Characterization of volatile organic compounds (VOCs) and their sources in the air of Izmir, Turkey

Assessing VOC emissions from different gas stations: impacts, variations, and modeling fluctuations of air pollutants

Gas stations distributed around densely populated areas are responsible for toxic pollutant emissions such as volatile organic compounds (VOCs). This study aims to measure VOCs emission from three different kinds of gas stations to determine the extent of pollution from the gas stations and the most frequent type of VOC compound emitted. The concentrations of ambient VOCs at three refueling stations with a different type of fuels in Mashhad were monitored. The result of this study showed that CNG fuel stations are less polluting than petrol stations. In all the studied sites, the highest concentrations were related to xylene isomers, irrespective of the fuel type. Total VOCs at the supply of both compressed natural gas (CNG) and gasoline stations was 482.36 ± 563.45 µg m-3. At a CNG station and a gasoline station, total VOC concentrations were 1363.4 ± 1975 µg m-3 and 410.29 ± 483.37 µg m-3, respectively. The differences in concentrations of toluene and m,p-xylene between the fuel stations can be related to the quality and type of fuel, vapor recovery technology, fuel reserves, dripless nozzles, traffic density in these stations, meteorological conditions and the location of sampling sites. The combination of a sine function and a quadratic function could model the fluctuation behavior of air pollutants like m,p-xylene. In all the sites, the highest concentrations were related to xylene isomers, irrespective of the type of fuel. The changing rate of m,p-xylene pollutant in each station was also modeled in this study.

Distribution and ecological risk assessment of priority water pollutants in surface river sediments with emphasis on industrially affected areas

Priority water pollutants comprising six plasticizers, 18 volatile organic compounds (VOCs), total petroleum hydrocarbon (TPH), 1,4-dioxane, epichlorohydrin, formaldehyde, acrylamide, and cyanides were determined in surface river sediments to assess their distribution patterns and ecological risks. Among these, di (2-ethylhexyl) phthalate (DEHP), toluene, TPH, and acrylamide were frequently found in sediments. The industrial sites had higher concentrations of ∑plasticizers (median 628 ng/g dry weight (dw)), ∑VOCs (median 3.35 ng/g dw), acrylamide (median 0.966 ng/g dw), and TPH (median 152 μg/g dw) in sediments than the mixed and non-industrial areas. The other pollutants did not show the significant differences in levels according to site types because of their relatively low detection frequencies. Volatile and soluble substances as well as hydrophobic pollutants were predominantly detected in surface sediments from industrial areas. Sediment contamination patterns were affected by the size and composition of the industrial zones around the sampling sites. The ecological risks determined using the sediment quality guidelines (DEHP, VOCs, and TPH) and the mean probable effect level quotients (DEHP) were mostly acceptable. However, the two most representative industrial regions (the largest industrial area and the first industrial city) showed risks of concern for DEHP and TPH.

Molecular mechanisms of 1,2-dichloroethane-induced neurotoxicity

The production of industrial solvents and adhesives often utilizes 1,2-dichloroethane (1,2-DCE), a highly toxic halogenated hydrocarbon compound. Occupational 1,2-DCE poisoning occurs frequently and is a public health concern. Exposure to 1,2-DCE can damage the brain, liver, and kidneys. The main and most severe damage caused by exposure to 1,2-DCE is to the nervous system, especially the central nervous system. Current research on 1,2-DCE mainly focuses on the mechanism of brain edema. Several possible mechanisms of 1,2-DCE neurotoxicity have been proposed, including oxidative stress, calcium overload, blood-brain barrier damage, and neurotransmitter changes. This article reviews the research progress on 1,2-DCE neurotoxicity and the mechanism behind it to provide a scientific basis for the prevention and treatment of 1,2-DCE poisoning.

Ambient levels of BTEX at roadside in northern Iraq and its relationship with traffic volume

Among the mono-aromatic volatile organic compounds, benzene, toluene, ethylbenzene and xylene (BTEX) have occupied a large area in air pollution studies due to their carcinogenic and non-carcinogenic effect. In this study, a station was used to monitor BTEX concentrations at roadside in urban area at Mosul city along a year, with traffic volume and meteorological factors measurement. The annual mean of benzene was 12 µg/m³, which is more than twofolds of the standard European Union level of 5 µg/m³. In addition, 87.4% of the measured values in summer was higher than the standard level at roadside. Benzene was dominant in spring and summer among BTEX species, while the dominance changed to ethylbenzene in autumn and winter. Besides, benzene, toluene, ethylbenzene and o-xylene showed significant seasonal variation. BTEX and benzene concentrations increased as the number of vehicles on gasoline and diesel increased. In contrast, toluene and ethylbenzene were more affected with number of vehicles on diesel. On the other hand, the weak significant correlations among BTEX species and high T/B ratio indicate the difference in fuel types used and the existence of additional sources of BTEX emission with the vehicular exhausts. These results can be utilized in determining the control strategy in air quality management in Mosul city.

