Characteristics and health risk assessment of fine particulate matter and surface ozone: results from Bengaluru, India.

Urban air pollution is a complex problem, which requires a multi-pronged approach to understand its dynamics. In the current study, various aspects of air pollution over Bengaluru city were studied utilizing simultaneous reference-grade measurements (during the period July 2019 to June 2020) of fine particulate matter mass concentration (PM2.5), aerosol black carbon mass concentrations (BC), and surface ozone (O3) concentrations. The study period mean PM2.5, BC, and O3 were observed to be 26.8 ± 11.5 µg m-3, 5.6 ± 2.8 µg m-3, and 25.5 ± 12.4 ppb, respectively. Statistical methods such as principal component analysis, moving average subtraction method, conditional bivariate probability function, and concentration weighted trajectory analysis were performed to understand the dynamics of air pollution over Bengaluru and its long-range transportation pathways. Some of the major findings from the statistical analyses include (i) contrasting association in BC versus O3 and PM2.5 versus O3; (ii) around one-fourth of the observed receptor site BC was contributed by local sources/emissions; and (iii) the source locations potentially contributing to BC and PM2.5 were spatially different. In Bengaluru, long-term exposure to PM2.5 resulted in around 3413, 3393, 1016, and 147 attributable deaths for the health endpoints chronic obstructive pulmonary disorder, ischemic heart disease, stroke, and lung cancer, respectively. Long-term exposure to O3 resulted in around 155 attributable deaths for respiratory diseases, as estimated by the AirQ + model. Finally, the limitations of the study in terms of data availability and analysis have been detailed.

Crystal structures of CbpF complexed with atropine and ipratropium reveal clues for the design of novel antimicrobials against Streptococcus pneumoniae.

BACKGROUND: Streptococcus pneumoniae is a major pathogen responsible of important diseases worldwide such as pneumonia and meningitis. An increasing resistance level hampers the use of currently available antibiotics to treat pneumococcal diseases. Consequently, it is desirable to find new targets for the development of novel antimicrobial drugs to treat pneumococcal infections. Surface choline-binding proteins (CBPs) are essential in bacterial physiology and infectivity. In this sense, esters of bicyclic amines (EBAs) such as atropine and ipratropium have been previously described to act as choline analogs and effectively compete with teichoic acids on binding to CBPs, consequently preventing in vitro pneumococcal growth, altering cell morphology and reducing cell viability. METHODS: With the aim of gaining a deeper insight into the structural determinants of the strong interaction between CBPs and EBAs, the three-dimensional structures of choline-binding protein F (CbpF), one of the most abundant proteins in the pneumococcal cell wall, complexed with atropine and ipratropium, have been obtained. RESULTS: The choline analogs bound both to the carboxy-terminal module, involved in cell wall binding, and, unexpectedly, also to the amino-terminal module, that possesses a regulatory role in pneumococcal autolysis. CONCLUSIONS: Analysis of the complexes confirmed the importance of the tropic acid moiety of the EBAs on the strength of the binding, through π-π interactions with aromatic residues in the binding site. GENERAL SIGNIFICANCE: These results represent the first example describing the molecular basis of the inhibition of CBPs by EBA molecules and pave the way for the development of new generations of antipneumococcal drugs.

PM2.5 carbonaceous components and mineral dust at a COALESCE network site - Bhopal, India: Assessing the impacts of COVID-19 lockdowns on site-specific optical properties.

Thermal elemental carbon (EC), optical black carbon (BC), organic carbon (OC), mineral dust (MD), and 7-wavelength optical attenuation of 24-hour ambient PM2.5 samples were measured/estimated at a regionally representative site (Bhopal, central India) during a business-as-usual year (2019) and the COVID-19 lockdowns year (2020). This dataset was used to estimate the influence of emissions source reductions on the optical properties of light-absorbing aerosols. During the lockdown period, the concentration of EC, OC, BC880 nm, and PM2.5 increased by 70 % ± 25 %, 74 % ± 20 %, 91 % ± 6 %, and 34 % ± 24 %, respectively, while MD concentration decreased by 32 % ± 30 %, compared to the same time period in 2019. Also, during the lockdown period, the estimated absorption coefficient (babs) and mass absorption cross-section (MAC) values of Brown Carbon (BrC) at 405 nm were higher (42 % ± 20 % and 16 % ± 7 %, respectively), while these quantities for MD, i.e., babs-MD and MACMD values were lower (19 % ± 9 % and 16 % ± 10 %), compared to the corresponding period during 2019. Also, babs-BC-808 (115 % ± 6 %) and MACBC-808 (69 % ± 45 %) values increased during the lockdown period compared with the corresponding period during 2019. It is hypothesized that although anthropogenic emissions (chiefly industrial and vehicular) reduced drastically during the lockdown period compared to the business-as-usual period, an increase in the values of optical properties (babs and MAC) and concentrations of BC and BrC, were likely due to the increased local and regional biomass burning emissions during this period. This hypothesis is supported by the CBPF (Conditional Bivariate Probability Function) and PSCF (Potential Source Contribution Function) analyses for BC and BrC.

