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The increase in the number of motor vehicles has intensified the impact of traffic sources on air quality. Our aim was to illustrate the characteristics of PM2.5 emissions from vehicles fueled with E10 (a blend of 10% ethanol and 90% gasoline). A 21-day PM2.5 sampling in a fully enclosed urban tunnel and the component analysis were completed, and the characteristics, sources, and health risks of tunnel PM2.5 were studied. Moreover, the PM2.5 pH and its sensitivity were investigated by the thermodynamic model (ISORROPIA-II). In addition, exposure models were used to assess the health risks of different heavy metals in PM2.5 to humans through respiratory pathways. The two-point Cu/Sb ratio (entrance: 4.0 ± 1.4; exit: 4.4 ± 1.7) was close to the diagnostic criteria indicating a significant impact from brake wear. NO3−, NH4+, and SO42− constituted the main components of water-soluble ions in PM2.5 of the tunnel, accounting for 83.0–84.6% of the total concentration of inorganic ions. The organic carbon/elemental carbon ratio of the tunnel was greater than 2, indicating that the contribution of gasoline vehicle exhaust was significant. The average emission factors of PM2.5 in the fleet was 31.4 ± 16.6 mg/(veh·km). The pH value of PM2.5 in a tunnel environment (4.6 ± 0.3) was more acidic than that in an urban environment (4.9 ± 0.6). The main sensitive factors of PM2.5 pH in the urban atmosphere and tunnel environment were total ammonia (sum of gas and aerosol, NH3) and temperature, respectively. The results of the health risk assessment showed that Pb posed a potential carcinogenic risk, while As and Cd presented unacceptable risks for tunnel workers. The non-carcinogenic risk index of heavy metals of PM2.5 in the tunnel environment exceeded the safety threshold. [ABSTRACT FROM AUTHOR]

The pollution characteristics of multi-size atmospheric particulates in Xinxiang, which was one of the most polluted cities across China, are still unclear even through air quality in Xinxiang has been improved in recent years. PM10, PM2.5, and PM1 samples were synchronously collected from 21 December 2019 to 17 January 2020 to explore pollution levels and reveal sources of PM in Xinxiang. The average mass concentrations of PM10, PM2.5, and PM1 were as high as 155.53 μg m−3, 120.07 μg m−3, and 85.64 μg m−3 during the observation period, respectively. Almost all of the chemical compositions in PM10, PM2.5 and PM1 increased continuously and obviously with the aggravation of the pollution level. Compared with the clean period, the enhancement of sulfate (23–27%) in PM was obvious higher than nitrate (19–22%) during the pollution period, which demonstrated that sulfate was the main contributor to the high concentration of PM in this study. Similar source distributions for PM10, PM2.5, and PM1 were also found, including traffic source, combustion source, secondary aerosols, industrial source, and fugitive dust, by using the positive matrix factorization (PMF) model. Furthermore, the contributions of the combustion source and secondary aerosol were found to be higher in smaller particles (PM2.5 and PM1), while the contribution of fugitive dust was higher in PM10. Moreover, dust and sand were entrained by air masses from the northwest that increased the contribution of dust in PM at the observation site. The potential source contribution function (PSCF) analysis illustrated that regional emission sources in northern and eastern Xinxiang might be important potential contributors to PM pollution in Xinxiang. [ABSTRACT FROM AUTHOR]