Volatile organic compounds in ambient air of a major Asian port: spatiotemporal variation and source apportionment

This study investigated the spatiotemporal variation and source characteristics of volatile organic compounds (VOCs) in Kaohsiung Harbor, one of the busiest ports in the world. The VOCs' potential to form ozone (O₃) and secondary organic aerosols (SOAs) was also examined. The temporal variation was studied in February, May, July, and November of 2020, while the spatial distribution was investigated in the export processing zone (KEPZ) and at the two port entrances (E1 and E2). The most polluted month in the harbor was November (37.7 ± 12.6 ppbv), while the most polluted site was the industrial area (KEPZ). A significant positive correlation was found between VOCs and O₃ (r = 0.985). Meanwhile, a moderate positive correlation (r = 0.449) was observed between VOCs and secondary organic aerosol formation potential (SOAFP), mainly affected by the concentration of toluene in the study area. The diagnostic ratios indicated that the air parcels in the site were "fresh," and three possible ambient sources of VOC were identified by the positive matrix factorization (PMF): industrial emissions (53.6%), freight transport emissions (29.6%), and others (17.7%). The study highlights the current state of VOCs and their potential sources in the port city of Kaohsiung, which can be used to enhance the strategies for regulating and controlling industrial activities and improving air pollution control measures to reduce VOC emissions.

Environmental status of an Italian site highly polluted by illegal dumping of industrial wastes: The situation 15 years after the judicial intervention

In 2008 the Italian government classified the Bussi sul Tirino area (Central Italy) as Site of National Interest destined to remediation which, unfortunately, has not yet begun. The decision followed >20 years of illegal dumping of industrial wastes, lasting from 1984 to 2005, that generated the biggest illegal toxic waste disposal site in Europe. The contamination profile of the site was mainly characterized by PCDD/Fs, PCBs, PAHs, chlorinated solvents, Hg, and Pb. Due to the health concern of the population and local authorities, an extensive monitoring and biomonitoring campaign was carried out in 2017-2018, checking the site-specific pollutants in local food (free-range hens' eggs, milk from grazing sheep and goats, wild edible mushrooms, and drinking water), environmental (air and freshwaters) and biological (human urine) matrices. A total of 314 samples were processed, obtaining 3217 analytical data that were compared with regulatory limits, when available, and values reported by international literature. The sum PCDD/Fs and DL-PCBs ranged from 0.24 to 3.6 pg TEQ g^-1 fat, and from 0.46 to 8.3 pg TEQ g^-1 fat, respectively in milk in eggs, in line with the maximum levels established by CE Regulations except for an egg sample. As regards PAHs, all our results were lower than the literature data, as well as for Hg and Pb. Outdoor air showed levels of chlorinated solvents ranging from <LOD to 36 μg m^-3, and freshwaters from 0.21 to 2.8 μg L^-1. All drinking water samples resulted compliant with the maximum levels established by the current EU directive. Despite the severe pollution of the illegal dumping site and the remediation not yet carried out, the local environment and the population living in Bussi and surroundings seem not to be affected by significant exposure to the toxics characterizing the landfill.

Traffic-Related Airborne VOC Profiles Variation on Road Sites and Residential Area within a Microscale in Urban Area in Southern Taiwan

The sampling sites, including roadsides and residential areas, were set up to collect ambient air and determine the volatile organic species it contained. For the roadside air, the average VOCs (volatile organic compounds) abundant at rush hour periods was two times that at non-rush hour periods. In the residential area, the VOC concentrationswere106 and 129 ppb during rush hour periods. The VOC concentration ratios of roadside and residential areas were in the range of 1.08–1.75 and the traffic emissions were related to the VOCs abundant in air. The highest VOC concentration was 168 ppb at midnight at residential sites and the VOC abundance could be two times that of roadside sites. This level of concentration could be attributed to the application of solvents and to human activity in a nearby motorcycle/vehicle maintenance plant, laundry rooms, etc. High abundant species were similar in both the roadside and residential air samples. These highly abundant species included toluene, acetone, acetonitrile, m,p-xylene and n-pentane, all of which can be emitted from traffic exhaust. Benzene, acrolein, formaldehyde, vinyl chloride and 1,3-butadiene were the main species with health impacts collected at both sites. In the micro-scale environment, the residential ambient air was affected by traffic flow from morning to night. In the midnight period, some local activities (a motorcycle/vehicle maintenance shop and laundry shops) affected the concentrations of certain VOCs (acetonitrile, toluene, hexane, 2-methylpentane, methyl cyclopentane and 3-methylpentane). The traffic and motor vehicles’ effects were determined, which could be useful for air quality management and strategy development in an urban area.

