VOC Concentrations Research Articles

Metal-organic frameworks based on pyrazolates for the selective and efficient capture of formaldehyde

Indoor air pollution is one of the major threads in developed countries, notably due to high concentrations of formaldehyde, a harmful molecule difficult to eliminate. Addressing this purification challenge while adhering to the principles of sustainable development requires the use of innovative, advanced sustainable materials. Here we show that by combining state-of-the-art spectroscopic techniques with density-functional theory molecular simulations, we have developed an advantageous mild chemisorption synergistic mechanism using porous metal (III or IV) pyrazole- di-carboxylate based metal-organic framework (MOF) to trap formaldehyde in a reversible manner, without incurring significant energy penalties for regeneration. A straightforward, environmentally friendly, and scalable synthesis protocol was established for the porous, water-stable aluminum pyrazole dicarboxylate known as Al-3.5-PDA or MOF-303, capable of functioning as a highly efficient and reusable filter. It demonstrates selectivity and high storage capacity for formaldehyde under conditions typical of severe indoor use, such as in housing or vehicle cockpits, including varying VOC mixtures and concentrations, humidity, and temperature, without any accidental release. Furthermore, we have successfully regenerated this sorbent using a simple domestic protocol, ensuring the material reusability for at least 10 cycles.

Statistical analysis of natural and mechanical ventilation performance in improving indoor air quality, thermal comfort, and perceived air quality in a healthcare facility

Ventilation strategies in healthcare facilities are mainly directed towards mechanical systems. Due to patients’ preferences or the necessity of terminal reheat/recool, Air Handler Units are often turned off or windows are opened when mechanical systems are active. This leads to poor IAQ, nosocomial infections, and energy loss. Besides, ventilation systems are not typically intended to optimize user satisfaction. Using field measurements in 140 spaces, survey studies, and statistical analysis, this study compares ventilation strategies in providing IAQ, thermal comfort, and Perceived Air Quality as an indicator of user satisfaction. 315 samples were collected for air velocity, air temperature, relative humidity, PAQ, odor intensity, and VOC concentrations. Lowest to highest pollutant concentrations were observed respectively in mechanical ventilation with two open windows, mechanical ventilation with one open window, natural ventilation with two open windows, mechanical ventilation with closed windows, natural ventilation with one open window, and nonventilated spaces. There was no evidence of an effect of ventilation strategies on environmental parameters and user satisfaction. Users’ thermal comfort and air quality satisfaction were not guaranteed even when ventilation rate, pollutant concentrations, and environmental parameters were within the permissible range. Findings support the efficient performance of natural ventilation in providing acceptable air quality.

SPME arrow-based extraction for enhanced targeted and untargeted urinary volatilomics

BackgroundVolatile organic compounds (VOCs) present in human urine are promising biomarkers for various health conditions and environmental exposures. However, their reliable detection is challenging due to the complexity of urinary matrices and the low concentrations of VOCs. Moreover, untargeted approaches present considerable challenges in terms of data interpretation, increasing the complexity of method development. Here we address these challenges by developing a new method that combines solid-phase microextraction (SPME) Arrow with gas chromatography-high resolution mass spectrometry (GC-HRMS), using a design of experiments (DOE) approach for targeted and untargeted compounds. This methodology, specifically tailored for SPME Arrow, represents a significant advancement in untargeted urinary analysis. ResultsThe method was developed based on targeted and untargeted outcomes, were ranking results focus on the highest response area of 11 spiked target VOCs representative of urinary volatilomics, and on identifying the maximum untargeted number of VOCs. The method was developed focusing on the highest response area of 11 spiked target VOCs representative of urinary volatilomics and identifying the maximum number of VOCs. A univariate method determined the optimal coating type, urine volume, and salt addition. Subsequently, a central composite design (CCD) DOE was used to determine ideal temperature, extraction, and incubation times. The best method obtained has an extraction time of 60 min at a temperature of 53 °C, with an SPME Arrow CAR/PDMS using 2 mL of urine, with 0.25 % w/v of NaCl and a pH of 2. Compared to conventional SPME fibers, the SPME Arrow showed improved extraction efficiency, detecting more VOCs. Finally, the enhanced method was successfully applied to urine samples from children exposed and non-exposed to tobacco smoke, identifying specific VOCs, like p-cymene and p-isopropenyl toluene related to tobacco exposure. SignificanceBy integrating both targeted and untargeted approaches, the developed method comprehensively captures the complexity of urinary metabolomics. This dual strategy ensures the precise identification of known compounds and the discovery of novel biomarkers, thereby providing a more complete metabolic profile. Such an approach is crucial for advancing in non-invasive diagnostics and environmental health studies, as it offers deeper insights into the intricate relationships between metabolic processes and various health conditions.

