Accumulation Of Air Pollutants Research Articles

Numerical study of a local PM2.5 pollution event under the typhoon Neoguri (1408) background over a coastal metropolitan city, Shenzhen, China

In this study, the transport mechanism of a regional PM2.5 pollution event over Shenzhen on 8 July 2014 was studied using the Weather Research and Forecasting (WRF) model with Four-Dimensional Data Assimilation (FDDA) techniques and the FLEXPART-WRF model to understand the effects of the local atmospheric circulations under the typhoon NEOGURI (1408) background. WRF-FDDA produces the spatiotemporal variation of winds that are consistent with the regional wind profiler observations. The air quality observations show that in this typhoon related PM2.5 pollution episode, there are significant temporal and spatial variation of PM2.5 concentrations over Shenzhen and there are two obvious PM2.5 peaks during the day of 8 July 2014. The simulation results revealed that the first peak was developed due to a wind convergence associated with the offshore winds forced by NEOGURI which was located to the west of Shenzhen at around noon. In the afternoon, the wind convergence motivated the upward motion and suppressed by the downdraft from the typhoon's peripheral circulation. The northerly wind forced by the typhoon over the land and the southerly sea breezes led to a local circulation that was favorable for air pollutant accumulation over the Pearl River area. Part of these accumulated air pollutants was recirculated into west part of Shenzhen which resulting in the second PM2.5 peak in the afternoon, and then gradually transported to the middle and east part of the city. The FLEXPART-WRF analysis confirms the recirculation of air pollutants from the Pearl River. This study demonstrated that air pollution can form over Shenzhen under the typhoon background, and the complex interaction between typhoon circulations and sea breezes development controls the spatiotemporal distribution of the air pollution in the coastal metropolitan city.

Synoptic Weather Patterns and Associated Air Pollution in Taiwan

ABSTRACT In this study, cluster analysis is applied to the daily averaged wind fields and sea-level pressure observed at surface weather stations in Taiwan from January 2013 to March 2018 to classify the synoptic weather patterns and study the characteristics of corresponding air pollutants, including fine particulate matter (PM2.5), coarse particulate matter (PM10), and ozone (O3). The classification identified six weather types: Clusters 1, 2, and 3 (C1–C3), which are typical winter weather types and associated with high air pollutant concentrations—C3, in particular, influenced by weak synoptic weather, is associated with the lowest wind speeds and the highest PM2.5 and PM10 concentrations and represents the most prevalent weather type that is prone to the occurrence of PM2.5 events; C4, which occurs mostly during seasonal transition months and is associated with the highest O3 concentrations; and C5 and C6, which are summer weather types with low air pollutant concentrations. Further analysis of the local wind flow using the 0.3° ERA5 reanalysis dataset and surface-observed wind data indicates that in western Taiwan, the land-sea breeze is embedded within the synoptic weather type of C3, which is favorable to air pollutant accumulation. However, when the prevailing northeasterly wind is obstructed by the Central Mountain Range, southwestern Taiwan, being situated on the leeside of the mountains, often exhibits the worst air pollution due to stagnant wind conditions.

Impact of intervention of biomass cookstove technologies and kitchen characteristics on indoor air quality and human exposure in rural settings of India

