Benzene Concentrations Research Articles

Polymerization of Sodium 4-Styrenesulfonate Inside Filter Paper via Dielectric Barrier Discharge Plasma

This work explores the polymerization of sodium 4-styrenesulfonate (NaSS) inside filter paper using dielectric barrier discharge (DBD) plasma and its application in the environmental field. The plasma-based technique, performed under mild conditions, solves common problems associated with conventional polymerization inside porous materials. The polymerization process was monitored using Fourier-transform infrared (FTIR) spectroscopy, which confirmed the consumption of double bonds, particularly in NaSS samples containing the optimal concentration of crosslinker divinyl benzene (DVB) (0.25% wt). Our work demonstrates the effectiveness and promise of DBD plasma as a substitute polymerization approach, especially for those in porous materials.

Health Risk Assessment of Ambient Air Benzene Among Primary School Children in Urban and Rural Areas in Johor, Malaysia

Introduction: It is a fact that children are vulnerable, and are at risk from benzene, a volatile, carcinogenic organic compound. The aim of our study is to determine the levels of ambient air benzene and examine the non-carcinogenic and carcinogenic risks involved Methods: A cross-sectional study was conducted in two urban and two rural primary schools in Johor, Malaysia. Benzene concentrations were measured using BUCK Libra L-4 pumps and analyzed in the gas chromatography-mass spectrometry (GC-MS). Data were collected from 334 10-12 year old children, to calculate the exposure levels based on their body weights and heights. The hazard quotient (HQ) served to evaluate the non-carcinogenic risks, whereas the lifetime cancer risk (LCR) was determined with the aid of the United States Environmental Protection Agency (USEPA). Results and Discussion: Benzene concentrations were higher in rural than urban areas, surpassing the European Union (EU) standard of 5 μg/m³. It was also established that the highest average levels recorded were 6.89 ± 6.68 μg/m³. The HQ values, nonetheless, had indicated no immediate non-carcinogenic risk, while LCR estimates were found to be within a tolerable range across all sites. Findings showed that although the immediate risk from benzene exposure is low, long-term exposure still poses a significant cancer risk to children; even low levels of chronic exposure can heighten the likelihood of children to develop cancers. Conclusion: This study has produced a revelation that there are elevated benzene levels in rural areas in Johor. Despite the low, immediate non-carcinogenic risks, further investigation on the potential for long-term cancer risks is warranted. These risks can be addressed by conducting stricter air quality monitoring, enhancing vehicle emission standards, and introducing educational programs that can raise awareness about benzene exposure.

Mediating effect of oxidative stress on blood pressure elevation in workers exposed to low concentrations of benzene, toluene, and xylene (BTX).

To investigate the mediating effect of oxidative stress on the relationships between low-concentration benzene, toluene, and xylene (BTX) exposure and blood pressure in workers. A cross-sectional study involving 841 workers from a petroleum refining enterprise in Hainan, China, was conducted. Among the workers, 615 workers were exposed to low-concentration BTX, and 216 workers were in the control group. S-phenylmercapturic acid (S-PMA), hippuric acid (HA), and methyl hippuric acid (MHA, including the three isomers 2-MHA, 3-MHA, and 4-MHA) were measured in the urine of workers via high-performance liquid chromatography‒tandem triple quadrupole mass spectrometry to assess the internal BTX burden. Oxidative stress markers, blood pressure, and their correlations were analysed in both the exposed and control groups of workers. Mediation analysis was used to investigate the potential role of oxidative stress in the relationship between BTX exposure and blood pressure. The concentrations of BTX at the sampling points in the enterprise were all below the limits stipulated in China's national occupational health criteria: occupational exposure limits for hazardous agents. With respect to the internal burden of BTX, the concentrations of the benzene metabolite S-PMA, the toluene metabolite HA, and the xylene metabolites 3-MHA and 4-MHA in the urine samples in the exposure group were greater than those in the control group (P < 0.05). The correlation analysis results revealed that the concentration of the benzene metabolite S-PMA in workers' urine was positively correlated with diastolic blood pressure (DBP) (r = 0.265, P < 0.05). Compared with those in the control group, DBP was greater (β = 1.363, 95% CI 0.088 -2.639), serum superoxide dismutase (SOD) activity was lower (β = - 0.037, 95% CI - 0.060 to - 0.013), and the serum malondialdehyde (MDA) concentration was greater (β = 0.066, 95% CI 0.022-0.110) in the exposure group. Partial correlation analysis revealed a positive correlation between DBP and MDA (rs = 0.115, P < 0.01). The results of the mediation analysis indicated that MDA was a complete mediator between low BTX exposure and DBP (P < 0.05). Occupational exposure to low concentrations of BTX elevates blood pressure and oxidative stress among workers. A positive correlation between DBP and MDA was observed, with MDA acting as a complete mediator between low-concentration BTX exposure and DBP elevation.

