Trends in Occupational Heat-Health Research in Low-and Middle-Income Countries: A Mapping Review.

PURPOSE OF REVIEW: Extreme heat is increasingly threatening the health of workers worldwide and disproportionately impacting workers in low- and middle-income countries (LMICs). This mapping review was conducted to characterize the existing literature and to identify key gaps in field assessments of heat stress impacts on workers in LMICs.

RECENT FINDINGS: A total of 210 reports were included in the analysis. Almost two-thirds of included articles reported on studies conducted in lower-middle income countries (65%), with most reports from the South-East Asia Region (40%) and from India (30%), Iran (16%), and China (9%). At-risk populations were underrepresented, with 39% of reports not including any female participants and only 10% specifying migrant status, with wide variation in reporting of additional demographic, occupational, and workplace characteristics. Manufacturing and agriculture were by far the occupations most studied (36% and 33%, respectively). The most common index of heat stress was the wet bulb globe temperature (WBGT), with a report-level average ranging from 17.1 to 38.5 °C, with peaks as high as 54.4 °C. The most commonly reported outcomes were cardiovascular responses (50%) such as heart rate and blood pressure, body temperatures (43%), and self-reported symptoms of heat illness or heat strain (35%). Among all reports, only 9% included some form of intervention to protect workers. This review identifies the key trends and gaps in populations, occupations, and regions evaluated in heat-health research. As emerging technologies facilitate research expansion, this mapping review can guide future efforts to promote comparability of studies, overcome gaps, and protect worker health.