Air Pollution In Beijing Research Articles

Tobacco in China: taming the smoking dragon

Beijing's air pollution makes news headlines around the world: hazy images of people's faces shrouded in masks and iconic monuments obscured by smog are now as synonymous with the city as the monuments themselves. As expatriate residents of Beijing, our friends and family from home often ask us: “But living in Beijing, how do you breathe?” We hope the answer is more easily after June 1, 2015, when Beijing's new smoke-free law will take effect.1 Although Beijing's outdoor ambient air pollution routinely makes the news, indoor air pollution in the city—and across China—is often worse than outdoor air pollution.

Dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid in PM<sub>2.5</sub> aerosol collected during CAREBeijing-2007: an effect of traffic restriction on air quality

Abstract. Thirty water-soluble organic species, including dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, fatty acids and benzoic acid were determined as well as organic carbon (OC), elemental carbon (EC) and water-soluble organic carbon (WSOC) in PM2.5 samples collected during the Campaign of Air Quality Research in Beijing 2007 (CAREBeijing-2007) in the urban and suburban areas of Beijing. The objective of this study is to identify the influence of traffic emissions and regional transport to the atmosphere in Beijing during summer. PM2.5 samples collected with or without traffic restriction in Beijing are selected to evaluate the effectiveness of local traffic restriction measures on air pollution reduction. The average concentrations of the total quantified bifunctional organic compounds (TQBOCs), total fatty acids and benzoic acid during the entire sampling period were 1184±241, 597±159 and 1496±511 ng m−3 in Peking University (PKU), and 1050±303, 475±114 and 1278±372 ng m−3 in Yufa, Beijing. Oxalic acid (C2) was found as the most abundant dicarboxylic acid at PKU and Yufa followed by phthalic acid (Ph). A strong even carbon number predominance with the highest level at stearic acid (C18:0), followed by palmitic acid (C16:0) was found for fatty acids. According to the back trajectories modeling results, the air masses were found to originate mainly from the northeast, passing over the southeast or south of Beijing (heavily populated, urbanized and industrialized areas), during heavier pollution events, whereas they are mainly from the north or northwest sector (mountain areas without serious anthropogenic pollution sources) during less pollution events. The data with wind only from the same sector (minimizing the difference from regional contribution) but with and without traffic restriction in Beijing were analyzed to evaluate the effectiveness of local traffic restriction measures on the reduction of local air pollution in Beijing. The results suggested that the traffic restriction measures can reduce the air pollutants, but the decrease of pollutants is generally smaller in Yufa compared to that in PKU. Moreover, an enhancement of EC value indicates more elevated primary emissions in Yufa during restriction periods than in non-restriction periods. This study demonstrates that even when primary exhaust was controlled by traffic restriction, the contribution of secondary organic species formed from photochemical processes was critical with long-range atmospheric transport of pollutants.

Evolution of surface O3 and PM2.5 concentrations and their relationships with meteorological conditions over the last decade in Beijing

In this study, hourly and daily records since 2005 and correlation, regression and composite methods were used to analyze the long-term evolution of surface O3 and PM2.5 concentrations at the rural station of Shangdianzi (SDZ) and urban station of Baolian (BL) over Beijing and their relationships with meteorological conditions. The results show that the mean concentrations of PM2.5 (O3) decreased (increased) at the urban and rural stations over the last decade. The linear trends of the annual mean concentrations of PM2.5 at BL and SDZ were −31.8 ug/m3/10yr (−4.3%/yr) (p < 0.01) and −13.3 ug/m3/10yr (−2.9%/yr) (p < 0.05), respectively. In winter, the mean wind speed (Ws) and relative humidity (RH) were the most closely correlated with O3 at both stations, whereas RH and sunshine hours (S) were most closely correlated with PM2.5. The correlation coefficients and explained variances in spring and autumn were generally less than those in winter and greater than those in summer. Moreover, increase in precipitation can significantly reduce the PM2.5 concentration in both urban and rural areas in Beijing, whereas trace and light precipitation more effectively decreases the O3 concentration. Concentrations of PM2.5 (O3) on haze days increased by 114% (3%) and 162% (20%) compared with that on non-haze days at the urban and rural stations, respectively. This result suggests that haze is a major manifestation of air pollution in Beijing.

