Benzene In Air Research Articles

Triptycene-Roofed Quinoxaline Cavitands for the Supramolecular Detection of BTEX in Air.

Two novel triptycene quinoxaline cavitands (DiTriptyQxCav and MonoTriptyQxCav) have been designed, synthesized, and applied in the supramolecular detection of benzene, toluene, ethylbenzene, and xylenes (BTEX) in air. The complexation properties of the two cavitands towards aromatics in the solid state are strengthened by the presence of the triptycene moieties at the upper rim of the tetraquinoxaline walls, promoting the confinement of the aromatic hydrocarbons within the cavity. The two cavitands were used as fiber coatings for solid-phase microextraction (SPME) BTEX monitoring in air. The best performances in terms of enrichment factors, selectivity, and LOD (limit of detection) values were obtained by using the DiTriptyQxCav coating. The corresponding SPME fiber was successfully tested under real urban monitoring conditions, outperforming the commercial divinylbenzene-Carboxen-polydimethylsiloxane (DVB-CAR-PDMS) fiber in BTEX adsorption.

A new cataluminescence-based gas sensor for simultaneously discriminating benzene and ammonia

An efficient method based on cross-cataluminescence (CTL) on nano-Bi4SnV2O13 was proposed for simultaneously discriminating benzene and ammonia in air.

Study of red blood cell count, hemoglobin concentration, and platelets in petrol pump workers of Surat city

Background: Petrol pump workers are exposed to many air pollutants and chemicals such as benzene, lead, other heavy metals, carbon monoxide (CO), and their metabolites in the work premises of petrol pump, which has carcinogenic and hematotoxic effects. Aims and Objective: This study was conducted to find the effect of benzene and other air pollutants on red blood cell (RBC) counts, hemoglobin (Hb) concentration, and platelets in petrol pump workers of Surat city. Materials and Methods: Thirty (30) healthy male petrol pump workers aged 20–50 years, working for more than 1 year (more than 8 h/day) who volunteered for the study were taken as the study group. Thirty (30) healthy male non-petrol pump workers aged 20–50 years matching socioeconomically with the study group were taken as control group. Morning (8–10 AM) blood samples were collected under aseptic precautions from all the participants. Blood samples were analyzed by 3-part automated cell counter ABX MICROS 60 in the hematology lab of the Department of Physiology, GMC, Surat. Data were presented as mean ± SD and compared using unpaired t-test. P value

STAT3 methylation in white blood cells as a novel sensitive biomarker for the toxic effect of low-dose benzene exposure.

Alterations in DNA methylation patterns play an essential role in disease process and are associated with cancer risk. To explore the toxic effect and early sensitive biomarker of the health effects of low-dose benzene exposure (LDBE), and investigate the correlation between DNA methylation and the toxic effect of LDBE, a cross-sectional study was conducted in a sample of 571 workers; 312 workers who were exposed to a 1.82 ± 1.16 mg m-3 air benzene concentration were assigned to the LDBE group, while 259 non-known benzene exposure (NBE) workers were assigned to the control group, with an air benzene concentration of 0.06 ± 0.01 mg m-3. Routine blood indexes, alanine transaminase (ALT), oxidative stress parameters and signal transducer and activator of transcription 3 (STAT3) methylation were detected. Compared with the NBE population, the STAT3 methylation level (P = 0.001), Platelets (PLTs) (P = 0.002) and 8-isoprostane-PGFs (8-iso-PGF2a) (P = 0.001) manifested a significant reduction, while ALT (P = 0.002) and 8-hydroxy-2 deoxyguanosine (8-OHdG) (P = 0.002) showed a significant rise in the LDBE population. In addition, a significant correlation was observed between STAT3 methylation and oxidative stress, namely 8-OhdG and 8-iso-PGF2a. Furthermore, a multivariate analysis showed that the STAT3 methylation (structure loadings = 0.909) was the most strongly correlated with the other set of variables, especially with white blood cells (WBCs) (structure loadings = 0.675). Taken together, STAT3 methylation may be the underlying mechanism involved in the early toxic effect of LDBE, therefore, STAT3 methylation can be a novel sensitive biomarker for the toxic effect of low-dose benzene exposure.

Inhalation exposure or body burden? Better way of estimating risk--An application of PBPK model.

