Temporal evolution of speciated volatile organic compound (VOC) emissions from solvent use sources in the Pearl River Delta Region, China (2006-2019).

Volatile organic compounds (VOCs) emitted from solvent use sources constitute an important part of ozone (O3) and secondary organic aerosols (SOA) in the Pearl River Delta (PRD) region, China. While stringent control measures targeting VOCs have been implemented in recent years, an assessment of historical trends is imperative to evaluate their effectiveness. In this study, trends of VOC emissions, compositions, and reactivity from solvent use sources in the PRD region from 2006 to 2019 were estimated using a developed methodology, which considered the improvement of manufacturing equipment and removal efficiency. Results show that total VOC emissions from solvent use sources displayed an overall increase from 277 kt in 2006 to 400 kt in 2019 despites some fluctuations, with metal products contributing more than 20 % each year. Aromatics and oxygenated VOCs (OVOCs) accounted for over 70 % of total VOC emissions, increasing by 21 kt and 52 kt respectively. OFP and SOAFP increased by 40 % and 23 % respectively from 2006 to 2019. Specific aromatic species, including m/p-xylene, toluene, 1,2,3,5-tetramethylbenzene, o-xylene and ethylbenzene are identified as key species in both VOC emission amount and reactivity. This study aims to facilitate the understanding of VOC emission evolution from solvent use sources in the region and provide insights into the impact of enacted measures, aiding in the future development of more targeted and efficient strategies in the PRD region.

Characterization of ammonia emissions from light-duty gasoline vehicles based on real-world driving and dynamometer measurements.

Ammonia (NH3) contributes significantly to the formation of particulate matter, and vehicles represent a major source of NH3 in urban areas. However, there remains a lack of comprehensive understanding regarding the emission characteristics of NH3 from vehicles. This study conducted real-world driving emission (RDE) measurements and dynamometer measurements on 33 light-duty gasoline vehicles (LDGVs) to investigate their emission characteristics and impact factors. The tested vehicles include China 3 to China 6 emission standards. The results show that the average NH3 emission factors of LDGVs decreased by >80 % from China 3 to China 6 emission standards. The results obtained from dynamometer measurements reveal that independent from other conventional pollutants (such as HCHO and NOx), NH3 emissions do not exhibit significant emission peaks during the hot- or cold-start phase. The RDE measurement covers a more comprehensive range of the vehicle's real-world driving conditions, resulting in higher NH3 emission factors compared with dynamometer measurements. The analysis of RDE measurements revealed that NH3 emissions are influenced by vehicle speeds and accelerations. Acceleration processes contribute approximately 50 % of total NH3 emissions over a driving period. Finally, using real driving speed, acceleration, and road gradient as input parameters, an NH3 emission rate model based on vehicle specific power was developed. This emission rate model enables a more precise reflection of LDGVs' NH3 emissions of LDGVs across diverse driving conditions and provides valuable data support for high-resolution inventories of vehicle NH3 emissions.

[Evolution Characteristics of Atmospheric Formaldehyde Emissions in Guangdong Province from 2006 to 2020].

Atmospheric formaldehyde, a key precursor for ozone (O3) and secondary PM2.5, is carcinogenic and plays an important role in atmospheric photochemistry and the formation of secondary pollution. However, the lack of understanding of the emission sources of atmospheric formaldehyde limits the study on the formation mechanism of secondary pollution and the formulation of pollution control strategies. This study used the emission factor and source profile methods to establish the emission inventories of formaldehyde in Guangdong Province from 2006 to 2020 and identified the main emission sources of formaldehyde and spatial and temporal evolution characteristics. The results showed that the formaldehyde emissions in Guangdong Province fluctuated in the range of 39000-56000 tons during 2006 to 2020, exhibiting a very weak downward trend. Biomass combustion is an important source of formaldehyde emission in Guangdong Province, of which the contribution decreased from 58% in 2006 to 27% in 2020 owing to effective control measures implemented in Guangdong Province. The solvent use source became the predominant emission source of formaldehyde in 2020 by contributing up to 28%, primarily through plastic products and asphalt paving sources. The construction machinery and trucks fueled by diesel were important contributors of formaldehyde emissions from mobile sources. Although the formaldehyde emissions in the Pearl River Delta and the non-Pearl River Delta were equivalent, the spatial distributions showed that formaldehyde emission hotspots were concentrated in the center of the Pearl River Delta and the eastern and western areas of the non-Pearl River Delta. This was primarily because the solvent use and mobile sources were the main sources of formaldehyde emissions in the Pearl River Delta, whereas the biomass combustion source was the dominant source in the non-Pearl River Delta. Therefore, the formaldehyde emission mitigations of the industrial and mobile sources in the central region of the Pearl River Delta and the biomass combustion source in the western area of Guangdong should be further strengthened in the future.

