Benzene Compounds Research Articles

Investigation of some effective factors on urinary metabolites in biological monitoring of benzene, toluene, and xylene compounds

ABSTRACT The present study was performed to identify possible factors affecting the biological monitoring of benzene, toluene, and xylene (BTX) metabolites. Fifty persons with occupational exposure to BTX and 28 administrative employees were evaluated. Urinary trans, trans-muconic acid (t,t-MA), Hippuric Acid (HA) and Methyl Hippuric Acid (MHA) were determined as the biomarkers of exposure. The mean levels of t,t-MA, HA, and MHA in the exposed group were 541.90 (µg‧g creatinine−1), 0.0199, and 0.00205 (g‧g creatinine−1), respectively, which were higher than the non-exposed group (significant difference, Pvalue <0.001). In the regression model obtained from the amount of urinary t,t-MA, level of education, work experience, residence, length of work per shift, use of personal protective equipment (PPE), and habit of consuming industrial food or fruit juice had a significant effect. HA levels were affected by variables including education level, residence, consumption of industrial food or fruit juice in the past three days, and use of masks, gloves, and PPE. Due to the small amount of MHA in urine, there was a weak correlation between it and independent variables. Based on results, it was concluded that the health effects of exposure to BTX were significantly different between the two groups.

Cavitand Decorated Silica as a Selective Preconcentrator for BTEX Sensing in Air.

The monitoring of benzene and other carcinogenic aromatic volatile compounds at the ppb level requires boosting both the selectivity and sensitivity of the corresponding sensors. A workable solution is the introduction in the devices of preconcentrator units containing molecular receptors. In particular, quinoxaline cavitands (QxCav) resulted in very efficient preconcentrator materials for the BTEX in air to the point that they have been successfully implemented in a commercial sensor. In this work, we report a highly efficient quinoxaline-based preconcentrator material, in which the intrinsic adsorption capacity of the QxCav has been maximized. The new material consists of silica particles covalently coated with a suitable functionalized QxCav derivative (QxCav@SiO2). In this way, all the cavities are exposed to the analyte flux, boosting the performance of the resulting preconcentration cartridge well above that of the pure QxCav. It is noteworthy that the preconcentrator adsorption capacity is independent of the relative humidity of the incoming air.

Photophysics of α-azinyl-substituted 4,4-difluoro-8-(4-R-phenyl)-4-bora-3a,4a-diaza-s-indacenes

A series of 15 compounds of the general formula 8-(4-R1-phenyl)-3-R2-5-R3-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene, where R1 = NMe2, Me, Br, CN, or NO2, and R2, R3 = H, acridin-9-yl, or 6-phenyl-[1,2,5]oxadiazolo[3,4-b]pyrazyne-5-yl, have been synthesized and investigated for their fluorescence properties in tetrachloroethylene and benzene solutions. For tetrachloroethylene solutions of 8-(4-dimethylaminophenyl)-substituted compounds, bright fluorescence from a locally excited state has been observed. The same compounds in benzene show intramolecular charge transfer with an increased Stokes shift and greatly reduced radiative rate and fluorescence quantum yield. The rest of the compounds are characterized only by locally-excited fluorescence both in tetrachloroethylene and benzene. Their nonradiative rate constant knr obeys the equation ln knr = a + bnacr + cσp, where σp is the Hammett constant of the para-substituent, nacr is the number of acridine substituents; a, b, c are fitting parameters. The linearity of the formula implies an additive effect of the substituents on the activation energy of the nonradiative decay.

Ion Impregnation Effect of Fe, Cu, Cr-attributed Mordenite on Stearic Acid Cracking

The improvement in the design of mordenite-based catalysts focuses on the present study to fulfill the massive demand for bio-aviation fuel (BAF) as renewable energy. Modification of the mordenite through ionic impregnation of Fe, Cu, and Cr, has supported the mordenite to perform with better efficiency and activity in catalyzing the cracking process of stearic acid. The adjustment on catalytic activity was carried out by simply reacting the catalyst with stearic acid at 190 °C and investigating cracking products with Gas Chromatography-Mass Spectroscopy. The results of the GC-MS test of the cracking product showed the formation of alkane-alkene and aromatic compounds. BAF was selectively obtained (30.27%) when the reaction was catalyzed by FeCuCr/mordenite catalyst. The BAF derived from FeCuCr/mordenite contained hydrocarbons that include xylene, mesitylene, dodecane, tridecane, tetradecane, and pentadecane. However, reduced selectivity was realized (19.85%) when the reaction was catalyzed by nano FeCuCr/mordenite. Its hydrocarbon constituents include benzene, tetradecane, and pentadecane compounds.

