# Consistently higher and steeper apparent temperature–heat-related illness risk among occupational cases in Korea: evidence from national emergency department surveillance

## TL;DR

Occupational workers in Korea face higher heat-related illness risks at high apparent temperatures compared to non-occupational individuals, suggesting a need for targeted prevention strategies.

## Contribution

This study provides evidence that occupational workers experience steeper increases in heat-related illness risk with rising apparent temperature compared to non-occupational individuals.

## Key findings

- Heat-related illness incidence increased non-linearly with apparent temperature in both occupational and non-occupational groups.
- Occupational IRRs were consistently higher than non-occupational IRRs at higher apparent temperature bins (e.g., 31°C, 33°C, 34°C).
- The findings suggest a need for worker-centered heat risk communication and prevention in humid climates.

## Abstract

Heat-related illness (HRI) is increasing under climate change, particularly in humid regions. While heat alerts increasingly rely on apparent temperature (AT), evidence linking AT conditions to differential HRI risk by occupational status remains limited.

We linked national emergency department (ED)-based HRI surveillance with daily national mean AT for June–September 2015–2024. We summarized bin-wise mean daily counts and estimated bin-specific incidence rate ratios (IRRs; reference = 24 °C) using Poisson regression.

HRI increased non-linearly with AT in both groups, and occupational IRRs tended to be higher than non-occupational IRRs at warmer bins. At 31 °C, occupational IRR was 37.07 vs. 23.86 for non-occupational; at 33 °C, 104.75 vs. 72.25; and at 34 °C, 167.22 vs. 141.06.

Workers may experience higher HRI risk under rising AT, underscoring the need for worker-centered prevention and heat-risk communication in humid climates.