Winter Air Pollution Research Articles

The impacts of meteorology on source contributions of air pollution in winter in Beijing, 2015–2017 changes

In this study, a combination of monitoring data and the CAMx-PAST (comprehensive air quality model with particulate matter source apportionment technology) model was used to evaluate the meteorological effect of changes in the source apportionment results of PM2.5, SO42−, NO3−, NH4+ and their precursors (SO2, NO2, and NH3) in Beijing in January 2015, January 2016 and January 2017. The meteorological conditions in 2017 were more favorable than those in the other two years in terms of air pollution accumulation and formation, with a monthly high relative humidity of 72% and a low wind speed of 2.06 m s−1. PM2.5 pollution was more serious in 2017 than in other years, with an average concentration of 116 μg m−3. Both simulation and observation data demonstrated that nitrate accounted for the largest proportion of the total secondary inorganic aerosol (SO42−, NO3− and NH4+). In the winter in Beijing, residential areas were a major source of pollution and contributed to 51%~54% of the total pollution. Meteorology has a great influence on the regional transportation of pollution. The transport ratios of PM2.5 were 22%, 26% and 33% in 2015, 2016 and 2017, respectively. Regional transport has a significant effect on both SO42− and NO3− concentration. However, primary pollution is mainly affected by local pollution sources. Local residential emissions have the greatest impact on SO2, contributing 85%, 82% and 83% of the total concentration. The local emissions contributed 88%, 84% and 84% of the total NO2 concentration.

Toxic potentials of particulate and gaseous air pollutant mixtures and the role of PAHs and their derivatives

BackgroundAir pollution, which represents a major environmental risk to human health, comprises a complex mixture of compounds where only little is known about its specific toxicities. ObjectivesThis study examined the specific toxicities associated with ambient air pollutant mixtures with respect to gas/particle partitioning, particulate matter (PM) size, pollutant polarity and bioaccessibility from PM, and evaluated the contribution of PAHs and their oxygenated and nitrated derivatives (OPAHs, NPAHs). MethodsAir samples (gas phase, PM10 and size-segregated PM), were collected at urban (in winter and summer) and background (winter) sites in the Czech Republic. The total and bioaccessible concentrations were addressed using organic solvent extraction and simulated lung fluid extraction, respectively. Organic extracts were also further fractionated according to polarity. Aryl hydrocarbon receptor (AhR)-mediated activity, anti-/estrogenicity, anti-/androgenicity, thyroid receptor (TR)-mediated activity and cytotoxicity for bronchial cells were determined by human cell-based in vitro bioassays. The contribution of studied compounds to observed effects was assessed by both modelling and reconstructing the mixtures. ResultsSignificant effects were detected in the sub-micrometre size fraction of PM (estrogenicity, androgenicity, TR- and AhR-mediated activities) and in the gas phase (TR-mediated activity, antiandrogenicity). Compounds interacting with TR showed high bioaccessibility to simulated lung fluid. Relatively lower bioaccessibility was observed for estrogenicity and AhR-mediated activity. However, the toxicity testing of reconstructed mixtures revealed that the targeted pollutants are not the main contributors, except for urban PM air pollution in winter, where they accounted for 5–88% of several effects detected in the original complex environmental samples. DiscussionStudied toxicities were mostly driven by polar compounds largely attributed to the easily inhalable PM1, which is of high relevance for human health risk assessment. Except of parent PAHs in some cases, the targeted compounds contributed to the detected effects mostly to a relatively low extent implying huge data gaps in terms of endocrine disruptive potencies of targeted substances and the significance of other polar compounds present in ambient air.