Air pollution by BTEX and the related health risks due to the tobacco smoke, a systematic review

BTEX is a group of hazardous chemical compounds that include benzene, toluene, ethylbenzene, and xylene. The indoor concentration of BTEX is mostly influenced by tobacco smoking, the region within the house, and seasonal variations. This systematic review analyzed studies on BTEX concentrations in indoor air, using data from Google Scholar, Science Direct, and Springer from 2010 to 2020, and performed statistical analysis with R after thorough data extraction and evaluation. Duplicate studies were removed, and disagreements during the article selection process were resolved by a third reviewer. Out of the 1351 articles obtained from the keyword search, only 13 were eventually selected for this study. The most abundant compound found in houses among BTEX was toluene, with a concentration of 13.80±16.50 µg/m3. The results indicated that the concentration of ƩBTEX in houses where smoking occurred was lower than in houses where no smoking occurred (18.52 vs. 27.66 µg/m3); However, the concentration of benzene in smoking houses was higher than in non-smoking houses (7.17±9.42 vs. 2.65±3.77 µg/m3, unpaired Wilcoxon test: p&gt;0.05). The concentration of BTEX in houses was substantially lower than that in cafes (21.10±31.10 vs. 15,100±9740 µg/m3, unpaired Wilcoxon test: p&lt;0.05). The urban region had the most significant accumulation of all BTEXs, with the industrial and rural sectors following suit. The findings indicated that the average concentration of BTEX in warm months (such as spring and summer) were higher than in cold months (such as fall and winter) within houses (28.50±44.30 vs. 8.60±7.77 µg/m3, unpaired Wilcoxon test: p&gt;0.05). The findings indicated that the Cancer Risk (CR) associated with houses (3.11×10-6) and cafes (3.54×10-3) exceeded the permissible threshold. Moreover, the waterpipe cafes that utilized fruit-flavored tobacco had the greatest CR (4.98×10-3). Furthermore, the presence of smoking, regional factors, and seasonal variations did not result in an increase in the hazard quotient (HQ) in houses beyond the acceptable thresholds. Finally, smoking, seasonal variations, and region had critical impact on indoor BTEX concentrations, and they could increase the risk of carcinogenic potential in the indoor environments.

Pipeline-Related Residential Benzene Exposure and Groundwater Natural Attenuation Capacity in the Eastern Niger Delta, Nigeria

This study was conducted to investigate the presence of benzene in the ground and drinking water in the eastern Niger Delta, where multiple oil and gas production facilities are present. Samples from drinking water wells were collected for measurements of benzene, toluene, ethylbenzene, and xylenes (BTEX). Additionally, the dissolved organic carbon (DOC) concentration was determined for the first time to establish the groundwater’s total hydrocarbon and non-hydrocarbon load. The groundwater BTEX and benzene levels were up to 3904 µg/L and 3500 µg/L, respectively. DOC concentrations were up to 49 mg/L. The highest benzene concentrations were detected in wells near an underground petroleum pipeline. However, the concentrations decreased with distance from the pipeline to levels less than 0.1 µg/L. Despite benzene contamination, the aquifer has shown promising aerobic attenuation potential, having up to a 7.5 (95%) mg/L DO level and 2.11 mg/L BTEX biodegradation capacity for DO. However, the high groundwater temperature of up to 32.5 °C may weaken attenuation. The benzene and BTEX point attenuation rates ranged from 0.128 to 0.693 day−1 and 0.086 to 0.556 day−1, respectively. Hence, by natural attenuation alone, up to 66.5 and 85 years would be required to reach Nigeria’s groundwater benzene and BTEX remediation goals, respectively.

