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China enacted and implemented a carbon emissions trading pilot policy in 2011, and whether this carbon emissions trading scheme (ETS) can promote the development of green finance is crucial to realizing a win–win situation for both environmental and economic performance. Based on the panel data of 30 provinces in China from 2007 to 2019, this study constructs a multi-period double-difference model (DID) to explore the impact of carbon ETS on the development of green finance and uses the spatial Durbin model (SDM) to test whether there is a spatial spillover effect of the carbon ETS on the development of green finance. The results show that (a) the implementation of carbon ETS significantly promotes the development of green finance, and this conclusion still holds through a series of robustness tests; (b) the promotion effect of the carbon ETS on the development of green finance is more significant in eastern and western provinces, non-resource–based provinces, and provinces with a high level of openness to the outside world; (c) industrial structural upgrading and green innovation play pivotal roles in achieving the desired outcomes of carbon ETS; (d) carbon ETS have spatial spillover effects on the development of green finance, with the indirect effects being more significant than the direct effects. The findings of this study can serve as a valuable reference for expediting the establishment of a unified national carbon market and the development of a robust green financial system. This holds immense significance in effectively implementing the "dual-carbon" strategy. [ABSTRACT FROM AUTHOR]

Large petrochemical complex (PC) widely exists in both developing and developed countries, and is expected to have a special photochemical pollution in local scale due to huge VOCs emissions. Here, a typical large-scale PC in North China was selected as the study case, to explore the character, formation and influence of local photochemical pollution regarding PCs based on an improved 0-D chemical model. In the study PC, VOCs-rich character was apparent with THCs level of 90.8 ± 28.0 ppb and THCs/NOx ratio of ∼26.2 mol/mol. Severe O 3 pollution was found in warm months with monthly mean MDA1O3 of 67.3–96.0 ppb. Model simulations showed the heavy O 3 pollution in this PC was attributed to high precursors rather than to unfavorable meteorology, and was more sensitive to NOx (with response of 1.42 g/g) than to THCs (with response of 0.12 g/g). The photochemical pollution formation potential of the emission plumes of this PC was very enormous, with production rate of 19.6 ppb h−1 for O 3 , 2.9 ppb h−1 for HCHO and 1.1 ppb h−1 for CH 3 CHO on daytime average, 1–5 greater than in normal urban areas. The higher production rates happened in morning hours, which explained the earlier peak time of observed O 3 in PCs. And about 70% of photochemical pollution (represented by O 3) would be transported to surroundings, leading to the significant photochemical-pollution hazard to the vicinity of PCs. [Display omitted] • Severe O 3 pollution was found in large petrochemical complex. • Local photochemistry was simulated through box chemical model. • High O 3 was attributed more to high precursors than to unfavorable meteorology. • O 3 , HCHO and CH 3 CHO was produced at the rate of 19.6, 2.9 and 1.1 ppb h−1. • About 70% photochemical pollution formed would be downwind output. [ABSTRACT FROM AUTHOR]

Currently, China's municipal solid waste (MSW) management system has been changing from mixed collection and treatment system into separated collection and treatment system. Therefore, the source separated ability of MSW, the relevant policies of MSW classification and the MSW management system are still in the stage of exploration and improvement. This study chooses to integrate waste pickers (WPs) from the informal sector into the MSW management system, so that they can conduct secondary sorting of waste as a supplement to source separation. However, the existing research does not provide a method that allows the evaluation of integrated WPs from a dynamic and long-term perspective. In this paper, the system dynamics model of MSW management is improved to provide the ability to analyze the long-term evolution of social economic benefits of integrating WPs for secondary sorting. Taking Tianjin as an example, the scenario analysis is carried out. The results show that, on the basis of the existing mixed management mode, integrating WPs for secondary sorting (80% separated rate) can reduce the waste management cost per ton by 55 yuan in 2030. Under the current situation in Tianjin where the source separation rate of food waste is 20% and the source separation rate of recyclable waste is 60%, integrating WPs can reduce the social economic cost of Tianjin's urban MSW management system by 422.45 million yuan per year from 2022 to 2030. In addition, the results show that even if the source separated rate of food and recyclable waste increases, there is still room for 20%–80% increase in wages based on giving WPs a salary higher than the national per capita disposable income in 2022. This study provides a basis for integrating WPs into Tianjin MSW management system, as well as methods and quantitative tools to integrate WPs for cities in developing countries. • Dynamics model was developed to analyze the contribution of secondary sorting of WPs. • MSW generation and disposal as well as social economic benefits in Tianjin were simulated. • WPs reduce the social economic cost 422.45 million yuan per year in Tianjin's MSW. • Even with rising labor costs, the social economic benefits of WPs are significant. [ABSTRACT FROM AUTHOR]