Novel Bacterial Consortium for Mitigation of Odor and Enhance Compost Maturation Rate of Municipal Solid Waste: A Step Toward a Greener Economy

Composting is an integral component of sustainable Municipal Solid Waste (MSW) management within the circular bio-economy platform. However, it faces challenges due to malodorous emissions that impact environmental and societal equilibrium. The present study aims to minimize odorous emissions and expedite compost maturation using a novel, efficient microbial consortium. Bacteria sourced from open dump sites in Sri Lanka were carefully screened based on concurrent enzyme production. Five developed consortia were tested for their performance in reducing malodors during the composting process of MSW. Consortium No. 5 (C5), comprised of Bacillus haynesii, Bacillus amyloliquefaciens, and Bacillus safensis, demonstrated outstanding performance with a significant (p < 0.05) reduction in odorous emissions. Additionally, consortium C5 exhibited impressive control over gas emissions, maintaining VOC, CH4, NH3, and H2S concentrations within ranges of 0.5-6 ppm, 0.5-0.8 ppm, 0.3-0.5 ppm, and 0.5-0.6 ppm, respectively, compared to control concentrations of 4.5-10.2 ppm, 0.5-5.5 ppm, 0.3-5.5 ppm, and 0.5-6.4 ppm, respectively. Additionally, comprehensive Electronic nose (E-nose) analysis substantiated C5’s efficiency in attenuating Methane-Aliphatic compounds, Sulfur and Aromatic compounds, along with low-polarity aromatic and alkane compounds, all with statistical significance (p < 0.05). Further, the developed consortium could reduce the composting time from 110 ± 10 days to 17 ± 3 days, offering a sustainable solution for global MSW management.

VOCs Concentration, SOA Formation Contribution and Festival Effects during Heavy Haze Event: A Case Study in Zhengzhou, Central China

VOCs Concentration, SOA Formation Contribution and Festival Effects during Heavy Haze Event: A Case Study in Zhengzhou, Central China

CHARACTERIZATION OF LEACHATES FROM UNCONTROLLED OPEN DUMPSITE IN AHIAEKE, ISIEKE AND NSUKWE UMUAHIA, ABIA STATE

This study aimed to characterize the chemical in the leachates from uncontrolled open dumpsite in Ahiaeke, Isieke and Nsukwe in Umuahia, Abia State. Air, soil and leachate samples were analysed using an absolute instrument system, AIS (Aerocet model 5315) and standard procedures to measure the concentration of SO4, NH3, O3, CO2, VOC, PM10, PM2.5, H2S and CO in the air and some selected physicochemical and heavy metal content. From the result, SO4 ranges from 0.02 - 0.19 mg/m3, NH3(1.11 - 14.05), O3(0.01 - 0.15), CO2(618.50 - 832.50), VOC (1889.50 - 6343.50), PM10(46.19 -751.50), PM2.5(14.03 - 344.72), H2S (0.02 - 5.91), CO (1.91 - 6.91 mg/m3),For leachate and soil analysis, pH ranges from 8.75 - 9.01, Potassium (2.04 - 6.93 mg/l),Iodine (1.24 - 7.86), Fluorine (0.32 - 31.96), Acidity (344.70 - 821.65), Magnesium (209.70 - 498.66), Nitrate (0.34 - 2.07), DO (1.95 - 6.82), COD (3181.29 - 19090.56), Phosphate (13.42 - 57.35), Boron (0.79 - 3.15), Ammonia (0.85 - 3.55), Lead (0.00 - 3.76 mg/kg),Mercury (0.12 - 0.88), Cadmium (0.21 - 1.49), Manganese (2.13 - 14.72) , Chromium (0.10 - 0.61), Nickel (2.14 - 8.12), Iron (1.13 - 6.28), Zinc (0.15 - 1.22),Barium (24.15- 172.02), Copper (1.18 - 9.56 mg/kg). In this study, concentration of all air parameters was higher at distance closer to the dumpsites. The level of ammonia, PM10, PM2.5 and some heavy metals exceeded WHO guidelines. Hence, the waste dumps were observed to be the major contributors of increase in chemical and heavy metal levels in the leachate.