An example of a wastewater treatment project for high concentrations of benzene, xylene, acetophenone, and DOPO generated in the production of phosphorus flame retardant

ABSTRACT Wastewater generated in the production of phosphorus flame retardants contains benzene, xylene, acetophenone, and 9, 10-dihydro-9-oxa-10-phosphoxanthine-10-oxide (DOPO) with larger benzene rings, which are more difficult to biodegrade directly. In this study, the wastewater generated in the production of phosphorus flame retardants applied for high-temperature nylon and reactive phosphorus flame retardant was first treated by the combined process of lime emulsion–flocculation reaction and precipitation–ozone oxidation reaction for degradation of benzene, xylene, acetophenone, and DOPO, and then processed by the secondary combined process of upflow anaerobic sludge bed anaerobic digestion–air flotation–membrane bioreactor bio-contact oxidation; thus, the final concentration of pollutants in the wastewater can reach the relevant limit either for external discharge or as the supplemental water for other production devices. In addition, the detailed chemical degradation mechanisms and removal effects of benzene, xylene, acetophenone, and DOPO in an ozone reactor were explored. After the project had been normally operated for half a year, the test results of the effluent were as follows: chemical oxygen demand, 50 mg/L; BOD5, 20 mg/L; NH3-N, 5.0 mg/L; total phosphorus, 0.5 mg/L; benzene ≤ 0.1 mg/L; xylene ≤ 0.4 mg/L; acetophenone ≤ 0.4 mg/L; and DOPO ≤ 0.02 mg/L. Ultimately, the cost was 2.1 $/m3. It provides a useful process for wastewater treatment related to phosphorus flame retardants.

Measurement and health risks assessment of BTEX compounds exposure in beauty Lahijan City salons

The presence of BTEX (Benzene, Toluene, Ethylbenzene, and Xylene) compounds in beauty salons has raised concerns about potential health risks. This study aimed to measure the levels of BTEX compounds in the air of beauty salons in Lahijan, Iran and assess the associated health risks. Air samples were collected from 15 beauty salons, and the concentrations of BTEX compounds were measured according to 1501 NIOSH standard method. The results showed that the mean concentrations of benzene (20.62 µg/m3), toluene (18.3 µg/m3), ethylbenzene (38.36 µg/m3), and O and P-xylene (27.35, 23.6 µg/m3) were above the recommended levels. The indoor to outdoor ratios for benzene, toluene, ethylbenzene, O and P-xylene were 3.04, 2.36, 3.75, 4.89, and 6.54, respectively. Also, the toluene/benzene (T/B) ratio in indoor and outdoor was 20.9 and 2.68 respectively. Almost half of the technicians (49.12%) reported adverse health effects, including joint pain, itchy eyes and nose, and respiratory allergies. The IARC guideline suggests that there is a potential risk of cancer development for individuals in all salons with LCR values exceeding 10−6, but the HQ index values indicate no non-carcinogenic risk. The findings suggest that beauty salon workers and customers are at risk of developing health problems from exposure to BTEX compounds. Effective risk management strategies, such as proper ventilation, use of personal protective equipment, and substitution of harmful chemicals with safer alternatives, to minimize exposure and protect the health of salon workers and customers recommended.

