Benzene, Toluene, Ethylbenzene And Xylene Concentrations Research Articles

Influence of the seasonality and of urban variables in the BTEX and PM2.5 atmospheric levels and risks to human health in a tropical coastal city (Fortaleza, CE, Brazil).

The International Agency for Research on Cancer (IARC) classifies benzene in group 1 (carcinogenic to humans). Particulate matter (PM) has recently also been classified in this category. This was an advance toward prioritizing the monitoring of particles in urban areas. The aim of the present study was to assess levels of PM2.5 and BTEX (benzene, toluene, ethylbenzene, and xylene), the influence of meteorological variables, the planetary boundary layer (PBL), and urban variables as well as risks to human health in the city of Fortaleza, Brazil, in the wet and dry periods. BTEX compounds were sampled using the 1501 method of NIOSH and determined by GC-HS-PID/FID. PM2.5 was monitored using an air sampling pump with a filter holder and determined by the gravimetric method. Average concentrations of BTEX ranged from 1.6 to 45.5μgm-3, with higher values in the wet period, which may be explained by the fact that annual distribution is influenced by meteorological variables and the PBL. PM2.5 levels ranged from 4.12 to 33.0μgm-3 and 4.18 to 86.58μgm-3 in the dry and wet periods, respectively. No seasonal pattern was found for PM2.5, probably due to the influence of meteorological variables, the PBL, and urban variables. Cancer risk ranged from 2.46E-04 to 4.71E-03 and 1.72E-04 to 2.01E-03 for benzene and from 3.07E-06 to 7.04E-05 and 3.08E-06 to 2.85E-05 for PM2.5 in the wet and dry periods, respectively. Cancer risk values for benzene were above the acceptable limit established by the international regulatory agency in both the dry and wet periods. The results obtained of the noncarcinogenic risks for the compounds toluene, ethylbenzene, and xylene were within the limits of acceptability. The findings also showed that the risk related to PM is always greater among smokers than nonsmokers.

Use of statistical modeling for BTEX prediction in cases of crude oil spill in seawater

ABSTRACT Cases of oil spillage and leakage in marine environments are increasing, and generating a need to quickly assess the presence of these contaminants in seawater. This work aims to estimate the concentrations of benzene, toluene, ethylbenzene and xylenes (BTEX) dissolved in seawater in cases of oil spillage using experimental factorial planning. The study factors were oil °API and oil/seawater contact time after spillage. The models obtained were able to satisfactorily estimate BTEX concentrations, with accuracy greater than 99.3% within the ranges studied, with R² correlation coefficients ranging from 0.992 to 0.997. The models presented forecast efficiency higher than 88%, with low relative errors, ranging from 0.1% to 12%. The concentrations of benzene dissolved in seawater found experimentally with only one hour of spillage, for the two types of oils studied, were higher than allowed by Brazilian legislation, demonstrating real environmental risk in cases of spillage of these types of oil into the sea. These results can corroborate the development of a risk assessment in oil spills within the studied ranges and serve as a useful analytical tool for emergencies.

Models for BTEX evaluation in cases of oil spill on the sea, using Experimental Desing

The objective of this study was to evaluate and obtain mathematical models, using the experimental design methodology, capable of predicting the contamination of benzene, toluene, ethylbenzene and xylenes (BTEX) in cases of oil spillage at sea, and to evaluate the acute toxicity of the soluble petroleum fraction (FSA). The factorial experimental planning was developed to describe the concentration of each compound according to the variables: oil °API, contact time oil/seawater after spillage and ambient temperature. The models presented can be used to quantitatively predict BTEX contamination in seawater with accuracy greater than 99%, within the studied ranges. The contact time oil seawater was the most determining factor in the concentration/contamination of BTEX in the Petroleum FSA. According to CL50% the soluble fraction of oil of °API 39.8 showed higher toxicity, with a LC50% of 46.07 with 1 h, and 11.38 with 96 hours of contact time oil/seawater, while the oil °API 32.8 showed lower toxicity, however presented higher concentrations of BTEX in FSA, this is possibly due to the synergistic effect of other hydrocarbons that became bioavailable to Mysidopsis juniae during the tests. The samples demonstrated potential environmental risk in cases of oil spillage, and these results can help in the development of a risk assessment of oil spills and serve as a useful analytical tool for emergencies.

