Decade-long trends in chemical component properties of PM2.5 in Beijing, China (2011-2020)

Long-Term Changes in Summertime Nitrate Chemistry in the Top Boundary Layer of North China

Reducing fine particulate nitrate (pNO3-) is critical for further mitigating PM2.5 pollution in China. However, previous NOx emission reductions have failed to achieve the expected pNO3- decreases. The present study reports that pNO3- concentration in summer increased by 55.8% and 5.6% at North China Peak (1534 m a.s.l.) from 2007 to 2014 and 2014 to 2021, respectively. pNO3- formation enhancement was caused mainly by decreased aerosol acidity due to notable SO42- reduction. pNO3- formation changed from a process limited by NH4+ to one colimited by NO2 and NH4+, suggesting an increased effect of NOx reduction on decreasing pNO3- production. Vertical transport represents a significant source of pNO3- near the surface, illustrating a percentage as high as 98% recorded during daytime hours and a proportion of 34% in the dark over North China in the simulation scenario during summer 2020. The scheme to reduce NOx emissions by 10% from 2020 to 2025 is predicted to slowly decrease aloft pNO3- over North China, which may facilitate further reductions in pNO3- concentrations near the surface via vertical transport. The inflection of nitrate chemistry in the top boundary layer suggests an opportunity to accelerate PM2.5 reduction under projected further emission reductions.

Combustion-driven inorganic nitrogen in PM2.5 from a city in central China has the potential to enhance the nitrogen load of North China

Inorganic nitrogen (NH4+ and NO3-) is a significant component of PM2.5, influencing not only regional ecological systems but also on other regions through the migration of air masses. However, few studies have simultaneously investigated the sources of NH4+ and NO3-, and their potential transport pathways remain poorly understood. Here, daily PM2.5 samples were collected in Jiaozuo, a key city in the air pollution transmission channel to the north China, from 1 September to 5 December, 2017. Major water-soluble inorganic ions and the isotope compositions of NH4+ and NO3- in PM2.5 were analyzed. The results indicated substantial amounts of inorganic nitrogen in PM2.5, particularly at high PM2.5 concentrations. The Bayesian isotope mixing model (MixSIAR) results revealed that combustion sources contributed 79.5 % to NO3- and 51.6 % to NH4+. Moreover, the medium to high potential source regions for combustion-related NH3 is basically consistent with combustion-related NOx. Therefore, stringent regulation of combustion emissions has the potential to mitigate inorganic nitrogen pollution in PM2.5 in Jiaozuo. The results of the forward trajectory cluster and PSCF (potential source contribution function) analysis revealed that a significant amount of combustion-driven inorganic nitrogen in PM2.5 from Jiaozuo will transport to downwind area, particularly north China. Combustion-driven inorganic nitrogen levels carried by these air masses exceeded half the average value for cities in North China during the same period. Our study highlights that combustion emissions dominate the inorganic nitrogen sources in PM2.5 and that substantial amounts of combustion-driven inorganic nitrogen can be transported from Jiaozuo to North China, potentially enhancing the nitrogen load in those areas.

Refining δ15N isotopic fingerprints of local NOx for accurate source identification of nitrate in PM2.5

Stable nitrogen isotopic composition (δ15N) has proven to be a valuable tool for identifying sources of nitrates (NO3-) in PM2.5. However, the absence of a systematic study on the δ15N values of domestic NOx sources hinders accurate identification of NO3- sources in China. Here, we systematically determined and refined δ15N values for six categories of NOx sources in Tianjin using an active sampling method. Moreover, the δ15N values of NO3- in PM2.5 were measured during pre-heating, mid-heating and late-heating periods, which are the most heavily polluted in Tianjin. The results indicate that the isotopic fingerprints of the six types of NOx sources in Tianjin are indicative of the regional characteristics of China, particularly the North China Plain. The Bayesian isotope mixing (MixSIAR) model demonstrated that coal combustion, biomass burning, and vehicle exhaust collectively contributed more than 60 %, dominating the sources of NO3- during sampling periods in Tianjin. However, failure to consider the isotopic signatures of local NOx sources could result in an overestimation of the contribution from natural gas combustion. Additionally, the absence of industrial sources, an uncharacterized source in previous studies, may directly result in the contribution fraction of other sources being overestimated by the model more than 10 %. Notably, as the number of sources input to the model increased, the contribution of various NOx sources was becoming more stable, and the inter-influence between various sources significantly reduced. This study demonstrated that the refined isotopic fingerprint in China could more effectively distinguish source of NO3-, thereby providing valuable insights for controlling NO3- pollution.

