Effectiveness of a Multifaceted Intervention (TEMP) for Prevention of Occupational Heat-Related Illness among Outdoor Workers in the Power Grid Industry: A Cluster Randomized Controlled Trial

Occupational heat-related illness (OHI) is a health threat to workers that can be fatal in severe cases. Effective and feasible measures are urgently needed to prevent OHI. We evaluated the effectiveness of a multifaceted intervention, TEMP, in reducing the OHI risk among outdoor workers in the power grid industry. A cluster randomized controlled trial was conducted with power grid outdoor workers in Southern China from 4 July 2022 to 28 August 2022. Work groups were randomly allocated (1:1) to the intervention or control groups. The multifaceted intervention TEMP comprised mobile application (app)-based education training (T), personal protective equipment [PPE (E)], OHI risk monitoring (M), and educational posters (P). Four follow-ups were conducted every 2 wk after the trial began. The primary outcome was the OHI incidence, and the secondary outcome was PPE usage. The app usage was considered as the compliance of intervention in the intervention group. The primary analysis used was intention-to-treat analysis. Multilevel analyses using random effects logistic regression models were performed to compare the odds of OHI between the two groups, adjusted for individual-level (education and work position) and work-related (including water intake when feeling thirsty, cooling measures, and poor sleep before work) covariates. Of 528 participants, 422 (79.92%) were males, and the mean±SD age was 36.36±8.18 y. The primary outcome, OHI incidence, was 1.80% in the intervention group and 4.82% in the control group at the end of the whole follow-up. OHI mainly occurred between 1100 and 1500 hours, with nausea, significantly increased heart rate, and oliguria being the top three reported OHI symptoms. Compared with the control group, the adjusted odds ratios between the intervention group and control group were 0.73 [95% confidence interval (CI): 0.30, 1.76] in the first follow-up wave, with 0.38 (95% CI: 0.15, 0.97), 0.29 (95% CI: 0.08, 1.05), and 0.39 (95% CI: 0.13, 1.19) in the following three follow-up waves, respectively. The intervention also significantly improved PPE usage in the intervention group. This multifaceted intervention reduced the OHI risk among outdoor workers in the power grid industry. However, further research is needed to design a more flexible intervention strategy and evaluate its effectiveness in a larger population. https://doi.org/10.1289/EHP14172.