Applying land use regression model to estimate spatial variation of PM₂.₅ in Beijing, China.

Fine particulate matter (PM2.5) is the major air pollutant in Beijing, posing serious threats to human health. Land use regression (LUR) has been widely used in predicting spatiotemporal variation of ambient air-pollutant concentrations, though restricted to the European and North American context. We aimed to estimate spatiotemporal variations of PM2.5 by building separate LUR models in Beijing. Hourly routine PM2.5 measurements were collected at 35 sites from 4th March 2013 to 5th March 2014. Seventy-seven predictor variables were generated in GIS, including street network, land cover, population density, catering services distribution, bus stop density, intersection density, and others. Eight LUR models were developed on annual, seasonal, peak/non-peak, and incremental concentration subsets. The annual mean concentration across all sites is 90.7 μg/m(3) (SD = 13.7). PM2.5 shows more temporal variation than spatial variation, indicating the necessity of building different models to capture spatiotemporal trends. The adjusted R (2) of these models range between 0.43 and 0.65. Most LUR models are driven by significant predictors including major road length, vegetation, and water land use. Annual outdoor exposure in Beijing is as high as 96.5 μg/m(3). This is among the first LUR studies implemented in a seriously air-polluted Chinese context, which generally produce acceptable results and reliable spatial air-pollution maps. Apart from the models for winter and incremental concentration, LUR models are driven by similar variables, suggesting that the spatial variations of PM2.5 remain steady for most of the time. Temporal variations are explained by the intercepts, and spatial variations in the measurements determine the strength of variable coefficients in our models.

PM2.5 in Beijing – temporal pattern and its association with influenza

BackgroundAir pollution in Beijing, especially PM2.5, has received increasing attention in the past years. Despite Beijing being one of the most polluted cities in the world, there has still been a lack of quantitative research regarding the health impact of PM2.5 on the impact of diseases in Beijing. In this study, we aimed to characterize temporal pattern of PM2.5 and its potential association with human influenza in Beijing.MethodsBased on the data collected on hourly ambient PM2.5 from year 2008 to 2013 and on monthly human influenza cases from 2008 and 2011, we investigated temporal patterns of PM2.5 over the five-year period and utilized the wavelet approach to exploring the potential association between PM2.5 and influenza.ResultsOur results found that ambient PM2.5 pollution was severe in Beijing with PM2.5 concentrations being significantly higher than the standards of the World Health Organization, the US EPA, and the Chinese EPA in the majority of days during the study period. Furthermore, PM2.5 concentrations in the winter heating seasons were higher than those in non-heating seasons despite high variations. We also found significant association between ambient PM2.5 peak and human influenza case increase with a delayed effect (e.g. delayed effect of PM2.5 on influenza).ConclusionsAmbient PM2.5 concentrations were significantly associated with human influenza cases in Beijing, which have important implications for public health and environmental actions.

Oxidative potential and inflammatory impacts of source apportioned ambient air pollution in Beijing.

