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In this work an Operational Street Pollution Model was used to define the minimum number and the expected position of the stations for an air quality network with three monitoring stations to be installed in Battipaglia (Italy). The features of the urban background, the type of daily traffic, all the meteorological parameters typical of the investigated area, were implemented in the software to simulate the hourly emissions. These allowed to determine the feasible number of air sampling station and their best location points. [ABSTRACT FROM AUTHOR]

The adverse health impact of air pollution is becoming more serious. The purpose of this study is twofold: One is to analyze the effect of air pollution and temperatures on human health by analyzing the number of deaths from cardiovascular disease in Seoul, Korea; the other is to determine what impact the location of a monitoring site has on the results of a health study. For this latter purpose, air pollution and temperature monitors are sited at three locations termed green, public, and residential. Then, a decision tree model is used to analyze factors linked with deaths occurring at each monitoring site. The results show that the environmental temperatures before death and the PM2.5 concentrations on the day of death are highly linked with the number of deaths regardless of the monitoring location. However, results are most accurate with residential data. The results of this study can be used as base data for a similar analysis and ultimately, as a guide to minimize the health impact of air pollution. [ABSTRACT FROM AUTHOR]

Abstract As a major consumer of fossil fuels, the transportation sector in Shanghai presents a wide range of problems, including air pollution, noise, and traffic congestion. This study aims to explore the energy substitution effect based on a trans-log production function to evaluate the contribution of each input factor to sectoral output, and reveal the substitution possibilities between capital, labor, and energy. To deal with a multicollinearity problem, we adopt ridge regression to obtain the coefficient of each variable under the appropriate penalty value. The bootstrap method is used for making statistical inferences, and the 95% confidence interval is obtained with 1000 bootstrap samples. The empirical results demonstrate the following. (1) The output elasticities of capital (0.13–0.15), labor (0.24–0.25), and energy (0.43–0.48) are positive and show an increasing trend over the study period. (2) The substitution elasticity between labor and energy is the highest among the input factors (around 1.0095), with a slight decreasing trend. (3) The substitution elasticity between energy and capital ranges from 1.0018 to 1.0021, and the substitution elasticity between capital and labor is infinitely close to 1. Graphical abstract Image 1 Highlights • We analyze the energy substitution effect of Shanghai's transportation sector. • Elasticity of substitution between energy and labor trended down during 2000–2014. • Substitution between energy and labor can occur by mechanization and automation. • Elasticity of substitution between energy and capital ranges from 1.0018 to 1.0021. • Energy consumption can be cut by increasing capital inputs. [ABSTRACT FROM AUTHOR]

PM 2.5 samples were collected simultaneously at three urban sites including Beijing (BJ), Tianjin (TJ), Shijiazhuang (SJZ) and one background site Xinglong (XL) from June 2014 till April 2015. Typical polar organic aerosol tracers including 2-methylglyceric acid, 2-methyltetrols, 3-hydroxyglutaric acid, anhydrous saccharides and phthalic acid were analyzed by gas chromatography-mass spectrometry. Both Isoprene secondary organic aerosol (SOA) tracers and pinene SOA tracers had higher mass concentrations at background site than those at urban sites. But they showed different seasonal variations. The former had the highest mass concentration in summer while the latter had the highest mass concentration in spring. Anhydrous saccharides and phthalic acids at urban sites had higher mass concentrations than those at background site and showed higher mass concentration in autumn and winter, respectively. Corresponding estimated secondary organic carbons (SOCs) showed similar variation trends with tracers. In general, biogenic sources had more influence on background site while urban sites were more affected by anthropogenic sources. [ABSTRACT FROM AUTHOR]

China suffers from severe hazy conditions, and the central government has introduced a mandatory target responsibility system to curb haze pollution. It is of policy importance to explore whether the mandatory target responsibility system is effective at improving the performance of environmental governance in China. However, studies have tended to ignore the impact of mandatory targets on PM 2.5 concentration control. To fill this gap, this study, based on a nationwide dataset of 267 Chinese cities, applies a novel two-stage regression approach to identify the causal relationship between mandatory targets and PM 2.5 concentration reduction by solving the endogeneity bias. The results demonstrate that a 1% increase in mandatory PM 2.5 performance targets helped reduce the annual average PM 2.5 concentrations by 0.5283 μg/m 3 on average after nearly 2 years of implementation. Moreover, the PM 2.5 concentrations of Chinese cities showed strong positive spatial dependence, and when spatial dependence is controlled, the average marginal impact of mandatory targets on PM 2.5 concentration reduction decreased to 0.1998 μg/m 3 . This research confirms the spatial agglomeration of PM 2.5 concentrations across Chinese cities and highlights the effectiveness of the mandatory target responsibility system for the control of China's haze pollution. [ABSTRACT FROM AUTHOR]

The North China Plain (NCP) has experienced frequent severe haze pollution events in recent years. While extensive measurements have been made in megacities, aerosol sources, processes, and particle growth at urban downwind sites remain less understood. Here, an aerosol chemical speciation monitor and a scanning mobility particle sizer, along with a suite of collocated instruments, were deployed at the downwind site of Xingtai, a highly polluted city in the NCP, for real-time measurements of submicron aerosol (PM1) species and particle number size distributions during May and June 2016. The average mass concentration of PM1 was 30.5 (±19:4) µgm-3, which is significantly lower than that during wintertime. Organic aerosols (OAs) constituted the major fraction of PM1 (38 %), followed by sulfate (25 %) and nitrate (14 %). Positive matrix factorization with the multilinear engine version 2 showed that oxygenated OA (OOA) was the dominant species in OA throughout the study, on average accounting for 78% of OA, while traffic and cooking emissions both accounted for 11% of OA. Our results highlight that aerosol particles at the urban downwind site were highly aged and mainly from secondary formation. However, the diurnal cycle also illustrated the substantial influence of urban emissions on downwind sites, which are characterized by similar pronounced early morning peaks for most aerosol species. New particle formation and growth events were also frequently observed (58% of the time) on both clean and polluted days. Particle growth rates varied from 1.2 to 4.9 nm h-1 and our results showed that sulfate and OOA played important roles in particle growth during clean periods, while OOA was more important than sulfate during polluted events. Further analyses showed that particle growth rates have no clear dependence on air mass trajectories. [ABSTRACT FROM AUTHOR]

In an attempt to take effective action towards mitigating pollution episodes in Athens, precise knowledge of PM2.5 composition and its sources is a prerequisite. Thus, a 2-year chemical composition dataset from aerosol samples collected in an urban background site in central Athens from December 2013 to March 2016 has been obtained and a positive matrix factorization (PMF) was applied in order to identify and apportion fine aerosols to their sources. A total of 850 aerosol samples were collected on a 12 to 24 h basis and analyzed for major ions, trace elements, and organic and elemental carbon, allowing us to further assess the impact of residential heating as a source of air pollution over Athens. The ionic and carbonaceous components were found to constitute the major fraction of the PM2.5 aerosol mass. The annual contribution of the ion mass (IM), particulate organic mass (POM), dust, elemental carbon (EC), and sea salt (SS) was calculated at 31 %, 38 %, 18 %, 8 %, and 3 %, respectively, and exhibited considerable seasonal variation. In winter, the share of IM was estimated down to 23 %, with POMC EC being the dominant component accounting for 52% of the PM2.5 mass, while in summer, IM (42 %) and carbonaceous aerosols (41 %) contributed almost equally. Results from samples collected on a 12 h basis (day and night) during the three intensive winter campaigns indicated the impact of heating on the levels of a series of compounds. Indeed, PM2.5, EC, POM, NO-3, C2O2-4, non sea salt (nss) K+ and selected trace metals including Cd and Pb were increased by up to a factor of 4 in the night compared to the day, highlighting the importance of heating on air quality in Athens. Furthermore, in order to better characterize wintertime aerosol sources and quantify the impact of biomass burning on PM2:5 levels, source apportionment was performed. The data can be interpreted on the basis of six sources, namely biomass burning (31 %), vehicular emissions (19 %), heavy oil combustion (7 %), regional secondary (21 %), marine aerosols (9 %), and dust particles (8 %). Regarding night-to-day patterns their contributions shifted from 19 %, 19 %, 8 %, 31 %, 12 %, and 10% of the PM2.5 mass during day to 39 %, 19 %, 6 %, 14 %, 7 %, and 7% during the night, underlining the significance of biomass burning as the main contributor to fine particle levels during nighttime in winter. [ABSTRACT FROM AUTHOR]

