Sustainable solutions to mitigate occupational heat strain - an umbrella review of physiological effects and global health perspectives

Abstract

Background: Climate change is set to exacerbate occupational heat strain, the combined effect of environmental and internal heat stress on the body, threatening human health and wellbeing. Therefore, identifying effective, affordable, feasible and sustainable solutions to mitigate the negative effects on worker health and productivity, is an increasingly urgent need.

Objectives: To systematically identify and evaluate methods that mitigate occupational heat strain in order to provide scientific-based guidance for practitioners.

Methods: An umbrella review was conducted in biomedical databases employing the following eligibility criteria: 1) ambient temperatures > 28 °C or hypohydrated participants, 2) healthy adults, 3) reported psychophysiological (thermal comfort, heart rate or core temperature) and/or performance (physical or cognitive) outcomes, 4) written in English, and 5) published before November 6, 2019. A second search for original research articles was performed to identify interventions of relevance but lacking systematic reviews. All identified interventions were independently evaluated by all co-authors on four point scales for effectiveness, cost, feasibility and environmental impact.

Results: Following screening, 36 systematic reviews fulfilled the inclusion criteria. The most effective solutions at mitigating occupational heat strain were wearing specialized cooling garments, (physiological) heat acclimation, improving aerobic fitness, cold water immersion, and applying ventilation. Although air-conditioning and cooling garments in ideal settings provide best scores for effectiveness, the limited applicability in certain industrial settings, high economic cost and high environmental impact are drawbacks for these solutions. However, (physiological) acclimatization, planned breaks, shading and optimized clothing properties are attractive alternative solutions when economic and ecological sustainability aspects are included in the overall evaluation.

Discussion: Choosing the most effective solution or combinations of methods to mitigate occupational heat strain will be scenario-specific. However, this paper provides a framework for integrating effectiveness, cost, feasibility (indoors and outdoor) and ecologic sustainability to provide occupational health and safety professionals with evidence-based guidelines.

Keywords: Climate change; Environmental health; Heat stress; Occupational hygiene; Occupational medicine.

Fig. 1

Flow diagram of the review screening process

Fig. 2

Median (range) effect of type and timing of cooling intervention on physiological (pooled heart rate and core temperature) from systematic reviews included in the umbrella review. Number inside of bracket on y-axis denotes the number of effect size comparisons per intervention. Dashed upright lines denote threshold of no (0), small (0.2), moderate (0.5) and large (0.8) effect sizes

Fig. 3

Median (range) effect of type, timing and location of cooling intervention on physical performance from systematic reviews included in the umbrella review. Number inside of bracket on y-axis denotes the number of effect size comparisons per intervention. Dashed upright lines denote threshold of no (0), small (0.2), moderate (0.5) and large (0.8) effect sizes