Air pollution exposure is associated with a range of adverse health impacts. Knowledge of the chemical components and sources of air pollution most responsible for these health effects could lead to an improved understanding of the mechanisms of such effects and more targeted risk reduction strategies. We measured daily ambient fine particulate matter (<2.5 μm in aerodynamic diameter; PM2.5) for 2 months in peri-urban and central Beijing, and assessed the contribution of its chemical components to the oxidative potential of ambient air pollution using the dithiothreitol (DTT) assay. The composition data were applied to a multivariate source apportionment model to determine the PM contributions of six sources or factors: a zinc factor, an aluminum factor, a lead point factor, a secondary source (e.g., SO4(2-), NO3(2-)), an iron source, and a soil dust source. Finally, we assessed the relationship between reactive oxygen species (ROS) activity-related PM sources and inflammatory responses in human bronchial epithelial cells. In peri-urban Beijing, the soil dust source accounted for the largest fraction (47%) of measured ROS variability. In central Beijing, a secondary source explained the greatest fraction (29%) of measured ROS variability. The ROS activities of PM collected in central Beijing were exponentially associated with in vivo inflammatory responses in epithelial cells (R2=0.65-0.89). We also observed a high correlation between three ROS-related PM sources (a lead point factor, a zinc factor, and a secondary source) and expression of an inflammatory marker (r=0.45-0.80). Our results suggest large differences in the contribution of different PM sources to ROS variability at the central versus peri-urban study sites in Beijing and that secondary sources may play an important role in PM2.5-related oxidative potential and inflammatory health impacts.

Weekly cycle of magnetic characteristics of the daily PM2.5 and PM2.5–10 in Beijing, China

In recent years, Beijing has been shown to suffer one of the most serious air pollution problems of any major world city. The concentrations of particulate matter (PM) pollutants, PM2.5–10 and PM2.5, are commonly used as air pollution indexes. We conducted a detailed environmental magnetism study to investigate possible sources of air pollution in Beijing, China, using 283 pairs of the PM2.5 and PM2.5–10 samples collected daily from July 2010 to June 2011. Rock magnetic measurements, including magnetic susceptibility, anhysteretic remanent magnetization, isothermal remanent magnetization, saturation isothermal remanent magnetization, hysteresis loops, first-order reversal curves (FORCs), and thermomagnetism, indicate that the main magnetic mineral is low-coercivity pseudo-single domain (PSD) magnetite. Scanning electron microscope (SEM) observations and energy dispersive X-ray spectroscopy (EDS) analyses on the PM indicate that the major magnetic phase is coarse-grained magnetite, which is most likely from automobile exhausts and braking system debris. Magnetic parameters of PM2.5 and PM2.5–10 show significant seasonal patterns that may be attributed to domestic heating enhancing magnetization of the PM during late autumn to early spring. Power spectral analyses and box–whisker plots indicate that the magnetic parameters have strong weekly variations that may be due to traffic emissions. These results indicate that magnetic parameters can be used as efficient proxies for monitoring Beijing's air pollution, and that the atmospheric environment may be improved by controlling vehicle emissions.

Airborne endotoxin in fine particulate matter in Beijing

Endotoxin is an important biological component of particulate matter (PM) which, upon inhalation, can induce adverse health effects, and also possibly complicate the diseases in combination with other pollutants. From 1 March 2012 to 27 February 2013 we collected air samples using quartz filters daily for the quantification of airborne endotoxin and also fine PM (PM2.5) in Beijing, China. The geometric means for endotoxin concentration and the fraction of endotoxin in PM were 0.65 EU/m3 (range: 0.10–75.02) and 10.25 EU/mg PM2.5 (range: 0.38–1627.29), respectively. The endotoxin concentrations were shown to vary greatly with seasons, typically with high values in the spring and winter seasons. Temperature and relative humidity, as well as concentrations of sulfur dioxide and nitrogen oxides were found to be significantly correlated with airborne endotoxin concentrations (p < 0.05). Additionally, positive correlations were also detected between endotoxin concentrations and natural sources of Na+, K+, Mg2+, and F−, while negative correlations were observed between endotoxin concentrations and anthropogenic sources of P, Co, Zn, As, and Tl. Oxidative potential analysis revealed that endotoxin concentrations were positively correlated with reactive oxygen species (ROS), but not dithiothreitol (DTT) of PM. This study provided the first continuous time series of airborne endotoxin concentrations in Beijing, and identifies its potential associations with atmospheric factors. The information developed here can assist in the assessment of health effects of air pollution in Beijing.