Identification of response regulation governing ozone formation based on influential factors using a random forest approach

The pursuit of enhanced scientific, refined, and precise ozone and air quality control continues to pose significant challenges. Using data visualization techniques and random forest (RF) algorithms, the temporal distribution of atmospheric pollutants and the interrelationship between O3 concentration and its influential factors were investigated with one-year monitoring data in Deqing county in 2021. The local atmospheric conditions predominantly belonged to NOx-sensitive and transition zone. Extremely high O3 concentration were primarily observed when temperatures (T) exceeded 30 °C, with relative humidity (RH) ranging between 30 and 60 %. NO2, RH and T were identified as the top 3 important factors, and O3 concentration have stronger linearly relationship to RH and T, while stronger nonlinearly relationship to NO2. By employing an optimized RF model, controlling consistent mild and high reaction atmospheric conditions, the O3 concentration response to the change of individual influencing factors was acquired. The O3 concentration increased and then decreased in response to the increasing NO2 concentration, displaying a characteristic inflection point at 10 μg m−3. More reactive radicals produced at higher VOCs concentration and continuing NOx cycle at lower NO2 concentration, resulting in the acceleration in the direction of producing more O3. Therefore, the significant different O3 response to variation of VOCs and NOx concentration between mild and high reaction atmospheric conditions, as well as the existing of oxidant elevation should be considered in local air quality control. This study demonstrates the efficacy of ML methods in simulating nonlinear response of O3, supports the understanding of local O3 formation and quick guidance for precise local O3 pollution control and the related strategies.

Air quality assessment of poultry and swine houses in Chonburi Province

ABSTRACT The increased consumption of animal products has led to a proliferation of animal husbandry operations, particularly in agricultural countries. Animal husbandry facilities or livestock farming directly impact the physical, chemical, and biological aspects of the environment, giving rise to various issues such as odors, contamination of water and air sources with pathogens, and potential contamination of meat products originating from these facilities. This research aims to assess the impacts on the physical (temperature, relative humidity and air velocity), chemical (carbon dioxide, total volatile organic compounds and particulate matter), and biological air quality assessment (amount and type of bioaerosols) aspects resulting from pig and poultry farming. The findings will serve as valuable data for managing and addressing these aforementioned issues. It was found that both in poultry and swine houses generated total suspended particles (TSP) and PM10 (Particulate Matter with a diameter of 10 µm or less). Analysis of poultry house exhaust revealed elevated concentrations of TSP and PM10 exceeding established health benchmarks. Chickens tend to produce a higher concentration of VOCs (2.07 ± 0.57 ppm) compared to swine (0.82 ± 0.53 ppm). Staphylococcus epidermidis was predominant bacteria in both swine and poultry houses while Cladosporium sp was the most prevalent fungi in poultry houses. These results in this study are very useful for developing targeted mitigation strategies, products, devices to address specific pollutants produced by each type of livestock, reducing overall environmental impact and improving air quality within and around animal husbandry facilities. Implications: This research highlights how the growing demand for meat is affecting the environment, especially in farming areas. By studying the effects of pig and poultry farming on things like air and water quality, the study shows the challenges these farms pose, like bad smells and pollution. They found that both types of farms release a lot of tiny particles and smelly chemicals into the air, but there are differences between them. Understanding these findings can help us develop ways to reduce the pollution from these farms and make the air cleaner for everyone.

