Evaluation of the Reduction in PM2.5 Concentration During the National Traditional Games of Ethnic Minorities in Zhengzhou

Abstract

To evaluate the effect of the implementation of emission reduction measures and the improvement in air quality during the National Traditional Games of Ethnic Minorities in Zhengzhou, a series of online instruments were used to continuously observe air pollutants and components of PM2.5 from August 5 to September 30, 2019. Three cases, including before emission reduction (August 5-24), during emission reduction (August 25 to September 18), and after emission reduction (September 19-30), were classified by the implementation of control measures. The results show that the growing concentration of PM2.5 after the cancellation of emission abatement measures (11.7 μg·m-3) was greater than that during the emission reduction (2.3 μg·m-3) compared to the PM2.5 concentration before emission reduction. This thus indicates that the control measures have a significant effect on reducing particulate matter. The main components of PM2.5 were organic matter, nitrate, ammonium, sulfate, and crustal elements. Compared to the proportion of components in PM2.5 before and during the control periods, organic matter and nitrate increased by 3.9% and 0.9%, respectively, while sulfate, ammonium, and crustal elements decreased by 1.1%, 1.9%, and 2.2%, respectively. The results of source appointment by positive matrix factorization show that secondary sulfate, secondary nitrate, secondary organic aerosols, vehicular emissions, industrial emissions, dust, and coal combustion are the main sources of PM2.5. Emission abatement measures reduced the contributions of primary sources such as dust, coal combustion, and industry by 8.3%, 8.2%, and 8.1%, respectively. In contrast, the contributions of secondary organic and nitrate aerosols increased during the control periods, which suggested that the control measures implemented in Zhengzhou had a weaker emission reduction effect on nitrogen oxide and volatile organic compounds than on primary sources of PM2.5.