Meteorology of air pollution in Los Angeles

The meteorology of air pollution in Los Angeles (LA) is studied via daily near-surface air chemistry, aerosol and weather data assimilated from insitu and satellite measurements in the period 2005–2016. Atmospheric fields are regressed onto seasonal air pollution indices and reveal that a ridge of high pressure north of California weakens the longshore circulation and reduces dispersion.A 10-case composite of atmospheric anomalies during winter air pollution episodes was analyzed. Periods of high nitrogen dioxide and carbon monoxide show increasing temperature gradients that induce the converging of land-seabreezes beneath a strengthened thermal inversion. The atmospheric environment of an air pollution episode in December 2005 reveals recirculating trajectories. Efforts to limit emissions have contributed to reductions of nitrogen dioxide, but other constituents remain a public health concern. Knowledge of weather conditions underlying air pollution episodes will improve warnings and the effectiveness of mitigating actions.

Regional PM2.5 Estimation in Beijing Based on WRF-Chem Model

Air pollution remains to be a challenge for the government and scholars, especially the particulate matter (PM2.5), resulting in many casualties and huge economic losses. It is imperative to understand the distribution characteristics of PM2.5 and analysis some influencing factors including the wind speed, humidity and atmospheric boundary conditions. A certain scholars have studied the relationship between the PM2.5 and the atmospheric boundary condition. However, there is no study about the correlation analysis between the PM2.5 and wind speed or humidity. Considering all components in the atmosphere affecting each other and the ability of WRF-Chem simulating all of the atmospheric parameters, we utilized the WRF-Chem to simulate the wind speed, humidity and PM2.5. Then firstly the PM2.5 simulated from WRF-Chem are validated with those at the ground stations to evaluate the reliability of WRF-Chem. Secondly, the correlation analysis between the PM2.5 and wind speed or humidity was done, with the correlation coefficient -0.7 and 0.48 in January, 2019. And the results demonstrate that the wind is helpful to decrease the serious air pollution in winter while the humidity has a little effect on the elimination of the particulate matter. The WRF-Chem is potential and an effective tool for the study of the air pollution.

Air Pollution as a Slow-Onset Disaster in Ulaanbaatar

Objectives: This research aimed to better understand how exposure to high levels of winter air pollution may be affecting the health of children living in areas where housing is predominantly ger type traditional homes and houses compared to those living in areas where housing is predominantly apartments in Ulaanbaatar. The objective of the research was to study the differences in health and missed school days in children from these areas. Methods: Data were gathered from 36 childcare centers (kindergartens), schools and primary centers and interviews conducted among 148 individuals in three districts of Ulaanbaatar namely Chingeltei, Songinokhairkhan and Khan-uul. The study was performed between October 1, 2015 and December 31, 2015. Results: This study revealed that at the beginning of the study, the rate of children reported to be sick was about the same for both ger and apartment district primary schools, however by the end of the study the number of children reported sick each day living in predominantly gers and cabins was more than reported in apartment districts, that is, about 4 per 10,000 in apartment districts vs about 7 per 10,000 in ger districts. At the end of the study, rates of sickness reported was 5 to 6 times higher in children in childcare centers compared to children attending in primary schools regardless of where they lived. Conclusion: This study suggests that air pollution is not only affecting children’s health, but also affecting their education in Ulaanbaatar.

Concentration Characteristics and Assessment of Model-Predicted Results of PM2.5 in the Beijing-Tianjin-Hebei Region in Autumn and Winter