Urinary concentrations of BTEX in waterpipe smokers and nonsmokers: Investigating the influence of conventional activities and multiple factors

The aim of this study was to compare the concentrations of the benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in the urine of smokers and the control group considering the role of age, weight, job, history of waterpipe and cigarette smoking, and driving time. The chemicals in the urine of 99 smokers and 31 nonsmokers were extracted by liquid-liquid extraction method and their concentrations were measured by liquid injection GC/MS. The mean concentration of benzene, toluene, ethylbenzene, m-xylene, o-xylene, p-xylene, and total BTEX in waterpipe smokers were found to be 471.40, 670.90, 127.91, 167.64, 90.62, 46.04, and 1574.50 ng/g. creatinine, respectively. For the waterpipe&cigarette smokers, the concentration of the compounds were 708.00, 959.00, 146.40, 192.50, 93.30, 53.07, and 2152.00 ng/g.creatinine, respectively. For nonsmokers the concentrations of these compounds were 88.12, 140.40, 36.68, 57.29, 31.53, 26.21, and 380.30 ng/g.creatinine, respectively. Driving time, waterpipe smoking and cigarette smoking were positively associated with BTEX concentration (p < 0.05). Fruity tobacco showed higher concentrations of BTEX compared to the regular tobacco, and athlete persons had les urinary BTEX than the non-athletes. There was not significant correlation between the BTEX and age, height, weight, and BMI. High concentrations of BTEX compounds in the urine of waterpipe and cigarette smokers compared to nonsmokers indicate that waterpipe and cigarette can be an important source of exposure to these compounds and the known adverse effects of these compounds, especially carcinogenicity, threaten the health of smokers.

The characteristics of bio-oil hydrothermal pyrolysis empty fruit bunches based on powder size and hydrogen gas pressure

Bio oil is the result of pyrolysis of biomass raw materials in the form of dark-colored liquids containing major chemical compounds such as benzene compounds, aromatic compounds, aliphatic, and other organic compounds. In the future, bio-oil is expected to be a substitute for fossil fuels as they are more environmentally friendly. Empty fruit bunches (EFB) from oil palm are one type of biomass that can be used as bio-oil products. The elements of pyrolysis that were analyzed were High Heating Value (MJ/kg), pH, viscosity, density and analysis of the components of hydrocarbon compounds formed using GCMS analysis. The results showed that HHV value 35.66 MJ / - 39.09 MJ/kg, the pH value of bio-oil was somewhat similar to normal pH 4 - 6, and viscosity was 4 - 9 cp. The results of GCMS analysis showed that the content of the optimal percentage of hydrocarbon compounds was treated with 40 mesh powders with a hydrogen pressure of 15 bar. 19 types of hydrocarbon compounds were found with a total percentage of 13.79 %.

The chemical adsorption effect of surface enhanced Raman spectroscopy of nitrobenzene and aniline using the density functional theory