We aim to establish a new way for estimating the risk from internal dose or body burden due to exposure of benzene in human subject utilizing physiologically based pharmacokinetic (PBPK) model. We also intend to verify its applicability on human subjects exposed to different levels of benzene. We estimated personal inhalation exposure of benzene for two occupational groups namely petrol pump workers and car drivers with respect to a control group, only environmentally exposed. Benzene in personal air was pre-concentrated on charcoal followed by chemical desorption and analysis by gas chromatography equipped with flame ionization detector (GC-FID). We selected urinary trans,trans-muconic acid (t,t-MA) as biomarker of benzene exposure and measured its concentration using solid phase extraction followed by high performance liquid chromatography (HPLC). Our estimated inhalation exposure of benzene was 137.5, 97.9 and 38.7 μg/m(3) for petrol pump workers, car drivers and environmentally exposed control groups respectively which resulted in urinary t,t-MA levels of 145.4±55.3, 112.6±63.5 and 60.0±34.9 μg g(-1) of creatinine, for the groups in the same order. We deduced a derivation for estimation of body burden from urinary metabolite concentration using PBPK model. Estimation of the internal dose or body burden of benzene in human subject has been made for the first time by the measurement of t,t-MA as a urinary metabolite using physiologically based pharmacokinetic (PBPK) model as a tool. The weight adjusted total body burden of benzene was estimated to be 17.6, 11.1 and 5.0 μg kg(-1) of body weight for petrol pump workers, drivers and the environmentally exposed control group, respectively using this method. We computed the carcinogenic risk using both the estimated internal benzene body burden and external exposure values using conventional method. Our study result shows that internal dose or body burden is not proportional to level of exposure rather have a non-linear relationship. At a higher exposure level such as for occupational exposure of petrol pump workers and drivers, the conventionally estimated risk is higher than risk estimated from internal body burden. Likewise, for environmental exposure the conventional risk estimation predict lower level than estimated in our study. This emphasizes the importance of body burden and to consider it as a key parameter while estimating health risk at varying level of exposure.

Mesoporous silica nanoparticle film as sorbent for in situ and real-time monitoring of volatile BTX (benzene, toluene and xylenes)

A strategy is described for the real time and selective monitoring of benzene, toluene and xylenes (BTX) in air. Rapid preconcentration and recovery have been achieved with films made of mesoporous silica nanoparticles assembled on a quartz plate. The resulting nanoparticle films displayed high transmittance and allowed the detection of toluene up to 1ppm within a minute and a regeneration of the sensor in less than 30s. The sensor response increased while increasing the concentration of benzene (detection at 252nm), toluene (detection at 267nm) or p-xylene (detection at 274nm) in the polluted air from 1 to 100ppm. The order of sensitivity, i.e. p-xylene>toluene>benzene, was correlated with their respective molar extinction coefficients. The BTX adsorption on mesoporous silica nanoparticle films has been analyzed with the Freundlich adsorption model. The repeatability of the detection was good in intraday (2%) and extra-day (4%) experiments with a given sensor. The ability to detect toluene in the presence of volatile compounds often encountered in working environments (i.e., methyl ethyl ketone, ethanol, acetone and cyclohexane) has been shown. The introduction of a gas dryer before the measurement cell allowed application of the sensor in humid atmosphere. This sensor could be used to alert if permissible values of exposure to toluene and xylenes have been reached during work.

Feasibility the Biological Monitoring of Workers Exposed to Benzene and Toluene via Measuring the Parent Compounds in the Exhaled Breath

Background: Solvents such as benzene and toluene are commonly used in tire manufacturing, and significant occupational exposure to these chemicals adversely affects the health of workers. In biological monitoring, a complementary method for personal monitoring, the internal absorbed dose is measured and individual, environmental, and exposure differences are taken into consideration. Objectives: The present study evaluated external doses by personal monitoring and investigated a more practical approach to biological monitoring by measuring the internal doses of benzene and toluene in workers involved in tire manufacturing. Materials and Methods: Personal monitoring of 100 workers in tire factories A and B (n = 50 samples from each factory, n = 100 total personal samples) was performed using the national institute for occupational safety and health 1501 method. Biological monitoring of the workers was performed by collecting exhaled air in Tedlar ® bags (n = 100). Personal and biological samples were analyzed by a gas chromatograph equipped with a flame ionization detector. Data were analyzed by independent t-test and correlation coefficients. Results: There were no significant differences between factories with respect to worker age or work history. Personal exposure to benzene exceeded the current threshold limit value in 68% of workers. Occupational exposure to benzene and toluene as external (i.e. in the breathing area) and internal doses (i.e. in the exhaled air) were significantly higher in factory B than factory A. In addition, the external and internal doses of both compounds were significantly correlated. Conclusions: The workplace conditions of tire factories must be improved. The biological exposure index can be calculated by determining the unchanged benzene and toluene concentrations in exhaled air; this can be used as a more reliable method for personal monitoring.