This study investigates the impact of increased levels of indoor air pollution (IAP) caused due to biomass burning in the rural households of Northern India. A comparative assessment of the impact of traditional cookstoves (TCS) and improved cookstoves (ICS) coupled with the characteristics of kitchen was conducted to estimate the PM (PM10, PM2.5, PM1), CO/CO2 concentrations in the micro-environments of kitchen and living area of the households. The study incorporated both extensive and intensive real-time indoor air quality (IAQ) monitoring during the two cooking sessions of the day. The pollutant concentrations were reported in terms of 24-h as well as 8-h (cooking hours including morning and evening meal) averages. Influence of the three types of kitchen characteristics, i.e., enclosed, semi-enclosed and open was also comprehensively analyzed to measure its impact on the IAQ. In addition to this, the IAQ was further used to evaluate the particle size distribution (PSD), respiratory tract deposition and exposure index to assess its impact on health status of the exposed group including women involved in cooking practices. The results of the study highlighted that deployment of ICS would help in improving the IAQ of the kitchen area by resulting in reducing the concentrations of PM10, PM2.5, PM1 and CO by 21–62%, 20–80%, 24–87% and 19–93%, respectively. It was also highlighted that the kitchen characteristics significantly influence the accumulation of air pollutants, demonstrated by the results that the IAQ being worst in the case of enclosed kitchen, resulted in the highest exposure index values. Multivariate regression models to predict PM1 concentration were also developed for three kitchen categories for both TCS and ICS. Thus, the current study concludes that usage of ICS coupled with efficient designing of the kitchen can improve the overall IAQ of the household along with immense health benefits. Overall, the study emphasized the need of more comprehensive studies to fully assess the association of household air pollution (HAP) and health of individual in the rural settings by considering the toxicity of PM.

Characterization and source apportionment of marine aerosols over the East China Sea

Awareness of the importance of marine atmosphere for accurately estimating global aerosol budget and climate impacts has arisen recently. However, studies are limited due to the difficulty and inconvenience in sampling as well as the diversity of sources. In this study, the Community Multiscale Air Quality (CMAQ) model was applied to investigate the fine particulate matter (PM2.5) and its chemical components over the East China Sea (ECS) and offshore regions. In spite of slight under-predictions, model predictions agree well with observations over the ECS and along the coast. PM2.5 and its major components in the mainland are higher than in marine area, suggesting Asian continent is a major emitter of marine aerosols. PM2.5 and its components in marine regions show higher abundance during daytime than nighttime, while it is opposite in continental regions. Aerosol phase SO42− is the most abundant component of PM2.5 over the ECS with an average concentration of 5.12 μg m−3, followed by NH4+ (1.02 μg m−3) and primary organic aerosol (POA) (0.92 μg m−3). Industry and ship emissions are the top two contributors to primary (PPM) and total PM2.5 over the ECS, while industry and agriculture sectors are major sources for secondary inorganic aerosols (SIA), followed by ship emissions. For terrestrial regions, industry and agriculture are predominant sources of PM2.5 and SIA, while industry and residential activities are the top two contributors to PPM. This study improves the understanding of transport and accumulation of air pollutants over the ECS and adjacent regions, and provides useful information for designing efficient control strategies.

Variations of Haze Pollution in China Modulated by Thermal Forcing of the Western Pacific Warm Pool

In addition to the impact of pollutant emissions, haze pollution is connected with meteorology and climate change. Based on the interannual change analyses of meteorological and environmental observation data from 1981 to 2010, we studied the relationship between the winter haze frequency in central-eastern China (CEC) and the interannual variations of sea surface temperature (SST) over Western Pacific Warm Pool (WPWP) and its underlying mechanism to explore the thermal effect of WPWP on haze pollution variation in China. The results show a significant positive correlation coefficient reaching up to 0.61 between the interannual variations of SST in WPWP and haze pollution frequency in the CEC region over 1981–2010, reflecting the WPWP’s thermal forcing exerting an important impact on haze variation in China. The anomalies of thermal forcing of WPWP could induce to the changes of East Asian winter monsoonal winds and the vertical thermal structures in the troposphere over the CEC region. In the winter with anomalously warm SST over the WPWP, the near-surface winds were declined, and vertical thermal structure in the lower troposphere tended to be stable over the CEC-region, which could be conducive to air pollutant accumulation leading to the more frequent haze occurrences especially the heavy haze regions of Yangtze River Delta (YRD) and Pearl River Delta (PRD); In the winter with the anomalously cold WPWP, it is only the reverse of warm WPWP with the stronger East Asian winter monsoonal winds and the unstable thermal structure in the lower troposphere, which could attribute to the less frequent haze pollution over the CEC region. Our study revealed that the thermal forcing of the WPWP could have a modulation on air environment change in China.