Nitrate-Photolysis Shortens the Lifetimes of Brown Carbon Tracers from Biomass Burning

Biomass burning is an important source of brown carbon (BrC) aerosols, which influence climate by affecting the Earth's radiative balance. However, the transformation pathways of BrC chromophores, especially in the presence of photochemically active species, such as nitrate, are not well understood. In this study, the nitrate-mediated aqueous-phase photooxidation of three typical BrC chromophores from biomass burning was investigated, including 4-nitrocatechol, 3-nitrosalicylic acid, and 3,4-dinitrophenol. Variations in nitrate concentrations, pH, and temperatures were systematically examined to assess their impacts on the apparent photolysis rates of these BrC chromophores. The results show that increasing nitrate concentrations significantly enhances apparent photolysis rates to 3-3.5 times compared to nitrate-free conditions. Also, a temperature rise from 0 to 30 °C increases apparent photolysis rates by a factor of 1.3-2.5 for these chromophores. However, the effect of pH varies among these chromophores, depending on the substituents and their positions on the benzene ring. High-resolution mass spectrometric analysis suggests that the photooxidation of these chromophores initiates with the addition of nitro and/or hydroxyl groups to the benzene ring, followed by a ring-opening reaction and the formation of smaller, highly oxygenated molecules including formic acid, glyoxylic acid, malonic acid, and nitropropanoic acid. This study highlights the key role of nitrate in the aqueous-phase photooxidation of BrC, altering the aging pathways and shortening the atmospheric lifetimes of BrC. These results are of particular importance for a better understanding of BrC aging and its radiative forcing, given the increase of the nitrate mass fraction in aerosols of China in recent years.

Heavy metal emissions from on-road vehicles in Xia-Zhang-Quan metropolitan area in southeastern China from 2015 to 2060: impact of vehicle electrification

Vehicle electrification is an important means of reducing urban air pollution. However, vehicle electrification does not necessarily reduce particulate matter (PM2.5 and PM10) and heavy metals (HM) due to the increase in non-exhaust emissions. In this study, we established the emission inventories of PM2.5, PM10, and their associated heavy metals (PM2.5-HM and PM10-HM) from the on-road vehicles in the Xiamen-Zhangzhou-Quanzhou metropolitan area in southeastern China between 2015 and 2060. In the base year 2021, brake wear emissions account for 66.6% of PM2.5-HM and 76.9% of PM10-HM, much higher than the contributions of exhaust emissions to PM2.5-HM (12.4%) and PM10-HM (6.2%). Light-duty passenger vehicles, heavy-duty trucks, and light-duty trucks are the three main contributors to PM and HM. HM emissions have a high emission density in urban areas. In the business-as-usual (BAU) scenario, HM emissions continue to increase from 2021 to 2060 due to the combined effects of the stricter emission standards and the growth of vehicle population, while the health risk of HM shows an initial decrease and then an increasing trend. Compared with BAU, moderate and aggressive electrification scenarios show a significant reduction in PM2.5-HM emissions between 2030 and 2060, but not in PM10-HM emissions. Further increases in vehicle electrification will bring forward the peak of PM2.5-HM emissions, with the potential to reduce adverse health effects. In the process of vehicle electrification, the reduction of heavy metal emissions from the braking system should be prioritized in order to effectively reduce traffic pollution.

New insights into black carbon light absorption enhancement: A comprehensive analysis of two differential behaviors

