scholarly journals Biogenic isoprene and implications for oxidant levels in Beijing during the 2008 Olympic Games

2013 ◽  
Vol 13 (10) ◽  
pp. 25939-25967 ◽  
Author(s):  
C.-C. Chang ◽  
M. Shao ◽  
C. C. K. Chou ◽  
S.-C. Liu ◽  
J.-L. Wang ◽  
...  
Keyword(s):  
Air Quality ◽  
Air Pollutants ◽  
Olympic Games ◽  
Control Period ◽  
Light Flux ◽  
Control Measures ◽  
Oxidation Products ◽  
Daily Maximum ◽  
Ozone Formation ◽  
Early Afternoon

Abstract. As the host of the 2008 Summer Olympic Games, Beijing implemented a series of stringent, short-term air quality control measures to reduce the emissions of anthropogenic air pollutants. Large reductions in the daily average concentrations of primary pollutants, e.g., non-methane hydrocarbons (NMHCs) and nitrogen oxides (NOx) of approximately 50% were observed at the air quality observatory of Peking University. Nevertheless, high levels of ozone were present during the control period. Although anthropogenic precursors were greatly reduced, the meteorological conditions in summer, including high temperature and light flux, are conducive to the production of large amounts of biogenic isoprene, which is extremely reactive. The diurnal pattern of isoprene showed daily maximum mixing ratios of 0.83 ppbv at noon and a minimum at night, reflecting its primarily biogenic properties. Using the ratio of isoprene to vehicle exhaust tracers, approximately 92% of the daytime isoprene was estimated from biogenic sources, and only 8% was attributed to vehicular emissions. In terms of OH reactivity and the ozone formation potential (OFP), biogenic isoprene with its midday surge can contribute approximately 20% of the total OFPs and 40–50% of the total OH reactivities of the 65 measured NMHCs during the midday hours. The discrepancy between decreased precursor levels and the observed high ozone was most likely caused by a combination of many factors. The changes in the partition among the components of oxidation products (O3, NO2 and NOz) and the contribution of air pollutants from regional sources outside Beijing should be two primary reasons. Furthermore, the influences of biogenic isoprene as well as the non-linearity of O3-VOC-NOx chemistry are other major concerns that can reduce the effectiveness of the control measures for decreasing ozone formation. Although anthropogenic precursors were greatly reduced during the Olympic Games, sufficient biogenic isoprene and moderate NOx were still present in the conditions of high radiation flux and temperature during midday and early afternoon, which can still contribute a significant fraction of midday and early afternoon O3.

scholarly journals Air quality improvement in a megacity: implications from 2015 Beijing Parade Blue pollution control actions

2017 ◽  
Vol 17 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Wen Xu ◽  
Wei Song ◽  
Yangyang Zhang ◽  
Xuejun Liu ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Quality Improvement ◽  
Air Quality ◽  
Control Period ◽  
Emission Control ◽  
Monitoring Network ◽  
Control Measures ◽  
Integrated Analysis ◽  
Air Quality Improvement ◽  
Emission Control Measures ◽  
Control Regions

Abstract. The implementation of strict emission control measures in Beijing and surrounding regions during the 2015 China Victory Day Parade provided a valuable opportunity to investigate related air quality improvements in a megacity. We measured NH3, NO2 and PM2.5 at multiple sites in and outside Beijing and summarized concentrations of PM2.5, PM10, NO2, SO2 and CO in 291 cities across China from a national urban air quality monitoring network between August and September 2015. Consistently significant reductions of 12–35 % for NH3 and 33–59 % for NO2 in different areas of Beijing during the emission control period (referred to as the Parade Blue period) were observed compared with measurements in the pre- and post-Parade Blue periods without emission controls. Average NH3 and NO2 concentrations at sites near traffic were strongly correlated and showed positive and significant responses to traffic reduction measures, suggesting that traffic is an important source of both NH3 and NOx in urban Beijing. Daily concentrations of PM2.5 and secondary inorganic aerosol (sulfate, ammonium and nitrate) at the urban and rural sites both decreased during the Parade Blue period. During (after) the emission control period, concentrations of PM2.5, PM10, NO2, SO2 and CO from the national city-monitoring network showed the largest decrease (increase) of 34–72 % (50–214 %) in Beijing, a smaller decrease (a moderate increase) of 1–32 % (16–44 %) in emission control regions outside Beijing and an increase (decrease) of 6–16 % (−2–7 %) in non-emission-control regions of China. Integrated analysis of modelling and monitoring results demonstrated that emission control measures made a major contribution to air quality improvement in Beijing compared with a minor contribution from favourable meteorological conditions during the Parade Blue period. These results show that controls of secondary aerosol precursors (NH3, SO2 and NOx) locally and regionally are key to curbing air pollution in Beijing and probably in other mega cities worldwide.

