For the 29th Olympic Summer games in 2008, surface measurements reveal that
concentrations of vehicle-related trace gases such as NO x and VOCs in Beijing
decreased by more than 20% since the emission control started; SO 2 and CO concentrations during the Olympic Games period were also lower than the same period in
2005 (Okuda et al. 2011; Wang et al. 2010). This result indicates the success of the
government’s effort to reduce emissions of gas pollutants. However, no significant
decreases in PM 2.5 , SO 4
2À
, and NO 3
À concentrations were detected. Xing et al. (2011)
demonstrated that, compared to the years 2005–2007, the meteorological conditions in
the summer of 2008 were more favorable for the formation of secondary particles,
which explains the lack of a decrease in aerosol concentrations.
A large decrease in the concentration of particulate matter was observed during
APEC and the Grand Military Parade. Surface observations in Beijing revealed that
PM 1 was dominated by secondary NO 3
À (approximately 30%) during three heavy
polluted episodes before the APEC summit, and the concentration of secondary
inorganic aerosols decreased by more than 50% during the APEC period (Sun et al.
2016). The chemical composition of PM 1 changed in the APEC period, and the SNA
proportion decreased from 48% to 59% in the earlier period to 37% during APEC.
Zhao et al. (2017) reported that the PM 1 concentration in Beijing during the emission
control period (August 20 to September 3) for the Grand Military Parade was more
than 50% lower than after the control period (September 4–30). SNA concentrations
during the control period were 62.8%, 74.3%, and 70.5% lower than during the
non-control period, respectively. On the other hand, the proportion of SNA in PM 1
increased from the control period to after the control period, indicating that emission
control had a larger impact on SNA than other species. Notably, during the control
period, PM 1 was dominated by organics (53–55%), followed by SO 4
2À (15–18%)
and NO 3
À (12–15%), whereas during the non-control period, the NO 3
À proportion
increased to more than 20%.
The decrease in the particulate matter concentration resulted from the influence of
emission reduction and changes in meteorological conditions. Zhang et al. (2018)
reported that emission control strategies contributed 26–30% of the good air quality
in Beijing during APEC and the parade, whereas the meteorological conditions
contributed the remaining 70–74%. A sensitivity analysis was also used to assess
the influence of emission controls during major events. Zhang et al. (2016) used the
adjoint model of GEOS-Chem to address the contribution of emission controls to
improving air quality during APEC 2014 in Beijing. Surface PM 2.5 and SO 2
observations were assimilated into the model to optimize emissions. The sensitivity
test was conducted for October 15 to November 14, 2014. Their results showed a
decrease of 8–33% in emissions in Beijing and a decrease of 6–30% in the BeijingTianjin-Hebei region during the APEC week. They also found that the PM 2.5
concentration shows large sensitivity to NH 3 and NO x emission changes during
the fall season because of the strong formation of NH 4 NO 3 , explaining the lower
percentage of SNA (especially NO 3
À ) during major events compared to the
referenced period, and it also indicated that the abatement of SNA precursor
emissions is more effective at reducing PM concentrations. Wang et al. (2017)
reported that vehicle control in Beijing resulted in a 13.5–14.7% reduction in the
PM 2.5 concentration during APEC and the parade period.
128
Y. Pan et al.
concentrations of vehicle-related trace gases such as NO x and VOCs in Beijing
decreased by more than 20% since the emission control started; SO 2 and CO concentrations during the Olympic Games period were also lower than the same period in
2005 (Okuda et al. 2011; Wang et al. 2010). This result indicates the success of the
government’s effort to reduce emissions of gas pollutants. However, no significant
decreases in PM 2.5 , SO 4
2À
, and NO 3
À concentrations were detected. Xing et al. (2011)
demonstrated that, compared to the years 2005–2007, the meteorological conditions in
the summer of 2008 were more favorable for the formation of secondary particles,
which explains the lack of a decrease in aerosol concentrations.
A large decrease in the concentration of particulate matter was observed during
APEC and the Grand Military Parade. Surface observations in Beijing revealed that
PM 1 was dominated by secondary NO 3
À (approximately 30%) during three heavy
polluted episodes before the APEC summit, and the concentration of secondary
inorganic aerosols decreased by more than 50% during the APEC period (Sun et al.
2016). The chemical composition of PM 1 changed in the APEC period, and the SNA
proportion decreased from 48% to 59% in the earlier period to 37% during APEC.
Zhao et al. (2017) reported that the PM 1 concentration in Beijing during the emission
control period (August 20 to September 3) for the Grand Military Parade was more
than 50% lower than after the control period (September 4–30). SNA concentrations
during the control period were 62.8%, 74.3%, and 70.5% lower than during the
non-control period, respectively. On the other hand, the proportion of SNA in PM 1
increased from the control period to after the control period, indicating that emission
control had a larger impact on SNA than other species. Notably, during the control
period, PM 1 was dominated by organics (53–55%), followed by SO 4
2À (15–18%)
and NO 3
À (12–15%), whereas during the non-control period, the NO 3
À proportion
increased to more than 20%.
The decrease in the particulate matter concentration resulted from the influence of
emission reduction and changes in meteorological conditions. Zhang et al. (2018)
reported that emission control strategies contributed 26–30% of the good air quality
in Beijing during APEC and the parade, whereas the meteorological conditions
contributed the remaining 70–74%. A sensitivity analysis was also used to assess
the influence of emission controls during major events. Zhang et al. (2016) used the
adjoint model of GEOS-Chem to address the contribution of emission controls to
improving air quality during APEC 2014 in Beijing. Surface PM 2.5 and SO 2
observations were assimilated into the model to optimize emissions. The sensitivity
test was conducted for October 15 to November 14, 2014. Their results showed a
decrease of 8–33% in emissions in Beijing and a decrease of 6–30% in the BeijingTianjin-Hebei region during the APEC week. They also found that the PM 2.5
concentration shows large sensitivity to NH 3 and NO x emission changes during
the fall season because of the strong formation of NH 4 NO 3 , explaining the lower
percentage of SNA (especially NO 3
À ) during major events compared to the
referenced period, and it also indicated that the abatement of SNA precursor
emissions is more effective at reducing PM concentrations. Wang et al. (2017)
reported that vehicle control in Beijing resulted in a 13.5–14.7% reduction in the
PM 2.5 concentration during APEC and the parade period.
128
Y. Pan et al.