Ambient volatile organic compounds in urban and industrial regions in Beijing: Characteristics, source apportionment, secondary transformation and health risk assessment.

Field measurements of volatile organic compounds (VOCs) were conducted simultaneously at an urban site and one industrial park site in Beijing in summer. The VOCs concentrations were 94.3 ± 157.8 ppbv and 20.7 ± 8.9 ppbv for industrial and urban sites, respectively. Alkanes and aromatics were the major contributors to VOCs in industrial site, while oxygenated volatile organic compounds (OVOCs) contributed most in urban site. The most abundant VOC species were n-pentane and formaldehyde for industrial site and urban site, respectively. The calculated ozone formation potential (OFP) and OH loss rates (LOH) were 621.1 ± 1491.9 ppbv (industrial site), 102.9 ± 37.3 ppbv (urban site), 22.0 ± 39.0 s-1 (industrial site) and 5.3 ± 2.2 s-1 (urban site), respectively. Based on the positive matrix factorization (PMF) model, solvent utilization I (34.1 %), solvent utilization II (27.9 %), mixture combustion source (19.3 %), OVOCs related source (9.6 %) and biogenic source (9.1 %) were identified in the industrial site, while OVOCs related source (27.8 %), vehicle exhaust (22.1 %), solvent utilization (19.3 %), coal combustion (16.0 %) and biogenic source (14.8 %) were identified in the urban site. The results of O3-VOCs-NOx sensitivity indicated that O3 formation were respectively under the VOC-limited and NOx-limited conditions in Beijing urban and industrial regions. Additionally, aromatics accounted remarkable SOA formation ability both in the two sites, and SOA potentials of xylene, toluene and ethylbenzene as the indicator species for the solvent utilization in industrial site were remarkable higher than those obtained in urban regions. The hazard index values in the industrial and urban sites were 1.72 and 3.39, respectively, suggesting a high non-carcinogenic risks to the exposed population. Formaldehyde had the highest carcinogenic risks in the two sites, and the cumulative carcinogenic risks in the industrial site and urban site were 1.95 × 10-5 and 1.21 × 10-5, respectively.

[Accurate Identification of Pollution Sources in a Chemical Enterprise Based on a Distributed Multi-channel VOCs Online Monitoring Mass Spectrometry System].

A monitoring and traceability management system for unorganized emissions of volatile organic compounds (VOCs) in industrial parks has been established. This system uses distributed multi-channel mass spectrometry to continuously monitor multiple online monitoring points within the enterprise and the factory boundary to initially identify the source of unorganized emissions of VOCs. Based on online monitoring data, the system combined a positive matrix factorization (PMF) model and conditional bivariate probability function (CBPF) methods to accurately identify pollution sources of different scales in the park. The system was successfully applied to a pharmaceutical chemical factory in Taizhou Chemical Industry Park, and VOCs online monitoring was carried out for more than three months at 10 monitoring sites in the factory area. The sources of VOCs were analyzed using the PMF model, and the geographical location information of each pollution source factor was identified by the CBPF method. During the monitoring period, the contribution of chlorobenzene emissions and the number of early warnings were much higher than those of other species. Compared with that of other species, the frequency of abnormal emissions of butene was higher, and the frequency of abnormal emissions of toluene was lower. Among the top ten species, only chlorobenzene had significant concentration changes in different monitoring sites. Ambient VOCs in the plant mainly came from six sources:butene emission, toluene emission, chlorobenzene emission, solvent use, sulfur-related processes, and industrial production. Based on the CBPF results of each pollution source factor relative to the ten monitoring stations, the local pollution source and external pollution source in the plant were distinguished, and the specific location of the local pollution source and the transmission direction of the external pollution source were identified.

Source apportionment of PM2.5 in Seoul, South Korea and Beijing, China using dispersion normalized PMF.