Characterizing Operating Condition-Based Formaldehyde Emissions of Light-Duty Diesel Trucks in China Using a PEMS-HCHO System.

Formaldehyde (HCHO) plays a critical role in atmospheric photochemistry and public health. While existing studies have suggested that vehicular exhaust is an important source of HCHO, the operating condition-based diesel truck HCHO emission measurements remain severely limited due to the limited temporal resolution and accuracy of measurement techniques. In this study, we characterized the second-by-second HCHO emissions from 29 light-duty diesel trucks (LDDTs) in China over dynamometer and real-world driving tests using a portable online HCHO emission measurement system (PEMS-HCHO), considering various operating conditions. Our results suggested that the HCHO emissions from LDDTs might be underestimated by the widely used offline DNPH-HPLC method. The HCHO emissions at a 200 s cold start from China V LDDT can be up to 50 mg/start. Different driving conditions over dynamometer and real-world driving tests led to a 2-4 times difference in the HCHO emission factors (EFs). Under real-world hot-running conditions, the HCHO EFs of China III, IV, V, and VI LDDTs were 43.5 ± 35.7, 10.6 ± 14.2, 8.8 ± 5.1, and 3.2 ± 1.2 mg/km, respectively, which significantly exceeded the latest California low emission vehicle III HCHO emission standard (2.5 mg/km). These findings highlighted the significant impact of vehicle operating conditions on HCHO emissions and the urgency of regulating HCHO emissions from LDDTs in China.

Characterizing the particle number emissions of light-duty gasoline vehicles under different engine technologies and driving conditions.

Vehicle particle number (PN) emissions have attracted increasing public attention due to their severe influence on human health. In this study, we selected 35 light-duty gasoline vehicles (LDGVs) with gasoline direct injection (GDI) and multi-port fuel injection (MPFI) engines to elucidate the main factors influencing PN emissions. Via real driving emission (RDE) and chassis dynamometer tests, we quantified the impact of engine technology, emission standards, engine-start conditions and engine load on vehicle PN emissions. The RDE test results indicated that GDI vehicles generated higher PN emissions than those of MPFI vehicles under hot-running conditions. MPFI vehicle PN emissions were greatly affected by rapidly changing driving conditions, especially vehicles equipped with automatic start-stop systems. In regard to China 6 GDI vehicles equipped with a gasoline particle filter (GPF), their PN emissions were usually low, and peak PN emissions could mainly be attributed to GPF regeneration. Engine manufacturers should optimize GPF regeneration conditions to further reduce particulate emissions. Furthermore, the analysis results of PN emissions for different road types indicated that PN emissions were related to vehicle driving conditions. The vehicle specific power (VSP) could be used as an important explanatory variable to characterize the PN emission rate when distinguishing different engine technologies and emission standards. A real-world LDGV VSP-based PN emission rate was suggested based on the RDE test dataset. The VSP-based emission rate could be considered to more accurately quantify vehicle PN emissions and support the formulation of urban vehicle particle emission control policies.

[Emission Characterstics of VOCs and n-alkanes from Diesel Forklifts].

Non-road diesel vehicle exhaust is an important emission source that affects air quality in China, yet knowledge regarding its chemical composition and potential influence factors remains limited. Six typical forklifts were selected to study the effect of diesel particulate filters (DPF) on the emission characteristics of volatile organic compounds (VOCs) and n-alkanes using online monitoring of gaseous components combined with offline analysis. The results showed that oxygenated volatile organic compounds (OVOCs), olefins, alkanes, aromatic hydrocarbons, and halogenated hydrocarbons accounted for 26%-37%, 16%-36%, 19%-22%, 13%-21%, and 4%-7% of the measured VOCs in forklift exhaust, respectively. The VOCs emission factors of low-power and high-power forklifts were(2.47±0.33)g·kg-1 and (1.48±0.24)g·kg-1, respectively. The forklift exhaust emission factors of total VOCs without and with DPF were(1.94±0.58)g·kg-1and (2.08±0.79)g·kg-1, respectively. Our results showed that DDF exerted minor impact on VOCs emission. However, it is worth noting that DPF can efficiently remove some types of OVOCs components. For example, the emission factors of acetaldehyde and acetone of the forklifts with DPF were reduced by 19% and 26%, respectively, compared to that of those without DPF. The carbon numbers of n-alkane fractions showed a bimodal distribution of C7-C17 and C24-C31, respectively, with C15 being the dominant peak carbon. The average emission factors of n-alkanes were (115±34) mg·kg-1 (without DPF) and (53.7±19)mg·kg-1 (with DPF), respectively, with a decrease of 53%, indicating that DPF can effectively reduce the emission of n-alkane in the exhaust of forklifts. Our results can provide scientific support for the precise control of non-road construction machinery exhaust emissions and the further improvement of regional air quality.

