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Background: The present research addressed the spatiotemporal variations in such pollutants as benzene, toluene, ethylbenzene, and xylene (BTEX) in the atmosphere of Arak, a city in central Iran. Also, the health risk evaluation and ozone formation potential (OFP) were assessed. Methods: The air samples were collected and evaluated through gas chromatography-mass spectrometry (GC-MS) over a one-year period. Results: The overall BTEX levels ranged between 2.7-256 μgr/m³. The seasonal levels showed considerable variations among benzene, toluene, ethylbenzene, and xylene, and the levels of total BTEX. Comparison of the air samples between morning and evening for the concentrations of BTEX components revealed that the values were higher in the evening; however, there were no significant differences observed among them. The spatial map indicated that the maximal concentration of BTEX components occurred in high-traffic zones of the city. The maximal and minimal OFP levels were recorded in the summer (2 54.8 μgr/m³) and autumn (64.9 μgr/m³), respectively. The average toluene/benzene (T/B) ratio found to be 4.3, indicating the fuel combustion was the major source of atmospheric BTEX from vehicles. Conclusion: The measured cancer risk value for benzene (6.68×10-5) was higher than those recommended by the WHO and U.S. Environmental Protection Agency. Therefore, exposure to atmospheric benzene had a carcinogenic risk for Arak inhabitants. This needs further investigation in future studies. The acceptable hazard quotients (<1) for all BTEX species posed minimal risks of non-cancer diseases for the population. [ABSTRACT FROM AUTHOR]

Chemical degradation-based methods including oxidation have shown great promise for controlling benzene, toluene, ethylbenzeneandxylene isomers (BTEX) in waste gas. This study presents an approach in which the emission of BTEX compounds in a bituminous waterproofing (BW) production unit located in the city of Delijan, Iran has been controlled through process modification. The process is modified by introducing a thermal oxidation unit using an incinerator design. The process simulation has been performed with Aspen Hysys software and, key parameters in the oxidation process are identifiedandoptimized. Finally, the environmentalandeconomic performances of the incinerator were assessed to provide a decision support tool for the selection of this approach. Finally, the environmentalandeconomic performances of the incinerator have been assessed to provide a decision support tool for the selection of this approach. The results indicated that the formation of the oxidation unit had prevented the release of BTEX pollutants up to 98.5%. Moreover, the economic analysis illustrated that the rate of return on investment in the proposed project is 0.27. Thus, the potential for attracting capital will have positive impacts on the environmentalandeconomic indicators of the region. [ABSTRACT FROM AUTHOR]

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/m 3 ), toluene (18.3 µg/m 3 ), ethylbenzene (38.36 µg/m 3 ), and O and P-xylene (27.35, 23.6 µg/m 3 ) 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., (© 2024. The Author(s).)

Exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) and styrene have been reported in tire manufacturing. This research was designed to evaluate the exposure to BTEX and styrene and their health risks in tire manufacturing in Iran. The health risk estimation was done by the United States Environment Protection Agency (USEPA) method using the Monte-Carlo simulation. Results showed that the concentration of benzene in some units, such as cement making; cement spraying, and tire building was more than the standard level. The units of cement spraying and calendaring had the highest and lowest cancer and no-cancer risks, respectively. [ABSTRACT FROM AUTHOR]

Benzene, toluene, ethylbenzene and xylene (BTEX) are a challenging group of volatile organic compounds in industrial and energy areas. Since these aromatics may cause serious diseases such as cancer and respiratory illnesses, they must be monitored. Pars Special Economic Energy Zone (PSEEZ) in Iran is the second largest energy zone of the world with numerous gas refineries and petrochemical complexes for producing a wide range of products. This study is focused on determination of BTEX concentration in the whole South Pars area (46 sampling points) which is the active site of PSEEZ using passive sampling. Then, the results of the passive sampling are used for providing spatial distribution of BTEX using GIS. The annual BTEX measurements revealed that benzene and toluene concentration violates the maximum permitted values at numerous points most of which are located in the vicinity of petrochemical complexes. Active sampling in these complexes not only confirms the results of passive sampling, but also suggests a more intensified BTEX pollution in the air quality of the area which reaches as high as 3500 μg.m−3 and 18,000 μg.m−3 for benzene and toluene, respectively, being far beyond the acceptable standards. Health risk analysis also confirms the intensity of BTEX at the selected points. This study suggests a reconsideration of the location of non-operational sites and personnel who are more vulnerable to BTEX contamination. Also, BTEX profile provided by GIS in this research gives a suitable plan for relocating. [ABSTRACT FROM AUTHOR]