Although central to the promotion of regional economic development, industrial parks discharge large quantities of air pollutants and CO2, counter to the goals of air quality improvement and CO2 reductions in China. In this study, 13 industrial parks in seven cities in Henan Province were chosen to evaluate their emission of air pollutants and CO2 in 2017, their reduction potential under different green measures, and their air quality improvements under a Green Upgrade scenario. The results show that: (1) The total emissions of SO2, NOx, CO, PM10, PM2.5, VOCs and CO2 in the 13 industrial parks were 43, 39, 351, 19, 7, 18, 2 kt and 36 Mt, and would decrease by 72, 56, 19, 30, 26, 77 and 30%, respectively, under the Green Upgrade scenario. (2) The industrial process was the major source of CO, PM2.5, VOCs and NH3, whereas power plants were the largest source of SO2 and NOx, and they would be reduced by 93, 59, 94, 91, 23 and 28%, respectively, under the Green Upgrade scenario. (3) The terminal energy use sector (including industrial boilers and industrial process sources) was the main source of CO2, accounting for 75% of total CO2 emissions, and would be reduced by 76% under the Green Upgrade scenario. (4) WRF-CMAQ simulation results show that, under the Green Upgrade scenario, the concentration of PM2.5 in a transmission channel city would be improved by 1–36 μg/m3, with an annual average value of 9 μg/m3. Our results demonstrate the significant effect of the synergistic reduction in air pollutants and CO2 emissions using Green Technologies in industrial parks and the subsequent improvement in regional air quality. [ABSTRACT FROM AUTHOR]

Tropospheric NO 2 and SO 2 concentrations are of great importance with regard to air quality, atmospheric chemistry, and climate change. Due to lack of surface monitoring stations, this study analyzes long term trend of NO 2 and SO 2 levels (2005–2014), retrieved from Ozone Monitoring Instrument (OMI) board on the NASA's Aura satellite, in an important region of China – Henan Province. Henan Province, located in North China Plain, has encountered serious air pollution problems including extremely high PM 2.5 concentrations and as one of the most polluted region in China. The satellite spatial images clearly show that high levels of both NO 2 and SO 2 are concentrated in north and northeastern regions with much lower levels observed in other parts of Henan. Both pollutants exhibit the highest levels in winter with the least in summer/spring. The temporal trend analysis based on moving average of deseasonalized and decyclic data indicates that for NO 2 , there is a continuous increasing pattern from 2005 to 2011 at 6.4% per year, thereafter, it shows a decreasing trend (10.6% per year). As for SO 2 , the increasing trend is about 16% per year from 2005 to 2007 with decreasing rate 7% per year from 2007 to 2014. The economic development with incredible annual 11% GDP growth in Henan is responsible for increasing levels of NO 2 and SO 2 . The observed decreasing SO 2 level starting in 2007 is due to reduced SO 2 emission, utilization of flue gas desulfurization (FGD) devices and to some extent, in preparation of Beijing 2008 Olympic Games. On the other hand, increasing vehicle numbers (155% from 2006 to 2012) and coal consumption (37% during the same span), along with the lack of denitration process for removing flue/exhaust gas NO x are responsible for increasing NO 2 trend until 2011. The ratio of SO 2 /NO 2 started decreasing in 2007 and dropped significantly from 2011 to 2013 indicating good performance of FGD and ever increasing NO x contribution from mobile sources. Unlike those observed in developed countries (US, EU and Japan) where a decreasing trend for both SO 2 and NO 2 has been observed since 1990s, the observed upward and downward trend found in Henan is similar to those found in North China Plain and other parts of China. The spatial and temporal trend analyses of SO 2 and NO 2 in four other regions in Henan further indicate a similar trend to those observed in Henan Province, albeit with different increasing and decreasing rate. The results provide regulatory agency to develop action plans to combat air pollution problem in general and SO 2 and NO 2 problems in particular in Henan. The implications of our findings and recommendations for decision makers are discussed in the paper. [ABSTRACT FROM AUTHOR]