Nitrobenzene and Aniline are representatives of the nitro or amino compounds of benzene, mainly used in the manufacture of dyes, spices, medicines, and so on. Extensive use of Nitrobenzene and Aniline may cause pesticide residue pollution and have carcinogenic effects on organisms. In this paper, the Nitrobenzene and Aniline single molecules and their complexes with gold nanoparticles are studied theoretically by Raman spectroscopy, the surface-enhanced Raman spectroscopy (SERS) and the density functional theory (DFT) simulations. Selective binding of gold nanoparticles (AuNPs) to the analyte was used to study the molecular electrostatic potential (MEP), frontier molecular orbital (FMO) and the Raman activity spectra of Nitrobenzene and Aniline, as well as the Raman activity spectrum of the complexes. The most electronegative sites of Nitrobenzene and Aniline are found in the MEP and the hypothesis that these sites might be the adsorption sites of Nitrobenzene/Aniline molecules at the gold surface. At the same time, the MEP of the Nitrobenzene/Aniline complexes also prove the existence of the charge transfer effect between Nitrobenzene/Aniline and Au. The FMO energy gap of Nitrobenzene/Aniline is 0.18983 eV and 0.18953 eV, respectively, and which, after adding the Au3 clusters, change to 0.03376 eV and 0.0797 eV, respectively, indicating that the Nitrobenzene/Aniline-Au3 complexes have stronger chemical activities and are more prone to the charge transfer effects. The electrophilic indices of Nitrobenzene (0.17921 eV) and Aniline (0.05635 eV) are calculated and analyzed, as well as that of Nitrobenzene/Aniline-Au3 complexes after adding the Au3 atomic clusters, 0.80819 eV and 0.19819 eV, respectively. The obvious increasing trend in the electrophilic indices of the Nitrobenzene/Aniline-Au3 complexes indicate their stronger biological activities and more prone to chemical reactions. The chemisorption of Nitrobenzene/Aniline and gold nanoparticles complexes is studied by the SERS, and the Raman formation of the complexes at different binding sites of Nitrobenzene/Aniline and Nitrobenzene/Aniline-Au3 is well explained by the surface selection rule. The reason for the selective enhancement of the spectral peaks presented in the Raman activity spectrum is calculated, and the enhancement factor of the chemical enhancement due to the charge transfer effect is calculated as well. The reason for the peak offset in the SERS spectrum to the conventional Raman spectrum is explained.

Determination of Benzene, Toluene, Ethylbenzene and Xylene Compounds in Surgical Smoke and Its Relationship with Body Mass Index and Duration of Surgery

Determination of Benzene, Toluene, Ethylbenzene and Xylene Compounds in Surgical Smoke and Its Relationship with Body Mass Index and Duration of Surgery

Aqueous Mediated Heterogeneous Catalysis

Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 °C, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550−600 °C). Especially, 550 °C tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650−800 °C) decreases, but the quality of tar obtained at 650−700 °C is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 °C is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 °C, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 °C, but more favorable for generation of which in the tar obtained below 700 °C

Research on the Pollutant Migration Law Based on Large-Scale Three-Dimensional Similar Simulation Experiments of Underground Coal Gasification.

The potential pollution risk of underground coal gasification (UCG) has become a key factor restricting the development of UCG industrialization. Therefore, studying the migration and diffusion behavior of harmful pollutants is of great significance for preventing UCG pollution. In this paper, a large-scale three-dimensional similar simulation experimental device for UCG is used to simulate the gasification of Tianjin fat coal under actual working conditions. The rock layer around the simulated coal seam was sampled after the gasification was completed, the contaminants in the samples were examined by XRD, and the changes in the relative content of the contaminants at different sampling points were studied by FTIR. The results showed that benzene, phenols, aldehydes, aromatic hydrocarbons, and aromatic heterocyclic compounds remained after the gasification of No. 7 sampling point in Qianjiang, Tianjin, and that the main pollutants were aromatic hydrocarbons. The migration and enrichment of phenol and aldehyde pollutants were about the same on the east and west sides of the gasification center, while benzene pollutants were more easily migrated and enriched than aromatic heterocyclic compounds. The migration distance of phenolic pollutants on the south side of the gasification area is smaller than that of other pollutants and their maximum vertical distance from the gasification reaction area to the south is about 0.7 m. The results can provide a scientific basis for pollutant risk identification and prevention and control in the later UCG field test.

Microbial bioremediation of produced water under different redox conditions in marine sediments

