Impact of industrial activities on atmospheric volatile organic compounds in Sihwa-Banwol, the largest industrial area in South Korea

Enhancement of light-driven adsorption efficacy through the integration of NiCo2O4 onto CeO2 for photo-ozone catalytic degradation of toluene

In this study, a co-catalytic route was explored to enhance the photo-ozone catalytic degradation of volatile organic compounds (VOCs). NiCo2O4 was loaded onto the surface of CeO2 nanoparticles to create a composite catalyst (10%NiCo2O4/CeO2). The integration of NiCo2O4 onto CeO2 enhanced the interaction between the catalyst and toluene, a representative VOC, resulting in significantly increased toluene adsorption without a corresponding increase in specific surface area. This integration also improved the utilization of charge carriers and conversion of ozone to O2-. Under visible light irradiation, H2O accumulated charge carriers at 10%NiCo2O4/CeO2's surface, facilitating both ozone utilization and toluene adsorption. Another benefit of NiCo2O4 loading was its ability to enhance the conversion efficiency of solar energy. Consequently, the toluene removal and mineralization efficiencies of 10%NiCo2O4/CeO2 were enhanced by 182% and 309% compared to CeO2, and by 201% and 357% compared to NiCo2O4, respectively. Overall, this study demonstrated a novel co-catalyst design strategy for enhancing the photo-ozone catalytic degradation of VOCs.

Ambient air pollution and the risk of neurological diseases in residential areas near multi-purposed industrial complexes of korea: A population-based cohort study

Emerging evidence suggest that long-term exposure to air pollution may induce adverse effects on the central nervous system. However, no study explored the associations in large industrial complex (IC) areas which are one of the major contributors to air pollution. Therefore, we aimed to investigate the pollution status and the association between residential proximity and incidence of neurological diseases near two major ICs characterized as multi-purposed ICs in Korea. A retrospective cohort of residents near the ICs was constructed using Korea's health insurance data and monitored from 2008 to 2019. Emission amounts of the ICs and the air pollution status in the nearby (exposed) and remote (control) area were evaluated using data from national regulatory networks, and hazard ratios (HRs) and 95% confidence intervals (CIs) for neurological diseases of the exposed group compared to the control group were calculated using Cox proportional regression models. Overall, the complexes emitted large amounts of VOCs, CO, NOx, and PM10, and annual levels of ambient PM (2.5, 10), gaseous substances (NO₂, SO₂), VOCs and PAHs were higher in the exposed area compared to the control and/or the national average. The risk of inflammatory disease of the CNS (G00-09) and extrapyramidal and movement disorders (G20-26) were higher in the exposed area with a HR (95% CI) of 1.36 (1.10-1.68) and 1.33 (1.27-1.39) respectively. Among the subclasses, other extrapyramidal and movement disorders (G25) and epilepsy (G40) were associated with higher risks in the exposed area (HR (95%CI): 1.11 (1.04-1.18), 1.08 (1.00-1.16)) after adjusting for potential confounders. These results suggest that people living near ICs are more likely to be exposed to higher air pollution levels and have higher risks of developing several neurological disorders. However, further epidemiological studies in these industrial areas supplemented with other indicators of environmental exposure and control of other diverse factors are warranted.

Graphene Oxide Thin Films for Detection and Quantification of Industrially Relevant Alcohols and Acetic Acid

Industrial environments are frequently composed of potentially toxic and hazardous compounds. Volatile organic compounds (VOCs) are one of the most concerning categories of analytes commonly existent in the indoor air of factories' facilities. The sources of VOCs in the industrial context are abundant and a vast range of human health conditions and pathologies are known to be caused by both short- and long-term exposures. Hence, accurate and rapid detection, identification, and quantification of VOCs in industrial environments are mandatory issues. This work demonstrates that graphene oxide (GO) thin films can be used to distinguish acetic acid, ethanol, isopropanol, and methanol, major analytes for the field of industrial air quality, using the electronic nose concept based on impedance spectra measurements. The data were treated by principal component analysis. The sensor consists of polyethyleneimine (PEI) and GO layer-by-layer films deposited on ceramic supports coated with gold interdigitated electrodes. The electrical characterization of this sensor in the presence of the VOCs allows the identification of acetic acid in the concentration range from 24 to 120 ppm, and of ethanol, isopropanol, and methanol in a concentration range from 18 to 90 ppm, respectively. Moreover, the results allows the quantification of acetic acid, ethanol, and isopropanol concentrations with sensitivity values of (3.03±0.12)∗104, (-1.15±0.19)∗104, and (-1.1±0.50)∗104 mL^-1, respectively. The resolution of this sensor to detect the different analytes is lower than 0.04 ppm, which means it is an interesting sensor for use as an electronic nose for the detection of VOCs.