Distribution, Sources, and Health Risk Assessment of Volatile Organic Compounds in Hefei City

Volatile organic compounds (VOCs) are involved in the formation of ozone formation, which plays a significant role in regional air contamination and poses a great threat to human health. The VOCs were collected from the urban area of Hefei city via an off-line sampling method (SUMMA canister) and determined by gas chromatography-mass spectrometer. The average concentrations of VOCs were 17.65 ± 28.36 ppbv, which were mainly contributed by aromatics (10.02 ± 13.37 ppbv), haloalkane (5.37 ± 8.90 ppbv), ally halide (1.25 ± 3.36 ppbv), and aryl halid (1.02 ± 2.73 ppbv). According to the principal component analysis, three major sources were identified, including solvent use, vehicle exhaust, and industrial release, accounting for 70.6% of the total variance of the data. Health risk assessment was utilized to evaluate the potential adverse health effects of the individual VOC. The total hazard ratio in the selected area was higher than 1, where could pose health threat to exposed population. The cancer risk for benzene, carbon tetrachloride, trichloromethane, and 1, 2-dichloroethane were 4.8 × 10^-5, 4.5 × 10^-5, 3.3 × 10^-5, and 2.5 × 10^-5, respectively, indicating definite health risks.

Diurnal variation of BTEX at road traffic intersection points in Delhi, India: source, ozone formation potential, and health risk assessment

The present study was carried out to observe the variation of volatile organic compounds (VOCs) namely benzene, toluene, ethylbenzene, and xylene isomers (BTEX) at three different sites of Delhi, during 2016-2017. Four hourly sampling was carried out day and night separately. Results showed that BTEX concentration was highest in post-monsoon and lowest in monsoon season. Again, daily variation shows that benzene (47%) and toluene (35%) were more during night than day when it was 44% and 33% respectively. Mean concentration of BTEX was observed in following order: ethylbenzene ~ o-xylene < m,p-xylene < toluene < benzene, while overall seasonal variation was observed as follows: post-monsoon > summer > winter > monsoon. Possible emission sources of BTEX were also established through corresponding ratios of individual compounds. Xylene isomers together accounted highest ozone formation potential. The risk assessments of BTEX were carried out in terms of non-cancer (the hazard quotient, HQ) and cancer (the incremental lifetime cancer risk, ILCR) regarding the inhalation exposure only. It was observed that benzene and xylene isomers possessed higher HQs than ethylbenzene and toluene at all sites throughout the study. Again, benzene was found with higher mean ILCR (3.58 × 10^-5) than ethylbenzene (1.47 × 10^-5).

Analysis of benzene air quality standards, monitoring methods and concentrations in indoor and outdoor environment

Benzene is a proven carcinogen. Its synergistic action with other pollutants can damage different components of the biosphere. Literature comparing the air quality standards of benzene, its monitoring methods and global concentrations are sparse. This study compiles the worldwide available air quality standards for benzene and highlights the importance of strict and uniform standards all over the world. It was found that out of the 193 United Nation member states, only 53 countries, including the European Union member states, have ambient air quality standard for benzene. Even where standards were available, in most cases, they were not protective of public health. An extensive literature review was conducted to compile the available monitoring and analysis methods for benzene, and found that the most preferred method, i.e, analyzing by Gas Chromatography and Mass spectroscopy is not cost effective and not suitable for real-time continuous monitoring. The study compared the concentrations of benzene in the indoor and outdoor air reported from different countries. Though the higher concentrations of benzene noticed in the survey were mostly from Asian countries, both in the case of indoor and outdoor air, the concentrations were not statistically different across the various continents. Based on the analyzed data, the average benzene level in the ambient air of Asian countries (371 μg/m3) was approximately 3.5 times higher than the indoor benzene levels (111 μg/m3). Similarly, the outdoor to the indoor ratio of benzene level in European and North American Countries were found to be 1.2 and 7.7, respectively. This compilation will help the policymakers to include/revise the standards for benzene in future air quality guideline amendments.

Characteristics of atmospheric volatile organic compounds (VOCs) at a mountainous forest site and two urban sites in the southeast of China

Volatile organic compounds (VOCs) are important trace gases in the atmosphere, affecting air quality (e.g. ozone and secondary organic aerosol formation) and human health. To understand the emission, transport and chemistry of VOCs in the southeast of China (Fujian Province), a campaign was conducted in summer and winter of 2016 at three contrasting sites in close proximity. One measurement site (Mt. Wuyi) is a mountainous forest site (1139 m a.s.l.) located in a natural reserve, while the other two sites (Fuzhou, Xiamen) are coastal urban sites with high population and vehicle density. Comparison of VOCs at these three sites provides a valuable perspective on regional air pollution and transport. Many of the measured alkanes, alkenes and aromatics exhibited clear seasonal and diurnal patterns, driven by variations of hydroxyl (OH) radicals, which is the predominant oxidant of VOCs in the atmosphere. By examining tracer-tracer correlations for VOCs, variability-lifetime analysis and 36 h backward trajectories, strong emissions from vehicular exhaust, liquefied petroleum gas (LPG) and solvent usage were identified as key sources in Fuzhou and Xiamen, whereas at Mt. Wuyi the main emission sources were local emissions (e.g. biomass burning) in summer and long-range transport in winter. The results indicate that natural sites could be impacted strongly by surrounding urbanization. Isoprene and propylene in summer and propylene in winter contributed the most to ozone formation at the three sites. The data in this study provides a useful benchmark for future research on air quality monitoring and emission sources in the region.