VOCs and PM concentrations in underground parking garages of the commercial center and high-rise residential buildings

In China, due to the high density of population and vehicles in megacities, the commercial center and high-rise residential buildings have been widely equipped with large underground parking garages (UPGs). Volatile organic compounds (VOCs) and particulate matters (PM) have been confirmed as major pollutants in underground parking garages. And therefore, exposure to these air pollutants, especially ultrafine particles and BTEX (benzene, toluene, ethylbenzene, and xylenes), is closely associated with the health of the car owners or the garage workers. This study sampled or online monitored the concentrations of benzene, toluene, xylenes, formaldehyde, TVOC (total volatile organic compounds), PM2.5, and PM10 in the underground garage of three commercial center and high-rise residential buildings. The time-weighted average (TWA) concentrations of pollutants in the underground garage in the commercial center/high-rise residential buildings were as follows: benzene 0.12/0.11 mg·m−3, toluene 0.33/0.31 mg·m−3, xylenes 0.23/0.20 mg·m−3, TVOC 1.04/1.19 mg·m−3, PM2.5 0.20/0.19 mg·m−3, and PM10 0.24/0.22 mg·m−3. Indoor PM concentrations were slightly higher than outdoor PM concentrations, and there was a significant positive relationship between the difference of I/O PM concentrations and traffic volume. This paper also compared and analyzed BTEX concentration ratios (e.g., toluene/benzene and xylenes/benzene) at every sampling point of different underground garages. These ratios were compared and analyzed to evaluate the influence of vehicle emissions and outdoor air quality on the spatial distribution of indoor air quality quantitatively.

Tempo-spatial variability in volatile emissions from a sewage-treatment plant in Surat, India

The purpose of this research work was to evaluate the Benzene, toluene, ethylbenzene and xylene (BTEX) emissions from a Bamroli sewage-treatment plant (STP) in Surat City, India. Tiger handheld gas detector was utilised to measure emissions of BTEX during three periods of monitoring, and sewage samples were collected to determine the characteristics of sewage. The spatial variation of BTEX was determined at various treatment units of the STP during the months of November and April and represented as interpolation maps using ArcGIS. Box charts were plotted to represent the temporal variation of BTEX, which categorise the resultant data on the basis of their frequency. It has been noticed from the interpolation maps that the concentration of BTEX decreases as sewage travels from the inlet to subsequent units. Approximately 50% of all readings obtained of BTEX concentration fall within 0.5 parts per million, which exceeds the limits stipulated by the National Ambient Air Quality Standards, 5 μg/m3 for benzene. It can be concluded that more vent pipes have to be provided for the dispersion of these compounds in transmission lines. Also, some safety aids such as face masks have to be utilised by labourers who are continuously subjected to these compounds.

Petroleum hydrocarbon pollution in the Niger Delta: human health risk assessment of BTEX in biota