Air pollution continues to be one of the main issues in urban areas. In addition to air quality plans and emission abatement policies, additional measures for high pollution episodes are needed to avoid exceedances of hourly limit values under unfavourable meteorological conditions such as the Madrid's short-term action NO 2 protocol. In December 2016 there was a strong atmospheric stability episode that turned out in generalized high NO 2 levels, causing the stage 3 of the NO 2 protocol to be triggered for the first time in Madrid (29th December). In addition to other traffic-related measures, this involves access restrictions to the city centre (50% to private cars). We simulated the episode with and without measures under a multi-scale modelling approach. A 1 km 2 resolution modelling system based on WRF-SMOKE-CMAQ was applied to assess city-wide effects while the Star-CCM+ (RANS CFD model) was used to investigate the effect at street level in a microscale domain in the city centre, focusing on Gran Vía Avenue. Changes in road traffic were simulated with the mesoscale VISUM model, incorporating real flux measurements during those days. The corresponding simulations suggest that the application of the protocol during this particular episode may have prevented concentrations to increase by 24 μg·m −3 (14% respect to the hypothetical no action scenario) downtown although it may have cause NO 2 to slightly increase in the city outskirts due to traffic redistribution. Speed limitation and parking restrictions alone (stages 1 and 2 respectively) have a very limited effect. The microscale simulation provides consistent results but shows an important variability at street level, with reduction above 100 μg·m −3 in some spots inside Gran Vía. Although further research is needed, these results point out the need to implement short-term action plans and to apply a consistent multi-scale modelling assessment to optimize urban air quality abatement strategies. [ABSTRACT FROM AUTHOR]

Background Epidemiologic studies of PM 2.5 (particulate matter with aerodynamic diameter ≤2.5 μm) and black carbon (BC) typically use ambient measurements as exposure proxies given that individual measurement is infeasible among large populations. Failure to account for variation in exposure will bias epidemiologic study results. The ability of ambient measurement as a proxy of exposure in regions with heavy pollution is untested. Objective We aimed to investigate effects of potential determinants and to estimate PM 2.5 and BC exposure by a modeling approach. Methods We collected 417 24 h personal PM 2.5 and 130 72 h personal BC measurements from a panel of 36 nonsmoking college students in Shanghai, China. Each participant underwent 4 rounds of three consecutive 24-h sampling sessions through December 2014 to July 2015. We applied backwards regression to construct mixed effect models incorporating all accessible variables of ambient pollution, climate and time-location information for exposure prediction. All models were evaluated by marginal R 2 and root mean square error (RMSE) from a leave-one-out-cross-validation (LOOCV) and a 10-fold cross-validation (10-fold CV). Results Personal PM 2.5 was 47.6% lower than ambient level, with mean (±Standard Deviation, SD) level of 39.9 (±32.1) μg/m 3 ; whereas personal BC (6.1 (±2.8) μg/m 3 ) was about one-fold higher than the corresponding ambient concentrations. Ambient levels were the most significant determinants of PM 2.5 and BC exposure. Meteorological and season indicators were also important predictors. Our final models predicted 75% of the variance in 24 h personal PM 2.5 and 72 h personal BC. LOOCV analysis showed an R 2 (RMSE) of 0.73 (0.40) for PM 2.5 and 0.66 (0.27) for BC. Ten-fold CV analysis showed a R 2 (RMSE) of 0.73 (0.41) for PM 2.5 and 0.68 (0.26) for BC. Conclusion We used readily accessible data and established intuitive models that can predict PM 2.5 and BC exposure. This modeling approach can be a feasible solution for PM exposure estimation in epidemiological studies. [ABSTRACT FROM AUTHOR]

Ulaanbaatar, the capital of Mongolia, is subject to high levels of atmospheric pollution during winter, which severely threatens the health of the population. By analyzing surface meteorological data, ground-based LIDAR data, and radiosonde data collected from 2008 to 2016, we studied seasonal variations in particulate matter (PM) concentration, visibility, relative humidity, temperature inversion layer thickness, and temperature inversion intensity. PM concentrations started to exceed the 24-h average standard (50 μg/m3) in mid-October and peaked from December to January. Visibility showed a significant negative correlation with PM concentration. Relative humidity was within the range of 60-80% when there were high PM concentrations. Both temperature inversion layer thickness and intensity reached maxima in January and showed similar seasonal variations with respect to PM concentration. The monthly average temperature inversion intensity showed a strong positive correlation with the monthly average PM2.5 concentration. Furthermore, the temperature inversion layer thickness exceeded 500 m in midwinter and overlaid the weak mixed layer during daytime. Radiative cooling enhanced by the basin-like terrain led to a stable urban atmosphere, which strengthened particulate air pollution. [ABSTRACT FROM AUTHOR]

Our study focuses on the carbon emission and mitigation potential in the domain of daily travel in Beijing. Using a sample with the focus on working class, the average individual carbon emissions from daily travel are computed as 1.46 kg/day•person and 2.40 kg/day•person for weekday and weekend. Except for residents who need to conduct more long-distance trips, the main contributor to the emissions of the rest high emitters are not the need of longer daily travel distances or the need to conduct more long distance trips, but the need to use cars more intensively for trips with similar distances compared with low emitters. High emitters are associated with the characteristics of being male, having higher income, owning cars, and being in the age between 30s and 40s. On the other hand, living within fifth ring and having good accessibility to public transport are associated with lower emissions. We innovatively use trip-based information to obtain a more relevant and realistic assessment of mitigation potential through mode shift under the current transport system. The mitigation percentage can be as high as 20%–25% if only travel time is considered, but will be substantially constrained by practical barriers. Therefore mitigation policy for daily transport should not only focus on improving travel time of low emission modes to comparable levels with cars but also tackle practical barriers for car drivers to use low emission modes. [ABSTRACT FROM AUTHOR]

Traffic Related Air Pollution ( TRAP ) studies are usually investigated using different categories such as air pollution exposure for health impacts, urban transportation network design to mitigate pollution, environmental impacts of pollution, etc. All of these subfields often rely on a robust air pollution model, which also necessitates an accurate prediction of future pollutants. As is widely accepted by the heath authorities, TRAP is considered to be the major health issue in urban areas, and it is difficult to keep pollution at harmless levels if the time sequenced dynamic pollution and traffic parameters are not identified and modelled efficiently. In our work here, artificial intelligence techniques, such as Bayesian Networks with an optimized configuration, are used to deliver a probabilistic traffic data analysis and predictive modelling for air pollution (SO 2 , NO 2 and CO) at very local scale of an urban region with up to 85% accuracy. The main challenge for traditional data analysis is a lack of capability to reveal the hidden links between distant data attributes (e.g. pollution sources, dynamic traffic parameters, etc.), whereas some subtle effects of these parameters or events may play an important role in pollution on a long-term basis. This study focuses on the optimisation of Bayesian Networks to unveil hidden links and to increase the prediction accuracy of TRAP considering its further association with a predictive GIS system. [ABSTRACT FROM AUTHOR]