In recent years, the air quality in urban areas of China has been a significant improvement. However, further advancements in air quality remain challenging, particularly in addressing the persistent problem of severe particulate matter (PM) pollution in winter. In-depth research on the aerosol acidity (pH) is beneficial for analyzing the pollution characteristics of PM and providing support for the continuous improvement of PM pollution. In this study, the sources of water-soluble inorganic ions (WSIIs) of PM 2.5 in Zhengzhou were analyzed based on the PMF-GAS method, and the contribution of different sources to aerosol acidity was further investigated in conjunction with the ISORROPIA-II thermodynamic model. The research results indicate that secondary aerosols are the main source, and controlling the emissions of secondary aerosols and gaseous precursors is a crucial measure for reducing PM 2.5 concentrations. Furthermore, the study revealed that targeted reductions of major pollution sources across varying pH ranges could significantly lower PM 2.5 concentrations. In the range of pH < 4, when the contribution of secondary aerosol source is 23.9%, PM 2.5 concentrations can be reduced by 40.6%, resulting in an additional emission reduction of 5.9 μg m−3. In the range of 4 < pH < 6, PM 2.5 can be reduced by 36.9% at a contribution of 16.5% from secondary aerosol source, achieving an additional emission reduction of 7.0 μg m−3. This research provides important theoretical support for gaining a deeper understanding of the sources and control of atmospheric pollution, offering strategies to expedite the achievement of PM 2.5 standards and further mitigating its impacts on human health and the environment. [Display omitted] • PMF-GAS method identified secondary aerosols contribute 48.6% to pH. • Reducing secondary aerosol and gaseous precursor is crucial for PM 2.5 control. • At pH < 6, reducing secondary aerosol can achieve a maximum 40.6% PM 2.5 reduction. • A max additional PM 2.5 reduction of 7.0 μg m−3 by reducing secondary aerosol. [ABSTRACT FROM AUTHOR]

At present, the air quality in urban areas in China has continued to improve, but PM 2.5 is still severely polluted in autumn and winter and is difficult to meet the Chinese standard. With the renovation of coal-fired boilers and the transformation of ultra-low emissions in factories, NO 3 − has gradually become the main inducing species for high levels of PM 2.5. In this study, a high-resolution (1 h) online instrument was used to analyze the characteristics of atmospheric PM 2.5 in the autumn and winter periods from October 2019 to February 2020 at Zhengzhou University in Zhengzhou. The inorganic nitrate in PM 2.5 mainly existed in the form of semivolatile NH 4 NO 3 , and the method of reducing NH 4 NO 3 was studied through data analysis. The basic method of reducing particulate nitrate in PM 2.5 is not only to reduce nitrate precursors (NO x) but also to transform particulate nitrate into gas by reducing the aerosol pH value (enhancing aerosol acidity). The simulation analysis of NH x (NH x = NH 3 +NH 4 +), NO 3 T (NO 3 T=HNO 3 +NO 3 −), and SO 4 2− reduction using the thermodynamic model ISORROPIA-II revealed that total ammonia (TA) has an obvious peak clipping effect on particulate NO 3 − when it is reduced by 60% and can effectively reduce NH 4 NO 3 in PM 2.5. The reliability and credibility of the data results were enhanced through long-term observation and local time analysis, and reducing TA and NO 3 − in areas with high ammonia emissions was proven to be feasible. This study is beneficial for formulating measures to reduce the average annual concentration of PM 2.5 in ammonia-rich areas. [Display omitted] • High level of NH 4 NO 3 , accounting for 42% of PM 2.5 , is the main reason of PM 2.5 not meeting standard. • Distribution coefficient of NO 3 − in particle phase is decreased by reducing aerosol pH. • Novel method of reducing total ammonia by 60% in ammonia-rich areas significantly reduces the level of key species NO 3 −. • The reduction of NO 3 − with the maximum contributing 82%. [ABSTRACT FROM AUTHOR]