The discharge of produced water from offshore oil platforms is an emerging concern due to its potential adverse effects on marine ecosystems. In this study, we investigated the feasibility and capability of using marine sediments for the bioremediation of produced water. We utilized a combination of porewater and solid phase analysis in a series of sediment batch incubations amended with produced water and synthetic produced water to determine the biodegradation of hydrocarbons under different redox conditions. Significant removal of benzene, toluene, ethylbenzene and xylene (BTEX) compounds was observed under different redox conditions, with biodegradation efficiencies of 93−97% in oxic incubations and 45−93% in anoxic incubations with nitrate, iron oxide or sulfate as the electron acceptor. Higher biodegradation rates of BTEX were obtained by incubations dominated by nitrate reduction (104−149 nmolC/cm3/d) and oxygen respiration (52−57 nmolC/cm3/d), followed by sulfate reduction (14−76 nmolC/cm3/d) and iron reduction (29−39 nmolC/cm3/d). Chemical fingerprint analysis showed that hydrocarbons were biodegraded to smaller alcohols/acids under oxic conditions compared to anoxic conditions with nitrate, indicating that the presence of oxygen facilitated a more complete biodegradation process. Toxicity of treated produced water to the marine copepod Acartia tonsa was reduced by half after sediment incubations with oxygen and nitrate. Our study emphasizes the possibility to use marine sediment as a biofilter for treating produced water at sea without extending the oil and gas platform or implementing a large-scale construction.

Effects of syngas from semi-coke in situ gasification on yield and quality of tar from pyrolysis of Naomaohu coal

Pyrolysis atmosphere has significant effect on yield and composition of coal tar. A pyrolysis and gasification integrated reactor in laboratory was used to investigate effects of gasification syngas on yield and composition of coal tar. The results show that tar yield of Naomaohu coal reaches the maximum at 600 °C, and gasification syngas (G-gas) is more beneficial to improve the tar yield at low temperature (550−600 °C). Especially, 550 °C tar yield increases by 4.4% compared with that under N2. With the introduction of G-gas, the yield of tar obtained at high temperature (650−800 °C) decreases, but the quality of tar obtained at 650−700 °C is improved obviously due to the increase of light components. The cracking reaction of aliphatic hydrocarbons and oxygen-containing compounds in volatiles from pyrolysis at 550 and 600 °C is intensified by G-gas, thus substituted benzene and naphthalene compounds in coal tar increase. For the volatiles obtained above 650 °C, the secondary cracking reaction of phenolic compounds is enhanced with the introduction of G-gas, which results in a decrease of phenolic compounds in tar. G-gas is also favorable for the secondary cracking reaction of polycyclic aromatic hydrocarbons in volatiles from pyrolysis at 800 °C, but more favorable for generation of which in the tar obtained below 700 °C

Analysis of Bitter honey using gas chromatography and Tandem Mass Spectrometry.

Honey has been consumed by humans since ancient times. Honey contains volatile compounds like aldehyde, alcohol, ketone, hydrocarbon, terpenes, acids, benzene compounds. These compounds represent the fingerprint of monofloral honey there by providing information about the floral and geographical origin of honey. The volatile compounds present in honey not only contribute the aroma but also associated with the therapeutic activities of honey. In the present study, the GCMS/MS analysis of bitter honey was carried out to identify the presence of volatile compounds. This is the first study to determine the volatile compounds from ethyl acetate extract of bitter honey produced in the Nilgiri biosphere. Among the eighteen compounds detected, the majority of the compounds were reported to be therapeutically active. Hence further studies regarding the isolation of these compounds could be beneficial in the treatment of various diseases.

PENGEMBANGAN METODE ANALISIS BENZENA, TOLUENA, DAN XYLENA DALAM UDARA LINGKUNGAN KERJA MENGGUNAKAN IN HOUSE METODE DI PT UNILAB PERDANA

Benzene, Toluene and Xylene (BTX) compounds are compounds that have colorless and flammable characteristics, have a sweet odor with a low toxicity level, and are not soluble in water. This compound is often used as a solvent, extractor and as a chemical intermediary. The testing of BTX parameters in the working environment refers to the National Institute of Occupational Safety and Health (NIOSH) method number 1501. The method must be modified or developed in terms of equipment and instruments, due to looking at the condition of the materials and equipment in PT UP, i.e. using different columns, capillary columns, fused silica, 30m x 0.32-mm ID; 1-μm film 100% PEG becomes a Rtx-5MS column, and measurements using a FID detector become a Mass Spectrometer detector. And the solvent used is Carbon Disulfiida (CS2) to Methanol for gas chromatography. CS2 solvents are carcinogenic in the body so that they are harmful to human health. Besides being harmful to health, the waste produced by CS2 causes damage to the ozone layer on the earth's surface so that it can trigger global warming which will make the earth feel hot. In addition, CS2 solvents in Indonesia have begun to be reduced in production and will be illegal inthe future. Therefore, this method needs to be validated before doing a routine analysis so that the data obtained is valid.