Spatial and temporal characteristics of ambient atmospheric hydrocarbons in an active shale gas region in North Texas

Over the past decade, significant development in shale gas extraction technologies has led to a massive increase in oil and gas production within the Barnett Shale region in North Texas. This region abuts a fast-growing Dallas-Fort Worth urban area with increasing air quality concerns. Air quality information for 2011-2015 from two urban and three non-urban monitoring sites within the Barnett Shale region were analyzed to identify the spatial and temporal trends of volatile organic compounds (VOC) concentrations. The non-urban sites had higher mean concentrations of total non-methane organic compounds (TNMOC) at 123.6 ppb-C than 77.06 ppb-C at the urban sites. Alkanes, which includes ethane, propane and n-butane, were the dominant VOC group at all five monitoring sites, with 88% of TNMOC at urban sites and 95% at the non-urban sites. Alkenes, alkynes and aromatics composition at urban sites accounted for 3.96%, 0.72% and 4.72% of TNMOC, and at the non-urban sites these were 1.55%, 0.43% and 1.94%, respectively. Seasonal variations were noted in the VOC profiles with high concentrations during the winter months and low during summer months. The alkane/TNMOC ratio also showed a similar seasonal pattern, with a median value of 0.8 at the urban sites and 0.9 at non-urban sites. Alkene/TNMOC ratios were highest during the summer months, while alkyne/TNMOC ratios were highest during spring and low in winter, due to the influence of localized urban emissions. Higher concentrations of isoprene were measured at one of the urban sites as a result of biogenic emissions from nearby urban forests. Spatial and temporal analysis of measured VOC concentrations at ambient air monitoring stations in North Texas revealed strong influence of source regions with high oil and gas activities in close proximity.

Characteristics and health effects of BTEX in a hot spot for urban pollution

This study reports a spatiotemporal characterization of toluene, benzene, ethylbenzene, and xylenes concentrations (BTEX) in an urban hot spot in Iran, specifically at an bus terminal region in Shiraz. Sampling was carried out according to NIOSH Compendium Method 1501. The inverse distance weighting (IDW) method was applied for spatial mapping. The Monte Carlo simulation technique was applied to evaluate carcinogenic and non-carcinogenic risk owing to BTEX exposure. The highest average BTEX concentrations were observed for benzene in the morning (at 7:00-9:00 A.M. local time) (26.15 ± 17.65 µg/m³) and evening (at 6:00-8:00 P.M. local time) (34.44 ± 15.63 µg/m³). The benzene to toluene ratios in the morning and evening were 2.02 and 3.07, respectively. The main sources of BTEX were gas stations and a municipal solid waste transfer station. The inhalation lifetime cancer risk (LTCR) for benzene in the morning and evening were 1.96 × 10^-4 and 2.49 × 10^-4, respectively, which exceeds the recommended value by US EPA and WHO. The hazard quotient (HQ) of all these pollutants was less than 1. The results of this work have implications for public health near 'hot spots' such as IKBT where large populations are exposed to carcinogenic emissions.

Environmental and biological monitoring of exposures to VOCs in a petrochemical complex in Iran

Exposure to volatile organic compounds (VOCs) can cause cancers in human. This study aimed to measure the concentration of four VOCs including benzene, styrene, ethylbenzene, and phenol in ambient air of a petrochemical complex in Iran. Also, their urinary metabolites including phenol, mandelic acid (MA), and phenylglyoxylic acid (PGA) in the workers were monitored. Urine samples were collected before and after the 8-h workshift according to the NIOSH methods. They were analyzed by a gas chromatograph coupled with a flame ionization detector (GC-FID). High levels of the ambient VOCs were detected in the units of recovery and olefin. The levels of ethylbenzene and phenol were less than the guidelines suggested by NIOSH and ACGIH. However, in some cases, the amounts of benzene and styrene were higher than the guidelines. Excellent positive correlations were observed between VOCs exposure and their urinary metabolites (r ² > 0.90), except for benzene (r ² = 0.26). Our finding verified that urinary biomarkers can be applied as bioindicators for ambient exposure to VOCs. There is a risk of exposure to high levels of the pollutants in some of the sites, and it is necessary to adopt some preventive measures to reduce health risk.

Assessment of spatial variation of ambient volatile organic compound levels at a power station in Kuwait

Twenty-four-hour integrated ambient air samples were collected in canisters at 10 locations within Kuwait's major power station: Doha West Power Station to assess the spatial distribution of volatile organic compounds (VOCs) within the perimeter of the station. A total of 30 samples, i.e., three samples per location, were collected during February and March. The samples were analyzed using a gas chromatography with flame ionization detection (GC-FID) system and following the U.S. EPA Method TO-14A with modification. The results reflected the emission activities on the site and the meteorological conditions during sampling. Generally speaking, there was a negative correlation between the ambient temperature and the VOC concentrations, which indicates the sources were local. The halogenated compounds formed the highest proportion (i.e. 50-75 %) of the total VOC concentrations at the ten locations. 1,2,4-Trichlorobenzene and Vinyl Chloride concentrations were the highest amongst the other halogenated compounds. The aromatic compounds formed the least proportion (i.e. 1-4%) of the total VOC levels at all locations with Toluene having the highest concentrations amongst the aromatic compounds at seven locations. Propene, which is a major constituent of the fuel used, was the highest amongst the aliphatic compounds. The findings of this study and other relevant work suggests the measured VOC levels were the highest over the year, nevertheless, further work is required to assess the precisely temporal variation of VOC due to change in meteorological conditions and the emission rates.