A newly integrated dataset of volatile organic compounds (VOCs) source profiles and implications for the future development of VOCs profiles in China.

Volatile organic compounds (VOCs) source profiles can be used for a number of purposes, such as creating speciated air pollutant emission inventories and providing inputs to receptor and air quality models. In this study, we first collected and schematically evaluated more than 500 Chinese domestic source profiles from literature and field measurements, and then established a most up-to-date dataset of VOCs source profiles in China by integrating 363 selective VOCs profiles into 101 sector-based source profiles. The profile dataset covers eight major source categories and contains 447 VOCs species including non-methane hydrocarbons (NMHCs) species and oxygenated VOCs (OVOCs) species. The results shown that (1) VOCs composition characteristics exhibit variations for most Level-II source sectors and Level-III sub-sectors even under the same Level-I source category; (2) OVOCs, which were significantly missing in previous profiles, account for more than 95% in cooking and 20- 40% in non-road mobile, biomass burning and solvent use sources; (3) aromatics account for 20%-40% in most emission sources except cooking source, alkenes and alkynes account for ~20% in combustion sources (stationary combustion, mobile source and biomass burning), alkanes are abundant in gasoline-related emission sources(on-road mobile source and fuel oil storage and transportation); (4) missing OVOCs species could bring 30%-50% to ozone formation potentials in most emission sources; and (5) there are considerable differences in VOCs chemical groups and individual species for most emission sources between this dataset and the widely used U.S. SPECIATE database, indicating the importance of developing domestic VOCs source profiles. The dataset developed in this study can help support reactive VOCs species-based ozone control strategy and provide domestic profile data for source apportionment and air quality modeling in China and other countries or regions with similar emission source characteristics.

Variability in real-world emissions and fuel consumption by diesel construction vehicles and policy implications.

Strategically reducing the emission of non-road mobile source especially diesel construction vehicle (DCV) has a large potential in improving air quality and has attracted much scientific and public attention in recent years around the world. In this study, we explored real-world fuel consumption rate and gaseous emissions factors for multiple pollutants of three typical DCVs in China. The sampling campaign considered the operation mode, cumulative operation hour, emission standard stage and engine power. Results show that the accumulated fuel consumption per hour of vehicle weight for working, load-free moving and idling modes was 0.3, 0.2 and 0.1 kg/h·tons, respectively. The fuel-based NOx emission factor exhibited a bimodal distribution at 27 and 41 g/kg. The fuel-based emission factors for volatile organic compounds (VOCs) were in the range of 0.8 to 2.6 g/kg, where alkene and alkane were the dominant components (>80%), i.e., ethylene, acetylene, propylene, and isobutane. We observed that the ratio of toluene and benzene concentration (T/B) (1.4 ± 1.3) differed from other key emission sources and may be used as the specific indicator of DCV emission exhaust. Our estimates suggest that in 2017 the fuel consumption and NOx emissions of DCV emission accounted for 22-28% of non-road mobile sources in China; NOX emissions were 2.7 times higher than those in 2006, and it is forecasted that NOx emissions would reduce by 23% between 2017 and 2025 with the implementation of stage IV and the strict supervision policy. The comprehensive dataset on DCV emissions will either guide the government to establish precise and effective policies to regulate the non-road mobile source or significantly improve our understanding of source apportionment of atmospheric NOx and VOCs, both of which are key precursors of haze and ozone pollution.

High Gaseous Nitrous Acid (HONO) Emissions from Light-Duty Diesel Vehicles.