Tailoring surface properties with O/N doping in CNT aerogel film to obtain sensitive and selective sensor for volatile organic compounds detection

Volatile organic compounds (VOCs), listed as toxins/hazardous air pollutants are harmful to human health, and challenges associated with VOCs detection are selectivity of sensors. An emerging material CNT aerogel can offer selective and sensitive detection capabilities of VOCs. The CNT aerogel sensor has been synthesized using scalable floating catalyst chemical vapor deposition and doped with oxygen/nitrogen via plasma treatment. The oxygen/ nitrogen doping was introduced to simultaneously manage defect creation, functional group generation, enhance surface chemistry to obtain superior analyte molecule detection. The surface and functional characterization confirm that plasma treatment introduces oxygen/nitrogen doping in individual CNT uniformly throughout the film without disturbing the mechanical integrity of standalone CNT aerogel film. The bare, oxygen and nitrogen-doped CNT aerogel sensors can detect the polar compounds acetone, ethanol, methanol, as well as non-polar compound benzene in the concentration range of 2–100 ppm. The nitrogen-doped CNT aerogel sensor showed the highest sensitivity, selectivity, response (~ 5 fold increase in comparison to bare) with a limit of detection of 50 ppb. Hence, the present study showed the existence of a critical trade-off between doping and sensing performance of CNT aerogel, and enabling proper composition in CNT aerogel, a sensor with significant performance can be fabricated.

Organic Chemical Contaminants in Water System Infrastructure Following Wildfire.

Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile organic compounds (VOCs) were found in public drinking water systems in fire-affected areas. The sources of the contamination and appropriate remediation have been urgent matters for investigation. This study characterizes target and non-target VOCs and semi volatile organic compounds (SVOCs) in water from a highly contaminated service line after the 2018 Camp Fire (Paradise, CA). Ninety-five organic compounds were identified or tentatively identified in the service line. Laboratory combustion experiments with drinking water pipes made of polyvinyl chloride (PVC), cross-linked polyethylene (PEX) and high-density polyethylene (HDPE) and a review of the literature were used to evaluate potential sources of the detected chemicals. Among the service line contaminants were thirty-two compounds associated with PVC pyrolysis and twenty-eight organic compounds also associated with the pyrolysis of polyethylene. The service line sample also contained fifty-five compounds associated with uncontrolled burning of biomass and waste materials. The findings support hypotheses that wildfires can contaminate drinking water systems both by thermal damage to plastic pipes and intrusion of smoke. Residual chlorine disinfectant in the water system modifies the contaminant distribution observed.

Development of a bacterial consortium from Variovorax paradoxus and Pseudomonas veronii isolates applicable in the removal of BTEX

In this study, we report on the development of a novel bacterial consortium, consisting of Variovorax paradoxus and Pseudomonas veronii isolates, applicable in the biodegradation of all six BTEX compounds (benzene, toluene, ethylbenzene, o-, m- and p-xylene) and the bioremediation of contaminated sites. The co-cultivability of the selected bacterial isolates was determined in nutrient-rich medium, as well as in BTEX amended mineral salts solution using Terminal Restriction Fragment Length Polymorphism (T-RFLP) and CFU determinations. BTEX biodegradation capacity of the two-strain consortium was assessed in mineral salts solution, where a series of BTEX depletions and supplementations occurred, as well as in a real, BTEX polluted environmental sample (contaminated groundwater) in the presence of the autochthonous bacterial community. The obtained results indicated that the developed bacterial consortium is very efficient in BTEX biodegradation. Under laboratory conditions, the acclimatized bacterial consortium completely degraded the BTEX mixture with a concentration as high as 20 mg l−1 in a mineral salt medium within a short span of 6 h. Close to in situ groundwater conditions (incubated at 15 °C under static conditions in the absence of light), groundwater microcosms containing the autochthonous bacterial community inoculated with the developed bacterial consortium showed more efficient toluene, o-, m-and p-xylene biodegradation capacity than microcosms containing solely the native microbial population originally found in the groundwater. In the inoculated microcosms, after 115 h of incubation the concentration (~ 1.7 mg l−1 each) of o-, m- and p-xylene decreased to zero, whereas in the non-inoculated microcosms the concentration of xylene isomers was still 0.2, 0.3 and 0.3 mg l−1, respectively. The allochthonous bioaugmentation of the contaminated groundwater with the obtained inoculant was successful and manifested in a better BTEX degradation rate. Our results suggest that the obtained bacterial consortium can be a new, stable and efficient bioremediation agent applicable in the synergistic elimination of BTEX compounds from contaminated sites.