IMPLICATIONS

Assessment of VOC concentrations around a power plant in Kuwait during the peak season showed halogenated compounds to be the dominant group. The calculated indoor concentrations were lower than those reported in a residential area about 12 km away.

Emission and profile characteristic of volatile organic compounds emitted from coke production, iron smelt, heating station and power plant in Liaoning Province, China

107 kinds of C₂-C₁₂ volatile organic compound (VOC) mass concentrations and profiles for four types of coal-fired stationary sources in Liaoning Province were studied by a dilution sampling system and GC-MS analysis method, which are of significant importance with regard to VOC emissions in northeast of China. The results showed that there were some differences among these VOC source profiles. The total mass concentrations of analyzed 107 VOC species varied from 10,917 to 19,652 μg m(-3). Halogenated hydrocarbons exhibited higher mass percentages for the VOC source profiles of iron smelt (48.8%) and coke production plant (37.7%). Aromatic hydrocarbons were the most abundant in heating station plant (69.1%). Ketones, alcohols and acetates held 45.0% of total VOCs in thermal power plant. For non-methane hydrocarbons (NMHCs), which are demanded for photochemical assessment in the USA, toluene and n-hexane were the most abundant species in the iron smelt, coke production and thermal power plant, with the mass percentages of 64.8%, 52.7% and 38.6%, respectively. Trimethylbenzene, n-propylbenzene and o,m-ethyltoluene approximately accounted for 70.0% in heating station plant. NMHCs emitted from coke production, iron smelt, heating station and power plant listed above presented different chemical reactivities. The average OH loss rate of NMHCs from heating station, was 4 to 5.6 times higher than that of NMHCs from iron smelt, coke production and power plant, which implies that VOCs emitted from heating station in northeast of China should be controlled firstly to avoid photochemical ozone pollution and protect human health. There are significant variations in the ratios of benzene/toluene and m, p-xylene/ethylbenzene of these coal-fired source profiles. The representativeness of the coal-fired sources studied and the VOC samples collected should be more closely examined. The accuracy of VOC source profiles related to coal-fired processes is highly dependent on location and sampling method.

New Look at BTEX: Are Ambient Levels a Problem?

Benzene, toluene, ethylbenzene, and xylene (BTEX) are retrieved during fossil fuel extraction and used as solvents in consumer and industrial products, as gasoline additives, and as intermediates in the synthesis of organic compounds for many consumer products. Emissions from the combustion of gasoline and diesel fuels are the largest contributors to atmospheric BTEX concentrations. However, levels indoors (where people spend greater than 83% of their time) can be many times greater than outdoors. In this review we identified epidemiological studies assessing the noncancer health impacts of ambient level BTEX exposure (i.e., nonoccupational) and discussed how the health conditions may be hormonally mediated. Health effects significantly associated with ambient level exposure included sperm abnormalities, reduced fetal growth, cardiovascular disease, respiratory dysfunction, asthma, sensitization to common antigens, and more. Several hormones including estrogens, androgens, glucocorticoids, insulin, and serotonin may be involved in these health outcomes. This analysis suggests that all four chemicals may have endocrine disrupting properties at exposure levels below reference concentrations (i.e., safe levels) issued by the U.S. Environmental Protection Agency. These data should be considered when evaluating the use of BTEX in consumer and industrial products and indicates a need to change how chemicals present at low concentrations are assessed and regulated.

Personal exposure of primary school children to BTEX, NO₂ and ozone in Eskişehir, Turkey: relationship with indoor/outdoor concentrations and risk assessment

Personal exposures of 65 primary school children to benzene, toluene, ethyl benzene, xylenes (BTEX), nitrogen dioxide (NO2) and ozone (O3) were measured during 24h by using organic vapor monitors and tailor-made passive samplers. Two schools were selected to represent students living in more polluted (urban) and less polluted (sub-urban) areas in the city of Eskişehir, Turkey. The pollutant concentrations were also measured in indoor and outdoor environments during the personal sampling to investigate the contribution of each micro-environment on measured personal concentrations. Socio-demographic and personal time-activity data were collected by means of questionnaires and half-hour-time resolution activity diaries. Personal exposure concentrations were found to be correlated with indoor home concentrations. Personal, indoor and outdoor concentrations of all studied pollutants except for ozone were found to be higher for the students living at the urban traffic site. Ozone, on the other hand, had higher concentrations at the sub-urban site for all three types of measurements (personal, indoor and outdoor). Analysis of the questionnaire data pointed out to environmental tobacco smoke, use of solvent based products, and petrol station nearby as factors that affect personal exposure concentrations. Cancer and non-cancer risks were estimated using the personal exposure concentrations. The mean cancer risk for the urban school children (1.7×10(-5)) was found to be higher than the sub-urban school children (0.88×10(-5)). Children living with smoking parents had higher risk levels (1.7×10(-5)) than children living with non-smoking parents (1.08×10(-5)). Overall, the risk levels were <1×10(-4). All hazard quotient values for BTEX for the non-cancer health effects were <1 based on the calculations EPA's Risk Assessment Guidance for Superfund (RAGS) part F.