Emission characteristics of volatile organic compounds from consumer spray products based on product type, spray method, and distance

Consumer spray products (CSPs) are widely used in daily life, yet it is challenging to find products that fully disclose all components posing health risks. Existing studies primarily focus on product components or VOC quantities emitted during use. Therefore, this study aimed to measure the VOC concentrations emitted by CSPs at varying distances. 47 CSPs available in the Korean market were selected, spanning three spray groups: antiseptics/insecticides (11), aromatic deodorants (16), and coating/polishing agents (20). VOC in air samples were collected using Tenax TA tube at a distance of 1 and 3 m from the sprayed CSPs and then analyzed by thermal desorption–gas chromatography–mass spectrometry system. Discrepancies were found between labeled and actual product components. Aromatic deodorants exhibited the highest total VOCs (TVOCs), while antiseptic/insecticide sprays exhibited the lowest. In the antiseptic/insecticide group and coating/polishing agent group, benzene as a propellant had a maximum concentration (30.9 ± 25.6 ppb), and as trigger, its concentration was 33.7 ± 30.7 ppb. Quantitative analysis using advanced analytical instruments only explained 26.1 ± 20.4% of toluene-equivalent TVOCs, suggesting the presence of additional substances. Concentrations varied by distance due to substance volatility and usage. Maintaining a distance of at least 1 m from CSPs is recommended.

Characterising indoor air quality in private vehicle cabins under unprecedented traffic conditions during COVID-19 lockdown

Air pollution negatively impacts human health, yet it is rarely studied inside vehicles. This study aimed to characterise indoor air quality (IAQ) in vehicle cabins, focusing on the concentrations of key pollutants and the influence of various factors on IAQ including vehicle-specific characteristics (self-pollution), traffic intensity, ventilation type, and enclosed spaces like parking garages. It addressed a significant literature gap by using real-world driving data, a multipollutant approach, real-time monitoring, and a detailed log of influencing factors. Additionally, part of the study was conducted during the COVID-19 lockdown, providing an unprecedented opportunity to gather real-world data with reduced traffic emissions. Forty trips were conducted with four diesel vehicles of different ages and emission standards. Concentrations of VOCs, CO, CO₂, NO₂, SO₂, O₃, and PM₁, PM₂.₅, PM₁₀, and TSP were monitored, alongside detailed logbook entries. This study evidenced the formation of O₃ inside vehicle cabins under conditions of high NO₂ and/or VOC concentrations and direct sunlight, a phenomenon not previously reported. Results also showed that IAQ inside vehicle cabins depended largely on vehicle-specific factors, the surrounding environment, and indoor-outdoor air exchange. CO, NO₂, SO₂, and PM levels varied mainly with the external environment and air exchange, while CO₂ levels were influenced primarily by ventilation settings. The concentrations of certain pollutants exceeded reference levels for indoor environments, potentially posing health risks to occupants. Further research is needed to study the pioneer evidence of O3 formation and to develop a comprehensive health risk assessment, thereby contributing to developing specific IAQ guidelines for vehicles.

Experimental validation of adsorption filter model under dynamic VOC concentrations: Prediction of long-term efficiency

Experimental validation of adsorption filter model under dynamic VOC concentrations: Prediction of long-term efficiency

Air Quality Assessment in Petroleum Flow Station: A Case Study of Oredo Flow Station

