Feasibility study of using nebulizer-retrofitted uavs at construction projects: The case study of residential jobsites in Utah

Increased heat stress and air pollution are two major causes of health issues and productivity loss in the construction industry. This will be exacerbated by global warming and an increased possibility of extreme weather conditions in the future. Previous studies revealed that each 1°C rise in temperature reduces construction workers' productivity by up to 2%. Also, it is found that a 10 μg/m3 particulate matter sized 2.5 μm (PM2.5) fluctuation over 25 days lowers workers' daily production by 1%. As an effective dust control and cooling strategy, water spraying is used by practitioners to mitigate the effect of air pollution and heat-related problems on construction workers. Considering low costs and high mobility, unmanned aerial vehicles (UAVs) could be considered as a potential alternative for ground-based, stationary water spraying systems. To this end, a case study approach is adopted in this project to investigate the feasibility of using nebulizer-retrofitted UAVs in controlling air pollution and reducing heat stress at construction job sites. The case study consists of two different residential job sites in the state of Utah: one in Salt Lake City and the other one in St. George. The main contribution of this study is to determine the effect of aerial water spraying on air temperature and pollution at job sites. The outcomes of this study show that the average wet bulb globe temperature (WBGT) decreases 1.7° during the flight phase compared to average values for preflight and postflight phases. The aerial water spraying technique yields better and more water-efficient results in decreasing temperature at job sites compared to the existing approaches, such as stationary fans. Moreover, the results of PM variations illustrate that the mean value of particulate change was significantly different between flight and preflight (p=0.005), and flight and postflight (p<0.001) modes. Future studies should include the deployment of multiple drones flying simultaneously at job sites to cover larger areas.