It is widely believed air pollution is an obstacle to cycling as it has negative effects on cyclists’ health outcomes and deteriorates their cycling experiences. However, the empirical studies investigating the impact of air pollution on cycling behaviour remains scarce. The aim of this paper is to fill the gap by looking at Beijing as a case study. The authors conducted a survey of 307 cyclists on the days with different levels of air quality in terms of concentration of PM 2.5 in 2015. The results show that in the polluted weather, those who persist in cycling are more likely to be male, over 30 years old, lower income or those who travel short distances. Specifically, female cyclists have a higher tendency to shift from cycling to public transit than the males and medium and high-income earners are more likely to shift to using a car than low income earners. The residents’ subjective perceptions of safety and comfort have major effects on their cycling behaviour. A higher perception of comfort and safety is related to a higher possibility of continuing cycling when air quality became polluted. Cycling for commuting trips is less likely to be replaced by other modes than cycling for non-commuting trips, such as shopping. Results of this study reveal that improving air quality in a metropolitan area such as Beijing has co-benefits of cycling renaissance. The huge investments into cycling infrastructure should be integrated with policies designed to create an attractive environment for cycling. [ABSTRACT FROM AUTHOR]

Since 2006, Beijing lowered its public transit fares as a way to improve air quality. However, Beijing increased public transportation fare prices from December 28, 2014, and commuters pay for the distance they traveled rather than a flat fare. This paper explores the effect of Beijing public transit fares increase on air quality. We collect daily data of air pollution and weather variables and use synthetic control method of Abadie and Gardeazabal (2003) to select control units. We then estimate a difference-in-differences model and assess the effect of the policy on air quality index (AQI). We find a 16.28% increase in air pollution in short run. However, we find no longer-run effect on air quality. [ABSTRACT FROM AUTHOR]

Beijing often suffers under heavy smog. During such events which occur mostly in autumn and winter, people are desperate for fresh air. The formation of heavy smog is due to foremost human induced air pollution, but geographic and meteorological conditions, especially below a surface inversion, play an important role. We propose to destroy the inversion by pumping air from above the inversion layer to the surface layer to alleviate the severity of the smog. While long-term air quality improvement depends on the reduction of air pollution emission, air pumping may provide relief in the interim for the Beijing citizens. We estimate that an air pumping at a rate 2×107 m3 s-1 can lead to significantly improved air quality in Beijing, due to (1) direct clean air input; (2) increased instability and vertical mixing and (3) a positive radiation-mixing feedback. The pumping requires an energy input of 10 GW, comparable with the energy consumption in Beijing for air conditioning in summer. We propose to use wind energy from Inner Mongolia for the pumping, which has currently an installed wind energy capacity of 70 GW. [ABSTRACT FROM AUTHOR]

Few studies have linked social factors to air pollution exposure in China. Unlike the race or minority concepts in western countries, the Hukou system (residential registration system) is a fundamental reason for the existence of social deprivation in China. To assess the differences in ozone (O 3 ) exposure among social groups, especially groups divided by Hukou status, we assigned estimates of O 3 exposure to the latest census data of the Beijing urban area using a kriging interpolation model. We developed simultaneous autoregressive (SAR) models that account for spatial autocorrelation to identify the associations between O 3 exposure and social factors. Principal component regression was used to control the multicollinearity bias as well as explore the spatial structure of the social data. The census tracts (CTs) with higher proportions of persons living alone and migrants with non-local Hukou were characterized by greater exposure to ambient O 3 . The areas with greater proportions of seniors had lower O 3 exposure. The spatial distribution patterns were similar among variables including migrants, agricultural population and household separation (population status with separation between Hukou and actual residences), which fit the demographic characteristics of the majority of migrants. Migrants bore a double burden of social deprivation and O 3 pollution exposure due to city development planning and the Hukou system. [ABSTRACT FROM AUTHOR]

Objectives. To demonstrate the benefits-mapping software Environmental Benefits Mapping and Analysis Program-Community Edition (BenMAP-CE), which integrates local air quality data with previously published concentration-response and health-economic valuation functions to estimate the health effects of changes in air pollution levels and their economic consequences. Methods. We illustrate a local health impact assessment of ozone changes in the 10-county nonattainment area of the Dallas-Fort Worth region of Texas, estimating the short-term effects on mortality predicted by 2 scenarios for 3 years (2008, 2011, and 2013): an incremental rollback of the daily 8-hour maximum ozone levels of all area monitors by 10 parts per billion and a rollback-to-a-standard ambient level of 65 parts per billion at only monitors above that level. Results. Estimates of preventable premature deaths attributable to ozone air pollution obtained by the incremental rollback method varied little by year, whereas those obtained by the rollback-to-a-standard method varied by year and were sensitive to the choice of ordinality and the use of preloaded or imported data. Conclusions. BenMAP-CE allows local and regional public health analysts to generate timely, evidence-based estimates of the health impacts and economic consequences of potential policy options in their communities. [ABSTRACT FROM AUTHOR]

At a storefront museum approximately 25 miles southeast of Pittsburgh, Pennsylvania, a sign reads, "Clean Air Started Here." This is not hyperbole. At the end of October 1948, the communities of Donora and Webster in Pennsylvania were visited by a smog that changed the face of environmental protection in the United States. Conservative estimates showed that 20 individuals died, while an additional 5900--43% of the population of Donora--were affected by the smog. This event led to the first large-scale epidemiological investigation of an environmental health disaster in the United States. Questions remain about the long-term effects of the smog, because higher rates of cardiovascular disease and cancer than were expected were observed in the region in the decade following the smog. Recent work has suggested that environmental contaminants from a bygone era in Donora might have an impact even today. In addition, reports regarding air pollution have indicated that levels of pollutants similar to those estimated to have occurred in Donora are currently present in some rapidly industrializing regions of China and India. Seventy years after the smog, this event still resonates. [ABSTRACT FROM AUTHOR]

Objective To assess the relationship between short-term exposure to outdoor ambient air pollutants (fine particulate matter [PM 2.5 ] and black carbon [BC]), ischemic stroke (IS) and its different subtypes, and the potential modifying effect of neighborhood greenspace and noise. Methods This time-stratified case-crossover study was based on IS and transient ischemic attacks (TIA) recorded in a hospital-based prospective stroke register (BASICMAR 2005–2014) in Barcelona (Catalonia, Spain). Daily and hourly pollutant concentrations and meteorological data were obtained from monitoring stations in the city. Time-lags (from previous 72 h to acute stroke onset) were analyzed. Greenness and noise were determined from the Normalized Difference Vegetation Index (NDVI) and daily average noise level at the street nearest to residential address, respectively. Results The 2742 cases with known onset date and time, living in the study area, were analyzed. After adjusting for temperature, no statistically significant association between pollutants exposure and overall stroke risk was found. In subtype analysis, an association was detected between BC exposure at 24–47 h (odds ratio, 1.251; 95% confidence interval [CI], 1.001–1.552; P = 0.042) and 48–72 h (1.211; 95% CI, 0.988–1.484; P = 0.065) time-lag prior to stroke onset and large-artery atherosclerosis subtype. No clear modifying effect of greenness or noise was observed. Conclusions Overall, no association was found between PM 2.5 and BC exposure and acute IS risk. By stroke subtype, large-artery atherosclerotic stroke could be triggered by daily increases in BC, a diesel fuel-related pollutant in the study area. [ABSTRACT FROM AUTHOR]