Source apportionment of airborne volatile organic compounds near unconventional oil and gas development

Abstract Oil and natural gas (ONG) extraction activities have been associated with the release of volatile organic compounds (VOCs), including hazardous air pollutants (HAPs) that are known to have adverse health effects and other VOCs that contribute to ozone formation. This study investigated the impact of ONG operations on HAP and other VOC concentrations during the development of multi-well ONG pads in suburban Broomfield, Colorado. Weekly VOC measurements were collected at 18 sites across the community, including locations near the well pads, in adjacent neighborhoods, and at a regional background site. The measurements, from October 2018 to December 2020, encompassed different stages of well pad development, including well drilling, hydraulic fracturing, flowback, and production. Measured concentrations were analyzed using Positive Matrix Factorization (PMF) to characterize VOC sources. Six PMF source factors were identified, including factors associated with combustion, background/biogenic sources, light alkanes, complex alkanes, drilling activities, and ONG acetylene. The factors related to local ONG activities showed clear temporal and spatial correlations with Broomfield well development activities. A benzene source apportionment analysis revealed important source contribution gradients across the community, with ONG-related sources exhibiting the largest influence at locations near the well pads, especially during pre-production activities. Weekly average benzene concentration contributions from ONG-related sources ranged from 9% to 63% at a community background site and from 18% to 89% at a neighborhood site close to a well pad.&amp;#xD;

Evaluation of Benzene Presence and Formation in Benzoyl Peroxide Drug Products

The potent carcinogen, benzene, is a known degradation product of benzoyl peroxide (BPO) and was recently reported to form when BPO drug products, used for acne and rosacea treatment, are incubated at body temperature and elevated temperatures expected during storage and transportation. This study provides evidence for a wide range of benzene concentrations (0.16 ppm to 35.30 ppm) detected by GC-MS in 111 over-the-counter BPO drug products tested and maintained at room temperature. A prescription encapsulated BPO drug product was stability tested at cold (2°C) and elevated temperature (50°C), resulting in no apparent benzene formation at 2°C, and high levels of benzene formation at 50°C, suggesting that encapsulation technology may not stabilize BPO drug products but cold storage may greatly reduce benzene formation. Face model experiments where BPO drug product was applied to PolyMethyl MethAcrylate (PMMA) photoprotection test skin plates and benzene was detected in surrounding air by SIFT-MS, showed detectable benzene through evaporation and substantial benzene formation when exposed to UV light at levels below peak sunlight. Results suggest that potential benzene exposure from formation during BPO drug product use poses significant risks independent of the starting benzene concentration.

Quantification of cancer biomarkers in urine using volatilomic approach

Urine analysis is an attractive approach for non-invasive cancer diagnostics. In this study, a procedure for the determination of volatile organic compounds (VOCs) in human urine (acetone, acetonitrile, dimethylsulfide, dimethyl disulfide, dimethyl trisulfide, hexane, benzene, toluene, 2-butanone, 2-pentanone, pentanal) has been described including sample preparation using preconcentration of analytes in sorbent tubes followed by gas chromatography with mass spectrometry (GC-MS). Fractional factorial design and constrained surfaces design were used to optimize preconcentration of VOCs in sorbent tubes. The procedure was validated by analysis of synthetic urine containing VOC standards in the concentration range of 1–5000 ng/mL. Optimized procedure was applied to analyze urine samples of 89 healthy volunteers and 85 patients with cancer of various localizations: 42 patients with lung cancer, 25 – colon, 3 – stomach, 2 – prostate, 2 – esophageal, 2 – pancreas, 2 – kidney, 1 – ovarian, 1 – cervical, 1 – skin, 1 – liver. Concentrations of 2-butanone, 2-pentanone, acetonitrile, and benzene were found different in urine of patients with cancer and healthy individuals. Influence of cancer localization and tumor, nodule, metastasis stage on urine VOC profile was considered. The approach of using ratios of VOCs to the main ones instead of concentrations was considered. A diagnostic model based on significantly different VOC ratios was created to classify healthy individuals and patients with cancer using artificial neural network (ANN). The model was validated during construction by means of 3-fold cross-validation. Average area under receiver operating characteristic (ROC) curve on test dataset was 0.886. Average sensitivity and specificity of the created model were 91 % and 82 %.