Air quality is a vital aspect of environmental health and a key determinant of human wellbeing. This study was carried out to assess air quality parameters and noise levels around Oredo Flow Station in Edo State, Nigeria. Parameters measured during the study were temperature, suspended particulate matter (SPM), sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and noise. Each parameter was measured using appropriate equipment. Measurements were done at three points: Point A (300m from the flare site), Point B (200m from the flare site) and Point C (100m from the flare site) and in triplicates with mean values recorded. The result showed that temperature ranged from 28.60±0.3°C to 29.22±0.3°C; SPM ranged from 17.16±3.9 μg/m3 to 60.74±14.6 μg/m3 ; SO2 ranged from 0.01±0.0 ppm to 0.03±0.0 ppm; CO concentrations ranged from 0.03±0.0 ppm to 4.45±1.3 ppm; and VOC concentrations ranged from 0.01±0.0 ppm to 1.87±0.2 ppm. The mean noise levels ranged from 56.24±2.8dB to 87.78±2.8dB. Time-weighted average noise level ranged from 56.2dB to 87.8dB. For all parameters, there was a general decreasing trend in values as distance to the flare site increased indicating that air quality parameters in the area were influenced by gas flaring activities. Recommendations made include routine air quality monitoring, alternative use of natural gas and implementing noise control measures.

Nutrient composition, fermentation characteristics and mass balance of press juice and press cake obtained from biorefining of grass‐clover and red clover silage

AbstractBiorefining is seen as a potential method to produce protein‐rich feed for monogastric farm animals from grassland, which does not compete with human nutrition. Therefore, a new biorefinery facility was constructed and tested in this experiment by using silages from grass clover mixture and red clover. After biorefining, press juice was stored for further use while press cake was re‐ensiled. Samples from silage, press juice, fresh press cake and re‐ensiled press cake were analysed for nutrient composition, fermentation parameters, amino acids (AA) and biogenic amines (BA) concentrations. Furthermore, digestibility of silage and re‐ensiled press cake was tested in wethers. We found that press juice contained about 205 g crude protein (CP), more than 180 g crude ash and more than 130 g volatile organic compounds (VOC, all values per kg dry matter [DM]). Furthermore, press juice had an unfavourable AA ratio for use as a monogastric feed (methionine and cysteine were reduced). Forage type hardly affected nutritive value of press juice. Re‐ensiling of press cake was successful as a sufficient decrease of pH and VOC concentration was observed. Press cake had 26–36 g/kg DM lower CP content and 0.77–1.12 MJ/kg DM lower metabolisable energy content than silage with greater differences in red clover than in grass clover mixture. Press juice can be used as feed in monogastric animals, but its use is limited due to its low CP content and unfavourable AA profile. Press cake could be an appropriate feed for ruminants, especially dry cows or heifers.

Development of nitrogen-rich hierarchical porous carbon for high selective adsorption of methanol in multi-VOCs waste gas recovery processes

Methanol is a typical polar volatile organic compound that has been commonly used as a solvent in industrial processes and is considered as an important resource. It often appears with aromatic compounds in practical application scenarios. Conducting methanol and aromatic compounds recycle technology can provide us with a sustainable carbon source for fuels and materials well beyond the fleeting fossil fuel era. Post-synthesis modification (PSM) has been utilized to incorporate 3-amino-1,2,4-triazole (Atz) into ZIF-8, thereby enabling the derivation of mesopore structure and enhancement of nitrogen content in ZIF-8 derived carbon. With this method the obtained carbon exhibited a highly polarizable micro-mesoporous structure, resulting in high adsorption capacity for methanol adsorption at low concentrations. The experimental results showed that the VOCs adsorption on porous carbon is primarily dictated by its microporous structure at high pressure, and predominantly governed by the presence of nitrogen functional groups and the micro-mesoporous properties at low pressure. DFT theoretical analysis also showed that nitrogen functional group can improve the absorption capacity of methanol by adsorbents through changing the electron distribution and surface polarity of carbon-based materials. Finally, based on the emission properties that is low concentration and high volume of VOCs waste gas in industrial application, ZIF8-24-700 and BACs-36 materials (Wang et al., 2023) were used to further prove the feasibility of this technology under low VOCs concentration, which achieve recovery rates of 99 % for toluene and 95 % for methanol, respectively.