Variations of ground-level O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; and its precursors in Beijing in summertime between 2005 and 2011

Abstract. Elevated ground-level ozone (O3), reflecting atmospheric oxidative capacity, are of increasing concern. High levels of total oxidants (Ox= O3 + NO2) have been persistently observed as a feature of Beijing's air pollution. Beijing is a well-known megacity requiring the enforcement of stringent air quality controls as rapid economic growth continues. To evaluate the effect of air quality controls in recent years, ground-based on-line measurements at an urban site were conducted in summer and the variations in O3 with simultaneous changes in NOx and volatile organic compounds (VOCs) between 2005 and 2011 were analyzed. Both NOx and total VOCs in Beijing decreased over the study period, 1.4 ppbv yr−1 and 1.6 ppbv yr−1, respectively. However, VOCs reactivity, in terms of OH loss rate, showed an indistinct statistical trend due to unsteady variations from naturally emitted isoprene, though some anthropogenic species showed decreasing trends, such as pentane, benzene and toluene. Meanwhile, daytime average O3 increased rapidly at an annual rate of 2.6 ppbv yr−1, around 5% yr−1 between 2005 and 2011. Considering the influence of NO titration effect and elevated regional ozone background in the North China Plain (NCP), the main reason for such an increase in oxidants was subject to "local" photochemistry. A simplified model was used to evaluate the effect of changes in the levels of ozone precursors on ozone production. We found that between 2001 and 2006, the production rate of total oxidants, P(Ox) increased rapidly due to increased VOC levels and decreasing NO2, while from 2006 to 2011 P(Ox) remained high, though decreased slightly as a consequence of the decrease in both VOC reactivity (−5% yr−1) and NOx (−4% yr−1). Observations have shown that Beijing's efforts to control air pollution were somehow effective in cutting ozone precursors, but still left higher ground-level ozone. We surmised that it resulted from potential contributions from OVOCs and regional transport near Beijing. Therefore, Beijing needs deeper cooperation with adjacent provinces to control ozone pollution together. To impel this kind of joint prevention and control program, ground-level ozone should become a mandatory index for air quality management, and a faster reduction of VOCs, especially reactive VOCs, in urban areas, should coordinate with national NOx emission control programs.

Methionine oxidation in albumin by fine haze particulate matter: An in vitro and in vivo study

The potential effects of inhaled fine particulate matter (PM2.5), found in haze episodes, on the oxidation of the proteins in the lungs are not well understood. We investigated the effects of PM2.5 from haze episodes on protein oxidation. PM2.5 was collected from the air pollution in Beijing (BJ), Xian (XA), Xiamen (XM) and Hong Kong (HK) during a period of intensive haze episodes. The chemical characteristics of these samples and their effects on albumin oxidation were investigated. The levels of PM2.5 in BJ and XA were 4–6 times higher than in XM and HK. The concentrations of the polycyclic aromatic hydrocarbons (PAHs) components of the PM2.5 from BJ and XA were 10 times higher than those found in XM and HK. The haze PM2.5 increased oxidative stress. Addition of PM2.5 samples collected from haze episodes to albumin in vitro resulted in oxidation of methionine moieties; nasal instillation of PM2.5 suspensions in mice resulted in oxidation of methionine in the albumin in the bronchoalveolar lavage fluid. The methionine moieties participate in peptide chain crosslinking, and methionine oxidation in the albumin could be attributed to the PAH compounds. Our findings may be helpful in explaining the potential respiratory effects during haze episodes.

Characteristics of Particle Matter Pollution and its Control in Beijing

"Particulate matter," or PM, is a complex mixture of extremely small particles and liquid droplets. PM is usually divided into PM10 and PM2.5. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. PM2.5 causes the greatest health problems, and reduces the visibility (haze). Beijing is the capital of the Peoples’ Republic of China. The PM pollution in Beijing not only poses huge economic, environmental and healthy loses, but also impacts on the China government’s credibility and international image. The paper analyzed the characteristics of PM pollution and put up with some suggestions in order to provide some theoretical guidance for the government implementing environmental protection policy and pollution control measures. The paper indicates that the average mass concentration of PM in Beijing varies with time; PM emissions have increased in recent years; PM2.5 and PM10 are the primary air pollutants in Beijing; and finally the government should take effective measures to control particle pollution to realize the people’s hope that the sky becomes blue again.