Fuel fumes and foliage: the fate of speciated gasoline VOCs during phytoremediation and their impact on the bacterial phenotype

The capacity of indoor plants including green walls to capture, deposit and remediate individual volatile organic compounds (VOCs) has been well documented. However, in realistic settings, plant systems are exposed to a complex mixture of VOCs from highly varied various emission sources. Gasoline vapour is one of the major sources of these emissions, containing high concentrations of the carcinogens benzene, toluene, ethylbenzene and xylene (BTEX). Using both solid phase micro extraction (SPME) and quick, easy, cheap, effective, rugged and safe (QuEChERS) sampling techniques, we assessed the dynamics of individual speciated gasoline VOC phytoremediation from the air and uptake within green wall plant species and growth substrates within a small passive green wall system, along with quantifying the phenotypic changes within the plant-associated bacterial communities resulting from gasoline exposure. Over 8 hours the green wall system achieved 100% removal of atmospheric benzene, 1,2,3-trimethyl, eicosane and hexadecane, benzene 1,3-diethyl-; 1,3,5 cycloheptatriene,7- ethyl and carbonic acid eicosyl vinyl ester. All plant species tested demonstrated the accumulation 45 petrochemical VOCs (pVOCs) with Spathiphyllum wallisii successfully accumulating the majority of pVOC functional groups after 24 h of gasoline exposure. Within the plants phyllospheric bacterial communities, changes in both cellular complexity and granularity appeared to increase as a result of gasoline exposure, while cell size diminished. This work provides novel findings on the VOC removal processes of botanical systems for realistic and highly toxic VOC profiles.

Fabrication of surface functionalized QCM sensor for BTX detection at ambient conditions

Developing optimized gas sensors for detecting low concentrations of Benzene, Toluene, and Xylene (BTX) in ambient conditions is advantageous for health and environment monitoring applications. This study reports on the feasibility of using Quartz Crystals Microbalance (QCM) coated by Tungsten Oxide (WO3) to detect BTX compounds. A WO3 layer was deposited on the QCM surface using DC magnetron sputtering. Optical Profilometry (OP), Scanning Electron Microscopy (SEM), and X-ray Diffraction (XRD) were employed to analyze sensor surface morphology and structure. Adsorption properties were studied through the Langmuir adsorption isotherm. Thermal stability was evaluated by thermogravimetric analysis. The response to BTX vapours was investigated using a laboratory-designed gas-sensing setup in ambient conditions. The optimized film thickness was 200.81 ± 0.39 nm for 540 s of sputtering. XRD pattern confirms the amorphous nature, and SEM images of WO3 show the granular microstructure with 200 nm diameter. The developed sensor shows the highest sensitivity for xylene (5.10 ± 0.08 Hz/ppm), followed by toluene (5.69 ± 0.22 Hz/ppm) and benzene (3.36 ± 0.24 Hz/ppm). The limit of detection for BTX was 1.48 ppm, 0.79 ppm, and 0.33 ppm, respectively. The sensor exhibited faster response times of 30 s, 32 s, and 43 s for BTX, respectively. Repeatability of 99 % and reproducibility of 98 % were observed for BTX vapours. The fabricated WO3-coated QCM sensor can detect BTX vapour at room temperature with high sensitivity and response time. Thus, it can play a significant role in detecting BTX in the workplace for health and environment monitoring systems.

A monolithic self-supporting ZnFe2O4/ZnO/ZnNi foam photocatalyst and application in the decomposition of gaseous benzene

Volatile organic compounds (VOCs) are major air pollutants which seriously affect ecological environment and pose threats to human health. In this investigation, a monolithic self-supporting ZnFe2O4/ZnO/ZNF(ZFO/ZnO/ZNF) photocatalyst was developed by in-situ growing ZnFe2O4 and ZnO on ZnNi foam (ZNF). Using benzene as a representative of the target gaseous contaminants, the optimal 5ZFO/ZnO/ZNF achieved a 99.8 % removal efficiency and 99.7 % mineralization efficiency within 20 min at an initial benzene concentration of 600 ppm under simulated sunlight irradiation. Moreover, this catalyst presents the lower ullage during gas–solid reaction, and thus enables durable recycling reuse of the photocatalyst, which still retains a 95.8 % benzene decomposition after 30th consecutive run. The mechanism studies reveal that the metal-mediated Z-type heterostructure of ZFO/ZnO/ZNF enhances rapid transportation of the photo-generated electrons and promotes redox potential, leading to the excellent photocatalytic oxidation activity and mineralization efficiency. This study highlights the potential of self-supporting monolithic metal-mediated catalysts and provides a key strategy for effective VOCs degradation.