Cross-border transport is a crucial factor affecting air quality, while how to quantify the transport contribution through different technologies at multi–perspective and multi–scale have not been fully understood. This study established three quantification techniques, and conducted a systematic assessment of PM 2.5 transport over the North China Plain (NCP) based on numerical simulations and vertical observations. Results suggested that the annual local emissions, inter–urban and outer–regional transport contributed 44.5%–64.6%, 15.2%–27.9% and 18.0%–28.2% of total surface PM 2.5 concentrations, respectively, with transport intensity stronger in July and April, yet weaker in January and October. The southwest–northeast, northeast–southwest, and southeast–northwest were three prevailing transport directions near the surface. By comparison, the annual PM 2.5 transport contribution below the atmospheric boundary layer height increased by 16.8%–24.5% in Beijing, Tianjin and Shijiazhuang, with inter–urban and outer–regional contribution of 29.8%–32.1% and 18.5%–23.1%. Furthermore, observed fluxes from fixed-point and vehicle-based mobile lidar were in good agreement with the simulated flux. PM 2.5 net flux intensity varied with height, with generally larger at the middle- and high-altitude layer than that of low-altitude layer. In the early, during and late period of haze peak formation (Stage Ⅰ, Ⅱ, Ⅲ, respectively), the largest absolute flux intensity on average was Stage Ⅱ (566.7 t/d), followed by Stage Ⅲ (307.0 t/d) and Ⅰ (191.4 t/d). Besides, external transport may dominate the second concentration peak, while local emissions may play a more vital role in the first and third peaks. It has been noted that joint prevention and control measures should be proposed 1–2 days before reaching PM 2.5 extremes. These findings could improve our understanding of transport influence mechanism of PM 2.5 and propose effective emission reduction measures in the NCP region. [Display omitted] • Three transport quantification techniques were established. • The local and external transport contribution to surface PM 2.5 were identified. • External transport below the ABLH exceeded that at the surface. • The transport effect was stronger in July and April, weaker in January and October. • PM 2.5 flux intensity varied with the different altitudes. [ABSTRACT FROM AUTHOR]

The local-scale relationship between ambient ozone (O) and its precursors was examined around a coking plant in northern China. The upwind, plant boundary, and downwind locations were selected for investigation during the summer and autumn seasons in 2012. It was found that propene, toluene, and benzene were the top three non-methane hydrocarbon (NMHC) species for O formation at plant boundary, while propene, toluene, and m/ p-xylene were the top three NMHC species at downwind location. Isoprene was the dominant species for O formation at upwind location. It was also found that an O depressing process occurred at plant boundary as a result of high NO emissions. Both local photochemistry and transport led to O accumulation at the downwind locations. The variation of NMHC concentration during O polluted and non-polluted episodes was investigated, and it indicated that NMHC concentration was higher during non-polluted episodes than polluted episodes. The impacts of precursors on O formation under different meteorological conditions were also examined. [ABSTRACT FROM AUTHOR]

In the context of addressing climate change and promoting high-quality development, it is necessary to evaluate the impact of carbon emissions trading scheme (ETS) on China's total factor productivity (TFP). Based on a quasi-experimental design, we provide firm-level evidence of TFP improvement from China's pilot ETSs. Using panel data of Chinese listed firms during 2009–2018, the difference-in-differences method is adopted to evaluate the impact of ETS on the firm-level TFP. The results show that the ETS significantly improves the firm-level TFP, increasing it in pilot regions by approximately 14% when compared with non-pilot regions. Further analysis shows that this improvement is not affected by the heterogeneity of firms' ownership, but by industrial heterogeneity. Moreover, this improvement is realized