Fine particulate matter, temperature, and lung function in healthy adults: Findings from the HVNR study

Both ambient particulate air pollution and temperature alterations have been associated with adverse human health effects, but the interactive effect of ambient particulate and temperature on human health remains uncertain. The present study investigated the effects of ambient particulate matter with an aerodynamic diameter⩽2.5μm (PM2.5) and temperature on human lung function simultaneously in a panel of 21 healthy university students from the Healthy Volunteer Natural Relocation (HVNR) study in the context of suburban/urban air pollution in Beijing, China. Each study subject used an electronic diary meter to record peak expiratory flow (PEF) and forced expiratory volume in 1s (FEV1) twice a day for 6months in three periods before and after relocating from a suburban area to an urban area with changing ambient PM2.5 and temperature levels in Beijing. Hourly-averaged environmental data were obtained from central air-monitoring sites. Exposure effects were estimated using generalized linear mixed models controlling for potential confounders. Study subjects provided 6494 daily measurements on PEF and 6460 daily measurements on FEV1 over the study. PM2.5 was associated with reductions in evening PEF and morning/evening FEV1 whereas temperature was associated with reductions in morning PEF. The estimated PM2.5 effects on evening PEF and morning/evening FEV1 in the presence of high temperature were generally stronger than those in the presence of low temperature, and the estimated temperature effects on morning/evening PEF and morning FEV1 in the presence of high PM2.5 were also generally stronger than those in the presence of low PM2.5. For example, there were a 2.47% (95% confidence interval: −4.24, −0.69) reduction and a 0.78% (95% confidence interval: −1.59, 0.03) reduction in evening PEF associated with an interquartile range increase (78.7μg/m3) in PM2.5 at 4-d moving average in the presence of high temperature (⩾21.6°C) and low temperature (<21.6°C), respectively. Our findings suggest that ambient particulate and temperature may interact synergistically to cause adverse respiratory health effects.

Urban Boundary-Layer Stability and Turbulent Exchange during Consecutive Episodes of Particle Air Pollution in Beijing, China

Based on measurements at the Beijing 325-m Meteorological Tower,this study reports an analysis of atmospheric stability conditions and turbulent exchange during consecutive episodes of particle air pollution in Beijing(China),primarily due to haze and dust events(15–30 April 2012).Of particular interest were relevant vertical variations within the lower urban boundary layer(UBL).First,the haze and dust events were characterized by different atmospheric conditions,as quite low wind speed and high humidity are typically observed during haze events.In addition,for the description of stability conditions,the bulk Richardson number(RiB) was calculated for three different height intervals: 8–47,47–140,and 140–280 m.The values of RiB indicated an apparent increase in the occurrence frequency of stably-stratified air layers in the upper height interval—for the 140–280-m height interval,positive values of RiB occurred for about 85% of the time.The downward turbulent exchange of sensible heat was observed at 280 m for the full diurnal cycle,which,by contrast,was rarely seen at 140 m during daytime.These results reinforce the importance of implementing high-resolution UBL profile observations and addressing issues related to stably-stratified flows.

Seasonal and diurnal variations of atmospheric peroxyacetyl nitrate, peroxypropionyl nitrate, and carbon tetrachloride in Beijing