Occurrence and Concentrations of Toxic VOCs in the Ambient Air of Gumi, an Electronics-Industrial City in Korea.

This study was carried out to characterize the occurrence and concentrations of a variety of volatile organic compounds (VOCs) including aliphatic, aromatic, halogenated, nitrogenous, and carbonyl compounds, in the ambient air of Gumi City, where a large number of electronics industries are found. Two field monitoring campaigns were conducted for a one year period in 2003/2004 and 2010/2011 at several sampling sites in the city, representing industrial, residential and commercial areas. More than 80 individual compounds were determined in this study, and important compounds were then identified according to their abundance, ubiquity and toxicity. The monitoring data revealed toluene, trichloroethylene and acetaldehyde to be the most significant air toxics in the city, and their major sources were mainly industrial activities. On the other hand, there was no clear evidence of an industrial impact on the concentrations of benzene and formaldehyde in the ambient air of the city. Overall, seasonal variations were not as distinct as locational variations in the VOCs concentrations, whereas the within-day variations showed a typical pattern of urban air pollution, i.e., increase in the morning, decrease in the afternoon, and an increase again in the evening. Considerable decreases in the concentrations of VOCs from 2003 to 2011 were observed. The reductions in the ambient concentrations were confirmed further by the Korean PRTR data in industrial emissions within the city. Significant decreases in the concentrations of benzene and acetaldehyde were also noted, whereas formaldehyde appeared to be almost constant between the both campaigns. The decreased trends in the ambient levels were attributed not only to the stricter regulations for VOCs in Korea, but also to the voluntary agreement of major companies to reduce the use of organic solvents. In addition, a site planning project for an eco-friendly industrial complex is believed to play a contributory role in improving the air quality of the city.

Removal of low-concentration benzene in indoor air with plasma-MnO2 catalysis system

Non-thermal plasma (NTP) and combined plasma-MnO2 catalytic (CPMC) air cleaners were tested for removal of low-concentration benzene in air. Both air cleaners were made of stainless steel needle matrix plate and used DC corona discharger. The effects of discharge power and relative humidity (RH) on benzene removal efficiency were investigated in a closed chamber. The intermediate products produced in purification processes were analyzed using gas chromatography-mass spectrometer (GC-MS). The concentrations of discharge byproducts and CO2 selectivity produced in both processes were also compared. It was found that the benzene removal efficiency increased with discharge power in both systems; With the increase of RH in air, benzene removal efficiency firstly increased and then decreased in NTP while it gradually decreased in CPMC. For a fixed discharge power of 9 W and RH of 20% in CPMC, the conversion of benzene increased from 82.9% to 89.6%, the CO2 selectivity increased from 38% to 80%, the concentration of O3 decreased from 25.3 ppm to 1.3 ppm, and NO2 formation decreased from 234 ppm to 25.7 ppm, compared with NTP.

Benzene, toluene, ethylbenzene and xylene concentrations in atmospheric ambient air of gasoline and CNG refueling stations

This study aimed to assess workers’ exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) compounds in refueling stations of Ardabil city (Iran). Twenty-four refueling stations including 15 petrol and 9 compressed natural gas (CNG) stations from different regions were selected and monitored for ambient BTEX concentrations. Air samples were taken based on NIOSH Manual of Analytical Method no 1501. Target compounds were extracted using CS2 and analyzed by GC equipped with FID. Average concentrations of benzene, toluene, ethylbenzene, and xylene were obtained 2.01, 1.80, 2.72, and 1.65 mg/m3, respectively. Benzene concentrations exceeded the occupational exposure limit set by the Iran Ministry of Health and Medical Education. Its concentrations were significantly higher in commercial areas (2.72 mg/m3) compared to suburban areas (1.89 mg/m3). BTEX concentrations in gasoline stations were slightly, but not significantly, higher than those in CNG stations. Long-term exposure cancer risk of 1884 × 10−6 ± 390 × 10−6 and hazard index of 22.83 ± 3.66 were estimated for benzene and BTEX compounds, respectively. The results declare the necessity for controlling BTEX emission (mainly benzene) and monitoring employee’s exposure in refueling stations.