Nitrous acid (HONO) plays an important role in the budget of hydroxyl radical (•OH) in the atmosphere. Vehicular emissions are a crucial primary source of atmospheric HONO, yet remain poorly investigated, especially for diesel trucks. In this study, we developed a novel portable online vehicular HONO exhaust measurement system featuring an innovative dilution technique. Using this system coupled with a chassis dynamometer, we for the first time investigated the HONO emission characteristics of 17 light-duty diesel trucks (LDDTs) and 16 light-duty gasoline vehicles in China. Emissions of HONO from LDDTs were found to be significantly higher than previous studies and gasoline vehicles tested in this study. The HONO emission factors of LDDTs decrease significantly with stringent control standards: 1.85 ± 1.17, 0.59 ± 0.25, and 0.15 ± 0.14 g/kg for China III, China IV, and China V, respectively. In addition, we found poor correlations between HONO and NOx emissions, which indicate that using the ratio of HONO to NOx emissions to infer HONO emissions might lead to high uncertainty of HONO source budget in previous studies. Lastly, the HONO emissions are found to be influenced by driving conditions, highlighting the importance of conducting on-road measurements of HONO emissions under real-world driving conditions. More direct measurements of the HONO emissions are needed to improve the understanding of the HONO emissions from mobile and other primary sources.

[Emission Characteristics of Light-Duty Gasoline Vehicle Exhaust Based on Acceleration Simulation Mode].

In this study, 127 light-duty gasoline cars and 10 light-duty gasoline trucks with different emission standards were selected to explore the influences of different conditions and vehicle parameters on the emission characteristics of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons (HC), and methane (CH4) using a portable emission measurement system based on a chassis dynamometer under acceleration simulation mode. The results showed that the gaseous pollutants of light-duty gasoline vehicles displayed a relatively lower emission rate under the idle condition, which accounted for only 22.9% and 25.8% of the emission rate at the accelerated condition and constant speed condition, respectively. The pollutant emission characteristics were closely related to the working conditions. The emission rates of CO2 and NOx in the accelerated condition were less than those at the constant speed condition, while the emission rates of CO, HC, and CH4 in the accelerated condition were higher than those at the constant speed condition. In the constant low-speed condition, the emission factors of CO2, CO, NOx, HC, and CH4 were 383.20, 2.98, 1.60, 0.14, and 0.03 g·km-1 for light-duty gasoline cars, respectively, and 360.66, 2.64, 1.61, 0.0055, and 0.0027 g·km-1 for light-duty gasoline trucks, respectively. Tighter emission standards have caused significant reductions in emissions. The emission factors of CO, NOx, HC, and CH4 could be decreased by 87.5%, 97.3%, 97.9%, and 86.4%, respectively, from China Ⅰ to China Ⅴ. A non-linear relationship was found between the age, odometer, vehicle weight, and vehicular emissions. In addition, the engine displacement was positively correlated with vehicular emissions.

Characterization of particulate smoke and the potential chemical fingerprint of non-road construction equipment exhaust emission in China.

Non-road construction equipment (NRCE) is an important source of atmospheric pollution in many developing and urbanizing countries such as China. However, NRCE source is frequently ignored and failed to be identified in the processing of the source apportionment for atmospheric pollution due to the little knowledge on its chemical fingerprint. In this study, seven types of NRCE are selected with the objectives of quantifying the emission factors of fine particulate matter (PM2.5) (EFPM) and exploring their potential chemical fingerprints. Our results show that the NRCE EFPM in the working modes are ~2-3 times higher than those in idling modes, suggesting the important role of engine operating conditions in producing primary PM2.5. As expected, carbonaceous aerosol is the dominant specie of PM2.5, with a wide range of 64-95%. And, the ratio of organic carbon to elemental carbon displays a systematical decrease trend with the increase of engine rated powers. The analysis results show that NRCE PM2.5 chemical compositions are highly correlated with the engine rated powers. In addition, we confirm that the ratio of vanadium and nickel can be used as a good tracer of NREC emission, which is distinct from other key combustion sources such as industry and ship emission. Taken together, this study reveals the emission characteristics of NRCE-related particles and urgently calls on that the NRCE source should be considered in the source apportionment models in the future.

Acute exacerbation of interstitial lung disease after radical surgery for lung cancer: a case report.