Organic molecular tracers in atmospheric PM1 at urban intensive traffic and background sites in two high-insolation European cities

Atmospheric PM1 has an impact on health and the environment, and is highly variable. PM1 filter samples were collected in urban roof and street sites in two Mediterranean cities in Europe (Barcelona and Madrid) to study the spatial and temporal trends of primary and secondary organic tracer compounds. Both cities are exposed to modern urban emission sources with intensive traffic in their centers. Moreover, their geographical situation in the Mediterranean region favors photo-chemical reactions and accumulation of secondary aerosols, due to sunny anti-cyclonic weather conditions. Barcelona is located along the coast with high relative humidity and an active sea-mountain breeze system, while the relative humidity in Madrid is low in summer, due to its location in the center of the Iberian Peninsula. These differences may influence the accumulation of primary air pollutants and the formation of secondary aerosols. In street site samples, the levels of primary organics, such as polycyclic aromatic hydrocarbons, hopanes and nicotine, were about two times higher than those collected simultaneously at roof sites. Primary emitted levoglucosan and isomers from biomass burning were observed in higher concentrations in winter in both urban areas, but without significant difference between the road and roof sites samples, indicating regional transport of biomass smoke to the cities. Similar roof and street site sample concentrations were also observed for secondary organic aerosol (SOA) compounds, i.e. dicarboxylic acids and oxidation products of isoprene and α-pinene. The SOA compound concentrations were ten times higher in summer compared to winter samples, emphasizing the importance of SOA formation processes in summer. More evidence was obtained that linked the presence of cis-pinonic acid in the filter samples to new particle formation during nucleation. The urban organic PM1 is dominated by SOA, while the primary organic aerosol (POA) tracer compounds from combustion sources, including traffic and biomass burning, dominates in winter.

Carbonaceous PM10 and PM2.5 and secondary organic aerosol in a coastal rural site near Brindisi (Southern Italy).

Organic and elemental carbon were measured both in daily PM10 and PM2.5 and in 6h range time PM2.5 samples collected from September 2015 to October 2015 in a coastal rural site near Brindisi in the Apulia region (Italy), in order to determine factors affecting the carbonaceous aerosol variations. Carbon content (total carbon TC) represented a considerable fraction for both PM10 and PM2.5. In particular, in PM10 samples, organic carbon (OC) varied from 1.06 to 18.32μgm-3 with a mean concentration of 5 ± 4μgm-3 and EC varied from 0.11 to 0.88μgm-3 with a mean value of 0.41 ± 0.19μgm-3. In PM2.5 samples, OC varied from 0.54 to 12.91μgm-3 with a mean concentration of 3.5 ± 2.8μgm-3 and EC varied from 0.11 to 0.85μgm-3 with a mean value of 0.35 ± 0.18μgm-3. The highest values for both parameters were recorded when the air masses were coming from NE Europe and when Saharan Dust events were recognized. The results show that OC and EC exhibited higher concentrations during the night hours, suggesting that stable atmosphere and lower mixing conditions play important roles for the accumulation of air pollutants and promote condensation or adsorption of semivolatile organic compounds. In samples from a Saharan Dust event and in samples with the lowest and the highest OCsec, ATR-FTIR analysis allowed us to identify organic functional groups including the non-acid organic hydroxyl C-OH group (e.g., sugars, anhydrosugars, and polyols), carbonyl C=O group, carboxylic acid COOH group, aromatic and aliphatic unsaturated C=C-H group, aliphatic saturated C-C-H group, and amine NH2 group. Some inorganic ions were also identified: carbonates, sulfate, silicate, and ammonium. The dusty samples are mainly characterized by the presence of carbonate and hydrogen sulfate ions and by kaolinite (absorption at 914 and 1010cm-1), while in samples with air masses coming from the NE, OC is mainly characterized by aliphatic and aromatic C-H and O-H and N-H groups (absorptions in the range 3500-2700cm-1) and by the presence of organonitrate, aromatic amide and amine, and carboxylic acids (absorptions at 1630 and 1770-1700cm-1). Graphical abstract ᅟ.

