title: Mineral dust and NOx promote the conversion of SO2 to sulfate in heavy pollution days.
abstract: Haze in China has been increasing in frequency of occurrence as well as the area of the affected region. Here, we report on a new mechanism of haze formation, in which coexistence with NOx can reduce the environmental capacity for SO2, leading to rapid conversion of SO2 to sulfate because NO2 and SO2 have a synergistic effect when they react on the surface of mineral dust. Monitoring data from five severe haze episodes in January of 2013 in the Beijing-Tianjin-Hebei regions agreed very well with the laboratory simulation. The combined air pollution of motor vehicle exhaust and coal-fired flue gases greatly reduced the atmospheric environmental capacity for SO2, and the formation of sulfate was found to be a main reason for the growth of fine particles, which led to the occurrence of haze. These results indicate that the impact of motor vehicle exhaust on the atmospheric environment might be underestimated.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Yuesi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Qingxin
authors.initials: Q
authors.lastname: Ma
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Jinzhu
authors.initials: J
authors.lastname: Ma
authors.affiliation: 1] Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China [2] State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Biwu
authors.initials: B
authors.lastname: Chu
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Ji
authors.affiliation: State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
authors.forename: Guiqian
authors.initials: G
authors.lastname: Tang
authors.affiliation: Chinese Academy of Meteorological Sciences, Beijing 100081, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 10084, China.
authors.forename: Jiming
authors.initials: J
authors.lastname: Hao
mesh_terms: D000393:Air Pollutants; D002681:China; D006801:Humans; D009569:Nitric Oxide / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry; D013458:Sulfur Dioxide / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D013431:Sulfates; D013458:Sulfur Dioxide; D009569:Nitric Oxide