Characteristics and health risks of parent, alkylated, and oxygenated PAHs and their contributions to reactive oxygen species from PM2.5 vehicular emissions in the longest tunnel in downtown Xi'an, China.

A vehicular emission study was conducted in the longest inner-city tunnel in Xi'an, northwestern China in four time periods (I: 07:30-10:30, II: 11:00-14:00, III: 16:30-19:30, and IV: 20:00-23:00 LST). A sum of 40 PAHs, including parent (p-PAHs), alkylated (a-PAHs), and oxygenated (o-PAHs) in fine particulate matter (PM2.5) were quantified. The relationships between the PAHs and the formation of reactive oxygen species (ROS) were also studied. The average total quantified PAHs concentration was 236.3 ± 48.3 ng m-3. The p-PAHs were found to be the most dominated group, accounting for an average of 88.1% of the total quantified PAHs, followed by a-PAHs (6.1%) and o-PAHs (5.8%). On the base of the number of aromatic rings, the groups of ≤5 rings (92.5 ± 1.2%) had higher fractions than the high ones (≥6 rings, 7.5 ± 1.2%) for pPAHs. Diurnal variations of PAHs subgroups exhibited the highest levels in Period III, consistent with the largest traffic counts in evening rush hours. However, less reduction of few PAHs in the night period demonstrates that the emissions of compressed natural gas (CNG) and methanol-fueled vehicles cannot be ignored while their contribution increased. High ROS activity levels were observed in the traffic-dominated samples, implying the potential oxidative damages to humans. Additionally, diurnal variation of the ROS activity was consistent with the total quantified PAHs and toxic equivalency of benzo[a]pyrene. Good correlations (R > 0.6, p < 0.05) were seen between individual groups of PAHs (especially for 3-5 rings p-PAHs, 4 rings a-PAHs, and 2-3 rings o-PAHs) and ROS activity, supporting that the vehicular emitted PAHs possibly initiate oxidative stress. The multiple linear regression analysis further illustrated that chrysene contributed the highest (25.0%) to ROS activity. In addition to highlighting the potential hazards to the PAHs from the vehicular emission, their roles to mitigate the health effects by formations of ROS were firstly reported in northwestern China.

Efficacy and Safety of Maintenance Therapy Using Cetuximab in Patients with Metastatic Colorectal Cancer: Retrospective Study.

Purpose: Cetuximab (CET) combined with chemotherapy significantly improved the survival in RAS and RAF wild-type metastatic colorectal cancer (mCRC) patients, while clinical evidence was lacking on the use of maintenance therapy (MT). The study aimed to explore the role of maintenance therapy following Cetuximab + chemotherapy and the optimal Cetuximab-based maintenance therapy regimen. Patients and Methods: We retrospectively reviewed data on the efficacy and safety of CET-based MT in patients with mCRC who achieved disease control after induction therapy. Results: Eighty-one patients with mCRC who achieved disease control after CET + chemotherapy induction were enrolled. Overall median progression-free survival (PFS) was 10.5 (95% CI = 8.8-12.2) months and median maintenance/observation PFS (mnPFS) was 6.0 (95% CI = 5.0-7.0) months. Among these 81 patients, 61 patients were prescribed MT (CET alone for 21 patients and CET + chemotherapy for 40 patients). Median PFS and mnPFS in the MT group were significantly longer than those for the non-MT group. Different MT regimens did not affect PFS and mnPFS significantly. Univariate and multivariate analysis demonstrated MT, complete response/partial response during induction therapy, and absence of peritoneal metastasis to be positively associated with longer PFS and mnPFS. Treatment-related adverse events (AEs) were tolerable during MT, and AE-related deaths were not observed. Conclusion: MT with CET or CET + chemotherapy was an appropriate option following initial induction chemotherapy for patients with RAS and RAF wild-type mCRC. This strategy endowed survival benefits and a tolerable safety profile.

Characteristics and sources of oxygenated VOCs in Hong Kong: Implications for ozone formation.