Characteristics of Boundary Layer Structure during a Persistent Haze Event in the Central Liaoning City Cluster, Northeast China

The characteristics of boundary layer structure during a persistent regional haze event over the central Liaoning city cluster of Northeast China from 16 to 21 December 2016 were investigated based on the measurements of particulate matter (PM) concentration and the meteorological data within the atmospheric boundary layer (ABL). During the observational period, the maximum hourly mean PM2.5 and PM10 concentrations in Shenyang, Anshan, Fushun, and Benxi ranged from 276 to 355 μg m–3 and from 378 to 442 μg m–3, respectively, and the lowest hourly mean atmospheric visibility (VIS) in different cities ranged from 0.14 to 0.64 km. The central Liaoning city cluster was located in the front of a slowly moving high pressure and was mainly controlled by southerly winds. Wind speed (WS) within the ABL (< 2 km) decreased significantly and WS at 10-m height mostly remained below 2 m s–1 during the hazy episodes, which was favorable for the accumulation of air pollutants. A potential temperature inversion layer existed throughout the entire ABL during the earlier hazy episode from 0500 Local Time (LT) 18 December to 1100 LT 19 December, and then a potential temperature inversion layer developed with the bottom gradually decreased from 900 m to 300 m. Such a stable atmospheric stratification further weakened pollutant dispersion. The atmospheric boundary layer height (ABLH) estimated based on potential temperature profiles was mostly lower than 400 m and varied oppositely with PM2.5 in Shenyang. In summary, weak winds due to calm synoptic conditions, strong thermal inversion layer, and shallow atmospheric boundary layer contributed to the formation and development of this haze event. The backward trajectory analysis revealed the sources of air masses and explained the different characteristics of the haze episodes in the four cities.

Characteristics of long-lasting haze episodes observed in Seoul, South Korea, for 2009–2014

The meteorological, physical, chemical, and optical characteristics of long-lasting haze in Seoul were studied. Four episodes were observed between 2009 and 2014, all in winter. PM10 mass concentration (PM10), chemical species, and aerosol optical depth (AOD) were analyzed along with the synoptic meteorological conditions. During the episodes, the temporal variations of the PM10 generally proceeded from the west along the Yellow Sea. The ground-based AOD was also high in Seoul and other sites. High AOD (MODIS) distributions were observed to move from China to Korea. The high sulfate concentration, along with the high sulfur oxidation ratio value of the third and fourth episodes (Eps. 3 and 4), respectively, corroborated the possible long-range transport of air pollutants. Stagnant meteorological conditions were a reason for the occurrence of long-lasting hazes. An anticyclone system had a dominant influence on the Korean peninsula during all episodes. The air mass over China was able to rise, and that over Korea was more stagnant in terms of climatology except Ep. 2. In addition to transport from outside, locally emitted air pollutants contributed to the PM10 partly due to the stagnant conditions, during which diurnal variations in NO2 and nitrates showed similar peak times during Eps. 3 and 4. Analysis of the episodes consistently showed that the long-lasting haze episodes were influenced by both the long-range transport of air pollutants from outside Seoul, mostly from China, and the accumulation of air pollutants that were locally emitted and transformed.