Characteristics of volatile organic compounds in the metropolitan city of Seoul, South Korea: Diurnal variation, source identification, secondary formation of organic aerosol, and health risk

Atmospheric volatile organic compounds (VOCs) in Seoul, the capital of South Korea, have attracted increased attention owing to their emission, secondary formation, and human health risk. In this study, we collected 24 hourly samples once a month at an urban site in Seoul for a year (a total of 288 samples) using a sequential tube sampler. Analysis results revealed that toluene (9.08 ± 8.99 μg/m³) exhibited the highest annual mean concentration, followed by ethyl acetate (5.55 ± 9.09 μg/m³), m,p-xylenes (2.79 ± 4.57 μg/m³), benzene (2.37 ± 1.55 μg/m³), ethylbenzene (1.81 ± 2.27 μg/m³), and o-xylene (0.91 ± 1.47 μg/m³), indicating that these compounds accounted for 77.8-85.6% of the seasonal mean concentrations of the total (Σ₅₉) VOCs. The concentrations of the Σ₅₉ VOCs were statistically higher in spring and winter than in summer and fall because of meteorological conditions, and the concentrations of individual VOCs were higher during the daytime than nighttime owing to higher human activities during the daytime. The conditional bivariate probability function and concentration weighted trajectory analysis results suggested that domestic effects (e.g., vehicular exhaust and solvents) exhibited a dominant effect on the presence of VOCs in Seoul, as well as long-range atmospheric transport of VOCs. Further, the most important secondary organic aerosol formation potential (SOAFP) compounds included benzene, toluene, ethylbenzene, and m,p,o-xylenes, and the total SOAFP of nine VOCs accounted for 5-29% of the seasonal mean PM_2.5 concentrations. The cancer and non-cancer risks of the selected VOCs were below the tolerable (1 × 10^-4) and acceptable (Hazard quotient: HQ < 1) levels, respectively. Overall, this study highlighted the feasibility of the sequential sampling of VOCs and hybrid receptor modeling to further understand the source-receptor relationship of VOCs.

The concentration of BTEX in selected urban areas of Malaysia during the COVID-19 pandemic lockdown

Volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene and xylene (BTEX) are air pollutants that harm human health. This study aims to identify BTEX concentrations before the lockdown known as the Movement Control Order was imposed (BMCO), during the implementation of the Movement Control Order (MCO), and then during the Conditional Movement Control Order (CMCO). These orders were introduced during the COVID-19 pandemic in Malaysia. The study utilised data measured by the continuous monitoring of BTEX using online gas chromatography instruments located at three urban area stations. The results showed that the BTEX concentrations reduced by between -38% and -46% during the MCO compared to the BMCO period. The reduction of human mobility during the MCO and CMCO influenced the lower BTEX concentrations recorded at a station within the Kuala Lumpur area. The results of the BTEX diagnostic ratios and principal component analysis showed that the major source of BTEX, especially during the BMCO and CMCO periods, was motor vehicle emissions. Further investigation, using correlation analysis and polar plots, showed that the BTEX concentrations were also influenced by meteorological variables such as wind speed, air temperature and relative humidity.

An Inversion Framework for Optimizing Non-Methane VOC Emissions Using Remote Sensing and Airborne Observations in Northeast Asia During the KORUS-AQ Field Campaign