The Impact of the New Year Celebration on the Air-Pollution in Slovakia

Fireworks and pyrotechnics are an integral part of the New Year celebration that take place both in cities and rural areas as well. Depending on the meteorological conditions, these activities can raise air pollutant concentrations in ambient atmosphere. In order to estimate the size of this increase, air pollutant concentrations from up to 61 air quality stations situated in the Slovak Republic in period from 2010 to 2023 are analysed. Pollutant concentrations of PM10, PM2.5, CO, NO2, SO2, O3 and benzene from New Year's Eve evening to New Year's morning are compared with data from 25 December to 7 January. In case of PM10 557 cases were analysed. Among them in 64 % the significant exceedance in concentrations which can be attributed to the New Year celebration with high probability was observed. The statistical difference between mean PM10 concentrations during the New Year celebration hours and during the surrounding days was strong (p ≤ 0,001). For PM2.5 the situation was similar. The New Year celebration affects other pollutant concentrations studied in this work in less extend. For them it is difficult to attribute the exceedance to the fireworks. This analysis provides clear evidence of the negative impact of fireworks and pyrotechnics on the air quality, which can lead to public health risks. This work can support policy makers to implement more stringent strategies to reduce air pollution and its effects on health.

Long term analysis of air quality parameters for Ludhiana, India: sources, trends and health impact.

Ludhiana, a pollution hot spot in North India, has seen a rapid deterioration in air quality over the years due to urbanization and industrialization. This study interprets the variations of particulate matter (PM) and gaseous pollutants (Nitrogen oxide, Nitrogen dioxide, NOX, Sulphur dioxide, Carbon monoxide, Benzene, Toluene, Ozone, and Ammonia) for the data observed from 2017 to 2023 in Ludhiana. This also covers the analysis focused on capturing the changes that occurred at the times of lockdown imposed during the Coronavirus Disease (COVID-19). The maximum 24-h averaged mass concentration values exceeded the National Ambient Air Quality Standards (NAAQS) of 100µg/m3 for PM10 concentration and 60µg/m3 for PM2.5 concentration in 2018 by the factor of 5 and 8. With the onset of the COVID-19 lockdown in 2020year, PM10 and PM2.5 reached the minimum level while CO, T, O3, and NO2 increased by the factor of 3.9, 1.9, 1.4, and 1.3 from their previous year. This NO2 is a precursor of ozone formation, a higher NO2 to NO ratio observed during the lockdown, confirms the role of nitrogen compounds in the higher ozone formation rate. Based on the NO2/NO ratio, the probability rate of ozone formation determined using survival analysis is observed to be 94% from 2017 to 2023. The local sources' contribution to these air pollutants during Pre-Lockdown, Lockdown, and Post-Lockdown are analyzed using principal component analysis. The impact of the lockdown on ozone concentration sources has been observed. During the Pre- and Post-Lockdown phases, three sources (PC1, PC2, and PC3) were positively identified. Ozone levels are linked to PC3 in these phases, but during the lockdown, a negative loading in PC3 and positive loadings in PC1 and PC2 indicate a decrease in ozone from reduced emissions and an increase from secondary reactions involving nitrogen compounds. Moreover, the Toluene to Benzene concentration ratio is > 2, indicating the source of their origin from industrial emission or other non-traffic sources. Health assessment for the years 2017-2019 reveals a significant decrease in the number of cases of all-cause mortality, ischemic heart disease, stroke, and chronic obstructive pulmonary disease associated with reducing PM2.5 concentrations to national and international standards.