To investigate the characteristics of oxygenated volatile organic compounds (OVOCs) and their potential contribution to ozone (O3) generation, we conducted 3-h high-resolution observations during the summertime of 2022 and the wintertime of 2021. This study focused on a total of 28 OVOCs in five different chemical classes, which were encompassed at two representative sites in Hong Kong, including a roadside and an urban area. During the summertime, the total concentrations of quantified OVOCs (∑OVOCs) were 45 ± 12 and 63 ± 20 µg m-3 at the roadside and urban sites, respectively, whereas the ∑OVOCs decreased by 31 ± 11 % and 38 ± 13 %, respectively, during the wintertime. Among the classes of OVOCs, carbonyls and alcohols were the two predominant at both sites, with relatively higher concentration levels of acetone, methanol, butanaldehyde, and acrolein. The sources of OVOCs have significant spatial and temporal characteristics. Spatially, OVOCs were predominately attributed to primary emission and background at the roadside site, whereas they were a combination of primary emission, secondary formation, and background at the urban site. Temporally, background sources dominated the summertime OVOCs, while the contribution of primary emissions increased for the wintertime OVOCs. The O3 formation potential (OFP) for the OVOCs was calculated. The OFPs were 67 ± 16 and 119 ± 31 µg m-3 at the roadside and urban sites during the summertime, whereas the winter OFPs declined 30 % at the roadside and 38 % at the urban site. The background sources of carbonyls and alcohols at the roadside and of carbonyls and acrylates in the urban area were the major contributors to the summer OFP. Controlling the OVOC sources from local non-combustion sources such as gasoline-fuel evaporation and volatile chemical-containing products could lead to a reduction of OVOCs in the background and subsequently mitigate the OFP. This is beneficial for local O3 reduction in Hong Kong and surrounding regions.

Personal exposure monitoring of fine and coarse particulate matter using exposure assessment models for elderly residents in Hong Kong.

This study investigated the determinants of personal exposures (PE) to coarse (PM2.5-10) and fine particulate matter (PM2.5) for elderly communities in Hong Kong. The mean PE PM2.5 and PM2.5-10 were 23.6 ± 10.8 and 13.5 ± 22.1 µg/m3, respectively during the sampling period. Approximately 76% of study subjects presented statistically significant differences between PE and ambient origin for PM2.5 compared to approximately 56% for PM2.5-10, possibly due to the coarse-size particles being more influenced by similar sources (road dust and construction dust emissions) compared to the PM2.5 particles. Individual PE to ambient (P/A) ratios for PM2.5 all exceeded unity (≥1), suggesting the dominant influences of non-ambient particles contributed towards total PE values. There were about 80% individual P/A ratios (≤1) for PM2.5-10, implying possible effective infiltration prevention of larger size particulate matter particles leading to dominant influences from the outdoor sources. The higher concentration of NO3- and SO42- in PM2.5-10 compared to PM2.5 suggests possible heterogeneous reactions of alkaline minerals leading to the formation of NO3- and SO42- in PM2.5-10 particles. The PE and ambient OC/EC ratios in PM2.5 (8.8 ± 3.3 and 10.4 ± 22.4, respectively) and in PM2.5-10 (6.0 ± 1.9 and 3.0 ± 1.1, respectively) suggest possible secondary formed OC from surrounding rural areas. Heterogeneous distributions (COD >0.2) between the PE and ambient concentrations were found for both the PM2.5 and PM2.5-10 samples. The calibration coefficient as the association between personal and surrogate exposure measure of PE to PM2.5 (0.84) was higher than PM2.5-10 (0.52). The findings further confirm that local sources were the dominant contributor to the coarse particles and these coefficients can potentially be used to estimate different PE to PM2.5 and PM2.5-10 conditions. A comprehensive understanding of the PE to determinants in coarse particles is essential to further reduce potential exposure misclassification.

Chemical composition and potential health risks of tire and road wear microplastics from light-duty vehicles in an urban tunnel in China.

Tire and road wear microplastics (TRWMPs) are one of the main non-exhaust pollutants of motor vehicles, which cause serious environmental and health issues. Here, TRWMPs in PM2.5 samples were collected in a tunnel in urban Xi'an, northwest China, during four periods [I: 7:30-10:30, II: 11:00-14:00, III: 16:30-19:30, IV: 20:00-23:00 local standard time (LST)] in summer of 2019. The chemical components of rubbers, benzothiazoles, phthalates, and amines in TRWMPs were quantified, with a total concentration of 6522 ± 1455 ng m-3 (mean ± standard deviation). Phthalates were predominant in TRWMPs, accounting for 64.8% on average, followed by rubbers (33.2%) and benzothiazoles (1.19%). The diurnal variations of TRWMPs showed the highest concentration in Period III (evening rush hour) and the lowest concentration in Period I (morning rush hour), which were not exactly consistent with the variation of the number of light-duty vehicles passed through the tunnel. The result implied that the number of vehicles might not be the most important contributor to TRWMPs concentration, whereas meteorological variables (i.e., precipitation, and relative humidity), vehicle speed, vehicle class, and road cleaning also affected their abundances. The non-carcinogenic risk of TRWMPs in this study was within the international safety threshold, but their carcinogenic risk exceeded the threshold by 2.7-4.6 times, mostly dominated by bis(2-ethylhexyl)phthalate (DEHP). This study provides a new basis for the source apportionment of urban PM2.5 in China. The high concentrations and high potential cancer risks of TRWMPs represent the requirement for more efficient measures to control light-duty vehicle emissions.

