Heat exposure, heat strain, and off-work recovery of Guatemalan sugarcane workers

Agricultural workers are at high risk for heat-related illnesses when performing heavy labor in hot conditions. Occupational heat strain, the physiological response to heat stress, is hypothesized to be common in this worker population but has rarely been measured objectively through core body temperature (T_c). The objective of this study was twofold: 1) evaluate workday heat strain and 2) examine the trajectory of heat exposure and T_c from the workday through the off-work hours to advance understanding of the recovery process and conditions of heat-exposed agricultural workers. Among 55 male Guatemalan agricultural workers, individual heat exposure (using ambient temperature loggers) and T_c (via an ingestible pill) were measured across a 24-h period, including workday and off-work hours. Urine samples were collected to assess hydration status on and off-work. Workers reported off-work activities, hydration practices, sleep, and nutrition through a survey. Data were summarized using descriptive statistics and visualizations. Workers experienced excessive heat strain (44% with T_c > 38.0°C, 16% with T_c > 38.3°C, and 6% with T_c > 38.5°C) during the workday. Approximately 29% achieved a higher maximal T_c during off-work hours than during the workday. Nearly 15% of workers reported sleeping <7 h. There is a need to understand off-work conditions, practices, and resources available to workers to mitigate heat strain and related illnesses. Heat stress and T_c monitoring should extend to postwork shift for assessment of workers' physiological recovery and to inform more comprehensive interventions to protect worker health.NEW & NOTEWORTHY This study examined the trajectory of heat exposure and core body temperature (T_c) across the workday into off-work hours among agricultural workers at risk of heat-related illness. Workday heat strain was common, and a significant proportion of workers experienced higher off-work T_c compared with their workday T_c. Survey and environmental data collected from workers provide insights into the off-work practices and conditions of the home environment that could influence the recovery of workers.