First exploratory study of gaseous pollutants (NO2, SO2, O3, VOCs and carbonyls) in the Luanda metropolitan area by passive monitoring

An air quality monitoring campaign for gaseous pollutants using passive sampling techniques was carried out, for the first time, at 25 locations in the metropolitan area of Luanda, Angola, in June 2023. Concentrations of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes, SO2 and NO2 were generally higher in locations more impacted by traffic. Benzene, SO2 and NO2 levels did not exceed the World Health Organisation guidelines. Ozone concentrations surpassed those documented for other African regions. Higher O3 formation potential values were recorded at heavy-trafficked roads. The top 5 species with potential for ozone formation were m,p-xylene, toluene, formaldehyde, propionaldehyde and butyraldehyde. The Mulenvos landfill presented a distinctive behaviour with a very low toluene/benzene ratio (0.47), while values close to 5 were obtained at traffic sites. The maximum levels of α-pinene, D-limonene, formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, hexaldehyde and crotonaldehyde were recorded at the landfill. The formaldehyde/acetaldehyde ratio ranged from 0.40 at the Mulenvos landfill to 3.0, averaging 1.8, which is a typical value for urban atmospheres. Acetaldehyde/propionaldehyde ratios around 0.4–0.6 were found in locations heavily impacted by traffic, whereas values between 0.7 and 1.2 were observed in green residential areas and in places with more rural characteristics. All hazard quotient (HQ) values were in the range from 1 to 10, indicating moderate risk of developing non-cancer diseases. The exception was the Mulenvos landfill for which a HQ of 11 was obtained (high risk). The cancer risks exceeded the tolerable level of 1 × 10−4, with special concern for the landfill and sites most impacted by traffic. A mean lifetime cancer risk of 9 × 10−4 was obtained. The cancer risk was mainly due to naphthalene, which accounted, on average, for 94.6% of the total.

Catalytic pyrolysis of wheat straw based on dual catalyst CaO/ZSM-5 with acid washing and torrefaction pretreatment to enhance aromatic yield in bio-oils

In this paper, the catalytic pyrolysis integrating combined pretreatment (acid washing and torrefaction) and dual catalysts was adopted to improve the quality of bio-oil and the selectivity of aromatic hydrocarbons. Combined pretreatment is a highly effective method to improve the quality of biomass feedstock. It was capable of the removal of alkali and alkaline earth metals from wheat straw, with a K removal rate of 97.79 %. Under the combined pretreatment, the aromatic hydrocarbon content in bio-oil increased to 68.8 % using the ZSM-5 catalyst alone. Compared with ZSM-5, CaO could remove part of the oxygenated functional groups and had a better acid removal effect, but the aromatic hydrocarbon yield was low to 7.95 %. After combined pretreatment using simulated aqueous phase bio-oil for acid washing, catalytic pyrolysis using CaO/ZSM-5 dual catalysts greatly enhanced the quality of the bio-oil. The oxygenated compounds content was reduced to 17.58 %, and the total hydrocarbon yield was increased to 82.42 %, especially the aromatic hydrocarbons yield was increased to 79.91 %, of which the monocyclic aromatic hydrocarbons were as high as 68.38 %, and the benzene, toluene, and xylene content reaching 49.39 %. Thus, integrating dual catalysts (CaO/ZSM-5) with combined pretreatment can effectively increase the aromatic yield for producing high-quality bio-oil.

Sensitive analysis of some detrimental volatile organic compounds in fabric, carpet and air freshener using solid phase extraction and gas chromatography–mass spectrometry