C5-C12 volatile organic compounds at roadside, residential, and background locations in Ankara, Turkey: temporal and spatial variations and sources

Concentrations of 91 volatile organic compounds (VOCs) ranging from C5 to C12 were measured at three sites in Ankara, the capital of Turkey, in the summer of 2003 and winter of 2004. Samples were collected at roadside, residential and background stations at consecutive 4-hr intervals over a 24-hr period for six weeks in each season. Air samples were collected onto cartridges packed with Tenax TA and Carbopack B resins and analyzed by thermal desorption, followed by gas chromatography coupled to a mass selective detector (GC/MSD). Time resolved data provided information on ambient levels, temporal and spatial variations and sources of VOCs in Ankara. Toluene is the most abundant compound at all sites with and average concentration of 13.1 ?g m(-3). The mean concentrations of benzene are 12.6, 5.2, and 2.4 ?g m(-3) during winter at roadside, residential and background stations, respectively. Diurnal variation in the data together with toluene to benzene concentration ratio (T:B) that is close to 2.0 indicated the influence of traffic related emissions at residential and roadside stations during winter season. Higher T:B ratio observed at residential and background stations during summer period and correlation analysis indicated additional VOC sources. Temporal variations and low m,p-xylene to ethylbenzene ratio (mpX:E) indicated that transported air mass is the major VOC source influencing VOC concentrations measured at the background station.

Vertical concentration gradients of volatile organic compounds in two NS-oriented street canyons

Diffusive samplers were used to measure the vertical concentrations of benzene, toluene, n-hexane, cyclohexane, ethylbenzene and o-, m- and p-xylenes on both sides of two NS-oriented street canyons in Murcia (Spain) during a 5-day period. Non-dimensional relationships of concentration and height were calculated in order to study the behaviour of their concentration vertical profiles. The results show that the vertical profiles of benzene, toluene, n-hexane and cyclohexane concentrations were similar in both streets and on both sides of each street. Some differences were found in vertical profiles between streets and sides for ethylbenzene and xylenes, probably due to their higher affinity for adsorption into building materials. The similarities found for the first set of VOCs suggest that the dynamics of the dispersion was the same for both streets and was mainly influenced by microscale thermal effects. Finally, the concentration measurements of benzene, toluene, n-hexane, cyclohexane, and ethylbenzene were adjusted to expressions in the form c = c 0(h/h 0) A , and a regression coefficient R 2 = 0.962 (p = 0.0000) was obtained. The decreasing concentration of these compounds with height should be taken into account when assessing population exposure to these pollutants.

Effect of diurnal changes in VOC source strengths on performances of receptor models

INTRODUCTION

The effect of diurnal changes in strengths of volatile organic compound (VOC) sources on the performances of positive matrix factorization (PMF) and principal component analysis (PCA) was investigated using ambient measurement results that were taken during daytime and nighttime hours between March 24 and May 14, 2011, within Davutpasa Campus of Yildiz Technical University (Istanbul, Turkey).

METHODS

Forty-five VOC species, ranging from C(5) to C(11) in volatility, were measured in the samples, 40 of which are included in the analyses. Ambient samples were grouped as daytime, nighttime, and all day datasets, and both PMF and PCA were applied to each dataset. A total of six source groups were extracted from each dataset: solvent use, general industrial paint use, gasoline and diesel vehicle exhausts, and biogenic as well as evaporative emissions. Estimated source contributions showed great diurnal variations.

RESULTS

The results suggested that extraction of possible sources by PCA depends greatly on the number of samples and the strength of the sources, while PMF produced stable results regardless of number of samples and source strengths.

CONCLUSION

Although PMF was unable to resolve gasoline vehicle and evaporative emissions, it was found to be successful in explaining diurnal fluctuations in source strengths, while the performance of PCA depends on the strength of emission source.

Nonmethane Hydrocarbons in Ambient Air of Hazy and Normal Days in Foshan, South China

A first study of nonmethane hydrocarbons (NMHCs) on hazy and normal days was performed in Foshan for providing deep insight into the local deteriorating air quality. Ethane, propane, i-pentane, ethene, propene, ethyne, benzene, and toluene were eight most abundant compounds, accounting for 71%-85% of total NMHCs. Most hydrocarbons showed much higher levels on hazy days than normal days together with hydrocarbon/ethyne ratios and diurnal variations, indicating hazy days are more dominated by vehicular emission. Correlation coefficients (R(2)) of ethane, propane, ethane, propene, benzene, and total NMHCs with ethyne were 0.62-0.83, indicating these compounds are mainly related to vehicular emission. R(2) analysis indicated that solvent usage is responsible for toluene and other aromatic hydrocarbons (e.g., ethylbezene). Benzene/toluene (B/T) ratio was 0.44±0.23 during whole sampling periods, again indicating vehicular emission is the dominant source. Lower B/T ratio (0.30±0.14) on hazy days than that (0.58±0.21) on normal days suggested that solvent usage emitted toluene.