Many previous studies have investigated BTEX concentrations in urban areas; however, the available evidence on the association of different land-use types and BTEX concentrations is still scarce. In this study, the BTEX concentrations were measured and compared in different land-use types and traffic volumes of Mashhad metropolis, Iran. Sampling was conducted in summer and winter of 2018 based on NIOSH 1501 method in six land-use types, including Residential, Commercial/official, Industrial, Greenspace, Transportation, and Tourism. The spatial autocorrelation model was used to investigate the emission pattern. The Monte Carlo simulation technique and sensitivity analysis were used to assess the health risk of exposure to BTEX compounds. The median [interquartile range (IQR)] of benzene, toluene, ethylbenzene m-xylene, o-xylene and total BTEX concentrations based on overall mean were 4 (2.23), 8.37 (4.48), 1.2 (1.46), 0.89 (2.59), 0.8 (1.73) and 17.7 (8.19) µg/m3, respectively. Benzene and toluene had clustered emission patterns (z-score > 1.96). Exposure to benzene in the study area had a carcinogenic risk for inhabitants. The concentration of BTEX compounds was significantly different based on land-use type. The maximum and minimum concentrations of BTEX were observed in Transportation and Greenspace land uses, respectively. The BTEX concentrations in summer were significantly higher than in winter, and traffic had a significant effect on BTEX concentrations. Overall, our results supported a significant relationship between land-use type and BTEX concentrations in the urban area. Moreover, ambient benzene concentration had a carcinogenic risk potential for inhabitants of study area. [ABSTRACT FROM AUTHOR]

• Major sources of BTEX are traffic, bus, and stationary point source emissions. • Mean level of BTEX on non-working days significantly exceeds that of working-days. • Toluene to benzene ratios in bus cabins and stations ranged from 2.84 to 5.55. • Lifetime cancer risk for benzene in this study ranged from 3.08 × 10−5 to 7.07×10−5. • Hazard quotient of all studied pollutants in bus cabins/stations is less than 1. This study reports a spatiotemporal characterization of BTEX concentrations in urban air of hotspots in Iran, specifically at the Bus Rapid Transit system in Tehran Traffic Zone. The average concentrations ± (SD) of benzene, toluene, ethylbenzene, m/p -xylene, and o -xylene in bus cabins versus bus stations were 8.75±4.21 vs. 8.74±2.61, 24.33±19.19 vs. 32.77 ± 13.59, 25.90 ± 10.63 vs. 28.74 ± 6.41, 43.71 ± 21.88 vs. 45.19 ± 15.60, and 33.46 ± 14.88 vs. 39.46 ± 10.57 μg/m3, respectively. The toluene to benzene ratios in bus cabins and bus stations ranged from 2.84 to 2.95 and from 2.20 to 5.55, respectively, indicating that traffic, bus, and stationary point source emissions were the primary source of BTEX. The average lifetime cancer risks (LTCRs) of benzene for bus cabins and bus stations along various routes ranged from 3.08 × 10−5 to 7.07×10−5 and from 4.58 × 10−5 to 5.42 × 10−5, respectively, surpassing guideline values by EPA and WHO. Target pollutant concentrations increased on non-working days due to fewer traffic restrictions imposed by the city allowing people to travel without restrictions with their own vehicles. Hence, enforcing traffic restrictions on working and non-working days could reduce BTEX pollution, with implications for better public health as a result of reduced exposure to BTEX and associated non-carcinogenic and carcinogenic effects. [ABSTRACT FROM AUTHOR]

Exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) has been reported in gas stations. Exposure to BTEX can result in adverse health outcomes in workers such as cancer and neurological effects. The health risk assessments of exposure to BTEX could be useful in choosing suitable control measures. In this review, data from previous studies of gas station environments in Iran were collected from years 2000 to 2020. The health risk assessments were conducted through the estimation of cancer and noncancer risks using a Monte Carlo simulation based on the US Environmental Protection Agency method. The results showed that exposure to BTEX in some cities of Iran was greater than the occupational exposure limits. The results of cancer risk assessments demonstrated that cancer risk was not increased. However, results of noncancer risk assessments demonstrated that neurological toxicity from exposure to BTEX was significant in different cities of Iran. The health risk assessments indicated that workers at gas station are at health risk. [ABSTRACT FROM AUTHOR]

Nowadays, workers in petrochemical industry might be exposed to organic volatile compounds, including benzene, toluene, ethylbenzene, and xylene (BTEX). The aim of this study was to investigate the concentration of BTEX contaminations and the biological index in employees of petrochemical sites in the west of Iran. The study was conducted as a cross-sectional study on 30 stations and 60 inhalation and biological samples collected in winter and summer. The NIOSH 2549 and 1501 methods were used for sampling and analyzing the inhaled samples. Gas chromatography-mass spectrometry (GC-MS) equipped with flame ionization detector and high-performance liquid chromatography (HPLC) was used to measure the volatile contaminations. The results showed that the mean concentrations of benzene, toluene, and xylene were significantly different in summer and winter. Significant and strong correlations were observed between the concentrations of benzene, toluene, and xylene and the biological values (r > 0.7). Moreover, the concentration of benzene (β = 0.836), toluene (β = 0.718), and xylene (β = 0.786) predicted the changes in their biological values. Given the hazardous concentrations of benzene and toluene in industrial plants and the correlation of the concentration levels and biological values, management and control strategies should be implemented to eliminate and reduce the pollutants and the effects. [ABSTRACT FROM AUTHOR]

Urinary benzene, toluene, ethylbenzene, and xylenes (BTEX) can be used as a reliable biomarker of exposure to these pollutants. This cross-sectional study aimed to employ biomonitoring to assess BTEX exposure among South Pars Gas Field (SPGF) workers in Assaluyeh, Iran. Forty employees who were working on the site were recruited as the case group. Besides, 31 administrative employees were recruited as the control group. Pre-shift and post-shift spot urine samples were collected from the subjects in the case group, while the subjects in the control group provided mid-morning urine samples. Overall, 111 urine samples, including 80 samples from the case group and 31 samples from the controls, were collected. Gas chromatography-mass spectrometry (GC/MS) was used to determine the urinary levels of BTEX compounds. The median urinary levels of benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene in the post-shift samples of the exposed group were 1.24, 2.28, 0.5, 1.32, and 1.5 μg/l, respectively. Significant differences were observed in urinary BTEX levels among smokers and non-smokers in both studied groups (p < 0.05). Accordingly, the median urinary BTEX concentrations in smokers were 2 to 6.5 times higher than the corresponding values in non-smoker subjects. Smoking status was the only predictor of the urinary BTEX concentration. Our findings revealed that refinery workers are exposed to significant levels of BTEX compounds. Considering the health risks associated with BTEX exposure for refinery workers, implementation of suitable control strategies, such as using appropriate personal protective equipment and improving on-site ventilation systems, are recommended reducing their exposure to BTEX via the inhalation. [ABSTRACT FROM AUTHOR]

To determine the concentration of benzene series (BTEX) compounds, 33 samples were collected from indoor air of Ghalyan cafés (GHC), cigarette cafés (CC) and smoking-free cafés (SFC) in Bushehr city, Iran, and analyzed using gas-chromatography - flame ionization detector (GC-FID). The results of this study indicated that the mean±SD values of ΣBTEX in GHC, CC and SFC cafés were 19.46 ± 6.07, 11.34 ± 5.21 and 2.26 ± 0.76 mg/m3, respectively. The mean concentration of BTEX in the cafés with fruit-flavored tobacco was significantly higher than those in traditional cafés (p < 0.05). According to path analysis, the number of active waterpipe heads had the maximum impact on the production of pollutants inside the cafés. The results also indicated that the risk of exposure to BTEX in smoking cafés in Bushehr was very high; it can develop serious carcinogenic and noncarcinogenic risks. [ABSTRACT FROM AUTHOR]