This paper discusses the concentration characteristics of PM2.5, as well as its relationship with meteorological factors in autumn and winter (from September to the following February), from 2013 to 2018 in the Beijing-Tianjin-Hebei (BTH) region. The accuracy and uncertainty of the air quality forecast models NAQPMS(nested air quality prediction modeling system), CMAQ(community multiscale air quality modeling system), and CAMx (comprehensive air quality model with extensions) were analyzed based on the model-predicted and measured PM2.5 concentration in autumn and winter from 2015 to 2018. The accuracy of NAQPMS, CMAQ, and CAMx during typical heavy air pollution was also tested. Moreover, methods to improve the accuracy of the model forecast were discussed. The results showed that the mean concentrations of PM2.5 in the BTH region were 122, 98, 82, 99, and 65 μg·m-3 in the five autumn and winter periods, respectively. When the air quality index (AQI) exceeded 150 during each autumn and winter, it reached 229, 198, 210, 204, and 180 μg·m-3, respectively. There were 64 occurrences of heavy regional PM2.5 air pollution in autumn and winter from 2013 to 2018. The average duration was longest in the 2013 to 2014 period, and shortest in the 2017 to 2018 period. The peak concentration and average concentration of PM2.5 decreased year on year, except for the period from 2016 to 2017. In autumn and winter, PM2.5 concentration had a relatively close relationship with relative humidity, wind and sunshine duration, compared with a weak relationship with temperature and air pressure. Regional heavy air pollution always happened under the condition of low wind speed(less than 2 m·s-1),higher relative humidity(greater than 65%),and southwest and northeast wind direction. In addition, the heavy air pollution of PM2.5 in BTH in autumn and winter can be effectively forecasted by NAQPMS, CMAQ, and CAMx. The predicted and measured PM2.5 concentration showed a close relationship. The models performed well in forecasting Zhangjiakou, Chengde, and Qinhuangdao, but by contrast overestimated in Tangshan, Shijiazhuang, Baoding, Beijing, and Tianjin. The uncertainty of emission sources, measured and predicted meteorological data, and the atmospheric chemical reaction mechanism may be the main reasons for the overestimate.

Characteristics and source apportionment of PM2.5 on an island in Southeast China: Impact of sea-salt and monsoon

Abstract To study the combined effects of the East Asian monsoon and ocean emissions on wintertime and summertime PM2.5 in island cities, filter samples were collected simultaneously at four different functional sites. Based on the chemical compositions of PM2.5, and positive matrix factorization (PMF) model analysis, the pollution characteristics and sources were determined. Insignificant differences, and some correlation in PM2.5 reconstructed compositions were found among the sites (Pt-test > 0.05, P > .05), while significant differences, and no correlation, were found between winter and summer (PANOVA .05). There was more serious chloride depletion in summer (0.88 ± 0.05), caused by both significant Cl− depletion and Na+ enrichment, than in winter (0.18 ± 0.10). The concentrations of non-sea-salt-SO42− in winter were close to those in summer, but the sulfate oxidation ratio (SOR) in winter was much lower than that in summer. The results could be explained by the fact that sea-salt-SO42− has an important contribution to secondary inorganic aerosol on island cities. From both air trajectory clustering and PMF analysis, it was found that there was significant aerosol aging and regional transport in the island city during the East Asian monsoon, and that continental air masses control the variation of air pollution in winter, while sea breezes dominate the characteristics of PM2.5 in summer. This study helps to understand the characteristics and source mechanisms of PM2.5 pollution under complex meteorological conditions in island cities.

The Causes of “Vulnerable Regions” to Air Pollution in Winter in the Beijing-Tianjin-Hebei Region: A Topographic–Meteorological Impact Model Based on Adaptive Emission Constraint Technique

The Beijing-Tianjin-Hebei (BTH) region, with its complex terrain, has serious issues with air pollution. The northern and western parts of the BTH region are surrounded by the Yan Mountains and Loess Plateau (LP), and the south-central part of that region is a large open plain. Such special geographic configuration is prone to result in a concentrated pollution belt along the north-to-south direction on the eastern margin of the plateau, in addition to the influence of pollutant-emission sources and population distribution. In this study, based on an original adaptive nudging constraint method, we quantitatively analyzed the differences in the influence of emission sources under different dynamic and thermal conditions in the BTH region, which is impacted by a special large-scale leeward slope terrain. The mechanism of air pollution vulnerability and the comprehensive effects of terrain–meteorological conditions on air pollution in the BTH region were also discussed. The results indicated that the atmospheric diffusion conditions on the eastern side of the plateau were poor, and a sub-synoptic-scale “vortex sequence”, which was composed of a series of linked vortices, was identified. The corresponding atmospheric pollution convergence line stretched from Beijing to Hebei to Northern Henan in the lower atmosphere. On the eastern edge of the plateau, a “warm cover” formed by a temperature anomaly and a downdraft impeded the vertical diffusion of pollutants. Therefore, pollutants tended to converge at the eastern edge of the plateau, and the pollution belts would move longitudinally north and south along the topography of the eastern slope when south-westerly and north-easterly winds alternated. The movement generated a “train” of pollutants that were transported on the eastern edge of the plateau, which then caused air pollution to persist there. Such terrain–meteorological conditions amplified the effects of emissions by an average of 50% to 150% in the region, leading the eastern side of the LP to become a “naturally vulnerable region” to haze pollution.