by promoting firms' operating and profitability capacity. We also find that the impact of ETS on firm-level TFP is stable and exhibits no time lag. Our findings not only improve the effectiveness evaluation framework of the Chinese ETS, but also have some implications for how to promote the construction of a national carbon emissions trading market in the context of high-quality development. [Display omitted] • We evaluate the impact of China's ETS on firm-level TFP with the DID method. • ETS significantly improve the firm-level TFP in the pilot regions. • The policy effects are affected by the heterogeneity across industries. • The impact of the ETS on firm-level TFP is stable and exhibits no time lag. • The promotion of firm-level TFP by the ETS does not stem from innovation capacity. [ABSTRACT FROM AUTHOR]

In recent years, there have been a number of studies on bioretention during hot summer, with only few studies reported during low-temperature winters. The application of bioretention in cold areas still lacks effective guidance. In this study, runoff simulation experiments were conducted to explore the influence of wood chips filler and water treatment residue on the removal of runoff pollutants under different packing gradations and low temperature conditions. Under low temperature, nitrate nitrogen removal rate of wood chips filler decreased from 70% to 90% in autumn to −23%- 35% in winter, the total nitrogen removal rate decreased from 75 to 90% in autumn to 20%–50% in winter, the removal rate of ammonia nitrogen and total phosphorus exceeded 70% during the entire experiment. Water treatment residue filler maintained a high ammonia nitrogen and total phosphorus removal rate during the experiment, with the total phosphorus removal rate above 90% and ammonia nitrogen removal rate above 80%. The bioretention effluent concentration of nitrate and total nitrogen was higher than 7.3 mg/L and 8.5 mg/L, respectively, most of the time. However, at low temperature, the COD removal rate of the two fillers was 25%–50%, which was very poor. Therefore, wood chips filler was observed to be better suited for the removal of nitrate and total nitrogen from the runoff, while water treatment residue had a better effect on the removal of ammonia nitrogen and total phosphorus in winter. Thus, for the application of bioretention in northern China, appropriate fillers should be selected considering the water quality characteristics of the area. [Display omitted] • The removal rate of NH 4 +-N and TP remained high at low temperature. • In winter the solid carbon can't enhance the removal of NO 3 −-N and TN. • The effect of packing gradation on water purification is not obvious. • At low temperature, bioretention could not effectively remove COD. [ABSTRACT FROM AUTHOR]

A study was conducted on aerosol-radiation interactions over six cities in this region within the 2015-2019 period. WRF-Chem simulations on 2017 showed that based on the six-city average, the aerosol load (PM 2.5 concentrations) of 121.9, 49.6, 43.3, and 66.3 µg/m 3 in January, April, July, and October, mainly lowered the level of downward shortwave radiation by 38.9, 24.0, 59.1, and 24.4 W/m 2 and reduced the boundary layer height by 79.9, 40.8, 87.4, and 31.0 m, via scattering and absorbing solar radiation. The sensitivity of meteorological changes to identical aerosol loads varied in the order July > January > October and April. Then, the cooling and stabilizing effects of aerosols further led to increases in PM 2.5 , by 23.0, 3.4, 4.6, and 7.3 µg/m 3 respectively in the four months. The sensitivity of the effect of aerosols on PM 2.5 was greatest in January rather than in July, contrary to the effect on meteorology. Moreover, a negative linear relation was observed between daily BLH reductions and aerosol loads in fall and winter, and between PM 2.5 increases and aerosol loads in all seasons. With the PM 2.5 pollution improvements in this region, the aerosol radiative forcing was effectively reduced. This should result in daily BLH increases of 10-24 m in fall and winter, and the estimates in Beijing agreed well with the corresponding results based on AMDAR data. Additionally, the reduction in aerosol radiation effects brought about daily PM 2.5 decreases of 1.6-2.8 µg/m 3 , accounting for 7.0%-17.7% in PM 2.5 improvements., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Volatile organic compounds (VOCs) concentration, source profiles, O 3 and SOA formation, and health risks were investigated in the petrochemical industry in Beijing-Tianjin-Hebei. The results showed that total VOCs concentrations were 547.1-1956.5 μg·m -3 , and alkanes were the most abundant group in all processes (31.4%-54.6%), followed by alkenes (20.6%-29.2%) and aromatics (10.1%-25.1%). Moreover, ethylene (11.3%), iso-pentane (7.1%), n-hexane (5.1%), benzene (4.9%) and 2,2-dimethylbutae (4.8%) were identified as the top five species released for the whole petrochemical industry. The coefficient of divergence