Based on the context of extensive petroleum hydrocarbon pollution in southern Nigeria, the concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in seafood were determined, and the health risks of these compounds were evaluated. Biota samples (Crayfish, Goby fish, Moonfish, Mudskipper, Mullet, Sardine and Tilapia) were collected from the Bonny Estuary from 2016 to 2018 and analyzed according to US EPA method 5030/8260C to determine the concentrations of BTEX. Risk assessment of BTEX to humans through the dietary route was conducted based on the lifetime cancer risk (LTCR) for benzene and the hazard quotient (HQ) for BTEX. The following BTEX concentration ranges were observed: benzene: < 0.01–0.36 mg/kg; toluene: 0.22–19.85 mg/kg; ethylbenzene: < 0.00–1.54 mg/kg; xylene: < 0.00–7.28 mg/kg. The median LTCR for benzene in children and adults was 0.65 and 0.30, respectively, which are higher than the limit recommended by the World Health Organization. The model showed that the LTCR is reducible by 99.9% and 66.6% if the concentration of benzene is 0.00001 mg/kg, and fresh seafood consumption is reduced to 10.4 g/day. The HQ for all BTEX compounds was greater than 1 (benzene: 1.0 × 104 (child), 4.9 × 103 (adult); toluene: 1.9 × 105 (child), 9.0 × 104 (adult); ethylbenzene: 9.4 × 103 (child), 4.4 × 103 (adult); xylene: 2.5 × 104 (child), 1.2 × 104 (adult)), which signifies a high non-cancer health risk to humans. These results are a reflection of the high level of petroleum hydrocarbon pollution in southern Nigeria and the debilitating human health consequences that could accompany it.

Kriging-Based Land-Use Regression Models That Use Machine Learning Algorithms to Estimate the Monthly BTEX Concentration.

This paper uses machine learning to refine a Land-use Regression (LUR) model and to estimate the spatial–temporal variation in BTEX concentrations in Kaohsiung, Taiwan. Using the Taiwanese Environmental Protection Agency (EPA) data of BTEX (benzene, toluene, ethylbenzene, and xylenes) concentrations from 2015 to 2018, which includes local emission sources as a result of Asian cultural characteristics, a new LUR model is developed. The 2019 data was then used as external data to verify the reliability of the model. We used hybrid Kriging-land-use regression (Hybrid Kriging-LUR) models, geographically weighted regression (GWR), and two machine learning algorithms—random forest (RF) and extreme gradient boosting (XGBoost)—for model development. Initially, the proposed Hybrid Kriging-LUR models explained each variation in BTEX from 37% to 52%. Using machine learning algorithms (XGBoost) increased the explanatory power of the models for each BTEX, between 61% and 79%. This study compared each combination of the Hybrid Kriging-LUR model and (i) GWR, (ii) RF, and (iii) XGBoost algorithm to estimate the spatiotemporal variation in BTEX concentration. It is shown that a combination of Hybrid Kriging-LUR and the XGBoost algorithm gives better performance than other integrated methods.

Investigation of seasonal variation and probabilistic risk assessment of BTEX emission in municipal solid waste transfer station

ABSTRACT The municipal solid waste transfer stations (MSWTSs) affects both the environment and human health. The present study aimed to investigatethe Concentrations of BTEX (benzene, toluene, ethylbenzene and xylene) the important group of VOCs, in the ambient air of municipal solid waste transfer station (MSWTS) of Hamadan city and to estimate stochastic cancer and non-cancer risk for inhalation exposure to BTEX compounds by Crystal Ball software. The average produced amount of solid waste in Hamadan in 2109 has been estimated to be over 150,000 tons. The solid waste mostly consisted of a complex mixture containing kitchen/food waste (56.85%), consumed plastics (11.33%), paper (2.88%), glass (1.20%) and other materials (27.74%), which collected from households and commercial areas. The findings revealed that BETX concentration in the ambient air of MSWTS in summer is higher as compared to the spring season. The 95% percentile lifetime cancer risk (LCR) value for benzene was estimated to be 8 × 10−4, which is higher than the recommended standards (10−6). The obtained 95% percentile hazard quotient (HQ) value for xylene was found to be higher than the suggested value of 1. Also, the total cumulative value of the 95th percentile HQs for (toluene, ethylbenzene and xylene) TEX was obtained to be about 3.39, which is higher than the acceptable value of HQ. The results of sensitivity analysis for LCR of benzene and HQs of TEX disclosed that the parameter of pollutants concentration has the highest effect on risk’s variance. According to the values of cancer and non-cancer risk assessment, that were higher than safe levels and the major contribution of pollutant concentration in sensitivity analysis, it is concluded that the implementation and development of technical and engineering control measures must be regarded as an essential target to reduce workers exposure to the pollutants and to decrease the concentration of the pollutant in the ambient air of MSWTS.

Indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene in some Italian schools evaluation of areas with different air pollution

The air quality of indoor environments is an aspect of great importance and of growing interest, particularly considering the length of time that people stay in confined spaces. The objective of this study was to study the indoor and outdoor concentrations of benzene, toluene, ethylbenzene and xylene (BTEX) in 8 Italian schools, many of which are located in some of the most highly polluted areas in Italy. This wanted to provide useful information for understanding the status of air quality in sensitive indoor and outdoor areas (schools) and to support the development of recommendations and indications useful to territorial administrations in the improvement of environmental quality strategies. The sampling campaigns were performed with passive samplers from 2014 to 2015, studying both the hot and cold seasons. A common sampling and analytical protocol was applied in all the study areas. Passive sampler data were also compared with BTEX measurements from fixed-site monitoring stations selected as references for each school. Our findings showed the prevalence of low BTEX concentrations with relatively high values limited to toluene, ethylbenzene and xylene in a few monitoring sites and periods. The mean concentration values of benzene, toluene, ethylbenzene and xylene varied from 0.10 μg/m3 to 10.75 μg/m3, from 0.10 μg/m3 to 28.18 μg/m3, from 0.10 μg/m3 to 11.1 μg/m3 and from 0.10 μg/m3 to 14.45 μg/m3, respectively. In indoor environments, the concentrations were equal to or higher than the values measured outdoors in most cases, frequently reporting I/O ratios greater than 1.

Comparing BTEX concentration related to surgical smoke in different operating rooms

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/m3. The Curettage OR had the highest (12.93 μg/m3) and ENT OR had the lowest (7.42 μg/m3) 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 × 106). 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.

Monitoring BTEX compounds and asbestos fibers in the ambient air of Tehran, Iran: Seasonal variations, spatial distribution, potential sources, and risk assessment

ABSTRACT The toxic air pollutants such as benzene, toluene, ethylbenzene and xylene (BTEX) as well as asbestos are considered hazardous because of their role in adverse impacts on human health. Accordingly, this research was conducted to evaluate the levels, seasonal variations, spatial mapping, potential sources, and health risk assessment of BTEX compounds as well as asbestos fibres in the ambient air of Tehran. Air samples were collected by the NIOSH1501 method at 15 different sample stations from March 2018 to February 2019. Charcoal glass tube was used to collect samples and BTEX concentration was further determined using GC-FID method. The sampling of asbestos fibres was carried out via a low volume peripheral pump with analysis performed according to the NIOSH 7400 method via phase contrast microscopy (PCM). The findings showed that the mean±SD concentrations of ∑BTEX were 33.44 ± 11.77 and 59.97 ± 33.76 µg/m3 in warm and cold seasons, respectively. It was 1.46 × 10−3 and 2.31 × 10−3 fibre/ml for asbestos in the warm and cold seasons, respectively. The spatial mapping indicated that the maximum levels of both pollutants were observed in sampling sites S1, S11, and S15, which were located close to factories downtown (S1) and heavy traffic roads (S11 and S15). The mean inhalation lifetime cancer risk (LTCR) value for benzene was 1.64 × 10−5, which was higher than US EPA and WHO recommended limits. Further, the excess lifetime cancer risk (ELCR) suggested that the exposure to asbestos fibre in Tehran would cause the risk of developing cancer in 0.5 to 3.53 people per every 1000 individuals. Hence, much suitable managing strategies are required to control the concentration of these pollutants in the ambient air of Tehran.

Characterization and risk assessment of BTEX in ambient air of a Middle Eastern City

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.