High uncertainty in optical properties of black carbon (BC) involving heterogeneous chemistry has recently attracted increasing attention in the field of atmospheric climatology. To fill the gap in BC optical knowledge so as to estimate more accurate climate effects and serve the response to global warming, it is beneficial to conduct site-level studies on BC light absorption enhancement (Eabs) characteristics. Real-time surface gas and particulate pollutant observations during the summer and winter over Wuhan were utilized for the analysis of Eabs simulated by minimum R squared (MRS), considering two distinct atmospheric conditions (2015 and 2017). In general, differences in aerosol emissions led to Eabs differential behaviors. The summer average of Eabs (1.92 ± 0.55) in 2015 was higher than the winter average (1.27 ± 0.42), while the average (1.11 ± 0.20) in 2017 summer was lower than that (1.67 ± 0.69) in winter. Eabs and RBC (representing the mass ratio of non-refractory constituents to elemental carbon) constraints suggest that Eabs increased with the increase in RBC under the ambient condition enriched by secondary inorganic aerosol (SIA), with a maximum growth rate of 70.6% in 2015 summer. However, Eabs demonstrated a negative trend against RBC in 2017 winter due to the more complicated mixing state. The result arose from the opposite impact of hygroscopic SIA and absorbing OC/irregular distributed coatings on amplifying the light absorbency of BC. Furthermore, sensitivity analysis revealed a robust positive correlation (R > 0.9) between aerosol chemical compositions (including sulfate, nitrate, ammonium and secondary organic carbon), which could be significantly perturbed by only a small fraction of absorbing materials or restructuring BC through gaps filling. The above findings not only deepen the understanding of BC, but also provide useful information for the scientific decision-making in government to mitigate particulate pollution and obtain more precise BC radiative forcing.

Microscopic Characterization of Individual Aerosol Particles in a Typical Industrial City and Its Surrounding Rural Areas in China

Transmission electron microscopy was used to analyze individual aerosol particles collected in Lanzhou (urban site) and its surrounding areas (rural site) in early 2023. The results revealed that from the pre-Spring Festival period to the Spring Festival period, the main pollutants at the urban site decreased significantly, while the PM2.5 and SO2 concentrations increased at the rural site. During the entire sampling period, the main particles at the urban site were organic matter (OM), secondary inorganic aerosols (SIA), and OM-SIA particles, while those at the rural site were OM, SIA, and soot particles. The degree of external mixing of single particles in both sites increased from the pre-Spring Festival period to the Spring Festival period. The proportion of the OM particles increased by 11% at the urban site, and the proportion of SIA particles increased by 24% at the rural site. During the Spring Festival, the aging of the soot particles was enhanced at the urban site and weakened at the rural site. At the urban site, the SIA particle size was more strongly correlated with the thickness of the OM coating during the pre-Spring Festival period, while the correlation was stronger at the rural site during the Spring Festival.

Strategic control of combustion-induced ammonia emissions: A key initiative for substantial PM2.5 reduction in Tianjin, North China Plain

Information on the temporal and spatial variations in the sources of ammonium salts (NH4+), a crucial alkaline component in PM2.5, is limited. Here, we simultaneously collected PM2.5 and gaseous ammonia (NH3) samples in both summer and winter from two sites in Tianjin: an urban site (Tianjin University, TJU) and a suburban site (Binhai New-region, BH). NH3 concentrations, the contents of major water-soluble inorganic ions in PM2.5, and the compositions of ammonium‑nitrogen isotopes (δ15N-NH4+) were measured. As a result, (NH4)2SO4 and NH4NO3 were the predominant forms of NH4+ in PM2.5 during summer and winter, respectively. However, the NH4NO3 concentrations were notably greater at TJU (6.2 ± 7.3 μg m-3) than at BH (3.8 ± 4.7 μg m-3) in summer, with no regional differences observed in winter. Both sites displayed almost half the contribution of c-NH3 (combustion-related NH3) to NH4+, differing from the finding of previous isotope-based studies. This discrepancy could be attributed to the combined effects of NHx isotope fractionation and seasonal δ15N value variations in NH3 sources. The contribution fractions of v-NH3 (volatile NH3) and c-NH3 exhibited similar patterns at both sites seasonally, probably caused by coal combustion for heating in winter and temperature fluctuations. However, the contribution fraction of c-NH3 was lower at BH than at TJU in summer but greater in winter than at TJU. In summer, NH4NO3 was unstable and limited its delivery to TJU from BH, and the high contribution of c-NH3 to NH4+ at TJU could be attributed to local vehicle emissions. In winter, the stable particulate NH4NO3 that formed from the c-NH3 in the upwind area could be transported to the downwind area, increasing the NH4+ concentration at BH. Our study provides valuable insights for devising emission mitigation strategies to alleviate the increasing burden of NH3 in the local atmosphere.