Environmental and health impacts of household energy conversion on PAHs and their derivatives in PM2.5 in typical areas of northern China.

Heavy use of solid fuels in rural households of northern China emits huge amounts of fine particulate matter (i.e., PM2.5) that pose notable indoor air pollution and severe inhalation health risks. In this study, the environmental and health benefits of clean energy substitution were accessed by monitoring indoor and personal exposure to polycyclic aromatic hydrocarbons (PAHs) and their derivatives, and pulmonary function and biological parameters. After substitutions of traditional lump coal and biomass fuels by clean coal, indoor concentrations of parent PAHs (p-PAHs), alkylated PAHs (a-PAHs), oxygenated PAHs (o-PAHs), and nitro PAHs (n-PAHs) reduced by 71 %, 32 %, 70 %, and 76 %, while personal exposure concentrations decreased by 82 %, 87 %, 93 %, and 86 %, respectively. However, the proportion of low molecular weight PAHs increases, especially for 2-ring a-PAHs and 3-ring n-PAHs. Domestic solid fuel burning induces greater damage to the small airway than the large airway. Pulmonary function parameter reductions in the clean coal group are much less than those in the other two fuel groups. Salivary interleukin-6 (IL-6) and 8-hydroxy-2'-deoxyguanosine (8-OHdG) significantly correlated with PAH species, among which p-PAHs and PAHs derivatives strongly with IL-6 and 8-OHdG, respectively. The correlation between PAHs and biomarkers in urine is insignificant. In addition, the use of clean coal can reduce the cancer risk for the four classes of PAHs by 60 %-97 %, mainly owing to the lower contributions from p-PAHs and o-PAHs. The result of the study provides scientific support for clean energy retrofit and an understanding of health benefits from solid fuel substitutions.

Insight into personal exposure characteristics and health effects of PM2.5 and PM0.25-bound PAHs and their derivatives with different heating ways in the Fenwei Plain, China.

Personal exposure (PE) to polycyclic aromatic hydrocarbons (PAHs) and their derivatives in particulate matter with two aerodynamic sizes of 2.5 and 0.25 µm (PM2.5 and PM0.25) from rural housewives was studied in the Fenwei Plain, China. A total of 15 households were divided into five different groups based on the type of solid fuel and heating device used, including biomass briquette-furnace (BBF), biomass-elevated Kang (BEK), outdoor lump coal-boiler (OLC), indoor briquette coal-stove (IBC), and electricity (ELE). The PE concentrations of the PAHs and biomarkers in urine collected from the participants were determined. The results showed that the PE concentrations of total quantified PAHs in the biomass group (i.e., BBF and BEK) were 2.2 and 2.0 times higher than those in the coal groups (i.e., OLC and IBC) in PM2.5 and PM0.25, respectively. The housewives who used biomass as fuel suffered from higher potential health impacts than the coal fuel users. The incremental lifetime cancer risk for the PAHs in PM2.5 in the BBF and BEK groups exceeded the international safety threshold. Furthermore, the PE concentrations of oxygenated PAH (o-PAHs) in PM2.5 and PM0.25 in the biomass groups and the nitrated PAHs (n-PAHs) in PM0.25 in the coal groups showed strong correlations with the biomarkers. The results of this study proved the associations between exposure to the different classes of PAHs and health hazards. The findings could also serve as a guideline in establishing efficient measures for using solid fuels for cooking and household warming in northern China.

Associations of personal exposure to domestic heating and cooking fuel emissions and epidemiological effects on rural residents in the Fenwei Plain, China.