Satellite-driven statistical models have been proven to be able to provide spatially resolved PM 2.5 estimates worldwide. The North China Plain has been suffering from severe PM 2.5 pollution in recent years. An accurate assessment of the spatiotemporal characteristics of PM 2.5 levels in this region is crucial to design effective air pollution control policy. Our objective is to estimate daily PM 2.5 concentrations at 1 km spatial resolution from 2004 to 2014 in Beijing and its surrounding areas using the Multi-angle implementation of atmospheric correction (MAIAC) aerosol optical depth (AOD). A high-performance three-stage model was developed with AOD, meteorological, demographic and land use variables as predictors, which includes a custom-designed PM 2.5 gap-filling method. The 11-year average annual coverage increased from 177 days to 279 days and annual PM 2.5 prediction error decreased from 14.1 μg/m 3 to 8.3 μg/m 3 after gap-filling techniques were applied. Results show that the 11-year overall mean of predicted PM 2.5 was 67.1 μg/m 3 in our study domain. The cross-validation R 2 value of our model is 0.82 in 2013 and 0.79 in 2014. In addition, the models predicted historical PM 2.5 concentrations with relatively high accuracy at the seasonal and annual levels (R 2 ranged from 0.78 to 0.86). Our long-term PM 2.5 prediction filled the gaps left by ground monitors, which would be beneficial to PM 2.5 related epidemiological studies in Beijing. [ABSTRACT FROM AUTHOR]

Objectives: We examined the impact of ambient air pollution on television use among residents in Shanghai, China. Methods: Device-measured daily average duration of television use from January 2014 to December 2016 was obtained from a random sample of 300 households and was matched to air pollution and weather data. We used an autoregressive moving-average model to estimate the association between air quality index (AQI) and television use. Results: There was a negative non-linear relationship between air pollution level and television use. Compared to the days when air quality was good (0⩽AQI⩽50), days with fair air quality (50150) were associated with a reduction in daily average television use by 2.9 (p = .002), 4.6 (p < .001) and 1.9 (p = .369) minutes, respectively. Television use decreased with daytime temperature but increased on weekend days, holidays and rainy days. Conclusions: Modest but not more severe air pollution was associated with reduced television use. People might mitigate the detrimental impact of air pollution by engaging in other indoor activities and/or sleeping. [ABSTRACT FROM AUTHOR]

To investigate ecological risks and spatial distributions of heavy metals in atmospheric particles in the Beijing urban area, atmospheric dust was collected from 62 sites and 12 heavy metals in their <63 μm fractions were measured. Results indicate that V, Cr, Mn, Co, Ni, and Ba in the dust are basically unpolluted by human activities; whereas Cu, Zn, As, Cd, Sb, and Pb are moderately to heavily polluted. These metals (not including Ba) in most dust show a high ecological risk (RI = 809 ±585, ranging 291-4,848), predominantly contributed by Cd (71%) and Sb (14%). Relatively higher risks mainly occur in the eastern and northwestern urban areas. The high risks in the east are caused mainly by Cd pollution associated with coal-burning and industrial and traffic activities, while those in the northwest are caused mainly by Sb pollution associated with point pollution sources and Cd pollution from traffic activity. This is significant for controlling atmospheric heavy metal pollution over the Beijing urban area and investigating atmospheric metal pollution in other cities. [ABSTRACT FROM AUTHOR]

The present study was undertaken as a survey of radiological and chemical air pollution on both the European and Asian sides of Istanbul, Turkey. In this framework, radionuclide activity concentrations and selected metal amounts in moss samples collected from urban, suburban, industrial, and green zone areas in Istanbul were determined following the moss biomonitoring technique. The activity concentrations in the moss samples vary from 2 to 20 Bq/kg for 226Ra, from 4 to 23 Bq/kg for 232Th, and 359 to 2,809 Bq/kg for 40 K for both sides of the city. Concentrations of Al, As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, Sb, V, and Zn were determined by ICP-ES. Additionally, potential ecological impacts of atmospheric deposition for selected metals based on moss analysis around Istanbul were assessed. Results show that the enrichment factor for the European side was greater than 10 for Pb. [ABSTRACT FROM AUTHOR]

We conducted the first real-time continuous vertical measurements of particle extinction (bext), gaseous NO2, and black carbon (BC) from ground level to 260 m during two severe winter haze episodes at an urban site in Beijing, China. Our results illustrated four distinct types of vertical profiles: (1) uniform vertical distributions (37% of the time) with vertical differences less than 5%, (2) higher values at lower altitudes (29%), (3) higher values at higher altitudes (16%), and (4) significant decreases at the heights of ~100-150 m (14%). Further analysis demonstrated that vertical convection as indicated by mixing layer height, temperature inversion, and local emissions are three major factors affecting the changes in vertical profiles. Particularly, the formation of type 4 was strongly associated with the stratified layer that was formed due to the interactions of different air masses and temperature inversions. Aerosol composition was substantially different below and above the transition heights with ~20-30% higher contributions of local sources (e.g., biomass burning and cooking) at lower altitudes. A more detailed evolution of vertical profiles and their relationship with the changes in source emissions, mixing layer height, and aerosol chemistry was illustrated by a case study. BC showed overall similar vertical profiles as those of bext (R² = 0.92 and 0.69 in November and January, respectively). While NO2 was correlated with bext for most of the time, the vertical profiles of bext/NO2 varied differently for different profiles, indicating the impact of chemical transformation on vertical profiles. Our results also showed that more comprehensive vertical measurements (e.g., more aerosol and gaseous species) at higher altitudes in the megacities are needed for a better understanding of the formation mechanisms and evolution of severe haze episodes in China. [ABSTRACT FROM AUTHOR]

To evaluate air pollution and the public health burden of heavy metals in PM2.5 in a campus with a population of approximately 40,000 in a typical suburb area of Taiyuan, North China, PM2.5 measurements were conducted during the spring and winter of 2016. The average concentrations of PM2.5 in spring and winter were 97.3 ± 35.2 μg m-3 and 205.9 ± 91.3 μg m-3, respectively. The order of concentration of heavy metals in PM2.5 was as follows: Zn > Pb > Mn > Cu > Cr > Ni > Cd > As, in both spring and winter. The concentrations of Cd and Pb in winter and the concentrations of Cr in both spring and winter in this study were significantly higher than the corresponding air quality standard values. Road/soil dust, industrial emissions/coal combustion, and vehicle emissions/oil combustion and coal combustion/industrial emissions, road/soil dust, and vehicle emissions/oil combustion were identified by principal component analysis to be the major sources of heavy metals for spring and winter, respectively. The carcinogenic risks posed by Cr via the three exposure pathways (except for inhalation exposure to children) and by Pb via ingestion exposure exceeded the acceptable level for both children and adults. The non-carcinogenic risks posed by Mn via inhalation for both children and adults, and by Cr and Pb for children via ingestion exceeded the acceptable level. [ABSTRACT FROM AUTHOR]