Simulation and Analysis of Polluted Days in Tehran

The air pollution is a process which partially depends on the atmospheric conditions. The subject of the present research is analyzing the distribution of the pollutant “CO” in Tehran considering the effects of different wind patterns in cold seasons of year. The main objective of this research is to identify Tehran’s thermo-dynamical synoptic systems resulting in intensification of atmospheric stable condition, and to analyze the pollutant movements by wind. 14 samples of severe and widespread polluted days in the cold period (October to April) of 2002–2012 are selected and statistical, synoptic, and simulation methods are applied to investigate the air pollution in Tehran. According to the results, generally, concentrations of CO pollutant have reduced during the under studied decade. In addition, the results showed that the air pollution of Tehran follows a high-pressure system pattern which is located in the mid-levels of the atmosphere. In severe air pollution conditions, Tehran is located in the axis of a ridge which leads to the air subsidence due to the convergence of upper air currents. According to the analysis of upper air conditions, there was a column of steady air (about 1.5 km above the sea level) in which the density of pollutants increased and all indices confirmed stability conditions during the polluted days. The TAPM model is applied to simulate the wind pattern of Tehran. Four domains with horizontal resolutions of 5, 3, 2, and 1 km are chosen. The results of simulation show that winds in Tehran have different patterns during 24 h and local parameters such as slope directions can affect the air pollution concentration in stable synoptic conditions. In addition, Anabatic and Katabatic winds are frequent in Tehran due to its location in a valley in Alborz southern slopes and winds are considerably affected by the topography of the city. According to the results in the first hours of the day, calm winds are frequent and concentration of the pollutants is resulted from the limitation of boundary layer which caused the accumulation and intensification of air pollution in Tehran during the cold seasons.

Tackling Formidable Industrial Pollution by Sophisticated and Eco- Friendly Technology

The contemporary environmental awareness has emerged primarily from the concerns in the late 19th century about protection of the countryside in Europe and the wilderness in the United States and also from the health-issues ensuing the pollution during historic industrial revolution, took place in Britain in the 18th century. Its profound aftermaths such as climate change, urbanization, pollution and over- mining, etc. are challenging even the human existence, although there are certain benefits. It is no exaggeration to say that pollution will be a biggest cause of premature death since the estimations conclude that by 2050 there will be about 3.6 million deaths a year, most of them in China and India (OECD report). Although world leaders’ perpetual attention and solidarity on this topic, for instance the Paris agreement on 30 November 2015 on climate change, are more commendable, it has fallen by the wayside. In this research-initiative my paper would illustrate the use of sophisticated and eco-friendly technology to tackle the formidable challenges of industrial pollution. As the industrial activities are essential for an economy, citizens’ well-being and maintenance of employment, its complete elimination is practically beyond the bounds of possibility. Hence, one of the key methods for getting rid of these challenges in the advanced world can be attained through the technological development. My study focuses on industrial pollution and the use of advanced technologies, introduced as new industrial process or modification of existing one for reducing the impacts of the production on environment, such as accumulation of wastes, air pollution, water pollution and noise pollution, etc.

Study of Air Pollution and Atmospheric Stability in Ciuc Basin - Romania

The atmospheric stability plays an important role in the accumulation of air pollutants and greatly influences their degradation, dispersion and deposition. These atmospheric qualities can be determined with various methods (Richardson number, Monin - Obukhov length, SRDT method) and the pollutant concentration increase demonstrates the atmospheric stability. In this study the cold periods were the most stable as well the PM10 and CO pollutants had high concentrations. Between these two pollutants the correlation is high because their sources are the same: transport and biomass burning. The study of hourly averages highlighted the importance of traffic intensity since the concentration variation follows the traffic intensity. An increase in the wind speed in the basin results in the pollutants concentrations decrease, the negative correlation with the temperature indicating the importance of the photochemical processes.

A Year Air Quality Measures, 2016, and Risk Communication in Morelia City, Michoacan, Mexico