Solid fuel combustion for domestic heating in northern China in the wintertime is of great environmental and health concern. This study assesses personal exposure to particulate matter with different aerodynamic diameters and multiple gaseous pollutants from 123 rural residents in Yuncheng, the Fenwei Plain. The subjects are divided into groups based on the unique energy source applied, including biomass, coal, and electricity/no heating activities. The health effects of the exposures are expressed with four urinary biomarkers. The personal exposure levels to three different aerodynamic particle sizes (i.e., PM10, PM2.5, and PM1) of the electricity/no heating group are 5.1 % -12 % lower than those of the coal group. In addition, the exposure levels are 25 %-40 % lower for carbon monoxide (CO) and 10.8 %-20.3 % lower for ozone (O3) in the electricity/no heating group than the other two fuel groups. C-reactive protein (CRP) in the urine of the participants in biomass and coal groups is significantly higher than that in the electricity/no heating group, consistent with the observations on other biomarkers. Increases in 8-hydroxy-2 deoxyguanosine (8-OHdG), interleukin-8 (IL-8), and vascular endothelial growth factor (VEGF) are observed for the exposures to higher concentrations of air pollutants. For instance, PMs and nitrogen dioxide (NO2) show significant impacts on positive correlations with 8-OHdG and IL-8, while O3 positively correlates with CRP. PM1 exhibits higher effects on the biomarkers than the gaseous pollutants, especially on VEGF and IL-8. The study indicates that excessive use of traditional domestic solid fuels could pose severe health effects on rural residents. The promotion of using clean energy is urgently needed in the rural areas of northern China.

Could S-1-based non-platinum doublet chemotherapy be a new option as a second-line treatment for advanced non-small cell lung cancer patients? A multicenter retrospective study.

Background: For patients who have contraindications to or have failed checkpoint inhibitors, chemotherapy remains the standard second-line option to treat non-oncogene-addicted advanced non-small cell lung cancer (NSCLC). This study aimed to investigate the efficacy and safety of S-1-based non-platinum combination in advanced NSCLC patients who had failed platinum doublet chemotherapy. Methods: During January 2015 and May 2020, advanced NSCLC patients who received S-1 plus docetaxel or gemcitabine after the failure of platinum-based chemotherapy were consecutively retrieved from eight cancer centers. The primary endpoint was progression-free survival (PFS). The secondary endpoint was overall response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. By using the method of matching-adjusted indirect comparison, the individual PFS and OS of included patients were adjusted by weight matching and then compared with those of the docetaxel arm in a balanced trial population (East Asia S-1 Trial in Lung Cancer). Results: A total of 87 patients met the inclusion criteria. The ORR was 22.89% (vs. 10% of historical control, p < 0.001) and the DCR was 80.72%. The median PFS and OS were 5.23 months (95% CI: 3.91-6.55 months) and 14.40 months (95% CI: 13.21-15.59 months), respectively. After matching with a balanced population in the docetaxel arm from the East Asia S-1 Trial in Lung Cancer, the weighted median PFS and OS were 7.90 months (vs. 2.89 months) and 19.37 months (vs. 12.52 months), respectively. Time to start of first subsequent therapy (TSFT) from first-line chemotherapy (TSFT > 9 months vs. TSFT ≤ 9 months) was an independent predictive factor of second-line PFS (8.7 months vs. 5.0 months, HR = 0.461, p = 0.049). The median OS in patients who achieved response was 23.5 months (95% CI: 11.8-31.6 months), which was significantly longer than those with stable disease (14.9 months, 95% CI: 12.9-19.4 months, p < 0.001) or progression (4.9 months, 95% CI: 3.2-9.5 months, p < 0.001). The most common adverse events were anemia (60.92%), nausea (55.17%), and leukocytopenia (33.33%). Conclusions: S-1-based non-platinum combination had promising efficacy and safety in advanced NSCLC patients who had failed platinum doublet chemotherapy, suggesting that it could be a favorable second-line treatment option.

Immunotherapy combined with antiangiogenic agents in patients with advanced malignant pleural mesothelioma: A case report.

BACKGROUND: Malignant pleural mesothelioma has limited therapeutic options and a poor outcome. Antiangiogenic agents might increase the efficacy of immunotherapy as second-line treatment of advanced-stage malignancies. CASE SUMMARY: A patient with stage IIIB pleural mesothelioma received second-line treatment with a combination of pembrolizumab, bevacizumab and chemotherapy following standard chemotherapy under the guidance of second-generation sequencing. He achieved a partial response after four cycles of treatment with progression-free survival of 5 mo. Pembrolizumab was suspended due to grade 2 immunerelated pneumonia, which was resolved by oral glucocorticoids. However, disease progression was observed after immunotherapy rechallenge and anlotinib therapy. The patient had disease progression, multiorgan dysfuntion and died suddenly in October 2019. CONCLUSION: The combination of immune checkpoint inhibitor, anti-angiogenic agents and chemotherapy showed effective response for advanced pleural mesothelioma, but with adverse reactions.