• BTEXs and their spatial distribution, source identification and risk assessment were analyzed. • The ILCR for benzene and ethylbenzene were 6.49 × 10−7-1.27 × 10-5 and 1.21 × 10−7- 2.37 × 10-6. • Strong correlation among individual BTEXs suggests that traffic is the main source contributing. The present study aimed to assess BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations, their sources and health risk estimates in Shiraz, the fifth-most populous city in Iran. Air samples were collected from 19 sampling stations across Shiraz using passive samplers. Identification and quantification of BTEX were conducted by a Gas Chromatography–Mass Spectrometry (GC–MS). Spatial distribution of BTEX compounds were mapped by inverse distance weighting (IDW) procedure. Monte Carlo simulation was employed to assess the corresponding carcinogenic and non-carcinogenic risks of BTEX concentrations. BTEX concentrations were higher than current levels in Western countries but lower than concentrations measured in East Asia. Analysis of individual BTEX ratios and their strong correlation indicated that fresh traffic emissions were the main contributor to these compounds in Shiraz, with additional sources contributing to toluene (e.g. industrial solvent use) and benzene (e.g. evaporative emissions). The incremental lifetime cancer risk (ILCR) for benzene and ethylbenzene were estimated to be 6.49 × 10−7- 1.27 × 10-5 and 1.21 × 10−7- 2.37 × 10-6, respectively, exceeding the WHO and EPA recommendations. The current evaluation of BTEX sources and associated health risks will assist policymakers to define action plans to minimize BTEX exposure in Shiraz and similar cities in the Middle East. [ABSTRACT FROM AUTHOR]

Background: The main objective of this study was to evaluate the concentrations of heavy metals and BTEX (benzene, toluene, ethylbenzene and xylene) in smoke and water bowl of 5-most commonly used tobacco brand in waterpipe in Tehran, the capital of Iran. Methods: Five types of conventional tobacco in Tehran were investigated. Heavy metals and BTEX were analyzed in waterpipe smoke, tobacco, charcoal and water bowl prior to and after smoking by using ICP-OES and GC-MS, respectively. Results: Our results indicated that Khansar and Al Fakher brands had the maximum and minimum concentrations of metals among tobacco consumed, respectively. The results showed that there was a significant difference between content of heavy metals in burned and unburned tobacco. The highest and lowest concentrations of metals were related to Fe and Hg, respectively. Conclusion: Results showed that tobacco, charcoal and smoke of waterpipe contained significant contents of toxic metals and BTEX, and exposure to these components could be the main reason for the concerns about waterpipe smoking. [ABSTRACT FROM AUTHOR]

