Impact of emission controls on air quality in Beijing during the 2015 China Victory Day Parade: Implication from organic aerosols

To evaluate the influence of the implementation of emission reduction measures on air quality during the 2015 China Victory Day Parade, the characteristics of organic aerosols in particulate matter with a diameter less than 2.5 gm (PM2.5) were analyzed from 11 August to 10 September 2015 in Beijing, China. The average concentration of PM2.5 decreased by 64% during the 2015 China Victory Day Parade compared with that before the event. Local emissions were the main PM2.5 sources during the 2015 China Victory Day Parade; cooking and traffic emission were two significant contributors. During the 2015 China Victory Day Parade, the average concentrations of levoglucosan and dehydroabietic acid decreased by 31% and 12%, respectively, indicating the significant effects of regional air pollution controls on air quality. 17 alpha(H), 21 beta(H)-30-Norhopane and 17 alpha(H), 21 beta(H)-hopane concentrations decreased continuously throughout the entire study period, suggesting the significant effect of the "odd-even" traffic restrictions implemented. Similarly, o-phthalic acid, succinic acid, and 2,3-dihydroxy-4-oxopentanoic acid (DPA) concentrations also significantly decreased during the Parade, with reductions of 63, 50, and 61%, respectively, compared with before the event. Photochemical oxidation played an important role in the formation of o-phthalic acid, while the formation of DPA was influenced by both photochemical oxidation and liquid-phase chemical reactions. The lung cancer risk, caused by inhalation exposure to polycyclic aromatic hydrocarbons, to the exposed populations decreased by 40% during the 2015 China Victory Day Parade, the enhanced control measures implemented during Parade Blue would also have positive influence on the human health.