scholarly journals Air Quality Improvement in a Megacity: Implications from 2015 Beijing Parade Blue Pollution-Control Actions

2016 ◽  
Author(s):  
Wen Xu ◽  
Wei Song ◽  
Yangyang Zhang ◽  
Xuejun Liu ◽  
Lin Zhang ◽  
...  
Keyword(s):  
Quality Improvement ◽  
Air Quality ◽  
Control Period ◽  
Emission Control ◽  
Monitoring Network ◽  
Control Measures ◽  
Integrated Analysis ◽  
Beijing City ◽  
Air Quality Improvement ◽  
Emission Control Measures

Abstract. The implementation of strict emission control measures in Beijing and surrounding regions during the 2015 China Victory Day Parade provided a valuable opportunity to investigate related air quality improvements in a megacity. We measured NH3, NO2 and PM2.5 at multiple sites in and outside Beijing and summarized concentrations of PM2.5, PM10, NO2, SO2 and CO in 291 cities across China from a national urban air quality monitoring network between August and September 2015. Consistently significant reductions of 12–35 % for NH3 and 33–59 % for NO2 in different areas of Beijing city during the emission control period (referred to as the Parade Blue period) were observed compared with measurements in the pre- and post-Parade Blue periods without emission controls. Average NH3 and NO2 concentrations at sites near traffic were strongly correlated and showed positive and significant responses to traffic reduction measures, suggesting that traffic is an important source of both NH3 and NOx in urban Beijing. Daily concentrations of PM2.5 and secondary inorganic aerosol (sulfate, ammonium, and nitrate) at the urban and rural sites both decreased during the Parade Blue period. Concentrations of PM2.5, PM10, NO2, SO2 and CO from the national city-monitoring network showed the largest decrease (34–72 %) in Beijing, a smaller decrease (1–32 %) in North China (excluding Beijing), and an increase (6–16 %) in other regions of China during the emission control period. Integrated analysis of modeling and monitoring results demonstrated that emission control measures made a major contribution to air quality improvement in Beijing compared with a minor contribution from favorable meteorological conditions during the Parade Blue period. These results show that controls of secondary aerosol precursors (NH3, SO2 and NOx) locally and regionally are key to curbing air pollution in Beijing and probably in other mega cities worldwide.

scholarly journals Daily variability of air pollution in locations of different population density

2019 ◽  
Vol 100 ◽  
pp. 00011
Author(s):  
Robert Cichowicz ◽  
Artur Stelęgowski
Keyword(s):  
Air Pollution ◽  
Air Quality ◽  
Population Density ◽  
Air Pollutants ◽  
Daily Maximum ◽  
Air Contaminants ◽  
Daily Variability ◽  
Air Quality Monitoring Stations ◽  
Agricultural Areas ◽  
Daily Changes

The air quality levels vary during a day, especially in inhabited areas. Therefore, it seems reasonable to observe and analyze the occurrence of daily maximum and minimum level of air pollution. In this article, data obtained from automatic air quality monitoring stations located in 5 large, 5 small and medium cities and 5 villages in Poland was analyzed in 2012−2016. Those locations vary, inter alia, depending on number of inhabitants and population density, and for this reason also due to the presence of air contaminants. As an indicator of daily variability air pollution it was determined the ratio of maximum to minimum concentrations of selected air pollutants (NO2 and NOx, and O3, SO2, CO, PM10 and PM2.5, and benzene) in urban and agricultural areas. In winter, the daily changes were bigger in cities than in villages. While in summer, the level of daily variability was similar, irrespective of size of the settlement unit. The biggest daily changes concerned nitrogen oxides, the lowest − sulfur dioxide and dusts.

scholarly journals Use of a mobile laboratory to evaluate changes in on-road air pollutants during the Beijing 2008 Summer Olympics

2009 ◽  
Vol 9 (21) ◽  
pp. 8247-8263 ◽  
Author(s):  
M. Wang ◽  
T. Zhu ◽  
J. Zheng ◽  
R. Y. Zhang ◽  
S. Q. Zhang ◽  
...  
Keyword(s):  
Air Pollution ◽  
Pollution Control ◽  
Air Pollutants ◽  
Control Period ◽  
Control Measures ◽  
In Situ Monitoring ◽  
Air Pollution Control ◽  
Mobile Laboratory ◽  
The Road ◽  
On The Road