Deep Cavitand Self‐Assembled on Au NPs‐MWCNT as Highly Sensitive Benzene Sensing Interface

The unprecedented sensitivity and partial selectivity of quinoxaline‐walled thioether‐legged deep cavitand functionalized multiwall carbon nanotubes toward traces of benzene vapors are presented. The cavitand is grafted onto gold nanoparticle (Au‐NP) decorated oxygen plasma treated multiwall carbon nanotubes (O‐MWCNT) by a self‐assembled monolayer process affording a product referred to as cav‐Au‐MWCNT. The reported technique is suitable for the mass production of hybrid nanomaterials at low cost. The cav‐Au‐MWCNT resistive gas sensor operates at room temperature and shows an outstanding performance toward traces of benzene vapors. The detection of 2.5 ppb of benzene in dry air is demonstrated with a limit of detection (LOD) near 600 ppt. For the first time, it is shown that a CNT nanomaterial can effectively sense the extremely harmful benzene molecule with higher sensitivity than toluene or o‐xylene at the trace levels. The cavitand is well suited for binding benzene, which, being in close proximity to the MWCNT, affects its density of states (DOS) shifting the Fermi level away from the valence band. The binding of benzene is transduced in a diminution of MWCNT conductance. Furthermore, the inclusion of benzene is fully reversible at room temperature, implying that the sensor can operate at very low power consumption.

Comparative Analysis between Conventional PI and Fuzzy LogicPI Controllers for Indoor Benzene Concentrations

Exposure to hazardous concentrations of volatile organic compounds indoors in small workshops could affect the health of workers, resulting in respirative diseases, severe intoxication or even cancer. Controlling the concentration of volatile organic compounds is required to prevent harmful conditions for workers in indoor environments. In this document, PI and fuzzy PI controllers were used to reduce hazardous indoor air benzene concentrations in small workplaces. The workshop is represented by means of a well-mixed room model. From the knowledge obtained from the model, PI and fuzzy PI controllers were designed and their performances were compared. Both controllers were able to maintain the benzene concentration within secure levels for the workers. The fuzzy PI controller performed more efficiently than the PI controller. Both approaches could be expanded to control multiple extractor fans in order to reduce the air pollution in a shorter time. The results from the comparative analysis showed that implementing a fuzzy logic PI controller is promising for assuring indoor air quality in this kind of hazardous work environment.

Validation of Armadillo officinalis Dumèril, 1816 (Crustacea, Isopoda, Oniscidea) as a bioindicator: In vivo study of air benzene exposure

This study tests the potential for using Armadillo officinalis as a bioindicator of exposure to and activation of benzene metabolic pathways using an in vivo model.A. officinalis specimens collected in a natural reserve were divided into a control and three test groups exposed to 2.00, 5.32 or 9.09µg/m3 benzene for 24h. Three independent tests were performed to assess model reproducibility. Animals were dissected to obtain three pooled tissue samples per group: hepatopancreas (HEP), other organs and tissues (OOT), and exoskeleton (EXO). Muconic acid (MA), S-phenylmercapturic acid (S-PMA), two human metabolites of benzene, and changes in mtDNA copy number, a human biomarker of benzene exposure, were determined in each sample; benzene was determined only in EXO. MA was measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, S-PMA by triple quadrupole mass spectrometer liquid chromatography with electro spray ionization (LC-MS-ESI-TQD), mtDNA by real-time quantitative PCR and end-point PCR, and benzene by quadrupole mass spectrometer head-space gas chromatography (HSGC-MS).MA and S-PMA levels rose both in HEP and OOT; EXO exhibited increasing benzene concentrations; and mtDNA copy number rose in HEP but not in OOT samples. Overall, our findings demonstrate that A. officinalis is a sensitive bioindicator of air benzene exposure and show for the first time its ability to reproduce human metabolic dynamics.