Abstract This study characterized spatio-temporal variations in the concentration of benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in the vicinity of gas and compressed natural gas (CNG) stations in Tehran, Iran. Health risk assessment (HRA) was computed using Monte Carlo simulations (MCS) for evaluating inhalation lifetime cancer risk (LTCR), the hazard quotient (HQ), and sensitivity analysis (SA) for BTEX exposure in different age groups (birth to <81) and as a function of distance (0–250 m) from the center of the stations. For all monitoring stations, the average values of benzene, toluene, ethylbenzene, and xylene in winter were 466.09 ± 132.25, 873.13 ± 233.51, 493.05 ± 141.22, and 910.57 ± 145.40 μg m−3, respectively. The mean wintertime ratios of T/B for the 12 stations ranged from 1.69 to 2.04. Furthermore, there was no significant relationship between the concentration of BTEX with either the specific month or distance from the center of stations (p > 0.05). Factors promoting BTEX formation in the study region were fuel evaporation and gas/CNG station emissions. The LTCRs for the target compounds in the winter for different age groups and distances from the center of stations was limited to 2.11 × 10−4 to 1.82 × 10−3 and 2.30 × 10−4 to 2.01 × 10−3, respectively, which exceeded proposed values by U.S. EPA. Moreover, the HQs for BTEX for three age groups and distances were limited to between 2.89 × 10−5 and 9.33 × 10−2, which were lower than the acceptable limit (HQs < 1). The results of this work are applicable to similar areas that are heavily populated with vehicular traffic. This study motivates a closer look at mitigation strategies to limit the health effects of carcinogenic emissions such as benzene and ethylbenzene from gas/CNG stations. Graphical abstract Image 1 Highlights • BTEX concentrations were measured in 12 gas/CNG stations in Tehran, Iran. • T:B ratios for the twelve stations ranged from 1.69 to 2.04. • BTEX levels not impacted by month or distance from the center of gas/CNG station. • LTCR for BTEX in different groups and distances ranged from 2.11 × 10−4 to 2.01 × 10−3. • HQ for BTEX in different groups and distances was less than the acceptable limit. This is the first such study investigating BTEX in this understudied, yet largely populated, region in the Middle East with attention geared towards spatial and diurnal trends, health effects of BTEX, and amount of BTEX emissions in gas stations versus CNG stations. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate benzene, toluene, ethylbenzene, and xylene (BTEX) exposure among workers at four stations of a major oil distribution company. Personal BTEX exposure samples were collected over working shift (8 h) for 50 workers at four stations of a major oil distribution company in Iran. Measured mean values for workers across four sites were benzene (2437, 992, 584, and 2788 μg/m 3 respectively), toluene (4415, 2830, 1289, and 9407 μg/m 3 ), ethylbenzene (781, 522, 187, and 533 μg/m 3 ), and xylene (1134, 678, 322, and 525 μg/m 3 ). The maximum mean concentration measured across sites for benzene was 2788 μg/m 3 (Station 4), toluene was 9407 μg/m 3 (Station 4), ethylbenzene was 781 μg/m 3 (Station 1) and xylene was 1134 μg/m 3 (Station 1). The 8 h averaged personal exposure benzene concentration exceeded the recommended value of 1600 μg/m 3 established by the Iranian Committee for Review and Collection of Occupational Exposure Limit and American Conference of Governmental Industrial Hygienists. Mean values for excess lifetime cancer risk for exposure to benzene were then calculated across workers at each site. Estimates of excess risk ranged from 1.74 ± 4.05 (Station 4) to 8.31 ± 25.81 (Station 3). Risk was assessed by calculation of hazard quotients and hazard indexes, which indicated that xylene and particularly benzene were the strongest contributors. Tanker loading was the highest risk occupation at these facilties. Risk management approaches to reducing exposures to BTEX compounds, especially benzene, will be important to the health of workers in Iran. [ABSTRACT FROM AUTHOR]

This study evaluated the biodegradation of n-hexane as single pollutant, and in a mixture with benzene, toluene, ethylbenzene, and xylenes (BTEX) in a scoria/compost-based biofilter. Initially, the biofilter was fed with n-hexane and maximum elimination capacities (ECmax) of 10.7 and 8.1 g m−3 h−1 were obtained for inlet loading rates (ILR) of 14.0 and 11.6 g m−3 h−1 at empty bed retention times (EBRT) of 138 and 108 s, respectively. Michaelis–Menten kinetic model was well fitted to the experimental EC of n-hexane in the single pollutant condition. In the presence of BTEX, the removal efficiency of n-hexane dramatically decreased from 76 to 21% at EBRT of 108 s. In this condition, BTEX was easily degraded with an ECmax of 110.6 g m−3 h−1 for ILR of 119.1 g m−3 h−1. A competitive inhibition kinetic well described the n-hexane removal in the presence of BTEX with an inhibition constant of 0.151 g m−3. Moreover, the interaction index of benzene with the addition of BTEX was −0.702, indicating the significant inhibitory effect of BTEX on n-hexane biodegradation. This study revealed that, in the biofiltration of n-hexane/BTEX mixture, a significant decrease in BTEX concentration is a prerequisite for the efficient removal of n-hexane. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the level of exposure to BTEX (benzene, toluene, ethylbenzene, xylenes) in petrol pump stations in Ahvaz City. Two of the biggest fuelling stations were selected randomly among total 12 fuel stations of Ahvaz City, Iran, during September 2013. Thirty air samples were taken from different positions in the fuelling stations and 15 samples were taken from the personal breathing zone of operators and of customers in fuelling stations. Measuring the ambient concentration of benzene, toluene, ethylbenzene, and xylenes was done according to the method advised by National Institute for Occupational Safety and Health (NIOSH) 1501. This study showed that the concentration of benzene was very high (compared with the Iranian occupational exposure limit [OEL] standard) in ambient air of petrol stations in Ahvaz, which is considered as a high risk to the health of workers. Controlling the level of benzene in petrol stations is necessary. A new designed petrol nozzle was proposed for this purpose. [ABSTRACT FROM PUBLISHER]

