The 2026 FIFA World Cup will be held in 16 cities across the United States, Mexico, and Canada, exposing tens of thousands of workers to varying occupational heat stress in June-July. While prior research largely examined risks to players and spectators, this study evaluates heat exposure among the workforce. Using 30 years (1991-2020) of hourly meteorological data, we calculated wet-bulb globe temperatures (WBGT) and assessed exceedance of NIOSH Recommended Exposure Limits (REL) and Recommended Alert Limits (RAL) across multiple activity levels and work/rest schedules. Results show inter-city variation. Hot, humid locations such as Houston, Miami, and Monterrey often reach maximum WBGTs near 31°C, frequently exceeding safety thresholds, particularly for higher workloads and longer shifts. Cooler cities like Seattle and San Francisco usually have maximum WBGTs below 20°C and remain under thresholds in typical conditions but face acute hazards during extreme events, such as the 2021 Pacific Northwest heat wave when WBGTs exceeded 32°C. Shading reduces heat stress by lowering peak WBGTs by ~2-3°C and substantially decreasing RAL and REL exceedance frequencies. Acclimatization further influences risk, as lower RAL thresholds for unacclimatized workers result in more frequent and prolonged exceedances across all work intensities and rest schedules compared with acclimatized workers. These findings highlight the need for venue-specific heat management plans reflecting local climate, workload, and rest patterns. Given varied protections, FIFA and host cities should adopt evidence-based measures such as flexible scheduling, hydration and cooling access, and acclimatization protocols, along with contingency plans for rare extreme heat waves.
Grundstein et al. (Thu,) studied this question.