Ambient air benzene at background sites in China's most developed coastal regions: Exposure levels, source implications and health risks

Benzene is a known human carcinogen causing leukemia, yet ambient air quality objectives for benzene are not available in China. The ambient benzene levels at four background sites in China's most developed coastal regions were measured from March 2012 to February 2013. The sites are: SYNECP, in the Northeast China Plain (NECP); YCNCP, in the North China Plain (NCP); THYRD, in the Yangtze River Delta (YRD) and DHPRD, in the Pearl River Delta (PRD). It was found that the mean annual benzene levels (578–1297ppt) at the background sites were alarmingly higher, especially when compared to those of 60–480pptv monitored in 28 cities in the United States. Wintertime benzene levels were significantly elevated at both sites (SYNECP and YCNCP) in northern China due to heating with coal/biofuels. Even at these background sites, the lifetime cancer risks of benzene (1.7–3.7E−05) all exceeded 1E−06 set by USEPA as acceptable for adults. At both sites in northern China, good correlations between benzene and CO or chloromethane, together with much lower toluene/benzene (T/B) ratios, suggested that benzene was largely related to coal combustion and biomass/biofuel burning. At the DHPRD site in the PRD, benzene revealed a highly significant correlation with methyl tert-butyl ether (MTBE), indicating that its source was predominantly from vehicle emissions. At the THYRD site in the YRD, higher T/B ratios and correlations between benzene and tetrachloroethylene, or MTBE, implied that benzene levels were probably affected by both traffic-related and industrial emissions.

The relationship between low-level benzene exposure and blood cell counts in Korean workers

ObjectivesBenzene is a well-known haematological toxin causing aplastic anaemia and leukaemia. Some recent studies have shown that low-level benzene exposure (<1 ppm) disturbs the haematopoietic system. However, other studies showed...

Health risk assessment for exposure to benzene in petroleum refinery environments.

The health risk resulting from benzene exposure in petroleum refineries was calculated using data from the scientific literature from various countries throughout the world. The exposure data was collated into four scenarios from petroleum refinery environments and plotted as cumulative probability distributions (CPD) plots. Health risk was evaluated for each scenario using the Hazard Quotient (HQ) at 50% (CEXP50) and 95% (CEXP95) exposure levels. Benzene levels were estimated to pose a significant risk with HQ50 > 1 and HQ95 > 1 for workers exposed to benzene as base estimates for petroleum refinery workers (Scenario 1), petroleum refinery workers evaluated with personal samplers in Bulgarian refineries (Scenario 2B) and evaluated using air inside petroleum refineries in Bulgarian refineries (Scenario 3B). HQ50 < 1 were calculated for petroleum refinery workers with personal samplers in Italian refineries (Scenario 2A), air inside petroleum refineries (Scenario 3A) and air outside petroleum refineries (Scenario 4) in India and Taiwan indicating little possible adverse health effects. Also, HQ95 was < 1 for Scenario 4 however potential risk was evaluated for Scenarios 2A and 3A with HQ95 > 1. The excess Cancer risk (CR) for lifetime exposure to benzene for all the scenarios was evaluated using the Slope Factor and Overall Risk Probability (ORP) methods. The result suggests a potential cancer risk for exposure to benzene in all the scenarios. However, there is a higher cancer risk at 95% (CEXP95) for petroleum refinery workers (2B) with a CR of 48,000 per 106 and exposure to benzene in air inside petroleum refineries (3B) with a CR of 28,000 per 106.

Monitoring of benzene, toluene, ethyl benzene, and xylene isomers emission from Shahreza gas stations in 2013

Aims: The aims of this study were to monitor the concentration of benzene, toluene, ethyl benzene and xylenes (BTEX) in the ambient air of the city of Shahreza gas stations and to identify the spreading distance of the pollutants from the fueling stations. Materials and Methods: Sampling was carried out from the air of 10 existing fuel stations, (2 compressed natural gas and 8 gasoline and diesel stations) and points of 50, 150 and 250 m away from the stations during cold and warm seasons in 2013. Air samples were taken via active sampling process using activated carbon tubes, extracted by carbon disulfide and analyzed by a gas chromatograph coupled to a flame ionization detector. Results: The averages of all achieved BTEX concentrations were under/around the permitted guideline levels for occupational exposure. According to the ambient air guidelines, the benzene level was much higher than the suggested levels in all the stations. However, the average concentrations of toluene, ethyl benzene, and xylene were not exceeded from the standards. The seasonal variation had no influence on the concentrations of BTEX. There was no significant difference between the pollutants concentrations at points 50, 150 and 250 m away from the stations. Conclusions: Fuel stations could be the main sources of volatile organic compounds emission in the city of Shahreza. The number and volume of refueling in the gas stations influence the emission rates. Therefore, it is suggested to take preventive actions such as repairing of pumps and tanks leak and installing vapor return systems at the time of fuel transferring.

