Mineral dust and NOx promote the conversion of SO2 to sulfate in heavy pollution days

• Published in: Scientific reports Vol. 4; no. 1; p. 4172
• Main Authors: He, Hong, Wang, Yuesi, Ma, Qingxin, Ma, Jinzhu, Chu, Biwu, Ji, Dongsheng, Tang, Guiqian, Liu, Chang, Zhang, Hongxing, Hao, Jiming
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.02.2014; Nature Publishing Group
• Subjects: 639/638/169/824; 704/172/169/895; Air Pollutants; Air pollution; China; Coexistence; Dust; Flue gas; Haze; Humanities and Social Sciences; Humans; Motor vehicles; multidisciplinary; Nitric Oxide - chemistry; Nitrogen dioxide; Outdoor air quality; Science; Sulfates; Sulfates - chemistry; Sulfur dioxide; Sulfur Dioxide - chemistry; Synergistic effect; Vehicle emissions; China
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep04172

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 SO 2 , leading to rapid conversion of SO 2 to sulfate because NO 2 and SO 2 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 SO 2 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.