Can Data Assimilation of Surface PM2.5 and Satellite AOD Improve WRF-Chem Forecasting? A Case Study for Two Scenarios of Particulate Air Pollution Episodes in Poland

Based on the Weather Research and Forecasting model with Chemistry (WRF-Chem) model and Gridpoint Statistical Interpolation (GSI) assimilation tool, a forecasting system was used for two selected episodes (winter and summer) over Eastern Europe. During the winter episode, very high particular matter (PM2.5, diameter less than 2.5 µm) concentrations, related to low air temperatures and increased emission from residential heating, were measured at many stations in Poland. During the summer episode, elevated aerosol optical depth (AOD), likely related to the transport of pollution from biomass fires, was observed in Southern Poland. Our aim is to verify if there is a relevant positive impact of surface and satellite data assimilation (DA) on modeled PM2.5 concentrations, and to assess whether there are significant differences in the DA’s impact on concentrations between the two seasons. The results show a significant difference in the impact of surface and satellite DA on the model results between the summer and winter episode, which to a large degree is related to the availability of the satellite data. For example, the application of satellite DA raises the factor of two statistic from 0.18 to 0.78 for the summer episode, whereas this statistic remains unchanged (0.71) for the winter. The study suggests that severe winter air pollution episodes in Poland and Eastern Europe in general, often related to the dense cover of low clouds, will benefit from the assimilation of surface observations rather than satellite data, which can be very sparse in such meteorological situations. In contrast, the assimilation of satellite data can have a greater positive impact on the model results during summer than the assimilation of surface data for the same period.

Correlation between air pollution and birth defects in Liaoning province

Objective To investigate whether there is a correlation between ambient air pollution and the incidence of birth defects. Methods The data on 58 744 live births with birth defects were collected in Liaoning province among 3 198 348 puerperae having last menstrual period between January 1st, 2006 through December 2015. We also collected data on ambient air pollution during the same period from 71 monitoring sites in 14 cities across Liaoning province. The associations of exposure to various air pollutants of the puerperae before and after pregnancy with incidences of different types of birth defects were analyzed. Results Heavier ambient air pollution in winter and spring seasons were observed during the period in the province. The total incidence of birth defects was 18.67/10 000 for all the live births. The top five defects were congenital heart disease, cleft lip and palate, polydactyly, hydrocephalus and external ear malformation, altogether accounting for 51% of all the birth defects observed. For all the live births of the puerperae with their last menstrual periods in winter and spring seasons, the incidence of congenital heart disease was associated with following exposures: concentration of nitrogen dioxide (NO2) during the second month or whole duration of pregnancy, air pollution index (API) during the third or the fifth month or whole duration of pregnancy, sulfur dioxide (SO2) during the first month of pregnancy, and particulate matter less than 10 μm in aerodynamic diameter (PM10) during the third month of pregnancy; the incidence of polydactyly was related the exposure to SO2 during the fourth month of pregnancy; the incidence of external ear malformation was correlated with exposures to SO2 during the first month or the fourth month of pregnancy. Conclusion Maternal exposure to air pollution during some months of pregnancy is associated with incidences of some birth defects.

