from approximately 500 medical institutions nationwide. This system is designed to provide rapid information to the public and encourage preventive action, but it does not capture every heat-related death occurring outside of these reporting emergency departments.

Conversely, the National Data Agency’s vital statistics are based on death classification codes, specifically tracking deaths attributed to excessive natural heat (X30) and exposure to sunlight (X32). While these statistics offer a broader view, the reliance on two different datasets has led to concerns that the actual impact of heatwaves on public health may be consistently underestimated.

High Mortality Rates Among Elderly Populations

Heat-related mortality is heavily concentrated among older residents. According to the National Data Agency’s 2025 records, 74% of the 100 heat-related deaths that year involved individuals aged 60 or older. Specifically, those aged 80 and above accounted for 36 of those deaths. This demographic trend has remained consistent, with the 80-plus age group recording 45 deaths in 2023 and 47 deaths in 2024.

Calls for Excess Mortality Statistical Models

Lee Su-jin has urged the government to adopt an excess mortality statistical model, similar to those used in the United States, United Kingdom, Australia, and Japan. This approach would estimate total heat-related deaths by comparing total mortality during heatwaves against expected death rates from baseline periods, rather than relying solely on emergency room reports.

“However, the KDCA’s surveillance system relies solely on emergency room reports, so there is a risk of underestimating the actual heatwave risk and related deaths,” Lee pointed out. She added that South Korea needs to introduce the subsequent publication of provisional excess deaths based on total deaths, comparing the number of deaths during heatwaves with the number of deaths during baseline periods before and after the heatwave, as they do in the UK.

Lee Su-jin

While the KDCA reported a cumulative 13,922 heat-related patients over the last five years—with annual cases rising from 1,376 in 2021 to 4,460 in 2025—Lee stated that the integration of excess mortality data could provide more precise information for national and local government policy responses to climate-related disasters.