Trans,trans,trans-[ReO2I2(PPh3)2], a rare rhenium(VI) complex — Synthesis and DFT study

The heating of cis-[ReO2I(PPh3)2] at reflux in benzene in air led to the isolation of the rhenium(VI) complex [ReO2I2(PPh3)2] (1). The compound is centrosymmetric around the octahedrally coordinated rhenium center, and the ReO bond length of 1.797(2) Å is longer than in typical trans-dioxorhenium(V) complexes. The asymmetric ReO stretching frequency occurs at 744cm−1. Density functional theory has been used for the calculation of the vibrational spectrum density which confirms the experimental asymmetric ReO stretching frequency. DFT calculation within the polarizable continuum model shows that complex 1 is more stable in CH2Cl2 than in the gas phase. EPR spectroscopy confirms a single d electron in 1. The crystal structure was determined by X-ray single crystal diffraction. In addition, infra-red, redox and electronic properties are also reported.

Health Benefits of a Reduction in Ambient Benzene Levels in Mexico City

Background: Air pollution has a negative impact on social and economic development of the countries as it represents a major threat to public health. There is scientific evidence documenting a variety of adverse health outcomes due to exposure to toxic air contaminants. Objective: To assess the health impact of air pollution with benzene in residents of Mexico City. Materials and methods: Following the standard method established by World Health Organization and considering 2005 as the base year, we estimated the health benefits of long-term exposure in 2008 to 2015 period, in terms of the number of avoidable deaths of leukemia (ICD-10: C91- C95), assessing three different hypothetical scenarios of decrease of benzene concentrations. Information from a local air monitoring study was used and exposure assessment was made using Geographical Information Systems and ArcGIS® 10.1 software. Concentration-response functions documented in robust epidemiological studies were selected. Results: An annual average benzene concentration in the study area was estimated to 1.82 ppb. The population covered in this health impact assessment includes nearly 6.5 million inhabitants. Considering two latency periods of leukemia of 5 and 10 years, in the scenario of WHO, we estimated a total of 31 avoidable deaths for the year 2010, while for year 2015 53 were estimated. Sensitivity analysis showed a possible underestimation of the results. Conclusions: Residents of Mexico City are exposed to benzene concentrations above the guideline value of World Health Organization. The results of this study show that the reduction of benzene air pollution in Mexico City would cause significant health benefits. This research is a useful tool, which could assist in the development of policies for managing toxic air pollutants in Mexico.

Concentrations of Benzene, Toluene and Xylene (BTX) in Ambient air of Rohtak city, India

Environmental monitoring of a particular locality is very important because it has become a serious threat to human beings.The levels of benzene, toluene and xylene of Rohtak (one of the districts of Haryana) were monitored by Passive sampling method. The air samples collected from six different sites using thermal desorption tube were analyzed by Gas Chromatography (GC) with flame ionization detector (FID). Among all the selected sites, levels of benzene were found maximum at petrol pump as compared to the residential site, traffic intersection and industrial area. During winter season the BTX level was higher (Benzene: 4.3, 16.5, 12.2, 7.6, 22.3 and 15.6 µg/m3, Toluene: 16.3, 56.2, 30.9, 40.8, 55.5 and 50.2 µg/m3, Xylene: 6.3, 9.6, 8.5, 8.9, 9.2 and 8.4 µg/m3) as compared to summer (Benzene: 4.0, 12.6, 8.5, 8.8, 12.3 and 10.8 µg/m3, Toluene: 38.2, 53.1, 39.8, 42.6, 49.6 and 47.2 µg/m3 xylene: 2.3, 8.4, 6.8, 8.0, 7.5 and 5.4 µg/m3) and monsoon (Benzene: 2.3, 7.2, 5.6, 6.0, 7.0 and 7.4 µg/m3, Toluene: 5.0, 24.0, 14.5, 16.3, 24.8 and 24.6 µg/m3, Xylene: 1.8, 6.6, 4.2, 6.3, 6.6 and 6.4 µg/m3) seasons among all the sites. The levels of toluene were observed three times higher (50.2 µg/m3) than the benzene (15.6 µg/m3). The benzene level at petrol pump, industrial area and traffic intersection were observed higher than the standard values.