Submicron aerosols during the Beijing Asia-Pacific Economic Cooperation conference in 2014

Approximately 30%-40% of industrial practices and 50% of vehicles in operation were limited in Beijing and its surroundings regions during the Beijing Asia-Pacific Economic Cooperation (APEC) conference in 2014. Compared with values obtained prior to the APEC conference, the atmospheric concentration of submicron aerosol particles (PM1) decreased from 101 to 36.9 μg m−3, or 63%. Of all the inorganic species and black carbon present, the concentrations of nitrate to the total concentration of PM1 decreased the most in terms of both mass concentration, from 25.5 to 7.1 μg m−3, and relative contribution, from 21% to 14%. In addition, both sulfate and ammonium decreased substantially by 9.5 and 8.5 μg m−3, respectively. Accordingly, the relative contributions of ammonium nitrate and ammonium sulfate to light extinction decreased by 10% and 5%, respectively, as a result of the pollution control measures implemented during that period. In addition, polycyclic aromatic hydrocarbons in vehicle emissions were reduced significantly.