Explorations of tire and road wear microplastics in road dust PM2.5 at eight megacities in China.

Tire and road wear microplastics (TRWMPs) in road dust are a key source of atmospheric particulate matter and have an adverse impact on human health and the environment. In this study, samples of particulate matter with a diameter of 2.5 µm or less (PM2.5) in road dust were collected from eight megacities in China to determine the TRWMP content, including that of natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR). The total abundance of TRWMPs was the highest in Lanzhou (174.7 ± 17.0 µg g-1), followed by Xi'an (169.3 ± 23.8 µg g-1), Beijing (107.5 ± 7.5 µg g-1), Changchun (102.2 ± 8.4 µg g-1), Chengdu (101.6 ± 12.9 µg g-1), Guangzhou (98.8 ± 6.5 µg g-1), Wuhan (96.0 ± 5.3 µg g-1), and Shanghai (86.1 ± 30.1 µg g-1). A considerably higher TRWMP fraction in road dust PM2.5 was observed in the northern cities than in the southern cities and is attributable to the higher frictional resistance of roads subjected to less precipitation. The abundance of TRWMPs in the southern cities was dependent on road type, but this dependence was not observed in the northern cities. In the south, road dust PM2.5 on main roads contained more TRWMPs than that on branch roads. Correlation analysis indicated that TRWMPs were associated with tire, road, and break wear. In relation to intracellular oxidative stress factors, higher correlations were observed between TRWMPs and lactate dehydrogenase (r = 0.83) than between TRWMPs and reactive oxygen species (r = 0.59), possibly because TRWMPs destroy the integrity of the cell membrane, with NR exhibiting a higher cytotoxicity than SBR or BR. This study provides evidence that TRWMPs have an adverse impact on human health by inducing cellular oxidative stress. Therefore, further research on TRWMPs in respirable road dust is required.

Chemical characteristics and sources of nitrogen-containing organic compounds at a regional site in the North China Plain during the transition period of autumn and winter.

Organic nitrogen constitutes a significant fraction of the nitrogen budget in particulate matter (PM). However, the composition and sources of nitrogen-containing organic compounds (NOCs) in PM remain unclear currently in North China Plain (NCP), China. Rare local or regional studies on NOCs were conducted. In this study, ambient fine particles (PM2.5) were collected in Xianghe, a regional background site in NCP, from 26 October to 26 December 2017. The insights from this study include NOC molecule identification, concentration level, and NOC sources and origins. Specifically, we have identified and quantified >90 NOC species, with urea being the most abundant, accounting for 39.7 ± 4.7% of the total NOC followed by free amino acids (FAAs; 21.9 ± 1.5%), cyclic NOCs (15.3 ± 4.5%), amines (14.8 ± 1.5%), alkyl amides (5.8 ± 0.5%), isocyanates (1.7 ± 0.2%), and nitriles (1.1 ± 0.2%). The time series of FAAs was well correlated (r = 0.51-0.68, p < 0.01) with the organic marker of levoglucosan and was moderately correlated with Ox (r = 0.29-0.41, p < 0.01), suggesting biomass burning and secondary formation were important FAAs sources. We also show that amines can be oxidized and/or reacted by aqueous-phase processing to form secondary aerosols, which are further enhanced by the involvement of iron in the catalytic process. Using the receptor model of positive matrix factorization (PMF), six factors were identified including coal combustion, crustal sources, biomass burning, industry-related sources, traffic emissions, and secondary aerosols. Source apportionment of NOC shows biomass burning was the dominant factor, accounting for 31.8% of the total NOCs. This study provides a unique dataset of NOCs at this regional background site in the NCP, with the insights of NOC chemical composition and sources gained in this study being important for future NOC modeling as well as NOC health effects studies.

Chemical characterization of PM2.5 in heavy polluted industrial zones in the Guanzhong Plain, northwest China: Determination of fingerprint source profiles.