Atmospheric peroxyacetyl nitrate (PAN), peroxypropionyl nitrate (PPN), and carbon tetrachloride (CCl4) were measured from September 2010 to August 2011 in Beijing. PAN exhibited low values from mid-autumn to early spring (October to March) with monthly average concentrations ranging from 0.28 to 0.73 ppbV, and increased from early spring to summer (March to August), ranging from 1.37–3.79 ppbV. The monthly variation of PPN was similar to PAN, with low values (below detection limit to 0.18 ppbV) from mid-autumn to early spring, and a monthly maximum in September (1.14 ppbV). The monthly variation of CCl4 was tightly related to the variation of temperature, exhibiting a minimum in winter (69.3 pptV) and a maximum of 180.6 pptV in summer. Due to weak solar intensity and short duration, PAN and O3 showed no distinct diurnal patterns from morning to night during winter, whereas for other seasons, they both exhibited maximal values in the late afternoon (ca. 15:00 to 16:00 local time) and minimal values during early morning and midnight. Good linear correlations between PAN and PPN were found in autumn (R = 0.91), spring (R = 0.94), and summer (R = 0.81), with slopes of 0.130, 0.222, and 0.133, respectively, suggesting that anthropogenic hydrocarbons dominated the photochemical formation of PANs in Beijing. Positive correlation between PAN and O3 in summer with the low slopes (ΔO3/ΔPAN) ranging from 9.92 to 18.0 indicated serious air pollution in Beijing, and strong negative correlation in winter reflected strong O3 consumption by NO titration and less thermal decompositin of PAN.

The burden of air pollution on years of life lost in Beijing, China, 2004-08: retrospective regression analysis of daily deaths

Objectives To better understand the burden of air pollution on deaths, we examined the effects of air pollutants on years of life lost (YLL) in Beijing, China.Design Retrospective regression analysis...

Spatial and Temporal Distribution of Inhalable Particulate Matter Pollution in Beijing City during 2007-2012

Inhalable particles (PM10) and fine particles (PM2.5) have become the primary air pollutants in Beijing, seriously affecting visibility of the city , quality of the urban environment and the health of residents. To reflect the spatial and temporal variability condition of inhalable particles systematically in Beijing city in recent years , particulate matter of 0.3, 0.5,1.0, 3.0 and 5.0μm in heated period during 2007~2011 and non-heated period during 2007~2012 were measured in the field, statistical analysis about them was conducted . And spatial analytical method was used to study their distribution pattern. The results show that: (1) Differences of particle number concentration between heated period and non-heated period,were mainly reflected in PM0.3and PM1.0.The mean concentration of PM0.3(9.5E+07/ m3) in heated period was 2 times more of that (4.3E+07 /m3) in non-heated period. By contrast, the mean concentration of PM1.0(5.6E+06/m3) in non-heated period was 27% more than that (4.4E+06/m3) in heated period ; while concentration of other size was not very different. (2) The highest air pollution concentrations of particulate during non-heated period are in Fengtai District and Chaoyang District, which are respectively in the south and east of Beijing, followed by the city center . While the pollution in Shijingshan Dstrict in the west and Haidian District in the north was relatively lighter. (3) In heated period, the air particulate pollution of Beijing city was mainly concentrated in the east and southeast of Chaoyang District, as well as the city center and its surrounding area.

Association of lung function in a panel of young healthy adults with various chemical components of ambient fine particulate air pollution in Beijing, China

BackgroundAmbient fine particulate air pollution has been associated with impaired lung function, but the chemical components behind the association are not well understood. ObjectivesWe investigated the short-term effects of various air pollutants and chemical components of ambient fine particles (PM2.5) on lung function in a panel of 40 healthy university students. MethodsThe study subjects underwent biweekly spirometry tests for 12 times before and after their natural relocation from a suburban area to an urban area with changing air pollution levels and contents in Beijing, China. We estimated the short-term air pollution effects on lung function by applying four different mixed-effects models: single-pollutant model, component-PM2.5 joint model (two-pollutant model), component residual model, and exposure partitioned model. ResultsAmong the air pollutants, PM2.5 showed the most robust estimated effects on different lung function measures in a similar action pattern. Most air pollutants and PM2.5 chemical components were positively associated with lung function measures at a short-term averaging time (3-d moving average) and inversely associated with them at a longer averaging time (14-d moving average). We found consistent positive associations between chloride, zinc, copper, vanadium, lead, stannum and different lung function measures at 3-d moving average. We also found consistent inverse associations between calcium, magnesium and peak expiratory flow at 14-d moving average. ConclusionsOur findings suggest that PM2.5 and several metallic components may be the major air pollutants that contribute to the lung function changes. These findings may help achieve a better understanding of the features of a complex air pollution mixture that are most deleterious to health, and may also have implications for more targeted and effective pollution regulations aiming to improve the public health.