Air quality in ammonia-rich regions such as Zhengzhou is improving year by year, however, fine particulate matter (PM 2.5) pollution is serious in winter. Aerosol acidity (pH) affects every aspect of the surrounding particle composition and environment. Thermodynamic models of gaseous and particulate composition datasets can provide pH estimates. Nevertheless, for ammonia-rich regions in the presence of prolonged NH 3 deficiency, the thermodynamic model is limited in calculating pH by using only datasets composed of the particulate phase. In this study, an NH 3 concentration calculation method was established via SPSS-coupled multiple linear regression to simulate the trend of NH 3 concentration over a long period of time and to assess the long-term pH value in ammonia-rich regions. The reliability of this method was verified using multiple models. The range of NH 3 concentration change from 2013 to 2020 was found to be 4.3–68.6 μg·m−3, and the range of pH change was 4.5–6.0. The pH sensitivity analysis indicated that decreasing aerosol precursor concentrations and variations in temperature and relative humidity were the driving factors for aerosol pH changes. Therefore, policies to reduce NH 3 emissions are becoming increasingly necessary. This study provides a feasibility analysis for reducing PM 2.5 , thus achieving standards in ammonia-rich regions, including Zhengzhou. [Display omitted] • The PM 2.5 concentrations in winter shows a decreasing trend, but the NO 3 − proportion rises from 11% in 2013 to 17% in 2020. • A new method for estimating NH 3 by SPSS-coupled multiple linear regression equations was established. • The simulation indicates that the annual average NH 3 concentration from 2013 to 2020 is 33.3–11.7 μg·m−3. • Changes in the sensitivity of pH to SO 4 2− were significantly higher after 2016. [ABSTRACT FROM AUTHOR]

Source contributions and regional transport of maximum daily average 8-h (MDA8) O 3 during a high O 3 month (June 2019) in Henan province in central China are explored using a source-oriented Community Multiscale Air Quality (CMAQ) model. The monthly average MDA8 O 3 exceeds ∼70 ppb in more than half of the areas and shows a clear spatial gradient, with lower O 3 concentrations in the southwest and higher in the northeast. Significant contributions of anthropogenic emissions to monthly average MDA8 O 3 concentrations of more than 20 ppb are predicted in the provincial capital Zhengzhou, mostly due to emissions from the transportation sector (∼50%) and in the areas in the north and northeast regions where industrial and power generation-related emissions are high. Biogenic emissions in the region only contribute to approximately 1–3 ppb of monthly average MDA8 O 3. In industrial areas north of the province, their contributions reach 5–7 ppb. Two CMAQ-based O 3 -NO x -VOCs sensitivity assessments (the local O 3 sensitivity ratios based on the direct decoupled method and the production ratio of H 2 O 2 to HNO 3) and the satellite HCHO to NO 2 column density ratio consistently show that most of the areas in Henan are in NO x -limited regime. In contrast, the high O 3 concentration areas in the north and at the city centers are in the VOC-limited or transition regimes. The results from this study suggest that although reducing NO x emissions to reduce O 3 pollution in the region is desired in most areas, VOC reductions must be applied to urban and industrial regions. Source apportionment simulations with and without Henan anthropogenic emissions show that the benefit of local anthropogenic NO x reduction might be lower than expected from the source apportionment results because the contributions of Henan background O 3 increase in response to the reduced local anthropogenic emissions due to less NO titration. Thus, collaborative O 3 controls in neighboring provinces are needed to reduce O 3 pollution problems in Henan effectively. • Local emissions contributed to 10–25% (10–20 ppb) of MDA8 O 3 in Henan province. • Transportation and industry are the two largest sources of anthropogenic O 3. • Three approaches lead to consistent spatial distributions of O 3 -NOx-VOC sensitivity. • High background O 3 suggests the necessity of collaborative emission reduction measures. • Source-apportionment model could underestimate background O 3 due to titration by NO. [ABSTRACT FROM AUTHOR]