between the source profiles from different processes was 0.49-0.73, indicating that most source profiles must not be similar. Moreover, because of the different raw materials and technologies used, the source profiles in this study are significantly different from those of other regions. The ozone and secondary organic aerosol formation potentials (OFPs and SOAPs) were evaluated, suggesting that ethylene, propylene, 1-butene, m,p-xylene, and 1,3-butadiene should be preferentially controlled to reduce OFPs. That benzene, toluene, ethylbenzene, m,p-xylene, isopropylbenzene, o-ethyltoluene, and 1,3,5-trimethylbenzene should be priority control compounds for SOAPs. Additionally, the total hazard ratio for non-cancer risk ranged from 0.9 to 7.7, and only living area was unlikely to be related to adverse health effects. Cancer risks associated with organic chemicals, rubber synthesis, oil refining, and wastewater collection and treatment have definite risks, whereas other processes have probable risks. This study provides a scientific basis for VOCs emission control and management and guides human health in the petrochemical industry., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Cross-border transport is a crucial factor affecting air quality, while how to quantify the transport contribution through different technologies at multi-perspective and multi-scale have not been fully understood. This study established three quantification techniques, and conducted a systematic assessment of PM 2.5 transport over the North China Plain (NCP) based on numerical simulations and vertical observations. Results suggested that the annual local emissions, inter-urban and outer-regional transport contributed 44.5%-64.6%, 15.2%-27.9% and 18.0%-28.2% of total surface PM 2.5 concentrations, respectively, with transport intensity stronger in July and April, yet weaker in January and October. The southwest-northeast, northeast-southwest, and southeast-northwest were three prevailing transport directions near the surface. By comparison, the annual PM 2.5 transport contribution below the atmospheric boundary layer height increased by 16.8%-24.5% in Beijing, Tianjin and Shijiazhuang, with inter-urban and outer-regional contribution of 29.8%-32.1% and 18.5%-23.1%. Furthermore, observed fluxes from fixed-point and vehicle-based mobile lidar were in good agreement with the simulated flux. PM 2.5 net flux intensity varied with height, with generally larger at the middle- and high-altitude layer than that of low-altitude layer. In the early, during and late period of haze peak formation (Stage Ⅰ, Ⅱ, Ⅲ, respectively), the largest absolute flux intensity on average was Stage Ⅱ (566.7 t/d), followed by Stage Ⅲ (307.0 t/d) and Ⅰ (191.4 t/d). Besides, external transport may dominate the second concentration peak, while local emissions may play a more vital role in the first and third peaks. It has been noted that joint prevention and control measures should be proposed 1-2 days before reaching PM 2.5 extremes. These findings could improve our understanding of transport influence mechanism of PM 2.5 and propose effective emission reduction measures in the NCP region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Cooking process can produce abundant volatile organic compounds (VOCs), which are harmful to environment and human health. Therefore, we conducted a comprehensive analysis in which VOCs emissions from multiple cuisines have been sampled based on the simulation and acquisition platform, involving concentration characteristics, ozone formation potential (OFP) and purification efficiency assessments. VOCs emissions varied from 1828.5 to 14,355.1 µg/m 3 , with the maximum and minimum values from Barbecue and Family cuisine, respectively. Alkanes and alcohol had higher contributions to VOCs from Sichuan and Hunan cuisine (64.1%), Family cuisine (66.3%), Shandong cuisine (69.1%) and Cantonese cuisine (69.8%), with the dominant VOCs species of ethanol, isobutane and n-butane. In comparison, alcohols (79.5%) were abundant for Huaiyang cuisine, while alkanes (19.7%), alkenes (35.9%) and haloalkanes (22.9%) accounted for higher proportions from Barbecue. Specially, carbon tetrachloride, n-hexylene and 1-butene were the most abundant VOCs species for Barbecue, ranging from 8.8% to 14.6%. The highest OFP occurred in Barbecue. The sensitive species of OFP for Huaiyang cuisine were alcohols, while other cuisines were alkenes. Purification efficiency assessments shed light on the removal differences of individual and synergistic control technologies. VOCs emissions exhibited a strong dependence on the photocatalytic oxidation, with the removal efficiencies of 29.0%-54.4%. However, the high voltage electrostatic, wet purification and mechanical separation techniques played a mediocre or even counterproductive role in the VOCs reduction, meanwhile collaborative control technologies could not significantly improve the removal efficiency. Our results identified more