Recycled water: potential health risks from volatile organic compounds and use of 1,4-dichlorobenzene as treatment performance indicator

Characterisation of the concentrations and potential health risks of chemicals in recycled water is important if this source of water is to be safely used to supplement drinking water sources. This research was conducted to: (i) determine the concentration of volatile organic compounds (VOCs) in secondary treated effluent (STE) and, post-reverse osmosis (RO) treatment and to; (ii) assess the health risk associated with VOCs for indirect potable reuse (IPR). Samples were examined pre and post-RO in one full-scale and one pilot plant in Perth, Western Australia. Risk quotients (RQ) were estimated by expressing the maximum and median concentration as a function of the health value. Of 61 VOCs analysed over a period of three years, twenty one (21) were detected in STE, with 1,4-dichlorobenzene (94%); tetrachloroethene (88%); carbon disulfide (81%) and; chloromethane (58%) most commonly detected. Median concentrations for these compounds in STE ranged from 0.81 μg/L for 1,4-dichlorobenzene to 0.02 μg/L for carbon disulphide. After RO, twenty six (26) VOCs were detected, of which 1,4-dichlorobenzene (89%); acrylonitrile (83%) chloromethane (63%) and carbon disulfide (40%) were the more frequently detected. RQ(max) were all below health values in the STE and after RO. Median removal efficiency for RO was variable, ranging from -77% (dichlorodifluoromethane) to 91.2% (tetrachloroethene). The results indicate that despite the detection of VOCs in STE and after RO, their human health impact in IPR is negligible due to the low concentrations detected. The results indicate that 1,4-dichlorobenzene is a potential treatment chemical indicator for assessment of VOCs in IPR using RO treatment.

Characteristics of atmospheric non-methane hydrocarbons in Foshan City, China

Foshan is the most air-polluted city in Pearl River Delta. Non-methane hydrocarbons (NMHCs) were investigated for the first time in Foshan in winter 2008. Ethene, ethane, ethyne, propane, i-pentane, and toluene were the most abundant hydrocarbons and observed to be higher in Foshan than those in many other cities in China. Different from other cities, ethene and ethane were observed to be the two highest compounds in Foshan. Generally, the most abundant hydrocarbons showed high mixing ratios in the morning (0930-1030 hours), decreased to the lowest level in the afternoon (1430-1530 hours), and increased to higher value in the evening (1930-2030 hours). But i-pentane exhibited a different diurnal pattern with the highest level (13.4 ± 5.8 ppbv) in the afternoon, implying the acceleration of solvent evaporation resulting from higher temperature. Correlation coefficients (R(2) = 66% for n = 6 at 95% confidence level) of the individual hydrocarbons with ethyne and i-pentane indicated vehicular emissions were the main sources of ethene, propene, i-butene, isoprene, benzene and toluene, while gasoline evaporation was responsible for n-pentane, n-hexane, and n-heptane. The good correlation of most of the hydrocarbons with ethyne, indicating vehicular emissions, were the main sources of NMHCs. B/T ratio was 0.36 ± 0.06, implying vehicular emissions acted as the major contributors as well as additional emissions of toluene emitted from solvent usage. According to investigation, it also suggested that LPG leakage was the main source of propane, while NG leakage was responsible for ethane in Foshan City.

Regional assessment of ambient volatile organic compounds from biopharmaceutical R&D complex

Biopharmaceutical R&D complexes are major emission sources of volatile organic compounds (VOCs), which may pose potential health risks for staff on site and residents nearby. In this paper health risk assessments were performed for the VOCs in the ambient air of a typical biopharmaceutical R&D complex in China. Results showed halogenated and alkyl compounds were dominant components among 24 major VOCs from 9 selected sampling sites, inside or around the complex. The principal component analysis (PCA) indicated VOCs were generated predominantly from the biopharmaceutical research activities (factor 1 (F1), 71.6%) and traffic vehicles (factor 2 (F2), 15.4%), which were confirmed by contour maps of five selected VOCs (benzene, toluene, chlorobenzene, methylene chloride and n-hexane) simulated by Golden Software Surfer. The cumulative cancer risks for the staff on site and residents nearby were investigated and results showed the risk value were 1.01E--5 and 2.03E--5, respectively, higher than the threshold value of 1.0E--6. These results indicated that elevated VOCs from biopharmaceutical R&D complex are potential risks to the public health. Furthermore, the human health risk assessment revealed that 1,2-dichloroethane, methylene chloride, carbon tetrachloride and benzene were the dominant risk contributors for staff on site, while methyl chloride, carbon tetrachloride, 1,2-dichloroethane and tetrahydrofuran for residents nearby. As a conclusion, this work suggests that proper control strategy should be taken for VOCs releasing to minimize the public health risks, especially for the halogenated compounds.