Background The World Health Organization mentions that bad air quality causes 7 million premature deaths in the world associated to lung and heart diseases. Air pollution also affects ecosystems. The sources of air pollution is related with local economy, overloaded motor vehicle traffic, bad planning in urban zones and fuel consumption. Local geographic conditions and climate contributes to maintain good air quality breathing and with dispersion and accumulation of air pollutants. This is the first record of air quality in Morelia City, Mexico with local regulations. The study will establish control and risk communication assessment. Citizens do not considerate that bad air pollution is a threat. Methods Air quality measures during 365 days was done in around 2 km with TELEDYNE trade mark sensor tools for several pollutants and meteorological conditions, mainly, O 3, NO 2, SO 2, CO, PM 10, PM 2.5 . The data was revising with national law regulations on air quality. Results Particulate matter 2.5 )were 62.4 µg/m³ and 86.7 µg/m³ in 24 hours in April and May of 2016 (threshold levels is 45 µg/m 3 ); particulate matter 10 µm (PM 10 )was above 75 µg/m³ with highest values 160.7 µg/m³ since March through August, November and December, respectively. Ozone measures were above 0.095 ppm/hour with 0.920 ppm/hour in March, May and December in 2016. NO 2 and SO 2 were below threshold levels. Conclusions The highest air polluted months were March, April and May with particulate matter 10 µm, 2.5 µm and ozone in this zone of Morelia and their sources are by overloaded car traffic and forest fires on the landside mountains near from Morelia. April and May were the hottest months than ever registered before from NASA, NOAA reports and our air quality station. Local authorities must send early warnings on air quality in media access.

Influences of wind and precipitation on different-sized particulate matter concentrations (PM2.5, PM10, PM2.5–10)

Though it is recognized that meteorology has a great impact on the diffusion, accumulation and transport of air pollutants, few studies have investigated the impacts on different-sized particulate matter concentrations. We conducted a systematic comparative analysis and used the framework of generalized additive models (GAMs) to explore the influences of critical meteorological parameters, wind and precipitation, on PM2.5, PM10 and PM2.5–10 concentrations in Wuhan during 2013–2016. Overall, results showed that the impacts of wind and precipitation on different-sized PM concentrations are significantly different. The fine PM concentrations decreased gradually with the increase of wind speed, while coarse PM concentrations would increase due to dust resuspension under strong wind. Wind direction exerts limited influence on coarse PM concentrations. Wind speed was linearly correlated with log-transformed PM2.5 concentrations, but nonlinearly correlated with log-transformed PM10 and PM2.5–10 concentrations. We also found the PM2.5 and PM2.5–10 concentrations decreased by nearly 60 and 15% when the wind speed was up to 6 m/s, respectively, indicating a stronger negative impact of wind-speed on fine PM than coarse PM. The scavenging efficiency of precipitation on PM2.5–10 was over twice as high as on PM2.5. Our findings may help to understand the impacts of meteorology on different PM concentrations as well as discriminate and forecast variation in particulate matter concentrations.

Tree bark as bioindicator of metal accumulation from road traffic and air quality map: A case study of Chiang Mai, Thailand

Trees have been recognized as air quality bioindicators, but they have still not been fully implemented in tropical areas. In this study, bark of Cassia fistula was used to inspect accumulation of air pollutants (metals) emitted from road traffic in the city of Chiang Mai, Thailand. The mean concentrations of metal accumulated on tree bark (ng/cm2) in descending order were Al (1,238) > Fe (707) > Zn (162) » Cu (21.1) » Pb (6.37) > Cr (2.14). Correlations of Enrichment Factors: EFTS (metal concentrations on bark compared to those in soil) among metals were relatively strong (r > 0.6) meaning that they were probably generated from the same sources. Moreover, principal component analysis and cluster analysis of EFTS values revealed that Al and Fe were generated from soil resuspension that were attached on vehicle wheels and on road surfaces, while Cr, Cu, Pb and Zn resulted directly from vehicle emissions. The results lead to the conclusion that tree bark is a good bioindicator for air pollutant accumulation in this area. In addition, pollution indices, including total geoaccumulation index (IGEO-tot) and pollution load index (PLI), were applied to generate air quality maps of the city. The maps illustrated that the most polluted areas in the city are the areas that have high traffic volume and building density, in which hospitals and schools are located. The degree of pollution presented in each area was influenced by both road traffic volume and density of buildings in relation to air ventilation capacity.