Interannual evolution of the chemical composition, sources and processes of PM2.5 in Chengdu, China: Insights from observations in four winters

The air quality in China has improved significantly in the last decade and, correspondingly, the characteristics of PM2.5 have also changed. We studied the interannual variation of PM2.5 in Chengdu, one of the most heavily polluted megacities in southwest China, during the most polluted season (winter). Our results show that the mass concentrations of PM2.5 decreased significantly year-by-year, from 195.8 ± 91.0 µg/m3 in winter 2016 to 96.1 ± 39.3 µg/m3 in winter 2020. The mass concentrations of organic matter (OM), SO42-, NH4+ and NO3- decreased by 49.6%, 57.1%, 49.7% and 28.7%, respectively. The differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO3- and there was a larger contribution from mobile sources. The contribution of OM and NO3- not only increased with increasing levels of pollution, but also increased year-by-year at the same level of pollution. Four sources of PM2.5 were identified: combustion sources, vehicular emissions, dust and secondary aerosols. Secondary aerosols made the highest contribution and increased year-by-year, from 40.6% in winter 2016 to 46.3% in winter 2020. By contrast, the contribution from combustion sources decreased from 14.4% to 8.7%. Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants (e.g., OM and NO3-) and sources (secondary aerosols and vehicular emissions) in future policies for the reduction of pollution in Chengdu during the winter months.

Nonlinear effect of NOx concentration decrease on secondary aerosol formation in the Beijing-Tianjin-Hebei region: Evidence from smog chamber experiments and field observations

During the COVID-19 lockdown in the Beijing-Tianjin-Hebei (BTH) region in China, large decrease in nitrogen oxides (NOx) emissions, especially in the transportation sector, could not avoid the occurrence of heavy PM2.5 pollution where nitrate dominated the PM2.5 mass increase. To experimentally reveal the effect of NOx control on the formation of PM2.5 secondary components (nitrate in particular), photochemical simulation experiments of mixed volatile organic compounds (VOCs) under various NOx concentrations with smog chamber were performed. The proportions of gaseous precursors in the control experiment were comparable to ambient conditions typically observed in the BTH region. Under relatively constant VOCs concentrations, when the initial NOx concentration was reduced to 40% of that in the control experiment (labelled as NOx,0), the particle mass concentration was not significantly reduced, but when the initial NOx concentration decreased to 20 % of NOx,0, the mass concentration of particles as well as nitrate and organics showed a sudden decrease. A "critical point" where the mass concentration of secondary aerosol started to decline as the initial NOx concentration decreased, located at 0.2-0.4 NOx,0 (or 0.18-0.44 NO2,0) in smog chamber experiments. The oxidation capacity and solar radiation intensity played key roles in the mass concentration and compositions of the formed particles. In field observations in the BTH region in the autumn and winter seasons, the "critical point" exist at 0.15-0.34 NO2,0, which coincided mostly with the laboratory simulation results. Our results suggest that a reduction of NOx emission by >60% could lead to significant reductions of secondary aerosol formation, which can be an effective way to further alleviate PM2.5 pollution in the BTH region.

Multiphase interactions between sulfur dioxide and secondary organic aerosol from the photooxidation of toluene: Reactivity and sulfate formation

There is growing evidence that the interactions between sulfur dioxide (SO2) and organic peroxides (POs) in aerosol and clouds play an important role in atmospheric sulfate formation and aerosol aging, yet the reactivity of POs arising from anthropogenic precursors toward SO2 remains unknown. In this study, we investigate the multiphase reactions of SO2 with secondary organic aerosol (SOA) formed from the photooxidation of toluene, a major type of anthropogenic SOA in the atmosphere. The reactive uptake coefficient of SO2 on toluene SOA was determined to be on the order of 10-4, depending strikingly on aerosol water content. POs contribute significantly to the multiphase reactivity of toluene SOA, but they can only explain a portion of the measured SO2 uptake, suggesting the presence of other reactive species in SOA that also contribute to the particle reactivity toward SO2. The second-order reaction rate constant (kII) between S(IV) and toluene-derived POs was estimated to be in the range of the kII values previously reported for commercially available POs (e.g., 2-butanone peroxide and 2-tert-butyl hydroperoxide) and the smallest (C1-C2) and biogenic POs. In addition, unlike commercial POs that can efficiently convert S(IV) into both inorganic sulfate and organosulfates, toluene-derived POs appear to mainly oxidize S(IV) to inorganic sulfate. Our study reveals the multiphase reactivity of typical anthropogenic SOA and POs toward SO2 and will help to develop a better understanding of the formation and evolution of atmospheric secondary aerosol.