The health risk and burden of disease induced by exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) in the outdoor air in Tehran, 2019 were assessed based on the data of five fixed stations with weekly BTEX measurements. The non-carcinogenic risk, carcinogenic risk, and disease burden from exposure to BTEX compounds were determined by hazard index (HI), incremental lifetime cancer risk (ILCR), and disability-adjusted life year (DALY), respectively. The average annual concentrations of benzene, toluene, ethylbenzene, and xylene in the outdoor air in Tehran were 6.59, 21.62, 4.68, and 20.88 μg/m 3 , respectively. The lowest seasonal BTEX concentrations were observed in spring and the highest ones occurred in summer. The HI values of BTEX in the outdoor air in Tehran by district ranged from 0.34 to 0.58 (less than one). The average ILCR values of benzene and ethylbenzene were 5.37 × 10 -5 and 1.23 × 10 -5 , respectively (in the range of probable increased cancer risk). The DALYs, death, DALY rate (per 100,000 people) and death rate (per 100,000 people) induced by BTEX exposure in the outdoor air in Tehran were determined to be 180.21, 3.51, 2.07, and 0.04, respectively. The five highest attributable DALY rates in Tehran by district were observed in the districts 10 (2.60), 11 (2.43), 17 (2.41), 20 (2.32), and 9 (2.32), respectively. The corrective measures such as controlling road traffic and improving the quality of vehicles and gasoline in Tehran could reduce the burden of disease from BTEX along with the health effects of other outdoor air pollutants., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Abstract: Indoor air pollution in working places is widely recognized as one of the most serious potential environment risks to human health. Mean volatile organic compound (VOC) concentrations of 144 samples from four copy centers in Tehran, Iran in two seasons were monitored for the purpose of quantifying the various VOCs in these areas. Area samples were collected in thermal desorption tubes and were analyzed using gas chromatography/mass selective detector. Real-time personal total volatile organic compounds were measured using a data-logging photo-ionization detector. Simultaneously, BTEX (benzene, toluene, ethylbenzene, xylenes) outdoor measurements were performed in the same manner as were the indoor measurements. Nineteen different VOCs were detected in the area samples. The results show that in all photocopy centers, the indoor levels of toluene were much higher than the outdoor levels. During business hours, the VOC levels increased, especially toluene indoor concentration. The ventilation decreased the indoor VOC concentrations. The background and indoor VOC concentrations were higher in winter than in spring. The minimum ratio of the indoor to outdoor concentration of BTEX was estimated to be more than 42. This value proved that buildings with photocopiers can be a site of VOC accumulation. [Copyright &y& Elsevier]

Benzene, toluene, ethylbenzene, and xylene, known as BTEX, adversely affect human health. This study aimed to measure BTEX concentration and assess the health risk through inhalation exposure to these compounds in a municipal wastewater treatment plant. The ambient air samples were collected using the active sampling method in summer and winter. Sampling sites were close to wastewater treatment units, including bar screen & grit chamber (Site-1), aeration tank & secondary clarifiers (Site-2), anaerobic sludge digester (Site-3), and office & control building (Site-4). Results indicate that the mean levels of benzene and toluene in winter were higher than in summer. The levels of benzene and toluene were below the occupational exposure levels of the American Conference of Governmental Industrial Hygienists (ACGIH) and Occupational Safety and Health Administration (OSHA). The carcinogenic risk (CR) and hazard quotient (HQ) were assessed using the United States Environmental Protection Agency (U.S.EPA) method, and Monte Carlo simulation (MCS) was applied to quantify the uncertainty and sensitivity analysis. The CRs for all sampling sites were below the U.S.EPA threshold limit (1.0 × 10 -4 ). The HQ values for benzene nearby Site-2 were above 1.0, indicating inhalation exposure could pose a health hazard. Besides, the HQ results for exposure to toluene in all sampling sites were less than 1.0. The sensitivity analysis had shown that the risk determinant for carcinogenic and non-carcinogenic risk was exposure time, followed by concentration., (Copyright © 2021 Elsevier Inc. All rights reserved.)