Benzene, toluene, ethylbenzene and xylene are known to be lethal environmental contaminants that have carcinogenic and mutagenic influences in human being while styrene and benzaldehyde have a neurotoxic effect. In other hand, the constituents of air freshener considered as a probable source of volatile organic compound. In the present work, a solid phase extraction and gas chromatography–mass spectrometry (GC-MS) technique has been optimized and applied to the fabric, carpet and air freshener samples to determine the trace amounts of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde. The SupelcleanTM ENVITM - 18 cartridge with dichloromethane extracting solvent were found to be the optimal procedures. The system presented excellent performance in terms of limit of detection (0.08-0.61 ng/mL), coefficient of determination (0.994-0.997), precision with the relative standard deviation values ranging from 0.05-2.57%. According to the results, the concentration of benzene, toluene, ethylbenzene, xylene, styrene and benzaldehyde in fresheners’ samples was found in the range 0.03-53.27, 0.03-7.12, 0.02-6.51, 0.05-96.44, 0.04-7.06 and 0.22-23.02, respectively. The excellent recovery values were also obtained up to 99.93%. The SupelcleanTM ENVITM - 18 GC-MS system was found to appropriate for the monitoring of analytes in fabric, carpet, air freshener samples, and other samples of the similar constituents. KEY WORDS: BTEX, Styrene, Benzaldehyde, Air freshener, Solid phase extraction, Gas chromatography–mass spectrometry Bull. Chem. Soc. Ethiop. 2024, 38(6), 1543-1556. DOI: https://dx.doi.org/10.4314/bcse.v38i6.4

BTEX concentration and health risk assessment in automobile workshops

This study focused on the measurement of BTEX (benzene, toluene, ethylbenzene, and xylene) concentrations in the air of indoor and outdoor environments of automobile workshops in Damghan, Iran. Air samples from twenty-five workshops were actively collected and analyzed using Gas Chromatography-Flame Ionization Detection (GC-FID). The results showed that the concentrations of BTEX were higher in the indoor air compared to the outdoor air. The highest mean concentration of benzene (153.22 ± 34.21 μg m−3), toluene (94.41 ± 25.25 μg m−3), and xylenes (385.38 ± 34.21 μg m−3) was found in auto paint (AP) workshops, while the highest mean concentration of ethylbenzene (43.39 ± 12.57 μg m−3) was observed in auto body (AB) workshops. The significant negative correlations between benzene, ethylbenzene, xylene isomers, and relative humidity (RH) indicated that controlling humidity is an effective strategy. The mean inhalation lifetime cancer risk (LTCR) for benzene in both indoor and outdoor air of all automobile workshops exceeded the EPA (Environmental Protection Agency) recommended limits. The highest mean LTCR values for benzene and ethylbenzene were observed in the AP (3.24E10-4) and AB (2.95E10-5) workshops, respectively. The hazard quotient (HQ) of benzene and Xylene in the indoor air of the AP and AB workshops was >1, which indicates that the non-carcinogenic risks associated with exposure to these compounds are considerable. This study underscores the need for international attention to BTEX pollution in automobile workshops, highlighting the global health risks. The findings provide crucial data for developing strategies to mitigate these risks and protect workers’ health.

A framework and generic models for quantifying surface environmental impact of VOCs emissions from the complex fractured rocks

To analyze the surface cumulative mass of VOCs from residual sources in dual-media fractured rocks and assess environmental health risks, complex 3D numerical models were constructed. These models comprehensively considered fracture-rock interactions, density-driven effects, and surface pressure fluctuations. The investigation identified the key control factors affecting surface cumulative mass, including the fracture aperture, pollutant source location, fracture density, and so on. Additionally, a regression-based general surrogate model was established using the obtained representative dataset. According to U.S. EPA's Respiratory Inhalation Reference Concentrations, the cumulative mass of CH2ClCHCl2 in one day for one-third of the model exceeds the concentration limit. Benzene and TCE concentrations reached 29 and 740 times the reference limits, significantly impacting air quality and health. Surrogate model analysis showed that in the worst-case scenario, 1 min's surface cumulative mass could cause Benzene concentrations to exceed the limit by 57 times. The implications of the study lies in reminding us that even after groundwater remediation in the saturated zone, residual VOCs in the capillary zones can still significantly impact surface environmental health risks. This investigation also presents an effective framework that integrates complex, time-consuming numerical modeling with simple, efficient statistical modeling to predict concerned variables and their uncertainties. This study provides a reference basis for the control of environmental pollution pertaining to VOCs volatilization from buried capillary zones at specific depths.