Assessing Heat-Related Mortality and Morbidity Risks in Rural Populations and Sub-Populations

Heat stress is an environmental and occupational hazard exacerbated by climate change. Rural populations and sub-populations continue to experience disproportionate risks of heat-related impacts due to their low adaptive capacities in terms of infrastructure, information and other resources which are critical in dealing with heat. The study goals were to determine heat-related mortality risks in rural populations globally, explore the contribution of the outdoor work environment and other factors in association with occupational heat-related illnesses (HRI), and assess the risk of heat stress among crop workers using the Wet Bulb Globe Temperature (WBGT). Published peer-reviewed scientific literature on heat-related mortality in rural areas was used to assess heat-related risks among rural populations worldwide. Excess risks of both all-cause and cardiovascular mortalities were found although temperature had a stronger impact on cardiovascular deaths than for all-cause mortality. Also, using cross-sectional data from health screening clinics conducted during the summers of 2014, 2015, and 2016, a total of 425 patient encounters were analyzed using chi-square and logistic regression analyses to determine the role of the outdoor work environment and other factors associated with heat stress. As expected, the outdoor work environment was significantly associated with HRI. Out of the total of 67 HRI cases that were self-reported or diagnosed, 82% (55 cases) worked outdoors. There were nonsignificant elevations in HRI prevalence reported in males, workers below 40 years of age, individuals who have worked in agriculture for ten years or less, and those trained on heat safety. Further, a comprehensive evaluation of heat stress among crop workers was conducted using the four thermal climate factors-- air temperature, humidity, wind speed and solar radiation-- as well as work load and clothing factors. It found both acclimatized and non-acclimatized workers at risk of HRI. Regression analysis revealed that HRI prevalence was strongly correlated with the daily maximum WBGT (R2= 0.89; p= 0.03). Thus, effective heat safety precautions are needed, in addition to acclimatization, to protect vulnerable outdoor workers