Health risk assessment of heavy metals, BTEX and polycyclic aromatic hydrocarbons (PAHs) in the workplace in a secondary oil re-refining factory

The present study aimed to evaluate the health risk of heavy metals (iron, zinc, cadmium, arsenic, nickel, lead, and mercury), benzene, toluene, ethylbenzene and xylene (BTEX), and polycyclic aromatic hydrocarbons (PAHs) in the workplace in a secondary oil re-refining factory. In this descriptive, cross-sectional study, samples were collected and analyzed using the NIOSH 1501 method at eight sampling points with determined concentrations of BTEX, 16Ʃ PAHs, and heavy metals. The concentration of each pollutant was evaluated based on the type of workers (packaging/filtration). The risk assessment of the contaminants was carried out using the RAIS software, and the risk of non-carcinogenic compounds was estimated based on the reference respiratory concentration (mg/m3). The results showed that the lifetime cancer risk index (LCR) cumulative risk of the heavy metals was within the definitive risk range at all the sampling points. The highest carcinogenic risk of LCR belonged to arsenic at sampling point H (filtration chamber), and the highest cumulative carcinogenic risk of the total contaminants in the environmental sampling points belonged to sampling point H. At all the sampling points, the LCR carcinogenic risk accumulation for the hydrocarbon compounds was within the definitive range. The maximum cumulative lifetime cancer risk for the hydrocarbon compounds was evaluated in filtration (point B), and the most hazardous carcinogens were arsenic, benzo(a)pyrene, and naphthalene. The proposed risk assessment method was observed to be comprehensive, and its results could be used for corrective and controlling measures and the prioritization of risk reduction resources.

Gas flares contribution in total health risk assessment of BTEX in Asalouyeh, Iran

The health risk assessment of benzene, toluene, ethylbenzene and xylenes (BTEX) associated with the combustion of gas in gas flares of one of the largest gas refinery complex in Iran (South Pars gas complex in Asalouyeh, 1–10 phases) has been conducted based on Office of Environmental Health Hazard Assessment’s (OEHHA) method. In this regard, AERMOD dispersion model coupled with WRF model has been used to predict the ground level concentration of pollutants emitted from gas flares. The accuracy of the dispersion model has been verified with measured ambient SO2 data. The risk assessment results have shown that the chronic noncarcinogenic risk of BTEX emitted from gas flares is in the acceptable range in the residential area and most of refineries site. Regarding acute noncarcinogenic risk, the hazard indices (HIs) are only greater than one in refineries sites and are less than permitted level elsewhere in the study area. For carcinogenic risk, the cumulative risk of benzene and ethylbenzene are greater than 10−6 in refineries sites and two cities (Asalouyeh and Nakhl Taghi), but in two camps nearby the gas flaring sites, the value is less than the allowable limit. Besides, the relative contribution of gas flaring in health risk assessment of BTEX is accomplished by calculating the health risk parameters with the measured BTEX concentrations at 10 receptors, which reveal the cumulative effects of all potential sources of BTEX throughout the study area. The comparison of health risk parameters has shown that the health risk of BTEX associated with flaring is in average 42 %, 2.6 % and 10.8 % of the overall health risk of BTEX in industrial areas, two cities and camps, respectively. It can be concluded that the contribution of gas flaring in industrial areas is noticeable and application of emission reduction policies at gas flaring, has a major effect on industrial areas and maybe has minor effects on the air quality of the residential areas.

Determination of metals and BTEX in different components of waterpipe: charcoal, tobacco, smoke and water.

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. 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. 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. 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.