Design and key heating power parameters of a newly-developed household biomass briquette heating boiler

Using biomass briquette fuel for rural household heating is in line with the current Chinese policy and helpful to alleviate the air pollution in winter in northern China. However, the existing biomass briquette boilers have several defects on structure design, fuel feeding, and combustion control, while the design code for the biomass briquette heating boiler has not been proposed thus far. In this study, a newly-developed household biomass briquette heating boiler is designed. Performance test shows that under the optimal operating condition, the emissions of flue dust, NOx, CO, and SO2 are 33.20, 62.48, 426, and 0 mg/m3, respectively; the Ringelman emittance ≤1; the heating power is 12 kW; the thermal efficiency is 84.69%. The tested pollutant emissions and thermal efficiency are in compliance with the limits from the standard. The two key heating power parameters, the grate plan heat release rate and furnace volume heat release rate of this boiler are also determined to provide theoretical basis for the structure design of biomass briquette heating boilers. Results show that the optimal values of these two parameters are 181.98 kW/m2 and 292.04 kW/m3. For the design of household biomass briquette heating boilers, the ranges of 150–210 kW/m2 and 250–330 kW/m3 are considered as the reasonable intervals of these two parameters.

Meteorological aspects of winter air pollution episodes in the Cape Town area

Meteorological aspects of winter air pollution episodes in the Cape Town area

Pollution Characteristics and Source Apportionment of Fine Particulate Matter in Autumn and Winter in Puyang, China

As one of the air pollution transmission channels around the beijing-Tianjin-Hebei region, Puyang frequently suffer from severe airpollution in autumn and winter. In order to study the characteristics and main sources of fine particulate matter during these periods, manual membrane sampling of PM2.5 was conducted at three national control sites from October 15, 2017, to January 13, 2018. Chemical composition analysis was conducted and, combined with a PMF receptor model, source analysis of the fine particles was also undertaken. The results show that the average mass concentration of PM2.5 in Puyang was 94.16 μg·m-3 in the autumn and winter of 2017, and Pushuihe station was the most polluted site. During the heating season, the three control stations all recorded the frequent occurrence of severe and serious pollution events, while the frequency of mild pollution events decreased. When heavy pollution events occurred, the concentrations of NO2 and CO increased significantly. The main components of PM2.5 were water-soluble ions (52.33%), OCEC (25.32%), and crustal elements (0.08%). The concentrations of NO3- were high while the concentrations of SO42- were low. When heavy pollution occurred, the concentrations of water-soluble ions, OC, EC, and K in PM2.5 increased significantly, while the concentrations of crustal elements decreased. During the sampling period, the conversion ratios of sulfur and nitrogen in Puyang were high and atmospheric oxidation was strong. The transformation of sulfur and nitrogen promoted the occurrence of heavy pollution. Emissions of NOx, CO, and VOCs were higher in Puyang in 2017, and the source apportionment results showed that the main sources of PM2.5 in autumn and winter were secondary inorganic salts (37%), industrial sources (16%), secondary organic aerosol (SOA, 14%), biomass combustion (12%), mobile sources (9%), coal burning (7%), and dust (4%). Secondary transformation played an important role in the development of heavy pollution events in Puyang. It is necessary to focus on the control of emissions from industrial sources, biomass combustion, moving source, and civil coal combustion.

Nitrate dominates the chemical composition of PM2.5 during haze event in Beijing, China

Water-soluble inorganic ions (WSI), a major component of PM2.5, often increased rapidly during the haze event in Beijing. Sulfate (SO42−), Nitrate (NO3−), and Ammonium (NH4+) are three main components of WSI. Since year 2015, sulfate concentrations in PM2.5 has gradually decreased owing to the effective control of SO2 emissions. However, the contribution of nitrate to PM2.5 has significantly increased during haze events in Beijing at the same time. In this study, a highly time-resolved online analyzer (Monitor for Aerosols and Gases, MARGA) was employed to measure the WSI in PM2.5 in Beijing from 5 February to 15 November 2017. Three typical haze events during this sampling period were investigated. During heavy pollution episodes in winter, nitrate concentrations increased from 7.5 μg/m3 to 45.6 μg/m3 (45.0% of WSI), while sulfate increased from 4.2 μg/m3 to 20.1 μg/m3 (19.8% of WSI). This indicated that nitrate is more important than sulfate as a driver for the growth of PM2.5 during the period of heavy air pollution in winter. Nitrate also dominates the increase of WSI in the pollution episodes in autumn, with an average concentration of 52.5 μg/m3, and contributed up to 67% of WSI. The average concentration ratio of NH4+ to SO42− was higher in autumn (1.02) than that in summer (0.74) and close to that in winter (1.00). This is mainly because the emission control of coal combustion in Beijing and surrounding areas results in an NH3-rich and SO2-lean atmosphere, which promoted the formation of ammonium nitrate. Our study indicates that nitrate has become the most important component of WSI in PM2.5 and is driving the rapid growth of PM2.5 concentrations during heavy pollution episodes in Beijing. Therefore, more efforts shall be made to reduce the nitrogen oxide and ammonia emissions in Beijing and surrounding areas.