An Integrated WRF-CAMx Modeling Approach for Impact Analysis of Implementing the Emergency PM2.5 Control Measures during Red Alerts in Beijing in December 2015

ABSTRACTIn December 2015, the Beijing-Tianjin-Hebei (BTH) region experienced several episodes of heavy air pollution. Beijing municipal government therefore issued 2 red alerts on December 7 and 19, respectively, and also implemented emergency control measures to alleviate the negative effects of pollution. It is estimated that the heavy pollutions in 2 red alert periods in Beijing were due mainly to the accumulation of air pollutants from local emission sources and the transboundary transport of pollutants from surrounding areas. The collected meteorological and PM2.5 data indicate that the severity of air pollutions were enlarged by the poor meteorological conditions along with lower mixing layer height. In this study, the WRF-CAMx modeling system was utilized not only for analyzing the contributions of PM2.5 from different sources, but also for quantitatively assessing the effects of implementing various emergency control measures on PM2.5 pollution control during the red alert periods. The modeling results show that local emissions were the most dominant contributors (64.8%–83.5%) among all emission sources, while the main external contributions came from the city of Baoding (3.4%–9.3%). In addition, among 5 different emission source categories, coal and traffic were the two dominant contributors to PM2.5 concentration in urban area of Beijing. Then four pollution control scenarios were designed particularly to investigate the effectiveness of the emergency control measures, and the results show that, generally these emergency control measures have positive effects on air pollution reduction. In particular, restrictive measures of traffic volume control and industrial activity shutdown/suspension have been found as the most effective measures in comparison to other emergency control measures. It is recommended that such effective measures should be considered to implement when next time similar heavy air pollutions occur in the city of Beijing.

Spatial and Temporal Variation of PM2.5 and Atmospheric PCDD/Fs in Northern Taiwan during Winter Monsoon and Local Pollution Episodes

ABSTRACTWinter monsoonal air masses traveling from Inner Mongolia to downwind nations can transport cold temperature and air pollutants. This study investigated the effects of the long-range transport (LRT) of air pollutants by northeastern monsoons and local pollution (LP) episodes on atmospheric PM2.5, polychlorinated dibenzo-p-dioxin (PCDD), and polychlorinated dibenzofuran (PCDF) concentrations in northern Taiwan during the winters of 2014 and 2015. Air samples were collected in rural (Rural Site 1 was mountainous; Rural Site 2 was coastal) and urban (Urban Site 1 was urban; Urban Site 2 was suburban) areas in northern Taiwan as well as at a background site (Lulin Mountain) in central Taiwan. Atmospheric PCDD/F concentrations measured at different sites ranged from 11.0 ± 2.70 to 39.7 ± 22.7 fg international toxicity equivalency quantity (I-TEQ) m–3 in 2014 and 7.99 ± 5.58 to 17.5 ± 12.3 fg I-TEQ m–3 in 2015. During LRT and LP, the proportion of PCDFs was higher than that of PCDDs. Rural Site 1 (122 pg I-TEQ g–1) and Urban Site 2 (82.4 pg I-TEQ g–1) had the highest PCDD/F content in PM2.5 during LRT and LP, respectively. The proportion of PCDD increased when neither event occurred. Principal component analysis revealed relationships between the component variance of PCDD/Fs and the sampling site altitude. The results of potential source contribution function (PSCF) suggested that the cold-air masses reaching Taiwan via LRT were most likely arriving from northern China, with pollutants collected along their routes. Wind speed and direction and geographical factors affected the accumulation of air pollutants in the atmosphere during LP.

