Estimation of the Main Factors Influencing Haze, Based on a Long-term Monitoring Campaign in Hangzhou, China

Received: April 25, 2011
Revised: September 27, 2011
Accepted: September 27, 2011
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2011.04.0052  

Cite this article:
Xiao, Z.m., Zhang, Y.f., Hong, S.m., Bi, X.h., Jiao, L., Feng, Y.c. and Wang, Y.q. (2011). Estimation of the Main Factors Influencing Haze, Based on a Long-term Monitoring Campaign in Hangzhou, China. Aerosol Air Qual. Res. 11: 873-882. https://doi.org/10.4209/aaqr.2011.04.0052

ABSTRACT

Eight years of data on haze and visibility (2003–2010) and one year of (2010) data on surface meteorological elements (relative humidity, wind speed, air temperature), visibility and the concentrations of air pollutants (PM_2.5, SO₂, NO₂ and O₃) measured each hour of each day were analyzed using correlation analysis to investigate the main factors influencing haze in Hangzhou, China. The occurrence of hazy weather has become more frequent over the past eight years in Hangzhou, and haze appears about 160 days per year. The occurrence of haze during the day was more frequent in the spring and the winter and less frequent in the summer and the autumn. Low visibility occurred in the morning, and the maximum visibility occurred in the afternoon period. The results of the statistical analysis show that the relative humidity and the concentration of PM_2.5 played the most important roles in reducing visibility. The correlation coefficients between the concentration of PM_2.5 and the concentrations of O₃, SO₂ and NO₂ indicate that O₃ and NO₂ are the dominant factors contributing to PM_2.5 pollution, which, in turn, can lead to haze. To reduce the number of haze days, greater concern and more countermeasures should be taken to decrease the O₃ and NO₂ pollution in Hangzhou, China.

Keywords: Haze; Relative humidity; PM2.5; O3; NO2