Remediation of BTEX plume in a continuous flow model using zeolite-PRB

Adsorption is a well-known phenomenon that causes the remediation of BTEX (Benzene, Toluene, Ethylbenzene, and Xylene). Zeolite is typically useful for the removal of BTEX from groundwater. In this study, the migration of the BTEX plume was investigated in a bench-scale tank model as a shallow aquifer. The objective of this research was to analyze the performance of a natural zeolite in-situ PRB remediation technique. Natural zeolite was applied as a physical permeable reactive barrier. In the first part of the experiment, 40 ml of BTEX as a contaminant was injected at the injection point (BI) into the sand tank. Samples were taken periodically via 14 boreholes for BTEX test for 23 days and analyzed using a GC-FID instrument. The results indicated high removal rates of BTEX by passing through the zeolite barrier. Zeolite barrier reduced the BTEX concentration up to 90% of the initial value. However, the barrier efficiency started to decrease after 132 h since pollution injection reached a minimum amount (%53 of the initial value) due to occupying the free space and grain pore where BTEX was adsorbed onto the surface of zeolite, thereby decreasing the barrier efficiency.

Exploratory analysis of the atmospheric levels of BTEX, criteria air pollutants and meteorological parameters in a tropical urban area in Northeastern Brazil

Air pollution is responsible for serious damage to the environment and to the health of the population. The objective of this study was to apply chemometric methods to determine and evaluate the relationships between the atmospheric concentrations of BTEX (benzene, toluene, ethylbenzene and xylene) compounds, criteria air pollutants and meteorological parameters, as well as to identify the type of emission source associated with these pollutants at seven sites in the city of Salvador, Bahia, Brazil during rainy and dry periods. BTEX compounds were monitored using passive samplers with a solvent desorbable adsorbent (activated charcoal) for 14 days and determined by gas chromatography with flame ionization detection. Criteria air pollutants were determined using automatic continuous analyzers and the meteorological parameters by means of multi-parameters sensors. The average data obtained were submitted to multivariate analysis, using principal component analysis (PCA) with varimax rotation and hierarchical cluster analysis (HCA). Some diagnostic ratios between the BTEX species, besides correlation analysis between the pollutants and meteorological parameters were also used to identify the origin of the emissions. The sum of average concentrations of BTEX compounds was lower in the dry period (5.90 ± 3.28 μg m−3) than in the rainy period (7.95 ± 2.95 μg m−3), probably due to higher values of temperature and solar radiation which favor photochemical reactions in the dry period, thereby increasing the rate of removal of the BTEX compounds from the atmosphere. The first three principal components together (PC1, PC2 and PC3) explain 80.1% of the total data variance, with a tendency to separate the samples into two groups, depending on the seasonal period. According to HCA, four main groups were formed with high degrees of similarity. Strong correlations were found among BTEX species, and between these compounds with CO, NO, and NO2, thus indicating a common emission source for these compounds, the vehicular fleet. Toluene/benzene (T/B), m,p-xylene/benzene (m,p-X/B) and o-xylene/benzene (o-X/B) ratios suggested that vehicular emissions constituted the main source of BTEX compounds. PCA and HCA results also confirmed these observations.

Exposure to ambient volatile organic compounds in an area with excess cancer and asthma morbidity

TPS 671: Cardiometabolic effects of long-term air pollution exposure, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: The Haifa Bay Area (HBA) has been documented to experience relatively high morbidity from asthma and cancer. Previously, association with emissions from industrial facilities in the HBA has been examined. However, ambient concentrations of fine particulate matter, nitrogen oxides and BTEX (benzene, toluene, ethylbenzene and xylene) are lower in HBA than in other districts (such as the Tel-Aviv area). It has been proposed that this discrepancy may possibly result from unmeasured concentrations of certain volatile organic compounds and/or heavy metals, which are uniquely emitted by industrial facilities and are not characteristic of traffic, such as 1,2-dichloroethane and Isoamyl alcohol. A list of such compounds was formulated by the regulatory bodies and bi-weekly measurements began in 2015. Methods: Data on 25 distinct pollutants was collected from 30 locations spread within and outside of HBA. The measurements were generally performed on a bi-weekly basis from the start of 2015 until the end of 2018. The annual mean measurements within HBA were compared to those in other regions using a Mann-Whitney U-test. Results: A preliminary analysis indicates that there are significantly lower concentrations of butadiene, benzo(a)pyrene, and trichloroethylene in HBA than in other regions. The only pollutant whose concentrations seem to be significantly higher in HBA is particulate vanadium, which is commonly emitted into the atmosphere by metallurgical industries, oil refineries and the combustion of fossil fuels. No significant differences were found in the concentrations of the remaining 21 pollutants. Conclusion: The excess morbidity in the HBA was not found to be related to ambient air pollution. Future research of this issue should perhaps focus on indoor exposures and explanatory variables rather than on ambient air pollution.