PM 2.5 samples were collected in Zhengzhou during 3 years of observation, and chemical characteristics and source contribution were analyzed. Approximately 96% of the daily PM 2.5 concentrations and annual average values exceeded the Chinese National Ambient Air Quality Daily and Annual Standards, indicating serious PM 2.5 pollution. The average concentration of water-soluble inorganic ions was 2.4 times higher in heavily polluted days (daily PM 2.5 concentrations > 250 μg/m 3 and visibility < 3 km) than that in other days, with sulfate, nitrate, and ammonium as major ions. According to the ratio of NO 3 − /SO 4 2− , stationary sources are still the dominant source of PM 2.5 and vehicle emission could not be ignored. The ratio of secondary organic carbon to organic carbon indicated that photochemical reactivity in heavily polluted days was more intense than in other days. Crustal elements were the most abundant elements, accounting for more than 60% of 23 elements. Chemical Mass Balance results indicated that the contributions of major sources (i.e., nitrate, sulfate, biomass, carbon and refractory material, coal combustion, soil dust, vehicle, and industry) of PM 2.5 were 13%, 16%, 12%, 2%, 14%, 8%, 7%, and 8% in heavily polluted days and 20%, 18%, 9%, 2%, 27%, 14%, 15%, and 9% in other days, respectively. Extensive combustion activities were the main sources of polycyclic aromatic hydrocarbons during the episode (Jan 1−9, 2015) and the total benzo[a]pyrene equivalency concentrations in heavily polluted days present significant health threat. Because of the effect of regional transport, the pollution level of PM 2.5 in the study area was aggravated. [ABSTRACT FROM AUTHOR]

Vehicle emission is becoming one of the most important pollution sources because of the increase in vehicle population and activity in China. A more reasonable and complete vehicle emission inventory in Zhengzhou for the year 2013 was developed in this study. This inventory is suitable for local emission factors and vehicle kilometers of travel. Estimates show that the total carbon monoxide (CO), hydrocarbon (HC), nitrogen oxide (NO X ), particulate matter (PM 2.5 and PM 10 ) and sulfur dioxide (SO 2 ) emissions were 291 Gg, 35 Gg, 106 Gg, 6 Gg, 7 Gg, and 3 Gg, respectively. Approximately 55% of CO and HC emissions were from light duty gasoline vehicles and normal gasoline motorcycles, whereas approximately 60% of NO X , PM 2.5 , PM 10 and SO 2 were from heavy duty diesel vehicles, heavy duty diesel trucks, and medium duty diesel trucks. The spatial distribution of emissions was allocated in grid cells based on a road network and traffic flows with a resolution of 1 km × 1 km at different road types and locations, which shows that the six aforementioned air pollutants have similar characteristics in administrative districts. Emissions are mainly concentrated on the central grid cells of each part and in good agreement with line sources. The spatial characteristics were compared at a resolution of 3 km × 3 km and in a population-based approach. The network approach yields better level estimates in this study. Meanwhile, the preliminary temporal profiles were also established for on-road mobile source. [ABSTRACT FROM AUTHOR]

PM 2.5 and PM 10 samples were simultaneously collected in an urban site in Zhengzhou, China from October 2014 to July 2015 representing the four seasons. Organic carbon (OC), elemental carbon (EC), and non-polar organic compounds including n-alkanes (C 8 –C 40 ) and polycyclic aromatic hydrocarbons (PAHs) were quantified. The characteristics of their concentrations, seasonal variations, and sources of n-alkanes and PAHs were investigated. Diagnostic ratios and positive matrix factorization (PMF) were used to characterize carbonaceous species, identify their possible sources, and apportion the contributions from each possible source. The concentrations of the components exhibited distinct seasonal variation, that is, the concentrations are high in winter and low in summer. This finding could be associated with increase in air pollutant emissions during heating season and stable weather condition. The estimated total carbonaceous aerosol accounts for 32% of PM 2.5 and 30% of PM 10 . Hence, carbonaceous compounds were the major components of particulate matter in the study area. Moreover, OC, EC, PAHs, and n-alkanes preferentially accumulated into fine particles. The carbonaceous components exhibited high correlation in PM 2.5 and PM 10 , thereby indicating that their sources were similar. The PMF results revealed that the main sources of PAHs were coal combustion (40%) and motor vehicles (29%); n-alkanes were mainly from burning of fossil fuel (48%). These sources were consistent with the diagnostic ratios obtained. This study provides guidance for improving air quality and reducing human exposure to toxic air pollutants. [ABSTRACT FROM AUTHOR]