effective control technologies, which were conductive to alleviating air pollution from cooking emissions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Carbonyls have attracted continuous attention due to their critical roles in atmospheric chemistry and their potential hazards to the ecological environment and human health. In this study, atmospheric carbonyls were measured during several ground-level-ozone (O 3 ) pollution episodes at three urban sites (CRAES, IEP and BJUT) in Beijing in 2019 and 2020. Comparative analysis revealed that the carbonyl concentrations were 20.25 ± 6.91 ppb and 13.43 ± 5.13 ppb in 2019 and 2020 in Beijing, respectively, with a significant spatial trend from north to south, and carbonyl levels in urban Beijing were in an upper-intermediate range in China, and higher than those in other countries reported in the literature. A particularly noteworthy phenomenon is the consistency of carbonyl concentrations with variations in O 3 concentrations. On O 3 polluted days, the carbonyl concentrations were 1.3-1.5 times higher than those on non-O 3 polluted days. Secondary formation contributed more to formaldehyde (FA) and acetaldehyde (AA) on O 3 polluted days, while the anthropogenic emissions were more significant for acetone (AC) on non-O 3 polluted days. Vehicle exhaust and solvent utilization were the main primary contributors to carbonyls. Due to reduced anthropogenic emissions caused by the COVID-19 lockdown and the "Program for Controlling Volatile Organic Compounds in 2020" in China, the contributions of primary emissions to carbonyls decreased in 2020 in Beijing. Human cancer risks to exposed populations from FA and AA increased with elevated O 3 levels, and the risks still remained on non-O 3 polluted days. The residents around the BJUT site might experience relatively higher human cancer risks than those around the other two sites. The findings in this study confirmed that atmospheric carbonyl pollution and its potential human health hazards cannot be ignored in urban Beijing; therefore, more strict control strategies for atmospheric carbonyls are urgently needed to better protect human health in Beijing in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Estimating the impact of climate change risks on residential consumption is one of the important elements of climate risk management, but there is too little research on it. This paper investigates the impact of climate change risks on residential consumption and the heterogeneous effects of different climate risk types in China by an ARMAX model and examines the Granger causality between them. Empirical results based on monthly data from January 2016 to January 2019 suggest a significant positive effect of climate change risks on residential consumption, but with a three-month lag period. If the climate risk index increases by 1 unit, residential consumption will increase by 1.29% after three months. Additionally, the impact of climate change risks on residential consumption in China mainly comes from drought, waterlogging by rain, and high temperature, whereas the impact of typhoons and cryogenic freezing is not significant. Finally, we confirmed the existence of Granger-causality running from climate change risks to residential consumption. Our findings establish the linkage between climate change risks and residential consumption and have some practical implications for the government in tackling climate change risks.

Improving our understanding of air pollutant emissions from the asphalt industry is critical for the development and implementation of pollution control policies. In this study, the spatial distribution of potential maximum emissions of volatile organic compounds (VOCs) in the complete life cycle of asphalt mixtures, as well as the particulate matter (PM), asphalt fume, nonmethane hydrocarbons (NMHCs), VOCs, and benzoapyrene (BaP) emissions from typical processes (e.g., asphalt and concrete mixing stations, asphalt heating boilers, and asphalt storage tanks) in asphalt mixing plants, were determined in Beijing in 2017. The results indicated that the potential maximum emissions of VOCs in the complete life cycle of asphalt mixtures were 18,001 ton, with a large contribution from the districts of Daxing, Changping, and Tongzhou. The total emissions of PM, asphalt fume, NMHC, VOCs, and BaP from asphalt mixing plants were 3.1, 12.6, 3.1, 23.5, and 1.9 × 10 -3 ton, respectively. The emissions of PM from asphalt and concrete mixing stations contributed the most to the total emissions. The asphalt storage tank was the dominant emission source of VOCs, accounting for 96.1% of the total VOCs emissions in asphalt mixing plants, followed by asphalt heating boilers. The districts of Daxing, Changping, and Shunyi were the dominant regions for the emissions of PM, asphalt fume, NMHC, and BaP, while the districts of Shunyi, Tongzhou, and Changping contributed the most emissions of VOCs., (Copyright © 2021. Published by Elsevier B.V.)