Systematic analysis of the aroma profiles produced by Zygosaccharomyces rouxii Y-8 in different environmental conditions and its contribution to doubanjiang (broad bean paste) fermentation with different salinity

This study aimed to provide a systematic analysis of the effect of environmental factors on the growth and volatile flavor compounds (VFCs) production ability of Zygosaccharomyces rouxii Y-8 and further elucidate its contribution to doubanjiang fermentation in different salinity. Lower salinity (0–9%), acidic pH (4.5–5.5), moderate temperature (25–35 °C) and air exposure favored the growth and VFCs accumulation of Z. rouxii Y-8, which also had higher concentrations of key jiang flavor contributing compounds benzene ethanol, 2-methoxy-phenol and pyrazines. Interestingly, samples with higher VFCs concentration were found to contain less kinds of VFCs. When inoculated into doubanjiang fermentation, Z. rouxii Y-8 showed critical roles on the formation of VFCs in doubanjiang. Among doubanjiang samples fermented in different salinity, doubanjiang with 9% salinity had the highest kinds of VFCs. Moreover, its flavor was more balanced and the jiang flavor was stronger. This indicated that the presence of adequate salinity was necessary for Z. rouxii Y-8 to produce critical VCFs responsible for doubanjiang flavor. The results would provide researchers and manufacturers with a deeper understanding of the characteristics of Z. rouxii Y-8 and rationales to utilize Z. rouxii Y-8 as starter to produce high quality BBFFs.

Monitoring Benzene, Toluene, Ethylbenzene, and Xylene (BTEX) Levels in Mixed-Use Residential-Commercial Buildings in Shiraz, Iran: Assessing the Carcinogenicity and Non-Carcinogenicity Risk of Their Inhabitants.

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.

Measurement of BTEX (benzene, toluene, ethylbenzene and xylene) concentration at gas stations

Background: Fuel stations are one of the major sources of air pollution with volatile organic compounds, especially the four main petrol compounds benzene, toluene, ethylbenzene, and xylene (BTEX). BTEX in gasoline enters the air of gas stations due to high evaporation of gasoline. Therefore, determining the concentration of these compounds in gas stations in crowded and busy cities is one of the important priorities of environmental health, which is doubly important in terms of its negative effects on health. Methods: In this descriptive cross-sectional study, a total of 39 samples were collected from 13 gas stations. Sampling was performed in autumn 2018 in three working shifts (morning, noon, and night). The method NIOSH-1501 (i.e., using charcoal sorbent tubes and SKC pump with a flow rate of 0.2 L/min) was used for sampling the BTEX compounds. The mean difference and correlation of BTEX compounds based on meteorological parameters and the number of nozzles in gas stations were assessed using one-way ANOVA and correlation tests. Results: The mean and standard deviation of benzene, toluene, ethylbenzene, and xylene concentrations in the air of fuel stations were 2.784±1.461, 3.495±1.390, 2.091±0.811, and 1.140±0.419 mg/m3, respectively. The relationship between BTEX compounds and meteorological parameters such as humidity and exposure time is very important. There is a strong correlation between the concentrations of BTEX compounds. The highest correlation was observed between benzene and toluene and the lowest one was observed between benzene and xylene. In this study, no significant relationship was observed between air temperature and concentration of BTEX compounds, but there was a relationship between relative humidity and the concentration of BTEX compounds. Conclusion: The average benzene concentration in the air at the fuel stations was about 5.5 times the standard limit. Authorities should improve fuel quality and reduce its evaporation through engineering measures to overcome the issue.