Gas-phase autoxidation--regenerative peroxy radical formation following intramolecular hydrogen shifts--is known to be important in the combustion of organic materials. The relevance of this chemistry in the oxidation of organics in the atmosphere has received less attention due, in part, to the lack of kinetic data at relevant temperatures. Here, we combine computational and experimental approaches to investigate the rate of autoxidation for organic peroxy radicals (RO2) produced in the oxidation of a prototypical atmospheric pollutant, n-hexane. We find that the reaction rate depends critically on the molecular configuration of the RO2 radical undergoing hydrogen transfer (H-shift). RO2 H-shift rate coefficients via transition states involving six- and seven-membered rings (1,5 and 1,6 H-shifts, respectively) of a-OH hydrogens (HOC-H) formed in this system are of order 0.1 s-1 at 296 K, while the 1,4 H-shift is calculated to be orders of magnitude slower. Consistent with H-shift reactions over a substantial energetic barrier, we find that the rate coefficients of these reactions increase rapidly with temperature and exhibit a large, primary, kinetic isotope effect. The observed H-shift rate coefficients are sufficiently fast that, as a result of ongoing NOx emission reductions, autoxidation is now competing with bimolecular chemistry even in the most polluted North American cities, particularly during summer afternoons when NO levels are low and temperatures are elevated. [ABSTRACT FROM AUTHOR]

The objective of this article is to calculate the optimal gasoline tax for Quebec and, in particular, for its two largest urban areas: the Greater Montreal Area (GMA) and the Greater Quebec City Area (GQA). This optimal tax accounts for externalities resulting from traffic congestion, road accidents, local air pollution, and climate change. Our methodology draws on Parry's (2009) theoretical model, which we calibrate with parameters for the Quebec context from the literature or from original estimations. We find that the optimal gasoline tax should be $0.72/litre in the GMA, $0.65/litre in the GQA, and $0.28/litre in the rest of the province. Thus, at $0.292/litre, the actual level of excise tax turns out to be very close to the optimal level of gasoline tax if the congestion costs are internalized through other instruments such as congestion charges. [ABSTRACT FROM AUTHOR]

The growth of mega-cities leads to air quality problems directly affecting the citizens. Satellite measurements are becoming of higher quality and quantity, which leads to more accurate satellite retrievals of enhanced air pollutant concentrations over large cities. In this paper, we compare and discuss both an existing and a new method for estimating urban-scale trends in CO emissions using multi-year retrievals from the MOPITT satellite instrument. The first method is mainly based on satellite data, and has the advantage of fewer assumptions, but also comes with uncertainties and limitations as shown in this paper. To improve the reliability of urban-to-regional scale emission trend estimation, we simulate MOPITT retrievals using the Weather Research and Forecast model with chemistry core (WRF-Chem). The difference between model and retrieval is used to optimize CO emissions in WRF-Chem, focusing on the city of Madrid, Spain. This method has the advantage over the existing method in that it allows both a trend analysis of CO concentrations and a quantification of CO emissions. Our analysis confirms that MOPITT is capable of detecting CO enhancements over Madrid, although significant differences remain between the yearly averaged model output and satellite measurements (R² = 0.75) over the city. After optimization, we find Madrid CO emissions to be lower by 48% for 2002 and by 17% for 2006 compared with the EdgarV4.2 emission inventory. The MOPITT-derived emission adjustments lead to better agreement with the European emission inventory TNO-MAC-III for both years. This suggests that the downward trend in CO emissions over Madrid is overestimated in EdgarV4.2 and more realistically represented in TNO-MACC-III. However, our satellite and model based emission estimates have large uncertainties, around 20% for 2002 and 50% for 2006. [ABSTRACT FROM AUTHOR]

Traffic emissions contribute significantly to urban air pollution. Measurements were conducted over Highway 401 in Toronto, Canada, with a long-path Fourier transform infrared (FTIR) spectrometer combined with a suite of micrometeorological instruments to identify and quantify a range of air pollutants. Results were compared with simultaneous in situ observations at a roadside monitoring station, and with output from a special version of the operational Canadian air quality forecast model (GEM-MACH). Elevated mixing ratios of ammonia (0-23 ppb) were observed, of which 76% were associated with traffic emissions. Hydrogen cyanide was identified at mixing ratios between 0 and 4 ppb. Using a simple dispersion model, an integrated emission factor of on average 2.6 g km-1 carbon monoxide was calculated for this defined section of Highway 401, which agreed well with estimates based on vehicular emission factors and observed traffic volumes. Based on the same dispersion calculations, vehicular average emission factors of 0.04, 0.36, and 0.15 g km-1 were calculated for ammonia, nitrogen oxide, and methanol, respectively. [ABSTRACT FROM AUTHOR]

Data on fine particulate matter (PM 2.5 ) in China were first announced in 2013. The primary objective of this study was to evaluate the acute effects of PM 2.5 on asthma morbidity in Beijing, China. A total of 978,658 asthma hospital visits consisting of 928,607 outpatient visits, 40,063 emergency room visits and 9988 hospital admissions from January 1, 2010, to June 30, 2012, were identified from the Beijing Medical Claim Data for Employees. A generalized additive Poisson model was applied to explore the association between PM 2.5 and health service use. The mean daily PM 2.5 concentration was 99.5 μg/m 3 with a range from 7.2 μg/m 3 to 492.8 μg/m 3 . Ambient PM 2.5 concentration was significantly associated with increased use of asthma-related health services. Every 10 μg/m 3 increase in PM 2.5 concentration on the same day was significantly associated with a 0.67% (95% CI, 0.53%–0.81%), 0.65% (95% CI, 0.51%–0.80%), and 0.49% (95% CI, 0.35%–0.64%) increase in total hospital visits, outpatient visits and emergency room visits, respectively. The exposure–response association between PM 2.5 concentration and hospital visits for asthma exacerbations was approximately linear. In conclusion, this study found that short-term elevations in PM 2.5 concentration may increase the risk of asthma exacerbations. Our findings contribute to the limited scientific literature concerning the acute effects of PM 2.5 on asthma morbidity outcomes in developing countries. [ABSTRACT FROM AUTHOR]

The simultaneous observation and analysis of atmospheric fine particles (PM2.5) on a regional scale is an important approach to develop control strategies for haze pollution. In this study, samples of filtered PM2.5 were collected simultaneously at three urban sites (Beijing, Tianjin, and Shijiazhuang) and at a regional background site (Xinglong) in the Beijing-Tianjin-Hebei (BTH) region from June 2014 to April 2015. The PM2.5 at the four sites was mainly comprised of organic matter, secondary inorganic ions, and mineral dust. Positive matrix factorization (PMF) demonstrated that, on an annual basis, secondary inorganic aerosol was the largest PM2.5 source in this region, accounting for 29.2-40.5%of the PM2.5 mass at the urban sites; the second-largest PM2.5 source was motor vehicle exhaust, particularly in Beijing (24.9 %), whereas coal combustion was also a large source in Tianjin (12.4 %) and Shijiazhuang (15.5 %), with particular dominance in winter. Secondary inorganic aerosol plays a vital role in the haze process, with the exception of the spring haze in Shijiazhuang and Tianjin, for which the dust source was crucial. In addition to secondary transformations, local direct emissions (coal combustion and motor vehicle exhaust) significantly contribute to the winter haze at the urban sites. Moreover, with the aggravation of haze pollution, the OC/EC mass ratio of PM2.5 decreased considerably and the nitrate-rich secondary aerosol increased during all four seasons in Beijing, both of which indicate that local motor vehicle emissions significantly contribute to the severe haze episodes in Beijing. To assess the impacts of regional transport on haze pollution, the PMF results were further processed with backward-trajectory cluster analysis, revealing that haze pollution usually occurred when air masses originating from polluted industrial regions in the south prevailed and is characterized by high PM2.5 loadings with considerable contributions from secondary aerosols. This study suggests that control strategies to mitigate haze pollution in the BTH region should focus on the reduction of gaseous precursor emissions from fossil fuel combustion (motor vehicle emissions in Beijing and coal combustion in Tianjin, Hebei, and nearby provinces). [ABSTRACT FROM AUTHOR]