From Olympians to Mere Mortals

From Olympians to Mere Mortals

A Study of Energy Consumption and Exhaust Emissions from Beijing's Civil Vehicles from Years 2008 to 2020

ABSTRACT The number of Beijing's civil vehicles is growing rapidly due to the great support of the automobile industry and the Chinese government and the increasing average per capita income of China's people. Exhaust emissions from vehicles have already become the main source of Beijing's air pollution. Based on the Long-range Energy Alternatives Planning System (LEAP), this article predicts the energy consumption and exhaust emissions from Beijing's civil vehicles. Also, we estimated the reduction potentials of China's new fuel consumption standards and exhaust pollutants standards that will be implemented from 2008 to 2020. Two scenarios were developed: “Business as Usual” (BAU) and “New Standard” (NS). In the BAU scenario, the Chinese government would do nothing to improve the fuel consumption standards and exhaust pollutants standards in the future. In the NS scenario, the Chinese government would implement more strict fuel consumption standards and exhaust pollutants standards for Beijing's civil vehicles. By comparing the results of the two scenarios for year 2020, the energy consumption will experience a reduction of 7.8%, and the exhaust pollutants CO, HC, NOX, PM, and the emissions of CO2 would decrease by 43.3%, 36.4%, 60.3%, 81.2%, and 7.8%, respectively.

Chemical composition and size distribution of airborne particulate matters in Beijing during the 2008 Olympics

Abstract Size-segregated aerosol samples were collected daily in Beijing from 1 Jun. to 20 Sep. during the Beijing Olympic Games in 2008 to investigate aerosol concentrations, particle size distributions, and sources as well as the effects of pollution control measures on the chemical compositions (including Water-soluble ions, trace elements, elemental carbon (EC), and organic carbon (OC)) in aerosols of different sizes. Water-soluble ions, EC, OC, and trace elements accounted for 45.0%, 1.6%, 14.7%, and 11.4% of the total particle mass (PM), respectively. Approximately 56%, 56%, 30%, 71% and 55% of the PM, water-soluble ions, trace elements, EC and OC, respectively, were associated with particles smaller than 2.1 μm. Sulfate, nitrate, and ammonium were the dominant ions, which together accounted for approximately 77% of total water-soluble ions. The crustal elements accounted for the majority of the trace elements present. Different sources showed different mass size distributions. Anthropogenic source compounds, such as sulfate, nitrate, ammonium, OC, EC, and toxic elements, were mainly present in fine mode aerosols, whereas crustal elements, such as Al, Fe, Ca, Mg and Ba, primarily occurred in the coarse mode. SO 4 2 − and NH 4 + concentrations were strongly correlated (r2 = 0.90, slope = 1.63) in the fine mode, thereby indicating that SO 4 2 − was mainly present as (NH4)2SO4; in contrast, a weak correlation between SO 4 2 − and NH 4 + (r2 = 0.18, slope = 0.54) was observed in the coarse mode, indicating that SO 4 2 − was associated with other ions. Similarly, SO 4 2 − and NO 3 − exhibited a stronger correlation in the fine mode than in the coarse mode, indicating that SO 4 2 − and NO 3 − were formed via the same in-cloud processes in fine particles. The OC/EC ratio and the correlations between EC and OC concentrations showed that the sources of carbonaceous species were secondary organic carbon from fine particles and the long-range transport of coarse carbonaceous particles from biomass burning. The concentrations of atmospheric pollutants declined during the 2008 Olympic Games, indicating that the pollution control measures were effective in decreasing particulate air pollution in Beijing.