Reduced atmospheric sulfate enhances fine particulate nitrate formation in eastern China

Nitrate (NO3-) is a major component of atmospheric fine particles. Recent studies in eastern China have shown the increasing trend of NO3- in contrast to the ongoing control of nitrogen oxide (NOx). Here, we elucidate the effects of reduced sulfur dioxide (SO2) on the enhancement of NO3- formation based on field measurements at the summit of Mt. Tai (1534 m a.s.l.) and present detailed modelling analyses. From 2007 to 2018, the measured springtime concentrations of various primary pollutants and fine sulfate (SO42-) decreased sharply (-16.4 % to -89.7 %), whereas fine NO3- concentration increased by 22.8 %. The elevated NO3- levels cannot be explained by the changes in meteorological conditions or other related parameters but were primarily attributed to the considerable reduction in SO42- concentrations (-73.4 %). Results from a multi-phase chemical box model indicated that the reduced SO42- levels decreased the aerosol acidity and prompted the partitioning of HNO3 into the aerosol phase. WRF-Chem model analyses suggest that such a negative effect is a regional phenomenon throughout the planetary boundary layer over eastern China in spring. This study provides new insights into the worsening situation of NO3- aerosol pollution and has important implications for controlling haze pollution in China.

The role of OFDI in home-country pollution: insights from LMDI and 3SLS approaches

Under the global climate crisis, harnessing investment for sustainable development is a practical and effective measure for international society. Based on the logarithmic mean Divisia index (LMDI) decomposition and three-stage least squares (3SLS) structural approaches, this study explores the home-country pollution reduction effect of Chinese OFDI activities using the city-level panel data from 2007 to 2019. The findings of this study indicate that (1) China has made a remarkable achievement in PM2.5 pollution reduction and governance, especially from the year 2012. (2) The OFDI activities can significantly decrease the home-country PM_2.5 pollution. With every 1% increase in OFDI flows, the overall pollution level will decrease by 0.76%. (3) Compared with the scale mechanism, the technology and composition mechanism effects of OFDI flows are more evident in addressing the home-country PM_2.5 pollution. With several related policy implications, this study may fill the lacuna of how to play the role of OFDI activities in the home country, thus promoting sustainable development in the next stage.

Recent Progress in Atmospheric Chemistry Research in China: Establishing a Theoretical Framework for the "Air Pollution Complex"

Atmospheric chemistry research has been growing rapidly in China in the last 25 years since the concept of the "air pollution complex" was first proposed by Professor Xiaoyan TANG in 1997. For papers published in 2021 on air pollution (only papers included in the Web of Science Core Collection database were considered), more than 24 000 papers were authored or co-authored by scientists working in China. In this paper, we review a limited number of representative and significant studies on atmospheric chemistry in China in the last few years, including studies on (1) sources and emission inventories, (2) atmospheric chemical processes, (3) interactions of air pollution with meteorology, weather and climate, (4) interactions between the biosphere and atmosphere, and (5) data assimilation. The intention was not to provide a complete review of all progress made in the last few years, but rather to serve as a starting point for learning more about atmospheric chemistry research in China. The advances reviewed in this paper have enabled a theoretical framework for the air pollution complex to be established, provided robust scientific support to highly successful air pollution control policies in China, and created great opportunities in education, training, and career development for many graduate students and young scientists. This paper further highlights that developing and low-income countries that are heavily affected by air pollution can benefit from these research advances, whilst at the same time acknowledging that many challenges and opportunities still remain in atmospheric chemistry research in China, to hopefully be addressed over the next few decades.

Responses of sulfate and nitrate to anthropogenic emission changes in eastern China - in perspective of long-term variations