In the present study, PM 2.5 , volatile organic compounds (VOC), heavy metals, and polycyclic aromatic hydrocarbons (PAHs)-bonded PM 2.5 as well as asbestos fibers were investigated in two cities in the east of Tehran, Iran. To this end, 72 samples were collected from six stations located in the cities of Varamin and Pakdasht from March 2018 to March 2019. The concentration of BTEX compounds, PAHs, and heavy metals were measured using gas chromatography-flame ionization detector (GC-FID), gas chromatography-mass spectrometry (GC-Mas), and inductively coupled plasma atomic emission spectroscopy (ICP-OES), respectively. In addition, phase contrast microscopy (PCM) method was used to identify the properties of asbestos fibers. The results obtained from the present showed that the mean concentrations of PM 2.5 , heavy metals, PAHs, BTEX, and asbestos fibers were 52.05 µg/m 3 , 319.08 ng/m 3 , 3.97 ng/m 3 , 40.58 µg/m 3 , and 2.84 f/L, respectively. In addition, the results obtained from PCA and heavy metals sources showed that transport fleets were the natural source of most of these pollutants. In case of PAH sources, transport and incineration of coal had the highest contribution in the emission. Furthermore, the risk assessment showed that most of the compounds have a higher risk value than the guideline value spatial distribution and also showed that stations close to airports, city terminals, and highways were more polluted than other parts of the city. Therefore, in order to have healthy air and with the least pollution, it seems necessary to formulate the necessary strategies in the cities of Varamin and Pakdasht., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

The aim of this study is to investigate the concentration of Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) compounds in the indoor air of residential-commercial complexes and to compare it with other residential buildings (control) as well as to assess the carcinogenicity and non-carcinogenicity risk of these pollutants. BTEX concentration was investigated in the indoor air of 30 ground floor restaurants, 30 upper residential units of the complexes, 20 adjacent residential units (control), and their corridors. The mean BTEX concentration measured in the upper residential units was reported higher than in the control residential units, though they were not significantly different. The lifetime cancer risk (LTCR) value calculated for benzene in the upper residential units was lower than 10 -4 and higher than 10 -6 across all ages, indicating a carcinogenicity risk. Furthermore, the mean hazard quotient (HQ) for all compounds was obtained lower than 1, suggesting no concern about the non-carcinogenicity risk of these compounds in the studied region. Nevertheless, considering the sources of benzene production in the indoor air as well as the carcinogenicity of these pollutants and the risk they pose in human health, application towards the reduction of the sources and concentration of benzene in the indoor air are necessary.

This study focused on the measurement of BTEX (benzene, toluene, ethylbenzene and xylene) concentrations in the air of various regions and indoor-outdoor environments in Bandar Abbas, Iran. Air samples were taken actively and analyzed by gas chromatography-mass spectrometry (GC-MS) during two one-month periods i.e., Feb 2020 (period I) and Sep/Oct 2020 (period II). The mean air temperature and the levels of all BTEX compounds were higher in period II. The highest total BTEX (t-BTEX) levels (median [min-max]) were found in the urban region (18.00 [5.21-67.24] μg m -3 ), followed by industrial region (7.00 [2.05-14.76] μg m -3 ) and rural region (2.81 [ND-7.38] μg m -3 ). The significant positive correlations between all BTEX compounds and T/B ratio >1 indicated the vehicular traffic as the main source of emission. At 95th percentile probability, the non-cancer risk of t-BTEX in urban region was only less than one order of magnitude below the threshold level of unity (1.91E-01) and the cancer risk of benzene exceeded the recommended level of 1.0E-06 by U.S. EPA in urban (7.69E-06) and industrial (2.97E-06) regions. It was found that the indoor/outdoor ratio of BTEX concentration in beauty salon and hospital was greater than 1. Overall, the current levels of BTEX in the ambient air of study area, especially near urban roadside and in some indoor environments, should not be overlooked and appropriate mitigation actions should be undertaken., (Copyright © 2021 Elsevier Inc. All rights reserved.)