A method for testing the gas-phase air cleaners using sensory assessments of air quality

Present standards prescribe chemical analyses for testing the performance of gas-phase air cleaners. As a part of IEA Annex 78, this study examined a prototype method for testing gas-phase air cleaners based on sensory evaluations of air quality. Four common gas-phase air cleaners were tested using the proposed method. The testing consisted of two phases: Phase 1 ensured that air cleaners had no negative effect on air quality, and Phase 2 provided a detailed characterisation of the removal efficiency of air cleaners. Air cleaners were tested in experimental rooms called field laboratories, and pollution sources comprised of building materials and humans. Thirty-one panellists were recruited. They rated the acceptability of air quality and odour intensity immediately upon entering the rooms and of the air extracted from them and presented in diffusers. Chemical measurements were made as well only in Phase 2. The operation of air cleaners reduced concentrations of VOCs regardless of the pollution source; the perceived air quality was only improved when the pollution source was building materials,supporting the necessity of inclusion of sensory ratings. The results also confirmed that comprehensive testing of air cleaners in Phase 2 should only be performed once it is documented that air cleaners positively reduce pollution exposures in Phase 1. The study followed methodologies proposed by the ISO 16000-44 standard, so the results validate and support this standard. The tests of different air cleaner configurations and the round-robin test are recommended to advance the methodology proposed and examined in the present study.

Volatile Organic Compound-Based Predictive Modeling of Smoke Taint in Wine.

Smoke taint in wine has become a critical issue in the wine industry due to its significant negative impact on wine quality. Data-driven approaches including univariate analysis and predictive modeling are applied to a data set containing concentrations of 20 VOCs in 48 grape samples and 56 corresponding wine samples with a taster-evaluated smoke taint index. The resulting models for predicting the smoke taint index of wines are highly predictive when using as inputs VOC concentrations after log conversion in both grapes and wines (Pearson Correlation Coefficient PCC = 0.82; R2 = 0.68) and less so when only grape VOCs are used (Pearson Correlation Coefficient PCC = 0.76; R2 = 0.56), and the classification models also show the capacity for detecting smoke-tainted wines using both wine and grape VOC concentrations (Recall = 0.76; Precision = 0.92; F1 = 0.82) or using only grape VOC concentrations (Recall = 0.74; Precision = 0.92; F1 = 0.80). The performance of the predictive model shows the possibility of predicting the smoke taint index of the wine and grape samples before fermentation. The corresponding code of data analysis and predictive modeling of smoke taint in wine is available in the Github repository (https://github.com/IBPA/smoke_taint_prediction).

Simulation of inhibition and targeted adsorption of rubberized asphalt VOCs by UiO-66 based on molecular dynamics

The adsorption kinetics and molecular dynamics were modeled based on the structure-assembled technique of MOFs, conjugate bonding and targeted adsorption of characteristic pollutants. The mechanism of interaction between UiO-66 and rubber-modified asphalt (RMA) was simulated. The adsorption characteristics between UiO-66 and five class I carcinogens, high concentration VOCs components were simulated by Sorption module. The conjugate bonding and targeting adsorption mechanism between UiO-66 on VOCs was elucidated by combining the GC-MS analysis data. The results were showed that the interaction between UiO-66 and rubberized asphalt was influenced by the number of molecules, contact area, spatial site resistance, and active groups. The content of UiO-66 should be controlled below 3.31 %. The small size of vinyl chloride molecules made it easier to enter the pore structure of UiO-66 with a maximum inhibition rate of 91.75 %. The 1,2-dichloropropane has a large molecular size, spatial site resistance, non-conjugation effect, and the smallest adsorption amount of 72.2 %. The total concentration of VOCs was decreased from 726.38 mg/cm3 to 166.12 mg/cm3, a reduction of 77.13 %. The adsorption of UiO-66 on VOCs molecules was affected by molecular size, carbon chain length, conjugation effect, polarity and other factors. VOCs and UiO-66 form a p-d, d-d π conjugation effect based on the conjugated structure, targeting adsorption within the benzene ring of the organic framework.