Industrial emission has been proved to be an important source of atmospheric PM2.5, which causes serious air pollution and health impacts. The air quality of the industrial zones, which are the intermediate stationary areas between the direct emissions and diffusion to the atmosphere, is always overlooked. In this study, the PM2.5 filter samples were collected in the six representative types of industrial zones in four cities of the Guanzhong Plain in 2020. The chemical characteristics of fine particulate matter (PM2.5) in the zones were investigated. The mass concentrations of 13 elements and 39 polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were quantified. Cement and concrete (CC) and brick production (BP) exhibited a similar chemical composition profile characterized by high proportions of calcium (Ca), aluminum (Al), benzo[k]fluoranthene (BkF), 1-nitronaphthalene (1N-NAP), and 3-nitrofluoranthene (3N-FLA). Glassware and ceramics (GC) showed a distinguishable profile with a relatively low ratio of copper/cadmium (Cu/Cd) and lead (Pb)/Cd. The profile for metal forging (MF) was abundant in vanadium (V), Pb, indeno[1,2,3-cd]pyrene (IcdP) and also recognized by particular diagnostic ratios of nitrated-PAHs (n-PAHs). The highest proportions of several metals such as chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), zinc (Zn), Cd, and fluoranthene (FLA) were found in the thermoelectric industry (TI) due to a large amount of coal consumption in the manufacture processing. Chemical production (CP) was the only industrial type using natural gas as the main fuel in this study, which shows the distinguishing feature of relatively high proportions of low molecular weight parent-PAHs (p-PAHs) and 2-ring oxygenated-PAHs (o-PAHs). This study not only attains the detailed chemical fingerprints, but also the potential tracers and ratios, which are of great significance for refining source apportionment and relieving PM2.5 pollution contributed by the industrial sources.

Characterization of organic aerosols in PM1 and their cytotoxicity in an urban roadside area in Hong Kong.

Organic compounds in fine particles play major roles in cardiopulmonary diseases. A study was conducted to determine the characteristics and cytotoxicity of organic aerosols (OA) in an urban roadside area in Hong Kong. Chemical components in nonrefractory submicron aerosol (NR-PM1) were observed using a Quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM), and the chemical profile of organic compounds in NR-PM1 was examined with filter-based approach. Associations between cytotoxicity and organic sources and compositions were evaluated. NR-PM1 contributed to 84% of the PM1 concentrations. The NR-PM1 was composed of organics (55 ± 15%), followed by sulfate (21 ± 9%), ammonium (13 ± 6%), nitrate (10 ± 6%) and chloride (1 ± 1%). Three major organic sources were identified using positive matrix factorization, namely primary organic aerosol (POA, 40 ± 19%), more-oxidized oxygenated OA (MO-OOA, 32 ± 22%) and less-oxidized oxygenated OA (LO-OOA, 28 ± 19%). Variations in organic groups, including alkanes, hopanes, steranes, polycyclic aromatic hydrocarbons (PAHs), oxy-PAHs (OPAHs), and fatty acids, demonstrated that traffic and cooking emissions were dominant pollution sources in this roadside station. Human lung alveolar epithelial (A549) cells were exposed to PM1, revealing increases in lactate dehydrogenase (LDH), reactive oxygen species (ROS), and interlukin-6 (IL-6), which indicated the occurrence of inflammatory and oxidative responses. POA was significantly associated with ROS and IL-6, and alkanes, hopanes, steranes, PAHs and OPAHs, and fatty acids presented medium to high correlations with LDH and IL-6, demonstrating the importance of primary emissions and organic compounds in cytotoxicity. This study demonstrated that organic compounds emitted from traffic and cooking play critical roles in PM-induced oxidative stress and inflammation in urban areas.

Temporal and spatial discrepancies of VOCs in an industrial-dominant city in China during summertime.

Ozone (O3) pollution is currently problematic to cities across the globe. Many non-methane hydrocarbons (NMHCs) are efficient O3 precursors. In this study, target volatile organic compounds (VOCs), including oxygenated VOCs (known as carbonyls), were monitored at eight sampling sites distributed in urban and suburban in the typical and industrial-dominant city of Shaoxing, Zhejiang province, China. At the suburban sites, C8-C12 alkanes, aromatics with lower reactivity (kOH <13 × 10-12 cm3 mol-1 s-1) and acetonitrile were more abundant than urban ones due to higher emissions from diesel-fueled trucks and biomass burning. In general, higher abundances of total quantified NMHCs (ΣNMHC) were found on high O3 (HO) days. The increments of formaldehyde (C1) and O3 were higher in urban than suburban, while a reverse trend was seen for acetaldehyde (C2). Substantial and local biogenic inputs of C2 were found in suburban in the afternoon when both temperature and light intensity reached maximum of the day. In urban, higher increment was found for O3 than the carbonyls, representing that the secondary formation of O3 was more efficient. Distance decay gradient of most representative NMHCs were positively correlated to the distances from a westernmost industrial origin located at the upwind location. The net loss rates of the NMHCs ranged from -0.009 to -0.11 ppbv km-1, while the higher rates were seen for the most reactive species like C2-C4 alkenes. The results and interpretation of this study are informative to establish efficient local control measures for O3 and the related percussors for the microscale industrial cities in China.