The present study evaluated the concentrations, spatial distribution, seasonal variations, potential sources, and risk assessment of organic/inorganic pollutants in ambient air of Tehran city. Totally, 180 air samples were taken from 9 sampling stations from March 2018 to March 2019 and were analyzed to determine the concentrations of organic pollutants (BTEX compounds and PM 2.5 -bound PAHs) plus inorganic pollutants (PM 2.5 -bound metals and asbestos fibers). The results revealed that the mean concentrations of ∑ PAHs, BTEX, ∑ heavy metals, and asbestos fibers were 5.34 ng/m 3 , 60.55 µg/m 3 , 8585.12 ng/m 3 , and 4.13 fiber/ml in the cold season, respectively, and 3.88 ng/m 3 , 33.86 µg/m 3 , 5682.61 ng/m 3 , and 3.21 fiber/ml in the warm season, respectively. Source apportionment of emission of the air pollutants showed that PAHs are emitted from diesel vehicles and industrial activities. BTEX and asbestos are also released mainly by vehicles. The results of the inhalation-based risk assessment indicated that the carcinogenic risk of PAHs, BTEX, and asbestos exceeded the recommended limit by The US environmental protection agency (US EPA) and WHO (1 × 10 -4 ). The risk of carcinogenesis of heavy metal of lead and chromium also exceeded the recommended limit. Thus, proper management strategies are required to control the concentration of these pollutants in Tehran's ambient air in order to maintain the health of Tehran's citizens.

The available evidence on the indoor air quality of operating rooms (ORs) in the Low- and Middle-income Countries (LMICs) is very scarce. Moreover, there is no study on the comparing the concentration of indoor air pollutants in different ORs. Therefore, this study aimed to measure and compare the benzene, toluene, ethylbenzene and xylene (BTEX) concentrations in the air of different ORs in hospitals of Sabzevar, Iran. Moreover, carcinogenic and non-carcinogenic risk of exposure to these pollutants were assessed using Monte Carlo simulations technique. This cross-sectional study was based on volatile organic compounds (VOCs) passive sampling of eight ORs including General surgery, Curettage, Eye surgery, Neurosurgery, Orthopedic, Laparoscopic, Cesarean and Ear, nose, throat (ENT) in two monthly campaigns from November 2019 to February 2020. One-way ANOVA and Post-hoc analyses were used to compare the concentration of BTEX compounds in different ORs. The overall mean (standard deviation (SD)) of benzene, toluene, ethylbenzene, xylene and total BTEX concentrations were 10.0 (1.8), 7.2 (1.9), 1.8 (0.6), 0.4 (0.2) and 19.4 (4.1) μg/m 3 . The Curettage OR had the highest (12.93 μg/m 3 ) and ENT OR had the lowest (7.42 μg/m 3 ) benzene concentrations. The highest concentrations of toluene, ethylbenzene and total BTEX were observed in General surgery OR. The cancer risks of exposure to benzene in all ORs were higher than the acceptable range recommended by Unite State Environmental Protection Agency (USEPA, 1 × 10 6 ). However, the hazard quotient (HQ) values for all ORs were at safe level (HQ < 1). Overall, our study suggested that the concentrations of BTEX compounds were significantly difference in different ORs and benzene had a carcinogenic risk for personnel and surgical staff in different ORs., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Few studies have evaluated airborne exposures to benzene, toluene, ethylbenzene, and xylenes (BTEX) during operation of two-stroke and four-stroke small engines, such as those in lawn maintenance equipment. Full-shift, 8-hour personal samples were collected during a simulation study to characterize yard maintenance activities including mowing, trimming, and fueling. Short-term, 15-minute personal samples were collected to separately evaluate mowing and trimming exposures. Mean 8-hour time weighted average (TWA) BTEX concentrations were 2.3, 5.8, 0.91, and 4.6 ppb, respectively (n = 2). Mean 15-minute TWA BTEX concentrations were 1.6, 1.8, 0.22, and 1.3 ppb, respectively, during mowing and 1.2, 3.6, 0.68, and 3.3 ppb, respectively, during trimming (n = 3 per task). Measured BTEX concentrations during fueling were 20-110, 61-310, 8-41, and 40-203 ppb, respectively (n = 2, duration 2-3 minutes). These exposure concentrations were well below applicable US occupational exposure limits.