Peroxyacyl nitrates (PANs) are photochemical secondary pollutants that play a key role in the atmospheric chemistry of the troposphere. However, there have been few studies on the long-term variation and inter-regional transport of PANs. In this study, summertime ambient PAN concentrations were monitored at urban and rural sites in Beijing and Hebei, China, between 2006 and 2014. In Beijing, the peak concentrations of PAN and PPN were in the range of 6–17 ppbv and 0.6–2.2 ppbv, respectively, higher than concentrations in other provinces. The nitrogen oxide (NO x ) concentration decreased at a rate of 1.7 ppbv/yr (∼4% yr −1 ), and the PAN concentration decreased at a rate of 0.03 ppbv/yr (∼3% yr −1 ), while the ozone (O 3 ) concentration increased at a rate of 1.5 ppbv/yr (∼4% yr −1 ). Trajectory clustering analyses showed that high concentrations of PAN were mainly affected by low air masses transported medium/short distances from South Beijing, and the potential source contribution function maps showed that the likely pollution source area was concentrated in the southern region of Beijing. These findings provide a theoretical basis for pollution control in this region. [ABSTRACT FROM AUTHOR]

The randomness, non-stationarity and irregularity of air quality index series bring the difficulty of air quality index forecasting. To enhance forecast accuracy, a novel model combining grey accumulated generating technique and Holt-Winters method is developed for air quality index forecasting in this paper. The grey accumulated generating technique is utilized to handle non-stationarity of random and irregular data series and Holt-Winters method is employed to deal with the seasonal effects. To verify and validate the proposed model, two monthly air quality index series from January in 2014 to December in 2016 collected from Shijiazhuang and Handan in China are taken as the test cases. The experimental results show that the proposed model is remarkably superior to conventional Holt-Winters method for its higher forecast accuracy. [ABSTRACT FROM AUTHOR]

The emission of pollutants is extremely reduced during the annual Chinese Spring Festival (SF) in Shenzhen, China. During the SF, traffic flow drops by ~50% and the industrial plants are almost entirely shut down in Shenzhen. To characterize the variation in ambient air pollutants due to the "Spring Festival effect", various gaseous and particulate pollutants were measured in real time in urban Shenzhen over three consecutive winters (2014-2016). The results indicate that the concentrations of NOx, volatile organic compounds (VOCs), black carbon (BC), primary organic aerosols, chloride, and nitrate in submicron aerosols decrease by 50-80% during SF periods relative to non-Spring Festival periods, regardless of meteorological conditions. This decrease suggests that these pollutants are mostly emitted or secondarily formed from urban local emissions. The concentration variation in species mostly from regional or natural sources, however, is found to be much less, such as for bulk fine particulate matter (PM2.5). More detailed analysis of the Spring Festival effect reveals an urgent need to reduce emissions of SO2 and VOCs on a regional scale rather than on an urban scale to reduce urban PM2.5 in Shenzhen, which can also be useful as a reference for other megacities in China. [ABSTRACT FROM AUTHOR]

New particle formation (NPF) has been observed in many highly polluted environments of South East Asia, including Beijing, where the extent of its contribution to intense haze events is still an open question. Estimated characteristics of NPF events, such as their starting times and formation and growth rates of particles, are more accurate when the detection range of particles extends to smaller sizes. In order to understand the very first steps of particle formation, we used a neutral cluster and air ion spectrometer (NAIS) to investigate particle characteristics at sizes exactly at which atmospheric nucleation and cluster activity occurs. Observations over a continuous 3-month period in Beijing showed 26 NPF events. These events generally coincided with periods with relatively clean air when the wind direction was from the less industrialised north. No NPF events were observed when the daily mean PM2.5 concentration exceeded 43 µgm-3, which was the upper threshold for particle formation in Beijing. The fraction of particles that are charged in the size range 2-42 nm was normally about 15 %. However, this fraction increased to 20-30% during haze events and decreased to below 10% during NPF events. With the NAIS, we very precisely determined the starting times of NPF to a greater accuracy than has been possible in Beijing before and provided a temporal distribution of NPF events with a maximum at about 08:30 LT. Particle formation rates varied between 12 and 38 cm-3 s-1. Particle growth rates were estimated to be in the range of 0.5-9.0 nmh-1. These results are more reliable than previous studies in Beijing as the measurements were conducted for the first time at the exact sizes at which clusters form into particles and provide useful insight into the formation of haze events. [ABSTRACT FROM AUTHOR]

Radical measures for controlling ambient air pollution sources were employed by the Chinese government during the Asia-Pacific Economic Cooperation (APEC) meeting in 2014, providing a unique case to evaluate the health effect benefits from such measures. To examine the cancer risk reduction from the source control measures during the APEC meeting, we estimated the reduction in population exposure to PM 2.5 and PAHs and the reduction in PAHs-associated cancer risk if the control measures were sustained over time. We determined the population exposure to PM 2.5 and PM 2.5 -bound PAHs for the 21.52 million Beijing residents using a Land Use Regression model to determine the spatial distribution of PM 2.5 and a Monte Carlo approach to revise indoor/outdoor infiltration factor and time activity patterns. Into the model and approach, we incorporated the spatial variance and indoor/outdoor differences in the PM 2.5 and PM 2.5 -bound PAHs concentrations, based on measurements. We then estimated lung cancer risk using the population attributable fraction (PAF), assuming the control measures were sustained over time. The mean PM 2.5 exposure concentration decreased from 37.5 μg/m3 (CI:17.1–74.9 μg/m3) to 24.0 μg/m3 (CI:10.2–47.7 μg/m3), whereas the mean PM 2.5 -bound equivalent benzo[ a ]pyrene (BaP eq ) exposure concentration decreased from 7.1 ng/m 3 (CI:3.3–14.2 ng/m 3 ) to 4.2 ng/m 3 (CI:1.8–7.7 ng/m 3 ), resulting in a reduction in the lung cancer PAF from 0.75% to 0.45%, if the measures were sustained over time. [ABSTRACT FROM AUTHOR]