We investigate responses of sulfate (SO₄^2-) and nitrate (NO₃^-) to anthropogenic emission changes in 2006-2017 by fixing meteorology at the 2009 level using nested 3D chemical transport model GEOS-Chem. We find that sulfate concentration decreases following SO₂ emissions, but with a relatively smaller reduction rate (by 16 % in North China Plain (NCP) and 28 % in Yangtze River Delta (YRD)) due to larger sulfur oxidation ratio (SOR) at lower SO₂ level. SOR follows a power law with SO₂ emissions in general except in winter in NCP, when and where both SO₂ emission reduction and atmospheric oxidation capacity are critical to the inter-annual variations of SOR. Nitrate concentration ([pNO₃^-]) decreases along with NOx emission reduction in summer, but increases slightly in winter in 2011-2017. Equilibrium with gas phase HNO₃, NO₃^- in particle phase (pNO₃^-) is determined by total HNO₃ (TN = [pNO₃^-] + [gHNO₃]) oxidized from NO₂ and gas-particle partitioning (ε(NO₃^-) = [pNO₃^-]/TN). TN is decreasing faster in summer (~33 %) than in winter (~25 %) in 2011-2017. In contrast, ε(NO₃^-) changes marginally in summer (within 5 %) but increases by 36 % in NCP and by 51 % in YRD in winter in 2006-2017. The increasing of ε(NO₃^-) in winter is attributed to the strong reduction of [pSO₄^2-], which increases the relative abundance of NH₃ and thus favors partitioning of NO₃^- to the particle phase. The effect of increasing ε(NO₃^-) overcomes that of decreasing TN in winter. We suggest reduce SO₂ emissions to further reduce [pSO₄^2-] in eastern China. In addition, we recommend reduce NOx emissions in summer, and reduce atmospheric oxidation capacity and relative abundance of NH₃ in winter to reduce [pNO₃^-].

Dramatic changes in aerosol composition during the 2016-2020 heating seasons in Beijing-Tianjin-Hebei region and its surrounding areas: The role of primary pollutants and secondary aerosol formation

With the implementation of a series of air pollution mitigation strategies during the past decade, great air quality improvements have been observed in the BTH region. Despite of significant decreases in gaseous pollutants, such as SO₂ and NO₂, the enhancement of secondary aerosol formation was observed. NO₃^- has surpassed SO₄^2- and OM to become the dominant PM_2.5 component. We find that the reduction of POC mainly dominated the decreasing trend of OC. As for secondary inorganic components, the key processes or factors controlling the spatial-temporal variation characteristics were different. The areas with large SO₄^2- concentrations corresponded well to those with high SO₂ concentrations, while the synchronized NO₃^- better followed spatial patterns in O₃ than NO₂. From 2016 to 2020, the response of SO₄^2- to SO₂ was close to a linear function, while the reaction of NO₃^- to the decrease of NO₂ displayed nonlinear behavior. Such different relationships indicated that SO₄^2- was predominantly controlled by SO₂, while NO₃^- was not only related to NO₂ but also determined by the secondary conversion process. The ratios of SO₄^2-, NO₃^-, NH₄⁺, and OC to EC between 2016 and 2020 were generally higher than 1 in typical BTH cities, and the ratio of NO₃^- to EC was exceptionally high, with a range reaching up to 200 %. Besides, this ratio coincided well with the enhancement of O_x, indicating the potential role of O_x to secondary NO₃^- formation. The diurnal cycle of NO₃^-, O₃, and NO₂ concentration change rate indicated that the relative increase of O₃ during nighttime may offset the effectiveness of NO_X emission reduction. This study provided observational evidence of enhanced secondary NO₃^- formation with the rising trend of atmospheric oxidation and emphasized the importance of nighttime chemistry for NO₃^- formation in the BTH region.

Co-control of the haze pollution emissions in China: Insight from supply chains

Because of rapid economic development and the increase in social demand, China has been suffering from serious air pollution, in particular, haze pollution. To mitigate haze from the source, it is essential to achieve co-control of three important haze precursors: volatile organic compounds (VOCs), sulfur dioxide (SO₂ ), and nitrogen oxide (NO_x ). In this study, we used the environmentally extended input-output model, structural path analysis, and structural path decomposition method to investigate changes in consumption-based emissions of three major haze precursors (i.e., NO_x , SO₂ , and VOCs) in China during 2007-2017. First, the results revealed that fixed capital formation was the most critical final demand to co-control the three precursors. Investment in construction was the most important behavior for co-control. Second, the most crucial common path driving the changes in emissions of the three precursors was "transportation and warehousing→household consumption" during 2007-2012, and "electricity, gas, and water supply→household consumption" during 2012-2017. Finally, direct emission intensity of transportation and warehousing, and electricity, gas, and water supplies were critical to co-control precursors. The results of this study provided a comprehensive understanding of changes in haze precursor emissions driven by demand. Therefore, China must strengthen the co-control of multiple pollutant emissions on both the production and consumption sides by adjusting supply chains. Integr Environ Assess Manag 2022;00:1-16. © 2022 SETAC.