Outdoor and indoor benzene evaluation by GC-FID and GC-MS/MS

The evaluation of benzene in different environments such as indoor (with and without tobacco smoke), a city area, countryside, gas stations and near exhaust pipes from cars running on different types of fuels was performed. The samples were analyzed using gas chromatography (GC) with flame ionization detection (FID) and tandem mass spectrometric detection (MS/MS) (to confirm the identification of benzene in the air samples). Operating conditions for the GC-MS analysis were optimized as well as the sampling and sample preparation. The results obtained in this work indicate that i) the type of fuel directly influences the benzene concentration in the air. Gasoline with additives provided the highest amount of benzene followed by unleaded gasoline and diesel; ii) the benzene concentration in the gas station was always higher than the advisable limit established by law (5 μg m⁻³) and during the unloading of gasoline the achieved concentration was 8371 μg m⁻³; iii) the data from the countryside (Taliscas) and the urban city (Matosinhos) were below 5 μg m⁻³ except 5 days after a fire on a petroleum refinery plant located near the city; iv) it was proven that in coffee shops where smoking is allowed the benzene concentration is higher (6 μg m⁻³) than in coffee shops where this is forbidden (4 μg m⁻³). This method may also be helpful for environmental analytical chemists who use GC-MS/MS for the confirmation or/and quantification of benzene.

Traffic-related air pollution and cardiovascular mortality in central Taiwan

In this study, the relationship between cardiovascular mortality and traffic-related air pollutants (NO(2), CO, PM(10), and six volatile organic compounds (VOCs), propane, iso-butane, propylene, benzene, meta-, para-, and ortho-xylenes) was investigated. The concentrations of NO(2), PM(10) and CO from 1993 to 2006 were measured at a fixed-site air monitoring station, and VOC data from 2003 to 2006 were obtained from a photochemical assessment monitoring site in an urban area in central Taiwan. Outcome variables were data on mortality due to cardiovascular diseases (ICD-9-CM 410-411, 414, 430-437) from 1993 to 2006. Cardiovascular mortality averaged 1.5 cases, ranging between 0 and 9 cases per day. Daily air pollution levels ranged from 0.5 to 80.5ppb for NO(2) and from 0.1 to 3.8ppm for CO. From the subset of data from 2003 to 2006, daily average values ranged from 0.6 to 17.5ppb for propane, 0.3 to 6.7ppb for iso-butane, 0.3 to 6.7ppb for propylene, 0.2 to 3.8ppb for benzene, 0.3 to 26.0ppb for m,p-xylene, and 0.02 to 7.6ppb for o-xylene. Poisson generalized additive model was used to estimate the effects of elevated air pollutant levels on daily mortality, adjusting for meteorological conditions and temporal trends. Single-pollutant model showed that cardiovascular mortality was significantly associated with NO(2) lagged 2 days, and with propane, iso-butane, and benzene lagged 0 day. The relative risk for an interquartile range increase in air pollutant levels was 1.053 for NO(2), 1.064 for propane, 1.055 for iso-butane, and 1.055 for benzene. In conclusion, daily cardiovascular mortality showed association with data on acute exposure to traffic air pollutants in Taichung, which is an important factor to consider in studying cardiovascular mortality in urban environments.

Measurements of benzene and formaldehyde in a medium sized urban environment. Indoor/outdoor health risk implications on special population groups

In the present study, the results of a measurement campaign aiming to assess cancer risk among two special groups of population: policemen and laboratory technicians exposed to the toxic substances, benzene and formaldehyde are presented. The exposure is compared to general population risk. The results show that policemen working outdoor (traffic regulation, patrol on foot or in vehicles, etc.) are exposed at a significantly higher benzene concentration (3-5 times) than the general population, while the exposure to carbonyls is in general lower. The laboratory technicians appear to be highly exposed to formaldehyde while no significant variation of benzene exposure in comparison to the general population is recorded. The assessment revealed that laboratory technicians and policemen run a 20% and 1% higher cancer risk respectively compared to the general population. Indoor working place air quality is more significant in assessing cancer risk in these two categories of professionals, due to the higher Inhalation Unit Risk (IUR) of formaldehyde compared to benzene. Since the origin of the danger to laboratory technicians is clear (use of chemicals necessary for the experiments), in policemen the presence of carbonyls in indoor air concentrations due to smoking or used materials constitute a danger equal to the exposure to traffic originated air pollutants.

Source apportionment of PM(10) and PM(2.5) using positive matrix factorization and chemical mass balance in Izmir, Turkey

Atmospheric particulate matter (PM) fractions (PM(10) and PM(2.5)) were sampled concurrently between June 2004 and May 2005 at two sites (urban and suburban) in Izmir, Turkey. The elemental composition of PM (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, V, and Zn) was determined using inductively coupled plasma-optical emission spectrometer. Elemental compositions of several PM sources were also characterized. Positive matrix factorization (PMF) and chemical mass balance modeling (CMB) were applied to determine the PM sources and their contributions to air concentrations. The major contributors to PM were fossil fuel burning, traffic emissions, mineral industries and marine salt according to the PMF results. However, undetermined parts were more than 40%. On the other hand, the contributions to PM could be determined completely by CMB, and the dominant contributor was traffic with >70% at the two sites. Fossil fuel burning, mineral industries, marine salt and natural gas-fired power plant were the minor contributors.