Winter photochemistry in Beijing: Observation and model simulation of OH and HO2 radicals at an urban site

A field campaign was conducted from November to December 2017 at the campus of Peking University (PKU) to investigate the formation mechanism of the winter air pollution in Beijing with the measurement of hydroxyl and hydroperoxyl radical (OH and HO2) with the support from comprehensive observation of trace gases compounds. The extent of air pollution depends on meteorological conditions. The daily maximum OH radical concentrations are on average 2.0 × 106 cm−3 and 1.5 × 106 cm−3 during the clean and polluted episodes, respectively. The daily maximum HO2 radical concentrations are on average 0.4 × 108 cm−3 and 0.3 × 108 cm−3 during the clean and polluted episodes, respectively (diurnal averaged for one hour bin). A box model based on RACM2-LIM1 mechanism can reproduce the OH concentrations but underestimate the HO2 concentrations by 50% during the clean episode. The OH and HO2 concentrations are underestimated by 50% and 12 folds during the polluted episode, respectively. Strong dependence on nitric oxide (NO) concentration is found for both observed and modeled HO2 concentrations, with the modeled HO2 decreasing more rapidly than observed HO2, leading to severe HO2 underestimation at higher NO concentrations. The OH reactivity is calculated from measured and modeled species and inorganic compounds (carbon monoxide (CO), NO, and nitrogen dioxide (NO2)) make up 69%–76% of the calculated OH reactivity. The photochemical oxidation rate denoted by the OH loss rate increases by 3 times from the clean to polluted episodes, indicating the strong oxidation capacity in polluted conditions. The comparison between measurements at PKU site and a suburban site from one previous study shows that chemical conditions are similar in both urban and suburban areas. Hence, the strong oxidation capacity and its potential contribution to the pollution bursts are relatively homogeneous over the whole Beijing city and its surrounding areas.

Impact of Particulate Matter (PM 2,5 ) and children's hospitalizations for respiratory diseases. A case cross-over study

With seven million inhabitants, Santiago de Chile reaches high levels of air pollution in winter, the particulate matter usually exceeds WHO standards. To assess the influence of air pollution caused by particulate matter on children's hospitalizations due to respiratory diseases between 2001 and 2005 in the Metropolitan Region of Chile, independently from the environmental presence of respiratory syncytial virus (RSV). 72,479 public and private hospitalizations due to respiratory diseases of children under 15 years of age residing in the study region were analyzed using a time-stratified alternating case-control design. The main evaluations were: hospitalizations due to respiratory diseases (J00-J99), pneumonia (J12-J18); asthma (J21.0 - J21.9), and bronchiolitis (J45 - J46). Daily compilation of temperature data, PM10, PM2.5, ozone, respiratory virus (RSV), and environmental humidity. Mean values of PM10 and PM2,5 were 81.5 and 41.2 pg/m3 respec tively. The average temperature was 12.8 °C and air humidity 72.6%. An increase of 10 pg/m3 of PM25 with one and two days of lag was associated with an hospitalizations increase due to respiratory diseases close to 2%, this percentage increased to 5% when the exposure was with eight days of lag, reflecting synergism between particulate matter and respiratory viruses (RSV). Short air pollution exposure can lead to children's hospitalizations due to respiratory diseases.