The characteristics and transport pathways of air masses vary during heavy pollution episodes (HPEs). Three categories of HPEs have been defined: HPE Ι, II, and III, corresponding to HPE durations of 1, 2, and at least 3 days, respectively. Sixty HPEs were investigated in this study. The number of HPEs decreased from 2013 to 2017 and then increased from 2017 to 2019, dominated by emission reductions and meteorological conditions. The average and maximum PM 2.5 (i.e., aerodynamic diameter of <2.5 μm) concentrations during those HPEs in 2019 decreased by 5.6%-11.8% and 11.9%-38.5%, respectively, compared with those in 2013. The longer the duration of an HPE, the higher the PM 2.5 concentration. Secondary inorganic aerosol concentrations and their contents in PM 2.5 during HPE Ⅲ were found to be higher than those during HPEs Ι and Ⅱ, as secondary transformations of precursor gases are more intense during long-term HPEs. The dominant trajectories of airflow arriving in Jinan originated from the southern and southeastern regions during HPEs, realized using the Hybrid Single Particle Lagrangian Integrated Trajectory. The trajectories from the north and west of Jinan contained the highest PM 2.5 concentrations of 323.3-432.1 μg/m 3 during HPE Ⅲ, although these trajectories only contributed 5.6%-11.1% of the total dominant transport pathways, while those in trajectories from the northwest were highest during HPEs Ι and Ⅱ. The highest contributions of air masses from short distances were found during HPE Ⅲ, of 77.8%, while they were only 65.6% and 47.8% during HPEs Ι and II, respectively. More attention should be given to transport pathways within the short distance from Jinan. Therefore, enhancing regional cooperation in Jinan and surrounding regions (particularly in the south, southeast, northwest, west, and north) is critical for improving air quality in the North China Plain., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Although anthropogenic emissions decreased, polluted days still occurred in the Beijing-Tianjin-Hebei (BTH) region during the initial outbreak of the coronavirus disease (COVID-19). Analysis of the characteristics and source distribution of large-scale air pollution episodes during the COVID-19 outbreak (from 23 January to April 8, 2020) in the BTH region is helpful for exploring the efficacy of control measures and policy making. The results indicated that the BTH region suffered two large-scale air pollution episodes (23-28 January and 8-13 February), which were characterized by elevated PM 2.5 , SO 2 , NO 2 , and CO concentrations, while the O 3 concentration decreased by 1.5%-33.9% (except in Shijiazhuang, where it increased by 16.6% during the second episode). These large-scale air pollution episodes were dominated by unfavorable meteorological conditions comprising a low wind speed and increased relative humidity. The transport pathways and source distribution were explored using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT), potential source contribution function (PSCF), and concentration weighted trajectory (CWT) models. The air pollution in the BTH region was mainly affected by local emission sources during the first episode, which contributed 51.6%-60.6% of the total trajectories in the BTH region with a PM 2.5 concentration ranging from 146.2 μg/m 3 to 196.7 μg/m 3 . The short-distance air masses from the southern and southwestern areas of the BTH region were the main transport pathways of airflow arriving in the BTH region during the second episode. These contributed 51.9%-57.9% of the total trajectories and originated in Hebei, Henan, central Shanxi, and Shaanxi provinces, which were the areas contributing the most to the PM 2.5 level and exhibited the highest PSCF and CWT values. Therefore, on the basis of local emission reduction, enhancing regional environmental cooperation and implementing a united prevention and control of air pollution are effective mitigation measures for the BTH region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A field measurement campaign for ozone and ozone precursors (VOCs and NOx) was conducted in summer 2011 around a petroleum refinery in the Beijing rural region. Three observation sites were arranged, one at southwest of the refinery as the background, and two at northeast of the refinery as the downwind receptors. Monitoring data revealed the presence of serious surface O3 pollution with the characteristics of high average daily mean and maximum concentrations (64.0 and 145.4 ppbV in no-rain days, respectively) and multi-peak diurnal variation. For NOx, the average hourly concentrations of NO2 and NO were in the range of 20.5-46.1 and 1.8-6.4 ppbV, respectively. For VOC measurement, a total of 51 compounds were detected. Normally, TVOCs at the background site was only dozens of ppbC, while TVOCs at the downwind sites reached several hundreds of ppbC. By subtracting the VOC concentrations at background, chemical profiles of VOC emission from the refinery were obtained, mainly including alkanes (60.0% +/- 4.3%), alkenes (21.1% +/- 5.5%) and aromatics (18.9% +/- 3.9%). Moreover, some differences in chemical profiles for the same measurement hours were observed between the downwind sites; the volume ratios of alkanes with low reactivity and those of alkenes with high reactivity respectively showed an increasing trend and a decreasing trend. Finally, based on temporal and spatial variations of VOC mixing ratios, their photochemical degradations and dispersion degradations were estimated to be 0.15-0.27 and 0.42-0.62, respectively, by the photochemical age calculation method, indicating stronger photochemical reactions around the refinery.