Haze, public health and mitigation measures in China: A review of the current evidence for further policy response

With rapid economic development, China has been plagued by choking air pollution in recent years, and the frequent occurrence of haze episodes has caused widespread public concern. The purpose of this study is to describe the sources and formation of haze, summarize the mitigation measures in force, review the relationship between haze pollution and public health, and to discuss the challenges, potential research directions and policy options. Haze pollution has both natural and man-made causes, though it is anthropogenic sources that are the major contributors. Accumulation of air pollutants, secondary formation of aerosols, stagnant meteorological conditions, and trans-boundary transportation of pollutants are the principal causes driving the formation and evolution of haze. In China, haze includes gaseous pollutants and fine particles, of which PM2.5 is the dominant component. Short and long-term exposure to haze pollution are associated with a range of negative health outcomes, including respiratory diseases, cardiovascular and cerebrovascular diseases, mental health problems, lung cancer and premature death. China has paid increasing attention to the improvement of air quality, and has introduced action plans and policies to tackle pollution, but many interventions have only temporary effects. There may be fierce resistance from industry groups and some government agencies, and often it is challenging to enforce relevant control measures and laws. We discuss the potential policy options for prevention, the need for wider public dialogue and the implications for scientific research.

Typical synoptic situations and their impacts on the wintertime air pollution in the Guanzhong basin, China

Abstract. Rapid industrialization and urbanization have caused severe air pollution in the Guanzhong basin, northwestern China, with heavy haze events occurring frequently in recent winters. Using the NCEP reanalysis data, the large-scale synoptic situations influencing the Guanzhong basin during wintertime of 2013 are categorized into six types to evaluate the contribution of synoptic situations to the air pollution, including “north-low”, “southwest-trough”, “southeast-high”, “transition”, “southeast-trough”, and “inland-high”. The FLEXPART model has been utilized to demonstrate the corresponding pollutant transport patterns for the typical synoptic situations in the basin. Except for “southwest-trough” and “southeast-high” (defined as favorable synoptic situations), the other four synoptic conditions (defined as unfavorable synoptic situations) generally facilitate the accumulation of air pollutants, causing heavy air pollution in the basin. In association with the measurement of PM2.5 (particulate matter with aerodynamic diameter less than 2.5 µm) in the basin, the unfavorable synoptic situations correspond to high PM2.5 mass concentrations or poor air quality and vice versa. The same analysis has also been applied to winters of 2008–2012, which shows that the basin was mainly influenced by the unfavorable synoptic situations during wintertime leading to poor air quality. The WRF-CHEM model has further been applied to simulate the selected 6 days representing the typical synoptic situations during the wintertime of 2013, and the results generally show a good agreement between the modeled distributions and variations of PM2.5 and the corresponding synoptic situations, demonstrating reasonable classification for the synoptic situations in the basin. Detailed meteorological conditions, such as temperature inversion, low-level horizontal wind speed, and planetary boundary layer, all contribute to heavy air pollution events in the basin under unfavorable synoptic conditions. Considering the proportion of occurrence of unfavorable synoptic situations during wintertime, reduction of emissions is the optimum approach to mitigate the air pollution in the Guanzhong basin.

Assessment of seasonal variation for air pollutant accumulation by Zizyphus tree under washing treatment.

A field study was carried out near Jeddah Industrial Zone to estimate the leaf impairment, physiological disorders, and air pollutant accumulation potential of Ziziphus tree. The experiment was triplicated in RCBD design with factorial arrangement having seasonality as the main plot and washing as subplot treatments along with the control. Accumulation of heavy metals and micronutrients in plant foliage varied significantly under the influence of seasons and washing treatments. The maximum accumulation of cadmium, chromium, nickel, and lead were perceived in summer season while the minimum was observed in winter. Contrarily, a greater acquisition of iron, copper, zinc, and manganese was observed in autumn. Washing significantly reduced the accumulation of Cd, Cr, Ni, and Pb by 58, 90, 80, and 96%, while Fe, Cu, Zn, and Mn by 89, 37, 60, and 93%, respectively. Leaf protein and nitrogen content illustrated a greater adjustment for pollutants by presenting a minimum variation (14-18% and 2-3%) to seasonality. In contrast, leaf area and stomatal aperture were significantly disturbed and resulted in minimum recovery under washing. Correlation analysis revealed a stronger negative interaction of heavy metal accumulation to leaf features while non-significant interaction was perceived for microelements. In conclusion, planting of Ziziphus trees along industrial areas may impede potential threats of toxic pollutants to human and ecosystem.