Emission factors, characteristics, and gas-particle partitioning of polycyclic aromatic hydrocarbons in PM2.5 emitted for the typical solid fuel combustions in rural Guanzhong Plain, China.

Solid fuel is a the most dominant energy source for household usages in developing countries. In this study, emission characteristics on organic carbon (OC), elemental carbon (EC) and fifty-two polycyclic aromatic hydrocarbons (PAHs) in gaseous and particulate phases from seven fuel-stove combinations were studied in a typical rural village in northwest China. For the PAHs, the highest gaseous and particulate phase emission factors (EFs) were both observed for bituminous coal with one-stage stoves, ranging from 459 ± 154 to 1.09 ± 0.36 × 103 mg kg-1. In contrast, the PAHs EFs for the clean briquette coal with two-stage stoves were two orders of magnitude lower than those of the bituminous coals. For parent PAHs (pPAHs) and total quantified PAHs (∑PAHs), they mainly contributed in gaseous phases with compositions of 69-79% and 64-70%, respectively. The gas-to-particle partitioning was mostly governed by the absorption. Moreover, the correlation coefficient (r) between EC and ∑PAHs, OC and parent PAHs (pPAHs), OC and nitro PAHs (nPAHs) were 0.81, 0.67 and 0.85, respectively, supporting that the PAHs species were potential precursors to the EC formation during the solid fuel combustion. The correlation analyses in this study further deduced that the formations of pPAHs and nPAHs were more closely related to that of OC than alkylated PAHs (aPAHs) and oxygenated PAHs (oPAHs). Diagnostic ratios of selective PAHs were calculated and evaluated as well. Among those, the ratio of retene (RET)/[RET + chyrene (CHR)] was found to be an efficient tool to distinguish coal combustion and biomass burning. In general, it was found that the amounts of pollutant emissions from clean briquette coal combustion were definitely lower than those from bituminous coal and biomass combustions. It is thus necessary to introduce and recommend the use of cleaner briquette coal as energy source.

A comprehensive study on ozone pollution in a megacity in North China Plain during summertime: Observations, source attributions and ozone sensitivity.

Tropospheric ozone (O3) pollution has been becoming prominent in North China Plain (NCP) in China since last decade. In order to clarify the source contribution and formation mechanism of O3, the critical precursors of volatile organic compounds (VOCs) were measured with both on-line and off-line methods in Luoyang City in summer of 2019. The concentrations of nitrogen oxides (NOx, sum of NO and NO2) and O3 were simultaneously monitored. Fifty-seven VOCs measured in U.S. Photochemical Assessment Monitoring Station (PAMS) showed daily concentrations in a range of 14.5 ± 5.33 to 29.2 ± 11.2 ppbv in Luoyang, which were comparable with those in other Chinese megacities. The mass compositions of VOCs were determined, with comparatively low proportions of alkanes (<50%) but high fractions of photoreactive alkenes and alkyne. Source apportionment of VOCs was conducted by Hybrid Environmental Receptor Model (HERM). The results indicated that industrial (38.5%) and traffic (32.0%) were the two dominated pollution sources of VOCs in the urban, while the biogenic and residential sources had contributions of 15.8% and 13.8%, respectively. To further measure the O3 formation sensitivity and its source attribution, the WRF-CHEM model was adopted in this study. The variation of O3 between the observation and the stimulation using the local emission inventory showed an index of agreement (IOA) of 0.85. The simulation conducted by WRF-CHEM indicated an average of 43.5% of the O3 was associated with the regional transportation, revealing the importance of inter-regional prevention and control policy. Traffic and biogenic emissions were the two major pollution sources to an O3 episode occurred from July 21 to July 27, 2019 (when O3 concentration over 150 µg m-3) in Luoyang, with average contributions of 22.9% and 18.3%, respectively. The O3 isopleths proved that its formation in the atmosphere of Luoyang was in transitional regime and collectively controlled by both VOCs and NOx. This was different from the observations in main cities of NCP before implantations of strict emission controls. The isopleths additionally designated that the O3 formation regime would move forward or shift to NOx regime after a reduction of over 45% during the episode. Similar patterns were also reported in other Chinese megacities such as Beijing and Shanghai, due to the tightening of the NOx control policies. Our results do support that the simultaneous controls of NOx and VOCs were effective in reductions of tropospheric O3 in Luoyang. Meanwhile, joint regional control policies on the emissions of NOx and VOCs can potentially overwhelm the current O3 pollutions in China.