Aiming to provide basic data support for the improvement of air quality in the study region, this study established the emission inventory and speciated emission inventory of PM 2.5 and VOCs in Henan Province, and further estimated the ozone formation potential (OFP) and secondary organic aerosols formation potential (SOAFP) of VOCs to identify key species, priority sources and typical cities. The 2017-based emissions of PM 2.5 and VOCs were 598 and 1079 kt, respectively. Industrial process, fugitive dust and biomass burning were the three major contributors to PM 2.5 , with a combined contribution of 79%, while industrial process, on-road mobile, solvent utilization and biomass burning were the four major contributors to VOCs emissions, with a combined contribution of 90%. Other unidentified species had the highest emissions, followed by carbonaceous components and inorganic elements and water-soluble ions. The total amount of OFP and SOAFP were 3482 and 81 kt. The species categories of VOCs that contributed large fractions to the emissions were alkanes, aromatic hydrocarbons and oxygenated VOCs, to the OFP were aromatic hydrocarbons, olefins, and oxygenated VOCs, and to the SOAFP were aromatic hydrocarbons and alkanes. Considering OFP and SOAFP together, industrial process, solvent utilization, on-road mobile and biomass burning are the key emission sources to control. The overall spatial distribution showed that PM 2.5 and VOCs emissions were relatively low in the southwest and southeast of Henan province, while emissions were high in densely populated, industrial, agricultural and transportation developed areas, and the spatial distribution characteristics of OFP and SOAFP were similar to those of VOCs emissions. [Display omitted] • A new 2017-based comprehensive emission inventory of PM 2.5 and VOCs in Central China was developed. • 47 subsectors speciation of PM 2.5 emissions and 168 subsectors speciation of VOCs emission were established. • OFP and SOAFP were estimated based on VOCs speciated emissions. • PM 2.5 and VOCs were concentrated in densely populated, industrial, agricultural and transportation developed areas. [ABSTRACT FROM AUTHOR]

Intensive temporary air pollution control measures were implemented in Zhengzhou (ZZ), a megacity in central China, and six neighboring cities during the 2019 National Games of Ethnic Minorities. The Community Multiscale Air Quality (CMAQ) model and a high-resolution local emission inventory were applied to evaluate the control measures. Reductions of ~35–60% of primary PM (PPM), 45–65% of VOCs, ~5% of NH 3 , 35–45% of NO x , and 30–70% of SO 2 emissions in the central area (i.e., ZZ) and collaborative cities (i.e., the six neighboring cities) lead to significant reductions of daily PM 2.5 by 25–45% in ZZ. Hourly concentrations of PM 2.5 are reduced by as much as 100 μg m−3. Most of the reduction in PM 2.5 is due to primary PM, and NO 3 −, SO 4 2−, and NH 4 + ion concentrations only decrease by 5–6%. Emission reductions in the collaborative cities contribute to 10–30% of the decrease in PM 2.5 and PM 10 in ZZ. Concentrations of daily maximum 8-hr (DM8H) O 3 increase by 2–5% on high O 3 days. Isopleth analysis suggests that the local molar reductions ratio of NO x to VOC needs to be < 0.5 to avoid the increases. More stable meteorology conditions make emission controls in ZZ more effective for PM 2.5 and PM 10 but lead to higher increases in DM8H O 3. These results suggest that control of PPM emissions in ZZ is the most effective in reducing PM 2.5 and PM 10. However, reductions of precursor gaseous in ZZ and the six neighboring cities alone are not effective in reducing the secondary PM components and most likely lead to increases in DM8H O 3. Image 1 • First evaluation of temporary air pollution controls in a megacity in central China. • Most of the reduction in PM 2.5 is mostly due to local primary PM reductions. • Reduction of SO 2 and NO x changes secondary inorganic aerosol (SIA) slightly. • ΔNOx/ΔVOC needs to be < 0.5 to reduce O 3 if only local emissions are controlled. • Coordinated and broader regional controls are needed to further reduce SIA and O 3. [ABSTRACT FROM AUTHOR]