In order to investigate the effects of the temporary strengthening of air quality assurance controlling measures during the Beijing 2015 IAAF World Championships and the Military Parade Assurance Period (MPAP) in China, we collected daily PM 2.5 aerosol samples at three typical sites (urban downtown, suburban and rural background area, respectively) in Beijing and investigated the variations of concentration of the water-soluble ions, elemental constituents, organic carbon (OC) and elemental carbon (EC) in PM 2.5 from Aug.15 to Sept.10, 2015. Simultaneously, 1-h high-resolution continuous monitoring results of PM 2.5 mass concentration as well as the chemical components which were measured at another online monitoring urban site were incorporated. The concentrations of PM 2.5 and other gaseous pollutants (SO 2 , NO 2 and CO) during the parade control period (Aug.20-Sept.3) exhibited a substantially decrease compared with the concentrations during both the non-control (August 15 to August 19 and September 4 to September 10) period and the same period in 2014. According to the CMC results, the major components were identified as secondary inorganic aerosol (SIA, the combination of sulfate, ammonium and nitrate), mineral dust and particular organic matter (POM), which together accounted for more than 80% of PM 2.5 in urban and suburban sites. POM is found to account for the largest proportion, and the obviously higher proportion of POM in the urban area revealed the significance contribution from vehicles. Compared with the non-control period, the mass concentrations of SIA and secondary organic carbon (SOC) decreased obviously. However, SIA and SOC are observed to play an important role in contributing to the rapid growth process of PM 2.5 under unfavorable meteorological conditions during the control period. In view of the gradual improvement of air quality in Beijing, as well as the contribution of secondary aerosol formations in total PM 2.5 , effective control of primary gaseous pollutants and volatile organic compounds (VOCs) will be very significant for further lowering the concentration of PM 2.5 in Beijing in normal time. [ABSTRACT FROM AUTHOR]

Atmospheric particulate matter (PM) samples were collected from four ground-based sites located in the Houston, TX (September 21--28, 2013) and were analyzed for 12 organophosphate esters (OPEs; current-use plasticizers and flame retardants). Samples analyzed included daytime, nighttime, and 24 h PM of <2.5 µm aerodynamic diameter (PM2.5) and total suspended particulate (TSP) samples. PM2.5 and TSP atmospheric SOPE concentrations varied over an order of magnitude and were statistically significantly different between urban and suburban and industrial sites. Additionally, significant temporal variability was also identified; for example, daytime atmospheric concentrations of 2-ethylhexyl diphenyl phosphate (EHDPP; 610 ± 220 pg m-3) measured in TSP samples were significantly higher than nighttime concentrations (280 ± 180 pg m-3; p = 0.03). Detailed discussions of the spatial and temporal distribution are given for Tris-(1-chloro-2-propyl) phosphate (TCiPP), EHDPP, tri-n-butyl phosphate (TnBP), and triphenyl phosphate (TPhP). Correlations to bulk measurements of carbonaceous PM including organic carbon, elemental carbon, and water-soluble organic carbon were used to understand potential sources and urban atmospheric transport. These results highlight the fundamental complexity associated with assessing OPE atmospheric concentrations across a large urban landscape and specific knowledge gaps at the intersection of consumer products and safety with environmental and human health. [ABSTRACT FROM AUTHOR]

Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO2, coarse mode, and accumulation mode (100-500 nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO3-) followed by an increase of sulfate peaks (97HSO4-+ 96SO4-) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO2 on particles. High concentration of gaseous SO2, high relative humidity and high particle loading likely promoted SO2 oxidation. Secondary nitrate formed through gas-phase oxidation of NO2 to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays. [ABSTRACT FROM AUTHOR]

Over the last 30 years, China's economy has boomed. This trend has lifted hundreds of millions of Chinese out of poverty but it has also sharply increased local, regional, and global pollution levels. We look at the rise in air pollution over recent decades, and the perhaps surprising finding that in many of China's urban areas, levels of particulates (of less than 10 microns) have been decreasing during the last 10 to 15 years. We then turn to the costs and tradeoffs of air pollution, including costs to human health, reductions in worker productivity, and how people are seeking to reduce their exposure to pollution as shown by compensating differentials in real estate prices and purchases of masks and air filters. We discuss how rising incomes tend to raise the demand for environmental amenities and thus increase political pressure for environmental protection, and then we turn to the policy tools that China has used to reduce pollution. We conclude by arguing that as China's government is preparing for an additional 300 million people to move to urban areas over the next 30 years, it will have a number of opportunities for China to reduce pollution through a shift from manufacturing to services, along with various steps to improve energy efficiency and resource conservation. Overall, it seems that China is on track to improve its environmental performance in the years ahead. [ABSTRACT FROM AUTHOR]

In the present study, the WRF-CHEM model is used to evaluate the contributions of trans-boundary transport to the air quality in Beijing during a persistent air pollution episode from 5 to 14 July 2015 in Beijing-Tianjin-Hebei (BTH), China. Generally, the predicted temporal variations and spatial distributions of PM2.5 (fine particulate matter), O3 (ozone), and NO2 are in good agreement with observations in BTH. The WRF-CHEM model also reproduces reasonably well the temporal variations of aerosol species compared to measurements in Beijing. The factor separation approach is employed to evaluate the contributions of trans-boundary transport of non-Beijing emissions to the PM2.5 and O3 levels in Beijing. On average, in the afternoon during the simulation episode, the local emissions contribute 22.4 % to the O3level in Beijing, less than 36.6 % from non-Beijing emissions. The O3 concentrations in Beijing are decreased by 5.1 % in the afternoon due to interactions between local and non-Beijing emissions. The non-Beijing emissions play a dominant role in the PM2.5 level in Beijing, with a contribution of 61.5 %, much higher than 13.7 %, from Beijing local emissions. The emission interactions between local and non-Beijing emissions enhance the PM2.5 concentrations in Beijing, with a contribution of 5.9 %. Therefore, the air quality in Beijing is generally determined by the trans-boundary transport of non-Beijing emissions during summertime, showing that the cooperation with neighboring provinces to mitigate pollutant emissions is key for Beijing to improve air quality. [ABSTRACT FROM AUTHOR]

Nowadays, air pollution has become a major challenge in urban management despite rapid economic development. Meanwhile, vehicle exhaust has gradually turned into the main source of air pollution in the city. To reduce air pollution, many measures have been taken including the odd-and-even license plate rule in some cities. However, it is difficult to evaluate the effectiveness of those measures. In view of this, based on the Davis method, this article has taken Beijing as its subject and built an odd-and-even license plate model by a probabilistic modelling method and the analysis of means, thus to quantify the pollution caused by vehicle exhaust emissions and the actual effect of the license plate limitation rule. This paper also examines the relationship between the license plate limitation rule and urban air pollution control and to see whether, or not, the rule exerts a positive influence on air pollution control. The results showed that the odd-and-even license plate rule has positive impacts on air pollution control in the short-term; however, the influence of the limitation policy gradually diminishes and disappears as the overall number of cars increases. Therefore, it is suggested to tackle air pollution in a broader and more effective way. [ABSTRACT FROM AUTHOR]

Fine particle (PM 2.5 ) samples were collected in 2011 and 2012 simultaneously at three sites in Wuhan in an industrial area (ID), downtown Wuhan (DT), and the Wuhan botanical gardens (BG). The annual average concentration of PM 2.5 was highest in the industrial area at 180 μg m − 3 and lowest in the botanical gardens, with an average of 93 μg m − 3 . The average downtown PM 2.5 concentration was 113 μg m − 3 . All sites had concentrations well above the World Health Organization (WHO) guidelines and the Chinese air quality standard. The concentration of major constituents of PM 2.5 varied seasonally across all sites; specifically, sulfate, nitrate, and organic carbon varied most strongly during spring, followed by summer and fall. Organic carbon varied the most across sites for all seasons, which is attributable to large differences in local source emissions. The major primary sources contributing to OC were vehicle emissions (38.1 ± 8.3%), coal combustion (7.0 ± 6.2%), meat cooking (3.0 ± 1.6%), and biomass burning (3.0 ± 1.0%). All these sources had large seasonal variations across the three sites. Biomass burning had the largest impact at BG, mobile sources had the largest impact at DT, and coal combustion had the largest impact at ID. Mineral dust was a major contributor to PM 2.5 (average 16.8 ± 9.6 μg m − 3 ) and had very homogenous concentrations across the sites during springtime due to regional dust storms, but had much higher concentration at ID during the summer and fall. The results demonstrate the need for both regional and local air pollution control strategies to reduce air pollution in Wuhan. This research contributes to the field of particulate matter studies by providing information about seasonal and regional fluctuations in PM 2.5 in large urban areas, which helps advance understanding of the sources responsible for urban haze. [ABSTRACT FROM AUTHOR]