Abstract. China implemented systematic air pollution control measures during the 2008 Beijing Summer Olympics and Paralympics to improve air quality. This study used a versatile mobile laboratory to conduct in situ monitoring of on-road air pollutants along Beijing's Fourth Ring Road on 31 selected days before, during, and after the Olympics air pollution control period. A suite of instruments with response times of less than 30 s was used to measure temporal and spatial variations in traffic-related air pollutants, including NOx, CO, PM1.0 surface area (S(PM1)), black carbon (BC), and benzene, toluene, the sum of ethylbenzene, and m-, p-, and o-xylene (BTEX). During the Olympics (8–23 August, 2008), on-road air pollutant concentrations decreased significantly, by up to 54% for CO, 41% for NOx, 70% for SO2, 66% for BTEX, 12% for BC, and 18% for SPM1, compared with the pre-control period (before 20 July). Concentrations increased again after the control period ended (after 20 September), with average increases of 33% for CO, 42% for NOx, 60% for SO2, 40% for BTEX, 26% for BC, and 37% for S(PM1), relative to the control period. Variations in pollutants concentrations were correlated with changes in traffic speed and the number and types of vehicles on the road. Throughout the measurement periods, the concentrations of NOx, CO, and BTEX varied markedly with the numbers of light- and medium-duty vehicles (LDVs and MDVs, respectively) on the road. Only after 8 August was a noticeable relationship found between BC and S(PM1) and the number of heavy-duty vehicles (HDVs). Additionally, BC and S(PM1) showed a strong correlation with SO2 before the Olympics, indicating possible industrial sources from local emissions as well as regional transport activities in the Beijing area. Such factors were identified in measurements conducted on 6 August in an area southwest of Beijing. The ratio of benzene to toluene, a good indicator of traffic emissions, shifted suddenly from about 0.26 before the Olympics to approximately 0.48 after the Olympics began. This finding suggests that regulations on traffic volume and restrictions on the use of painting solvents were effective after the Olympics began. This study demonstrated the effectiveness of air pollution control measures and identified local and regional pollution sources within and surrounding the city of Beijing. The findings will be invaluable for emission inventory evaluations and model verifications.

scholarly journals Variation of ambient non-methane hydrocarbons in Beijing city in summer 2008

2010 ◽  
Vol 10 (2) ◽  
pp. 5565-5597 ◽  
Author(s):  
B. Wang ◽  
M. Shao ◽  
S. H. Lu ◽  
B. Yuan ◽  
Y. Zhao ◽  
...  
Keyword(s):  
Quality Control ◽  
Air Quality ◽  
Olympic Games ◽  
Control Measures ◽  
Balance Model ◽  
Urban Site ◽  
Vehicle Exhaust ◽  
Beijing City ◽  
Air Quality Control ◽  
Paralympic Games

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.

scholarly journals Photochemical production of ozone in Beijing during the 2008 Olympic Games

2011 ◽  
Vol 11 (18) ◽  
pp. 9825-9837 ◽  
Author(s):  
C. C.-K. Chou ◽  
C.-Y. Tsai ◽  
C.-C. Chang ◽  
P.-H. Lin ◽  
S. C. Liu ◽  
...  
Keyword(s):  
Air Quality ◽  
Olympic Games ◽  
Substantial Reduction ◽  
Control Measures ◽  
Ozone Production ◽  
Air Pollution Control ◽  
Oxides Of Nitrogen ◽  
Mixing Ratio ◽  
Production Rates ◽  
Mixing Ratios

Abstract. As a part of the CAREBeijing-2008 campaign, observations of O3, oxides of nitrogen (NOx and NOy), CO, and hydrocarbons (NMHCs) were carried out at the air quality observatory of the Peking University in Beijing, China during August 2008, including the period of the 29th Summer Olympic Games. The measurements were compared with those of the CAREBeijing-2006 campaign to evaluate the effectiveness of the air pollution control measures, which were conducted for improving the air quality in Beijing during the Olympics. The results indicate that significant reduction in the emissions of primary air pollutants had been achieved; the monthly averaged mixing ratios of NOx, NOy, CO, and NMHCs decreased by 42.2, 56.5, 27.8, and 49.7 %, respectively. In contrast to the primary pollutants, the averaged mixing ratio of O3 increased by 42.2 %. Nevertheless, it was revealed that the ambient levels of total oxidant (Ox = O3+NO2+1.5 NOz) and NOz were reduced by 21.3 and 77.4 %, respectively. The contradictions between O3 and Ox were further examined in two case studies. Ozone production rates of 30–70 ppbv h−1 and OPEx of ~8 mole mole−1 were observed on a clear-sky day in spite of the reduced levels of precursors. In that case, it was found that the mixing ratio of O3 increased with the increasing NO2/NO ratio, whereas the NOz mixing ratio leveled off when NO2/NO>8. Consequently, the ratio of O3 to NOz increased to above 10, indicating the shift from VOC-sensitive regime to NOx-sensitive regime. However, in the other case, it was found that the O3 production was inhibited significantly due to substantial reduction in the NMHCs. According to the observations, it was suggested that the O3 and/or Ox production rates in Beijing should have been reduced as a result of the reduction in the emissions of precursors during the Olympic period. However, the nighttime O3 levels increased due to a decline in the NO-O3 titration, and the midday O3 peak levels were elevated because of the shift in the photochemical regime and the inhibition of NOz formation.