Exposure to BTEX in buses: The influence of vehicle fuel type

Diesel-fueled buses have been replaced by Compressed Natural Gas (CNG) to minimize the high level of emissions in urban areas. However, differences in indoor exposure levels to Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in those vehicles have not been investigated so far. The primary aim of this study was to determine if passengers are exposed to different BTEX levels when using buses powered by CNG or by diesel, and further explore if indoor levels are influenced by external air quality. For this purpose, BTEX air concentrations were measured in bus cabins (CNG and diesel), parking stations and in a background urban area using passive air samplers. Results showed that BTEX concentrations inside vehicles were higher than outside, but no significant differences were found between buses powered by CNG or by diesel. In CNG vehicles, high and significant positive correlation was found between benzene and the number of journeys in the same route (rs = 0.786, p < 0.05), vehicle operating time (rs = 0.738, p < 0.05), exposure time (rs = 0.714, p < 0.05) and exposure index (rs = 0.738, p < 0.05), but this was not observed for diesel vehicles. Benzene in bus cabins was found to be significantly below reference value for human health protection. However, excepting p-xylene, all other aromatic pollutants have a mean concentration significantly above the lowest effect level (p ≤ 0.002 for all comparisons). Additionally, higher BTEX levels in cabin buses than in outdoor air suggest the presence of other emission sources in indoor cabins. These findings emphasize the need for further studies to fully characterize indoor emission sources in order to minimize the negative impact of BTEX exposure to human health.

BTEX compositions and its potential health impacts in Malaysia

This study aims to determine the composition of BTEX (benzene, toluene, ethylbenzene and xylene) and assess the risk to health at different sites in Malaysia. Continuous monitoring of BTEX in Kuala Lumpur City Centre, Kuala Terengganu, Kota Kinabalu and Fraser Hill were conducted using Online Gas Chromatograph. For comparison, BTEX at selected hotspot locations were determined by active sampling method using sorbent tubes and Thermal Desorption Gas Chromatography Mass Spectrometry. The hazard quotient (HQ) for non-carcinogenic and the life-time cancer risk (LTCR) of BTEX were calculated using the United States Environmental Protection Agency (USEPA) health risk assessment (HRA) methods. The results showed that the highest total BTEX concentrations using continuous monitoring were recorded in the Kuala Lumpur City Centre (49.56 ± 23.71 μg/m3). Toluene was the most dominant among the BTEX compounds. The average concentrations of benzene ranged from 0.69 ± 0.45 μg/m3 to 6.20 ± 3.51 μg/m3. Measurements using active sampling showed that BTEX concentrations dominated at the roadside (193.11 ± 114.57 μg/m3) in comparison to petrol station (73.08 ± 30.41 μg/m3), petrochemical industry (32.10 ± 13.13 μg/m3) and airport (25.30 ± 6.17 μg/m3). Strong correlations among BTEX compounds (p<0.01, r>0.7) at Kuala Lumpur City Centre showed that BTEX compounds originated from similar sources. The values of HQ at all stations were <1 indicating the non-carcinogenic risk are negligible and do not pose threats to human health. The LTCR value based on benzene inhalation (1.59 × 10−5) at Kuala Lumpur City Centre were between 1 × 10−4 and 1 × 10−5, representing a probable carcinogenic risk.