Large-Scale Spraying of Roads with Water Contributes to, Rather Than Prevents, Air Pollution
Fengzhu Tan,
Yuming Guo,
Wei Zhang,
Xingyan Xu,
Ming Zhang,
Fan Meng,
Sicen Liu,
Shanshan Li,
Lidia Morawska
Affiliations
Fengzhu Tan
Department of Environmental and Occupational Health, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
Yuming Guo
Climate, Air Quality Research Unit, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
Wei Zhang
Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China
Xingyan Xu
Department of Environmental and Occupational Health, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
Ming Zhang
Department of Environmental and Occupational Health, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
Fan Meng
Department of Environmental and Occupational Health, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
Sicen Liu
Department of Environmental and Occupational Health, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
Shanshan Li
Climate, Air Quality Research Unit, Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC 3004, Australia
Lidia Morawska
International Laboratory for Air Quality and Health, Queensland University of Technology, 2 George Street, Brisbane, QLD 4000, Australia
Spraying roads with water on a large scale in Chinese cities is one of the supplementary precaution or mitigation actions implemented to control severe air pollution events or heavy haze-fog events in which the mechanisms causing them are not yet fully understood. These air pollution events were usually characterized by higher air humidity. Therefore, there may be a link between this action and air pollution. In the present study, the impact of water spraying on the PM2.5 concentration and humidity in air was assessed by measuring chemical composition of the water, undertaking a simulated water spraying experiment, measuring residues and analyzing relevant data. We discovered that spraying large quantities of tap or river water on the roads leads to increased PM2.5 concentration and humidity, and that daily continuous spraying produces a cumulative effect on air pollution. Spraying the same amount of water produces greater increases in humidity and PM2.5 concentration during cool autumn and winter than during hot summer. Our results demonstrate that spraying roads with water increases, rather than decreases, the concentration of PM2.5 and thus is a new source of anthropogenic aerosol and air pollution. The higher vapor content and resultant humidity most likely create unfavorable meteorological conditions for the dispersion of air pollution in autumn and winter with low temperature.