East Asian countries experience severe air pollution owing to their rapid development and urbanization induced by substantial economic activities. South Korea and China are among the most polluted East Asian countries with high mass concentrations of PM2.5. Although the occurrence of transboundary air pollution among neighboring countries has been recognized for a long time, studies involving simultaneous ground-based PM2.5 monitoring and source apportionment in South Korea and China have not been conducted to date. This study performed simultaneous daily ground-based monitoring of PM2.5 in Seoul and Beijing from January to December 2019. The mass concentrations of PM2.5 and its major chemical components were analyzed simultaneously during 2019. Positive matrix factorization (PMF) as well as dispersion normalized PMF (DN-PMF) were utilized for the source apportionment of ambient PM2.5 at the two sites. 23 h average ventilation coefficients were applied for daily PM2.5 chemical constituents' data. Nine sources were identified at both sites. While secondary nitrate, secondary sulfate, mobile, oil combustion, biomass burning, soil, and aged sea salt were commonly found at both sites, industry/coal combustion and incinerator were identified only at Seoul and incinerator/industry and coal combustion were identified only at Beijing. Reduction of the meteorological influences were found in DN-PMF compare to C-PMF but the effects of DN on mobile source were reduced by averaging over the 23 h sampling period. The DN-PMF results showed that Secondary nitrate (Seoul: 25.5%; Beijing: 31.7%) and secondary sulfate (Seoul: 20.5%; Beijing: 17.6%) were most dominant contributors to PM2.5 at both sites. Decreasing secondary sulfate contributions and increasing secondary nitrate contributions were observed at both sites.

CEACAM1 Activation by CbpF-Expressing E. coli.

Recent studies on the oral, anaerobic, gram-negative bacterium Fusobacterium nucleatum revealed its presence and involvement in colorectal, esophageal and breast cancer. We previously demonstrated that F. nucleatum binds and activates the human inhibitory receptors TIGIT and CEACAM1 leading to inhibition of T and NK cell anti-tumor immunity. CEACAM1 was found to be bound and activated by the fusobacterial trimeric autotransporter adhesin CbpF. Here we report the generation of a recombinant E. coli expressing full-length CbpF that efficiently binds and activates CEACAM1.

Fusobacterium nucleatum CbpF Mediates Inhibition of T Cell Function Through CEACAM1 Activation.

F. nucleatum is an anaerobic bacterium that is associated with several tumor entities and promotes tumorigenesis. Recent evidence suggests that F. nucleatum binds the inhibitory receptor carcinoembryonic antigen cell adhesion molecule 1 (CEACAM1) via the trimeric autotransporter adhesin CbpF. However, whether this binding is functional or whether other fusobacterial trimeric autotransporter adhesins are involved in CEACAM1 activation is unknown. In this study, using F. nucleatum mutants lacking the type 5c trimeric autotransporter adhesins fvcA (CbpF), fvcB, fvcC, and fvcD, we show that F. nucleatum CbpF binds and activates CEACAM1 and also binds carcinoembryonic antigen (CEA), a tumor-associated protein. We further find that CEACAM antibodies directed against the CEACAM N-terminal domain block the CbpF-CEACAM1 interaction. In functional assays, we demonstrate CbpF-dependent inhibition of CD4+ T cell response. Thus, we characterize an immune evasion mechanism in which F. nucleatum uses its surface protein CbpF to inhibit T cell function by activating CEACAM1.

Characteristics and sources of volatile organic compounds during high ozone episodes: A case study at a site in the eastern Guanzhong Plain, China.

This study performed continuous measurements of 105 volatile organic compounds (VOCs) in Weinan in the eastern Guanzhong Plain from 1 July to September 19, 2019. Ozone (O3) episode and non-episode days were identified according to China Ambient Air Quality Standard, and the concentrations of total quantified VOCs (TVOCs) were 33.43 ± 13.64 ppbv and 29.13 ± 14.31 ppbv, respectively. During different O3 pollution episodes, alkanes comprised the highest proportion to TVOC concentrations, while alkenes contributed the most to ozone formation potential (OFP). In addition, O3 episode days were mainly caused by enhanced emissions of precursors and meteorological conditions favorable to O3 production. Based on Empirical Kinetic Modelling Approach (EKMA), the O3 formation in Weinan was found in the transitional regime, in which the synergistic reduction of VOCs and nitrogen oxide (NOx) would be more effective for O3 reduction. Eight sources were identified by positive matrix factorization (PMF) model, with natural gas (NG)/liquefied petroleum gas (LPG) usage as the most significant contributor to VOC concentration, followed by vehicle exhaust, biomass burning, solvent usage, fuel evaporation, rubber/plastic industrial emissions, biogenic source, and mixed industrial emissions. Furthermore, rubber/plastic industrial emissions, solvent usage, fuel evaporation, and vehicle exhaust were the most significant sources to O3 formation. Based on conditional bivariate probability function (CBPF), vehicle exhaust, fuel evaporation, and solvent usage were mainly local emissions, while other sources were mainly affected by regional transport. This study provides useful reference for research on the atmospheric photochemical formation of O3 and evidence for regional O3 reduction strategies.