Optimizing for clean-heating improvements in a district energy system with high penetration of wind power

Strong interdependence of heat and power generation makes most existing power grids in northern China unfriendly to wind energy. However, wind energy has increased significantly in the past 15 years. Furthermore, most areas in northern China suffer from severe air pollution in winter, which is caused by the substandard emissions from coal-fired heat generators. Therefore, introducing power-to-heat devices and thermal energy storage (TES) system to the existing district energy system (DES) is an effective way to improve wind power integration, reduce operating costs, and bring considerable economic benefits. In order to determine the optimal configurations of additional power-to-heat devices and TES system, a novel two-layer economic optimization model has been proposed. In the outer layer of such model, the annual net profit (ANP) of each clean-heating project is calculated by introducing a traditional economic dispatch model. Regarding the outer layer, the solution space of varied clean-heating schemes is searched globally by the Genetic Algorithms. Results show that both introducing power-to-heat devices and TES equipment possess the highest economic potential. From the economical aspect, it is not necessary to integrate all available wind energy; thus, wind curtailments still exist after conducting the optimal clean-heating improvements.

Possible Influence of the Antarctic Oscillation on Haze Pollution in North China

AbstractIn this study, the possible influence of the Antarctic oscillation (AAO) on winter haze pollution (indicated by atmospheric visibility after rain, fog, dust, snowstorms, etc. are removed) in North China (NC) was investigated. The results show that the mean winter visibility (December‐January‐February visibility) throughout most of eastern China is negatively correlated with the preceding AAO (August‐September‐October (ASO)‐AAO), especially in NC. The interannual correlation coefficient between DJF‐VIS in NC and the ASO‐AAO is −0.52, which is significant at the 99% level. The negative correlation suggests that an enhancing (weakening) ASO‐AAO could be conducive to increases (decreases) of haze pollution in NC in boreal winter. The responses of local and regional meteorological conditions to the ASO‐AAO support the relationship between the ASO‐AAO and winter air pollution in NC. A preliminary mechanism analysis shows that a positive ASO‐AAO may induce a sea surface temperature warming tendency in the Northwestern Southern Indian Ocean. This warming then causes a wave train‐like pattern in the upper troposphere along the jet stream and an anomalous zonal cell that weakens the regional Hadley circulation from the Maritime continents to East Asia. All of these factors are favorable to the formation of anomalous southerly and haze pollution in NC.

成都平原地区秋冬季节空气污染及其气象特征分析

成都平原地区秋冬季节空气污染及其气象特征分析

The contribution of the Beijing, Tianjin and Hebei region's iron and steel industry to local air pollution in winter

The Beijing, Tianjin and Hebei region (BTH) in China is a highly populated area that has recently experienced frequent haze episodes in winter. With high production capacities, the iron and steel industry (ISI) has long been a key source of air pollutants in BTH and is thus considered responsible for the degradation of local air quality. Here, we conducted a cross-disciplinary research combining the Weather Research and Forecasting with Chemistry (WRF/Chem) model, the multiregional input-output model (MRIO) and the health assessment model to explore the impacts of the ISI on air pollution in the BTH region in January 2012. Our results show large increases in air pollution due to direct ISI emissions, with up to a 90 μg/m3 monthly average of fine particulate matter (PM2.5) and sulfur dioxide (SO2) in eastern Tangshan and western Handan. In addition to direct emissions, the ISI has induced large quantities of indirect emissions from upstream sectors (e.g., the electricity and transportation sectors), leading to PM2.5, SO2 and NOx increases of 2–10 μg/m3 in BTH. Considering the direct and indirect emissions, we estimated that 275 (233–313) PM2.5-related mortalities occurred in January, and approximately 42% of these premature deaths occurred in Tangshan. A high rate of premature deaths also occurred in urban Beijing due to its high population density. Revealing the great health burden caused by the ISI, our results underscore the necessity for the Chinese government to reduce air pollutant emissions from the ISI and its upstream industries in BTH.