Prolonged heat exposure and health outcomes among construction workers in Saudi Arabia

Prolonged heat exposure can seriously affect the health and safety of workers. Construction workers in Saudi Arabia (SA) are highly vulnerable to this risk, particularly during the summer months. The risk of heat exposure can be amplified by personal and work-related factors. In SA, exposure to summer heat in construction work settings has not been subjected to thorough analysis. This has resulted in a lack of empirical data and poor awareness of this occupational risk. The aims of this dissertation are to: (1) assess the intensity and variability of heat stress exposure imposed on construction workers; (2) evaluate the impact of this exposure on the physiological response of workers; and (3) examine the health impact of heat stress on kidney injury (KI) and possible associated risk factors. Three studies were conducted to achieve these goals. In the first, worksite walkthrough surveys and daily environmental monitoring were performed over the study period (June–September, 2016). Excessive heat stress exposure was found both indoors and outdoors over a large portion of the working days. The highest intensity of exposure was outdoors from 9 a.m. to 12 p.m., a period associated with the highest heat stress exposure risk according to occupational heat stress guidelines. The heat index (HI) was found to be a reliable alternative to the wet bulb globe temperature (WBGT) index in assessing heat stress under the climate studied. In the second study, physiological monitoring of a subset group (n = 23) was carried out over 260 person-days, during which workload energy expenditure (EE), heart rate (HR) response, fluid intake, and pre- and post-shift urine specific gravity (USG) were measured. The calculated occupational heat stress exposure limits, based on WBGT measurements, (WBGTOEL) were exceeded on 60% of person-days indoors, indicating a high risk of heat strain. The ability of workers to self-pace their work helped them to tolerate heat stress and reduce heat strain occurrence as measured by heart rate reserves. USG concentrations indicated that workers began and ended their shifts dehydrated. The WBGTOEL showed higher sensitivity in identifying heat strain outdoors than indoors. In the third study, urinary albumin-creatinine ratio (ACR) was measured and survey data were collected at the start (June) and end (September) of the summer season from all the participating workers (n = 65). ACR levels as an indicator of KI were found to significantly increase across the summer months among most workers. Incidence of KI was observed in 18% of the cohort. Risk factors associated with KI included dehydration, short sleep, and obesity. These findings indicate that extreme heat exposure during summer represents a serious risk in construction work settings and possibly in other relevant industrial work settings. As such, there is an urgent need for heat stress management programs, especially given the projected increase in the duration and magnitude of occupational heat stress due to climate change.