Effect of odour-less additive on asphalt flue gas emission and performance of asphalt and asphalt mixture

In this study odour-less additive were added to modify the asphalt properties in order to reduce the asphalt flue gas produced during the application process.Three different brands of No. 70 asphalt were chosen as the base asphalt and different dosages of odour-less additive were added to prepare the odour-less asphalt. The effect of the odour-less additive on VOCs, CO, H2S, NO and SO2 were tested by a portable detector to determine the optimal dosage. Then, a gas chromatography was adopted to further analyze the effect of odour-less additive on the compounds in the VOCs. SEM was used to investigate the mechanism of odour-less asphalt. Finally, the effect of odour-less additive on the basic performance of asphalt and on the road performance of asphalt mixtures were analyzed. Research results indicate that the optimal dosage of odour-less additive for No.70 asphalt is 0.04%; The odour-less ratio of the total emissions of the five gases can reach up to 52.9%; Crude oil and the processing technology exert relative huge influence on the concentration of VOCs and the higher the concentration of the compound, the better the odour-less effect, and the odour-less ratio of ethanethiol can reach up to 73.7%. The odour-less asphalt inhibits the volatilization of small molecular substances by increasing the specific surface area of asphalt and improving the inter-molecular cohesion, thereby achieving the purpose of reducing asphalt flue gas; odour-less additive yields little effect on the performance of asphalt and asphalt mixtures.

Release characteristics of volatile organic compounds at residential garbage collection points: a case study of Hangzhou, China.

With the implementation of garbage classification, perishable waste has become increasingly concentrated. This has led to a significant change in the VOC release characteristics at residential garbage collection points, posing a potential risk with unknown characteristics. This study investigated the release characteristics, odor pollution, and health risks of VOCs at garbage collection points under different classification effectiveness, seasons, garbage drop-off periods, and garbage collection point types. The results showed that the average concentration of VOCs released from the garbage sorting collection points (SPs) was 341.43 ± 261.16 μg/m3, and oxygenated compounds (e.g., ethyl acetate and acetone) were the main VOC components. The VOC concentration increased as the community classification effectiveness improved, and it was higher in summer (followed by spring, autumn, and winter). Moreover, the VOC concentrations were higher in the evenings than in the mornings and at centralized garbage collection points (CPs) than at SPs. Further, odor activity value (OAV) assessments indicated that acrolein, styrene, and ethyl acetate were the critical odorous components, with an average OAV of 0.87 ± 0.85, implying marginal odor pollution in some communities. Health risk assessments further revealed that trichloroethylene, benzene, and chlorotoluene were the critical health risk substances, with an average carcinogenic risk (CR) value of 10-6-10-4, and a non-carcinogenic risk (HI) value < 1. These results indicated that HIs were acceptable, but potential CRs existed in the communities. Therefore, VOC pollution prevention and control measures should be urgently strengthened at the garbage collection points in high pollution risk scenarios.

Investigation on ozone formation mechanism and control strategy of VOCs in petrochemical region: Insights from chemical reactivity and photochemical loss

To investigate disparities in VOCs pollution characteristics, O3 generation activity, and source apportionment outcomes resulting from photooxidation, online monitoring of 106 VOCs was conducted in Jinshan District, Shanghai from April to October 2020. The observed VOCs concentrations (VOCs–obs) were 47.1 ppbv and 59.2 ppbv for clear days (CD) and O3-polluted days (OPD), respectively. The increase in daytime concentrations of alkenes is a significant factor contributing to the enhanced atmospheric photochemical activity during the OPD period, corroborated by VOCs-loss, ozone formation potential (OFP), propy-equiv concentration, and LOH. The sensitivity analysis of O3–NOx–VOCs indicated that O3 formation was in a transitional regime towards NOx-limited conditions. The results of positive matrix factorization (PMF) demonstrated that refining and petrochemicals (20.8–25.0 %), along with oil and gas evaporation (15.6–16.7 %) were the main sources of VOCs concentrations. Notably, source apportionment based on VOCs–obs underestimated the contributions from sources of reactive components. It is worth highlighting that the sunlight impact & background source was identified as the major contributor to LOH (21.6 %) and OFP (25.3 %), signifying its significant role in O3 formation. This study reiterates the importance of controlling reactive VOC components to mitigate O3 pollution and provides a scientific foundation for air quality management, with emphasis on priority species and controlling sources.