[Comparative Analysis on the Improvement of Air Quality in Beijing During APEC]

In order to evaluate the effects of the implementation of emission reduction measures and the revolution of air quality of Beijing during APEC, the evolution characteristics of air quality was analyzed based on the hourly monitored readings of Olympic Sports Center from 1 to 15 November 2014 released by Environmental Monitoring Station of China, and compared with that in 2013. The results showed that: (1) PM₂.₅ was the main pollutant in Beijing. The air quality was good during the period of APEC with three obvious pollution events, and it was better than that in the same period in 2013, indicating that the implementation of emission reduction measures had made significant contribution to the improvement of air quality. (2) During the period of APEC, the concentrations of PM₂.₅ of 5 days were below the World Health Organization (WHO) standard (25 µg · m⁻³), and the concentration of SO₂ met the WHO standard during this time. (3) During the period of APEC, the ratio of PM₂.₅, and PM₁₀ was less than 0.5 when the air quality was good, and gradually increased with the increasing pollution level. The ratio reached 0.9 when the air was seriously polluted. (4) Compared with the same time in 2013, although the implementation of emission reduction measures made contribution to the reduction of the concentration of PM₂.₅, its contributions to the reduction of SO₂ and CO concentration were much more obvious than that of PM₂.₅, and it had little impact on the reduction of NO₂ concentration, and the reduction order of pollutants emission was SO₂ > CO > PM > NO₂, indicating that the sources, effects and emission reduction of PM₂.₅ were complex, and further studies are required.