Istanbul, one of the mega cities in the world located between Asia and Europe, has suffered from severe air pollution problems due to rapid population growth, traffic and industry. Atmospheric levels of PAHs and PCBs were investigated in Istanbul at 22 sampling sites during four different sampling periods using PUF disk passive air samplers and spatial and temporal variations of these chemicals were determined. Soil samples were also taken at the air sampling sites. At all sites, the average ambient air Σ 15 PAH and Σ 41 PCB concentrations were found as 85.6 ± 68.3 ng m −3 and 246 ± 122 pg m −3 , respectively. Phenanthrene and anthracene were the predominant PAHs and low molecular weight congeners dominated the PCBs. The PAH concentrations were higher especially at urban sites close to highways. However, the PCBs showed moderately uniform spatial variations. Except four sites, the PAH concentrations were increased with decreasing temperatures during the sampling period, indicating the contributions of combustion sources for residential heating, while PCB concentrations were mostly increased with the temperature, probably due to enhanced volatilization at higher temperatures from their sources. The results of the Factor Analysis represented the impact of traffic, petroleum, coal/biomass and natural gas combustion and medical waste incineration plants on ambient air concentrations. A similar spatial distribution trend was observed in the soil samples. Fugacity ratio results indicated that the source/sink tendency of soil for PAHs and PCBs depends on their volatility and temperature; soil generally acts as a source for lighter PAHs and PCBs particularly in higher temperatures while atmospheric deposition is a main source for higher molecular weight compounds in local soils. Toxicological effect studies also revealed the severity of air and soil pollution especially in terms of PAHs in Istanbul. [ABSTRACT FROM AUTHOR]

Visibility is one of the parameters for indicating air pollution. In this study, visibility variation in Hong Kong during summer and winter is investigated. Visibility in Hong Kong has clear intraseasonal variation. Examination of different environmental parameters suggests that the intraseasonal component dominates the overall circulation anomalies in both summer and winter. Associated with the intraseasonal variation of environmental parameters, obvious variation in visibility impairment is found in both summer and winter. In summer, local visibility and air quality are found to be significantly affected by the (MJO) and the 10-30-day intraseasonal oscillation (ISO) through modulation of associated atmospheric circulations. In winter, the modulation effects appear to be weaker due to the southward shift of the associated convection. The results in this study highlight the importance of the ISO in contributing to the overall variation in visibility in Hong Kong, and provide useful implications for the development of possible mitigation strategies associated with visibility impairment and air pollution in Hong Kong. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although many time-series studies have established associations of daily pollution variations with daily deaths, there are fewer at low concentrations, or focused on locally generated pollution, which is becoming more important as regulations reduce regional transport. Causal modeling approaches are also lacking. OBJECTIVE: We used causal modeling to estimate the impact of local air pollution on mortality at low concentrations. METHODS: Using an instrumental variable approach, we developed an instrument for variations in local pollution concentrations that is unlikely to be correlated with other causes of death, and examined its association with daily deaths in the Boston, Massachusetts, area. We combined height of the planetary boundary layer and wind speed, which affect concentrations of local emissions, to develop the instrument for particulate matter ≥2.5 μm (PM[sub 2.5]), black carbon (BC), or nitrogen dioxide (NO2) variations that were independent of year, month, and temperature. We also used Granger causality to assess whether omitted variable confounding existed. RESULTS: We estimated that an interquartile range increase in the instrument for local PM[sub 2.5] was associated with a 0.90% increase in daily deaths (95% CI: 0.25, 1.56). A similar result was found for BC, and a weaker association with NO[sub 2] The Granger test found no evidence of omitted variable confounding for the instrument. A separate test confirmed the instrument was not associated with mortality independent of pollution. Furthermore, the association remained when all days with PM[sub 2.5] concentrations > 30 μg/m[sup 3] were excluded from the analysis (0.84% increase in daily deaths; 95% CI: 0.19, 1.50). CONCLUSIONS: We conclude that there is a causal association of local air pollution with daily deaths at concentrations below U.S. EPA standards. The estimated attributable risk in Boston exceeded 1,800 deaths during the study period, indicating that important public health benefits can follow from further control efforts. CITATION: Schwartz J, Bind MA, Koutrakis P. 2017. Estimating causal effects of local air pollution on daily deaths: effect of low levels. Environ Health Perspect 125:23-29; http://dx.doi. org/10.1289/EHP232 [ABSTRACT FROM AUTHOR]

Disparate residential hazard exposures based on disadvantaged gender status (e.g., among female-headed households) have been documented in the distributive environmental justice literature, yet no published studies have examined whether disproportionate environmental risks exist based on minority sexual orientation. To address this gap, we use data from the U.S. Census, American Community Survey, and the Environmental Protection Agency at the 2010 census tract level to examine the spatial relationships between same-sex partner households and cumulative cancer risk from exposure to hazardous air pollutants (HAPs) emitted by all ambient emission sources in Greater Houston (Texas). Findings from generalized estimating equation analyses demonstrate that increased cancer risks from HAPs are significantly associated with neighborhoods having relatively high concentrations of resident same-sex partner households, adjusting for geographic clustering and variables known to influence risk (i.e., race, ethnicity, socioeconomic status, renter status, income inequality, and population density). HAP exposures are distributed differently, however, for same-sex male versus samesex female partner households. Neighborhoods with relatively high proportions of same-sex male partner households are associated with significantly greater exposure to cancer-causing HAPs, whereas those with high proportions of same-sex female partner households are associated with less exposure. This study provides initial empirical documentation of a previously unstudied pattern and infuses current theoretical understanding of environmental inequality formation with knowledge emanating from the sexualities and space literature. Practically, results suggest that other documented health risks experienced in gay neighborhoods could be compounded by disparate health risks associated with harmful exposures to air toxics. [ABSTRACT FROM AUTHOR]

Epiphytic lichens, collected from 119 sampling sites grown over 'Roistonea Royal Palm' trees, were used to assess the spatial distribution pattern of lead (Pb) and identify possible pollution sources in Havana (Cuba). Lead concentrations in lichens and topsoils were determined by flame atomic absorption spectrophotometry and inductively coupled plasma (ICP) atomic emission spectrometry, respectively, while Pb in crude oils and gasoline samples were measured by ICP-time of flight mass spectrometry (ICP-ToF-MS). Lead isotopic ratios measurements for lichens, soils, and crude oils were obtained by ICP-ToF-MS. We found that enrichment factors (EF) reflected a moderate contamination for 71% of the samples (EF > 10). The Pb/Pb ratio values for lichens ranged from 1.17 to 1.20 and were a mixture of natural radiogenic and industrial activities (e.g., crude oils and fire plants). The low concentration of Pb found in gasoline (<7.0 μg L) confirms the official statement that leaded gasoline is no longer used in Cuba. [ABSTRACT FROM AUTHOR]