scholarly journals Insights for Air Quality Management from Modeling and Record Studies in Cuenca, Ecuador

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 998
Author(s):  
René Parra ◽  
Claudia Espinoza
Keyword(s):  
Air Quality ◽  
Public Transportation ◽  
Air Pollutants ◽  
Road Traffic ◽  
Nox Reduction ◽  
Primary Source ◽  
Daily Maximum ◽  
Reference Scenario ◽  
The Future ◽  
The Impact

On-road traffic is the primary source of air pollutants in Cuenca (2500 m. a.s.l.), an Andean city in Ecuador. Most of the buses in the country run on diesel, emitting high amounts of NOx (NO + NO2) and PM2.5, among other air pollutants. Currently, an electric tram system is beginning to operate in this city, accompanied by new routes for urban buses, changing the spatial distribution of the city’s emissions, and alleviating the impact in the historic center. The Ecuadorian energy efficiency law requires that all vehicles incorporated into the public transportation system must be electric by 2025. As an early and preliminary assessment of the impact of this shift, we simulated the air quality during two scenarios: (1) A reference scenario corresponding to buses running on diesel (DB) and (2) the future scenario with electric buses (EB). We used the Eulerian Weather Research and Forecasting with Chemistry (WRF-Chem) model for simulating the air quality during September, based on the last available emission inventory (year 2014). The difference in the results of the two scenarios (DB-EB) showed decreases in the daily maximum hourly NO2 (between 0.8 to 16.4 µg m−3, median 7.1 µg m−3), and in the 24-h mean PM2.5 (0.2 to 1.8 µg m−3, median 0.9 µg m−3) concentrations. However, the daily maximum 8-h mean ozone (O3) increased (1.1 to 8.0 µg m−3, median 3.5 µg m−3). Apart from the primary air quality benefits acquired due to decreases in NO2 and PM2.5 levels, and owing to the volatile organic compounds (VOC)-limited regime for O3 production in this city, modeling suggests that VOC controls should accompany future NOx reduction for avoiding increases in O3. Modeled tendencies of these pollutants when moving from the DB to EB scenario were consistent with the tendencies observed during the COVID-19 lockdown in this city, which is a unique reference for appreciating the potentiality and identifying insights for air quality improvements. This consistency supports the approach and results of this contribution, which provides early insights into the effects on air quality due to the recent operability of the electric tram and the future shift from diesel to electric buses in Cuenca.

scholarly journals Impacts of emission reduction and meteorological conditions on air quality improvement during the 2014 Youth Olympic Games in Nanjing, China

2017 ◽  
Vol 17 (21) ◽  
pp. 13457-13471 ◽  
Author(s):  
Qian Huang ◽  
Tijian Wang ◽  
Pulong Chen ◽  
Xiaoxian Huang ◽  
Jialei Zhu ◽  
...  
Keyword(s):  
Quality Improvement ◽  
Air Quality ◽  
Emission Reduction ◽  
Olympic Games ◽  
Model Simulation ◽  
Weather Conditions ◽  
Ambient Air ◽  
Quality Standard ◽  
Control Measures ◽  
Air Quality Improvement

Abstract. As the holding city of the 2nd Youth Olympic Games (YOG), Nanjing is highly industrialized and urbanized, and faces several air pollution issues. In order to ensure better air quality during the event, the local government took great efforts to control the emissions from pollutant sources. However, air quality can still be affected by synoptic weather, not only emission. In this paper, the influences of meteorological factors and emission reductions were investigated using observational data and numerical simulations with WRF–CMAQ (Weather Research and Forecasting – Community Multiscale Air Quality). During the month in which the YOG were held (August 2014), the observed hourly mean concentrations of SO2, NO2, PM10, PM2.5, CO and O3 were 11.6 µg m−3, 34.0 µg m−3, 57.8 µg m−3, 39.4 µg m−3, 0.9 mg m−3 and 38.8 µg m−3, respectively, which were below China National Ambient Air Quality Standard (level 2). However, model simulation showed that the weather conditions, such as weaker winds during the YOG, were adverse for better air quality and could increase SO2, NO2, PM10, PM2.5 and CO by 17.5, 16.9, 18.5, 18.8, 7.8 and 0.8 %. Taking account of local emission abatement only, the simulated SO2, NO2, PM10, PM2.5 and CO decreased by 24.6, 12.1, 15.1, 8.1 and 7.2 %. Consequently, stringent emission control measures can reduce the concentrations of air pollutants in the short term, and emission reduction is very important for air quality improvement during the YOG. A good example has been set for air quality protection for important social events.

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