Chemical and toxicological characterization of particulate emissions from diesel vehicles.

This paper presents a detailed chemical and toxicological characterization of the diesel particulate matter (PM) emitted from diesel vehicles running on a chassis dynamometer under different driving conditions. Chemical analyses were performed to characterize the contents of organic carbon (OC), elemental carbon (EC), and 31 polycyclic aromatic hydrocarbons (PAHs) in the collected PM samples. The OC-EC analysis results revealed that PM emissions from diesel vehicles in this study were dominated by OC and that the emission of vehicles equipped with diesel particulate filters had high OC/EC ratios. The PAH analysis results revealed that 4- and 5-ring PAHs were the dominant PAHs in the OC fraction of the PM samples. Particle toxicity was evaluated through three toxicological markers in human A549 cells, namely (1) acellular 2,7-dichlorofluorescein (DCFH) for oxidative potential, (2) interleukin-6 (IL-6) for inflammation, and (3) glutathione (GSH) for antioxidation after exposure. Statistical analyses revealed that vehicle sizes have statistically significant effects on the concentrations of the markers. Correlation analysis between PAHs and toxicological markers revealed that significant correlations existed between specific compounds and markers. Our results can be used as a reference by policy makers to formulate emission control strategies and as a dataset for other modeling studies.

Characterizations of PM2.5-bound organic compounds and associated potential cancer risks on cooking emissions from dominated types of commercial restaurants in northwestern China.

Cooking emissions are both indoor and outdoor sources for fine particulate matter (PM2.5) but their contributions are often ignored. The PM2.5-bound organic compounds, including alkanols, alkanes, monocarboxylic acids, dicarboxylic acids, and polycyclic aromatic hydrocarbons (PAHs) were determined in the emissions from the most popular types of restaurants in the capital city of northwestern China. The mean concentration of total quantified organic compounds (ΣPM_O) ranged from 1112 to 32,016 ng m-3, with the maximum for the Chinese barbecue restaurants. The ΣPM_O accounted for an average of 11% of PM2.5 mass, demonstrating their significances in the cooking emissions. Hexadecanoic acid (C16) and 1-hexadecanol (C16) were considered as the tracers for stir-frying, steaming, and boiling which are usually applied in the traditional Chinese cuisines; 1-undecanol (C11), 9-fluorenone, and indeno[1,2,3-cd]pyrene were found to be potential markers for grilling and deep-frying which are widely applied in the Western style cooking method. The PAH diagnostic ratios also illustrated their representatives to distinguish the emissions from traditional Chinese cuisines and the Western-style restaurants. The estimated carcinogenic risks for the restaurants that consumed a large amount of oils and employed high temperature cooking methods (e.g., barbecuing and deep-frying) were 2.6-4.2 times exceeded the international safety limit. The organic profiles obtained in this study could be contributed to refine PM2.5 source apportionment in urban areas in northwestern China. The estimations of potential cancer risks urge the establishment of more stringent legislations to protect the health of the catering staffs.

Cytotoxicity of PM2.5 vehicular emissions in the Shing Mun Tunnel, Hong Kong.

Associations between human exposures to vehicular emissions (VE) and cardiopulmonary diseases have been found, with a dearth of information on particle cytotoxicity. This study exposes human lung alveolar epithelial (A549) cells to PM2.5 (particulate matter with aerodynamic diameter <2.5 µm) samples collected in a tunnel and investigates the oxidative and inflammatory responses. The cytotoxicity factor (CF) is used to normalize the VE cytotoxicity. The emission factors (EFs) were 27.2 ± 12.0 mg vehicle-1 km-1 for PM2.5 and 4.93 ± 1.67 µg vehicle-1 km-1 for measured polycyclic aromatic hydrocarbons (PAHs). Higher EFs were found for high (4-6 rings) than low (2-3 rings) molecular-weight particulate PAHs. PM2.5 VE caused oxidative stress and inflammation of human lung cells. Organic carbon (OC), element carbon (EC), and several PAHs were significantly (p < 0.05) correlated with bioreactivity. Higher CFs were found when diesel vehicle counts were highest during the morning rush hour, implying that diesel-fueled VE were major contributors to cytotoxic effects. This study provides a broader understanding of the toxicity in an engine-exhaust dominated environment.