A 69-year-old male patient underwent a left upper lobectomy for lung cancer, showing slight interstitial changes in the lung before surgery. He suffered fever with cough and expectoration postoperatively, and high-resolution computed tomography (HRCT) of the thorax indicated that the interstitial lesion in the lung was aggravated. The course of the disease progressed rapidly, and treatment that included anti-infection and steroid pulse therapy was ineffective. We conducted a retrospective analysis of the clinical data and the process of diagnosis and treatment of this patient with acute exacerbation of interstitial lung disease (AE-ILD) after radical surgery for lung cancer. Patients with ILD should be given very careful consideration when selecting a therapeutic approach because interventions may aggravate AE-ILD, leading to a poor prognosis.

Inhibition of H3K27me3 demethylases attenuates asthma by reversing the shift in airway smooth muscle phenotype.

BACKGROUND: The shift in airway smooth muscle cells (ASMCs) phenotype between proliferation and contraction during asthma has been reported recently, highlighting a role of ASMCs plasticity in the pathophysiology of asthma. As an event involved in epigenetic post-translational modification, histone H3 lysine27 (H3K27) demethylation has attracted significant attention with respect to the epigenetic changes in diverse cells; however, little is known about its contribution to the switching of ASMCs phenotype in asthma. OBJECTIVE: To investigate the role of trimethylated H3K27 (H3k27me3) demethylation in ASM remodelling as well as the underling mechanism. METHODS: Mice were exposed five times a week to house dust mite (HDM) extract for 5 weeks. Lung function was measured following the final HDM challenge. Airway inflammation and remodelling were then assessed in lungs of individual mice. Human ASMCs were purchased from Sciencell Research Laboratories. Proliferation, synthesis, migration and contraction of ASMCs were analysed, respectively. RESULTS: We observed demethylation at H3k27me3 sites in lungs harvested from mice exposed to HDM extract. Administration of a selective inhibitor of H3K27 demethylase (GSK-J4) could ameliorate the classical hallmarks of asthma, such as airway hyperresponsiveness, airway inflammation and remodelling. We established a proliferative as well as a contractive model of human ASMCs to explore the impacts of H3K27 demethylase inhibition on ASMCs phenotype. Our results indicated that GSK-J4 decreased ASMCs proliferation and migration elicited by PDGF through the Akt/JNK signalling; GSK-J4 also prevented the upregulation of contractile proteins in ASMCs induced by TGF-ß through the Smad3 pathway. CONCLUSIONS: Inhibition of H3K27me3 demethylation alleviated the development of asthmatic airway disease in vivo and modulated ASMCs phenotype in vitro. Collectively, our findings highlight a role of H3K27me3 demethylation in experimental asthma and ASMCs phenotype switch.

Recent developments of anthropogenic air pollutant emission inventories in Guangdong province, China.

Emission inventory (EI) requires continuous updating to improve its quality and reduce its uncertainty. In this study, recent developments on source classification, emission methods, emission factors and spatial-temporal surrogates in the Guangdong regional anthropogenic emission inventory are presented. The developments include: ~40 additional emission sources in a re-classified source classification system, >50 improved spatial and temporal surrogates, 85% of local/domestic emission factors used, and updated estimation methods of on-road mobile, marine, and solvent use sources. The developments were updated to the recent 2012-based high resolution emission inventories, and their results were compared with previous 2006- and 2010-based emission inventories. The results indicated: (1) The total SO2, NOx, CO, PM10, PM2.5, BC, OC, VOCs and NH3 emissions in 2012 were 777.0kt, 1532.2kt, 7305.4kt, 1176.4kt, 480.9kt, 54.2kt, 79.9kt, 1255.1kt and 584.1kt, respectively, for Guangdong province, with higher emission densities observed in the central PRD region. (2) No great changes on source structures were found among three years, but their contributions varied. (3) SO2, PM10 and PM2.5 emissions showed downward trends, likely a result of strict control measures on power plant and industrial combustion sources. (4) NOx emission exhibited relatively stable levels in 2010 and 2012, but contributions from industrial, on-road and non-road mobile sources increased. (5) VOCs emissions showed an upward trend, mainly resulting from dramatically increased light-duty passenger car population and solvent use. (6) Spatial and temporal allocations were updated with constant improvements of spatial and temporal surrogates. (7) Uncertainty ranges of emission estimates were reduced, indicating that the 2012-based PRD regional EI are more reliable. The work shown in this study can be a reference example for other regions to continuously update their emission inventories.