We aim to reduce uncertainties in CH₂O and other volatile organic carbon (VOC) emissions through assimilation of remote sensing data. We first update a three-dimensional (3D) chemical transport model, GEOS-Chem with the KORUSv5 anthropogenic emission inventory and inclusion of chemistry for aromatics and C₂H₄, leading to modest improvements in simulation of CH₂O (normalized mean bias (NMB): -0.57 to -0.51) and O₃ (NMB: -0.25 to -0.19) compared against DC-8 aircraft measurements during KORUS-AQ; the mixing ratio of most VOC species are still underestimated. We next constrain VOC emissions using CH₂O observations from two satellites (OMI and OMPS) and the DC-8 aircraft during KORUS-AQ. To utilize data from multiple platforms in a consistent manner, we develop a two-step Hybrid Iterative Finite Difference Mass Balance and four-dimensional variational inversion system (Hybrid IFDMB-4DVar). The total VOC emissions throughout the domain increase by 47%. The a posteriori simulation reduces the low biases of simulated CH₂O (NMB: -0.51 to -0.15), O₃ (NMB: -0.19 to -0.06), and VOCs. Alterations to the VOC speciation from the 4D-Var inversion include increases of biogenic isoprene emissions in Korea and anthropogenic emissions in Eastern China. We find that the IFDMB method alone is adequate for reducing the low biases of VOCs in general; however, 4D-Var provides additional refinement of high-resolution emissions and their speciation. Defining reasonable emission errors and choosing optimal regularization parameters are crucial parts of the inversion system. Our new hybrid inversion framework can be applied for future air quality campaigns, maximizing the value of integrating measurements from current and upcoming geostationary satellite instruments.

VOCs characteristics and their ozone and SOA formation potentials in autumn and winter at Weinan, China

Frequent ozone and fine particulate matter (PM_2.5) pollution have been occurring in the Guanzhong Plain in China. To effectively control the tropospheric ozone and PM_2.5 pollution, this study performed measurements of 102 VOCs species from Sep.19-25 (autumn) and Nov.27-Dec. 8, 2017 (winter) at Weinan in the central Guanzhong Plain. The total volatile organic compounds (TVOCs) concentrations were 95.8 ± 30.6 ppbv in autumn and 74.4 ± 37.1 ppbv in winter. Alkanes were the most abundant group in both of autumn and winter, accounting for 33.5% and 39.6% of TVOCs concentrations, respectively. The levels of aromatics and oxygenated VOCs were higher in autumn than in winter, mainly due to changes in industrial activities and combustion strength. Photochemical reactivities and ozone formation potentials (OFPs) of VOCs were calculated by applying the OH radical loss rate (L_OH) and maximum incremental reactivity (MIR) method, respectively. Results showed that Alkenes and aromatics were the key VOCs in term ozone formation in Weinan, which together contributed 59.6% ̶ 65.3% to the total L_OH and OFP. Secondary organic aerosol formation potentials (SOAFP) of the measured VOCs were investigated by employing the fractional aerosol coefficient (FAC) method. Aromatics contributed 94.9% and 96.2% to the total SOAFP in autumn and winter, respectively. The regional transport effects on VOCs and ozone formation were investigated by using trajectory analysis and potential source contribution function (PSCF). Results showed that regional anthropogenic sources from industrial cities (Tongchuan, Xi'an city) and biogenic sources from Qinling Mountain influenced VOCs levels and OFP at Weinan. Future studies need to emphasize on meteorological factors and sources that impact on VOCs concentrations in Weinan.

Ambient volatile organic compounds in tropical environments: Potential sources, composition and impacts - A review

Volatile organic compounds (VOCs) are widely recognized to affect the environment and human health. This review provides a comprehensive presentation of the types and levels of VOCs, their sources and potential effects on human health and the environment based on past and current observations made at tropical sites. Isoprene was found to be the dominant biogenic VOC in the tropics. Tropical broad leaf evergreen trees are the main emitters of isoprene, making up more than 70% of the total emissions. The VOCs found in the tropical remote marine atmosphere included isoprene (>100 ppt), dimethyl sulfide (≤100 ppt) and halocarbons, i.e. bromoform (≤8.4 ppt), dibromomethane (≤2.7 ppt) and dibromochloromethane (≤1.6 ppt). VOCs such as benzene, toluene, ethylbenzene and xylene (BTEX) are the most monitored anthropogenic VOCs and are present mainly due to motor vehicles emissions. Additionally, biomass burning contributes to anthropogenic VOCs, especially high molecular weight VOCs, e.g. methanol and acetonitrile. The relative contributions of VOC species to ozone are determined through the level of the Ozone Formation Potential (OFP) of different species. Emissions of VOCs (e.g. very short-lived halogenated gases) in the tropics are capable of contributing to stratospheric ozone depletion. BTEX has been identified as the main types of VOCs that are associated with the cancer risk in urban areas in tropical regions. Finally, future studies related to VOCs in the tropics and their associated health risks are needed to address these concerns.