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Abstract. In conjunction with hosting the 2008 Beijing Olympics, the municipal government implemented a series of stringent air quality control measures. To assess the impacts on variation of ambient non-methane hydrocarbons (NMHCs), the whole air was sampled by canisters at one urban site and two suburban sites in Beijing, and 55 NMHC species were quantified by gas chromatography equipped with a quadrupole mass spectrometer and a flame ionization detector (GC/MSD/FID) as parts of the field Campaign for the Beijing Olympic Games Air Quality program (CareBeijing). According to the control measures, the data were presented according to four periods: 18-30 June, 8-19 July, 15-24 August (during the Olympic Games), and 6-15 September (during the Paralympic Games). Compared with the levels in June, the mixing ratios of NMHCs obtained in the Olympic and Paralympic Games periods were reduced by 35% and 25%, respectively. Source contributions were calculated using a chemical mass balance model (CMB 8.2). After implementing the control measures, emissions from target sources were obviously reduced, and reductions in vehicle exhaust could explain 48-82% of the reductions of ambient NMHCs. Reductions in emissions from gasoline evaporation, paint and solvent use, and the chemical industry contributed 9-40%, 3-24%, and 1-5%, respectively, to reductions of ambient NMHCs. Sources of liquefied petroleum gas (LPG) and biogenic emissions were not controlled, and contributions from these sources from July to September were stable or even higher than in June. Ozone formation potentials (OFPs) were calculated for the measured NMHCs. The total OFPs during the Olympic and Paralympic Games were reduced by 48% and 32%, respectively, compared with values in June. Reductions in the OFPs of alkenes and aromatics explained 77-92% of total OFP reductions. The alkenes andCorrespondence to: M. Shao (mshao@pku.edu.cn) aromatics were mainly from vehicle exhausts, and reductions of vehicle exhaust gases explained 67-87% of reductions in alkenes and 38-80% of reductions in aromatics. These findings demonstrate the effectiveness of the air quality control measures enacted for the 2008 Olympics and indicate that controlling vehicular emissions could be the most important measure to improve air quality in Beijing.

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Container ships have been widely recognized as an important emission source within maritime transport. Heavy fuel oil (HFO) and diesel oil (DO) are the two most commonly used fuels. This study reports the characteristics and toxicities of particulate matter (PM) emissions from HFO and DO combustion in a typical container ship. The PM number size distribution possesses a bimodal structure with peaks at ∼20 nm and ∼100 nm. The PM 2.5 emission factors (EFs) are 3.15 ± 0.39 and 0.92 ± 0.02 g/kg fuel for HFO and DO, respectively. The benzo[a]pyrene equivalent carcinogenic potency (BaP eq ) of 16 polycyclic aromatic hydrocarbons contained in HFO and DO PM 2.5 is approximately 0.81 ± 0.10 and 0.12 ± 0.04 mg/kg fuel, respectively. BaP eq concentration shows an increasing tendency with decreased PM size. The reactive oxygen species activity and cytotoxicity of HFO PM 2.5 samples are ∼2.1 and ∼2.5 times higher than those of DO PM 2.5 samples, respectively. These health risks are both significantly attributed to the BaP eq content in PM 2.5 with correlations of 0.86−0.92. Furthermore, the examined biological effects are much greater than those of atmospheric PM 2.5 collected in Shanghai. Our results imply that better fuel quality is important for improving air quality and reducing health risks.

To understand the air pollution problem in megacities such as Beijing, field measurement investigating the variation of NH 3 and its association with PM 2.5 chemical property was conducted from 25 November to 24 December 2013. The results indicated that the daily concentration of wintertime NH 3 tended to be high on the days with relatively high temperatures and low wind speeds. Affected by the synoptic condition, NH 3 concentration showed a bimodal diurnal variation pattern, which tended to peak at around 09:00 and 22:00 of the day. As the sole precursor for NH 4 + , NH 3 exerted a significant impact on the ion chemistry of PM 2.5 through enhancing the nighttime NH 4 Cl formation and promoting both homogeneous and heterogeneous formation of NO 3 -. During heavy pollution episodes with PM 2.5 concentrations over 200 µg m -3 , the NH 3 levels and NH 4 + /NH 3 ratios grew simultaneously with the increase of PM 2.5 levels, indicating that NH 3 is one of the key reasons for heavy pollution events. Revealed by the features of measured ionic species in PM 2.5 , in conjunction with the acidity analysis using thermodynamic model, our results suggested that NH 3 was frequently sufficient in wintertime atmosphere of urban Beijing and the fine particulates were neutralized nearly fully by NH 3 .

Abstract. In conjunction with hosting the 2008 Beijing Olympics, the municipal government implemented a series of stringent air quality control measures. To assess the impacts on variation of ambient non-methane hydrocarbons (NMHCs), the whole air was sampled by canisters at one urban site and two suburban sites in Beijing, and 55 NMHC species were quantified by gas chromatography equipped with a quadrupole mass spectrometer and a flame ionization detector (GC/MSD/FID) as parts of the field Campaign for the Beijing Olympic Games Air Quality program (CareBeijing). According to the control measures, the data were presented according to four periods: 18–30 June, 8–19 July, 15–24 August (during the Olympic Games), and 6–15 September (during the Paralympic Games). Compared with the levels in June, the mixing ratios of NMHCs obtained in the Olympic and Paralympic Games periods were reduced by 35% and 25%, respectively. Source contributions were calculated using a chemical mass balance model (CMB 8.2). After implementing the control measures, emissions from target sources were obviously reduced, and reductions in vehicle exhaust could explain 48–82% of the reductions of ambient NMHCs. Reductions in emissions from gasoline evaporation, paint and solvent use, and the chemical industry contributed 9–40%, 3–24%, and 1–5%, respectively, to reductions of ambient NMHCs. Sources of liquefied petroleum gas (LPG) and biogenic emissions were not controlled, and contributions from these sources from July to September were stable or even higher than in June. Ozone formation potentials (OFPs) were calculated for the measured NMHCs. The total OFPs during the Olympic and Paralympic Games were reduced by 48% and 32%, respectively, compared with values in June. Reductions in the OFPs of alkenes and aromatics explained 77–92% of total OFP reductions. The alkenes and aromatics were mainly from vehicle exhausts, and reductions of vehicle exhaust gases explained 67–87% of reductions in alkenes and 38–80% of reductions in aromatics. These findings demonstrate the effectiveness of the air quality control measures enacted for the 2008 Olympics and indicate that controlling vehicular emissions could be the most important measure to improve air quality in Beijing.

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