Method TO-14 Research Articles

Quantitative Measurements of Hazardous Gas Effluents from the Combustion of Crew Waste Simulant in Microgravity

Abstract In August 2021, Blue Origin launched their un-crewed NS-17 mission aboard their New Shepard launch vehicle. Among the scientific payloads was NASA’s Orbital Syngas Commodity Augmentation Reactor (OSCAR), a flight-capable test rig allowing the combustion of ~10 g of simulated astronaut trash. Developed at NASA’s Kennedy Space Center, OSCAR measured differences in the combustion of complex mixed waste materials between terrestrial gravity and microgravity conditions. OSCAR is self-contained and collects its own effluent gases, which were subsequently analyzed for trace volatile organic compounds (VOCs) with a modified EPA Method TO-15. It was found that combustion in microgravity produced higher levels of VOCs (2,883 mg measured VOCs per kg trash) than for analogous triplicate (terrestrial) laboratory experiments (1,237±286 mg measured VOCs per kg trash with 95% confidence interval), indicating significant differences that were consistent with previously reported combustion efficiencies. Also, the concentrations of the measured VOCs were compared to NASA’s Spacecraft Maximum Allowable Concentrations (SMAC) values. These results provide a basis for understanding important design considerations for spacecraft waste disposal systems as NASA and their commercial partners develop crewed vehicles for missions to the Moon and Mars.

16 Advanced Solutions for Comprehensive Ambient Air Monitoring

Abstract Growing concerns over harmful exposure to low levels of hazardous air pollutants has led to increasingly demanding volatile organic compound (VOC) monitoring programs. Regulations are evolving to increase monitoring frequency, expand the list of target compounds and set lower detection limits in ambient air. Alongside this ambient and indoor air research continues to identify new, challenging compounds. There have long been specific standard methods and regulations for subsets of compounds, each using different instrumentation. For example method TO-15 for air toxics requires TD-GC-MS, ozone precursors monitoring uses TD-GC-FID and aldehydes are sampled with DNPH cartridges, analyzed by HPLC. Each compound set has its own challenges. Even so there is a drive to combine all three analyses into a single analytical run with the possibility of monitoring in online and offline. Additional considerations are high levels of humidity and large sample volumes, required to meet lower reporting limits. These require sophisticated trapping and water management techniques. As such removal of water from canister and on-line samples without loss of polar species is paramount for successful analysis of the Ozone Precursors, Air Toxics and oxygenated VOCs. This presentation will address the challenges associated with this complex compound list and show how confident identification and quantitation, with maximum sensitivity, can be achieved using state of the art pre-concentration technology. The cryogen-free methodology allows remote, on-line analysis or off-line canister sampling, all with a sample-to-sample cycle time of <60 minutes, significantly reducing equipment overhead and analysis times whilst enhancing insight into air quality.

Trace Measurements of Ethylene Oxide Using Cavity-enhanced Absorption Spectrometry near 3066 cm–1

Ethylene oxide (EtO) is a key carcinogen that is widely used in chemical manufacturing and biotechnology industries. Recent work has suggested that permissible exposure limits for EtO be reduced from 1–5 ppm to sub-ppb levels. Such new standards will require new methodologies that are capable of measuring EtO with the requisite precision. In this paper, we demonstrate a new analyzer based on cavity-enhanced absorption spectrometry that utilizes a broad EtO absorption feature near 3066 cm-1. A fit function is developed that includes water, methane, and EtO absorbances and accounts for absorption both inside and outside the cavity. A methane standard is used to determine the cavity gain factor, and the EtO absorbance spectrum is empirically determined. The final system shows excellent linearity from 0 – 909 ppb EtO (R2 ~0.9999) with a measurement precision of better than ±1 ppb (1s, 60 seconds) that improved to ±0.5 ppb (1s, 15 minutes). Deliberate ambient EtO releases demonstrate the instrument’s utility in rapidly detecting hazardous conditions. Further work will include improving the measurement precision and directly comparing the system to EPA Method TO-15.

Health Misinformation about Toxic-Site Harm: The Case for Independent-Party Testing to Confirm Safety.

Health misinformation can cause harm if regulators or private remediators falsely claim that a hazardous facility is safe. This misinformation especially threatens the health of children, minorities, and poor people, disproportionate numbers of whom live near toxic facilities. Yet, perhaps because of financial incentives, private remediators may use safety misinformation to justify reduced cleanup. Such incentives exist in nations like the United States, where most toxic-site testing/remediation is semi-privatized or voluntary, conducted by private parties, commercial redevelopers, who can increase profits by underestimating health harm, thus decreasing required testing/remediation. Our objective is to begin to determine whether or not interested parties misrepresent health harm (at hazardous facilities that they test/remediate/redevelop) when they use traditional and social media to claim that these sites are safe. Our hypothesis is that, contrary to the safety claims of the world’s largest commercial developer, Coldwell Banker Real Estate/Trammell Crow (CBRE/TCC), the authors’ screening assessment, especially its lab-certified, toxic-site, indoor-air tests, show violations of all three prominent government, cancer-safety benchmarks. If so, these facilities require additional testing/remediation, likely put site renters at risk, and may reveal problems with privatized hazardous cleanup. To our knowledge, we provide the first independent tests of privatized, toxic-site assessments before cancer reports occur. Our screening assessment of this hypothesis tests indoor air in rental units on a prominent former weapons-testing site (the US Naval Ordnance Testing Station, Pasadena, California (NOTSPA) that is subject to carcinogenic vapor intrusion by volatile organic compounds, VOCs), then compares test results to the redeveloper’s site-safety claims, made to government officials and citizens through traditional and social media. Although NOTSPA toxic soil-gas concentrations are up to nearly a million times above allowed levels, and indoor air was never tested until now, both the regulator and the remediator (CBRE/TCC) have repeatedly claimed on social media that “the site is safe at this time.” We used mainly Method TO-17 and two-week sampling with passive, sorbent tubes to assess indoor-air VOCs. Our results show that VOC levels at every location sampled—all in occupied site-rental units—violate all three government-mandated safety benchmarks: environmental screening levels (ESLs), No Significant Risk Levels (NSRLs), and inhalation risks based on the Inhalation Unit Risk (IUR); some violations are two orders of magnitude above multiple safety benchmarks. These results support our hypothesis and suggest a need for independent assessment of privatized cleanups and media-enhanced safety claims about them. If our results can be replicated at other sites, then preventing health misinformation and toxic-facility safety threats may require new strategies, one of which we outline.

Impact on ground-level ozone formation by emission characterization of volatile organic compounds from a flex-fuel light-duty vehicle fleet in a traffic tunnel in Rio de Janeiro, Brazil

The present study aimed to evaluate the contribution of mobile source emissions from, in particular, light-duty vehicles (LDVs) to tropospheric ozone formation in the Rio de Janeiro Metropolitan Area (RJMA), by quantifying the volatile organic compounds (VOCs) in a representative urban road tunnel of the city. The importance of having this type of study in Brazil is because this country has a unique vehicle emission scenario that passenger cars can use different percentages of bioethanol mixed in gasoline. The concentration of speciated VOCs in Reboucas tunnel in Rio de Janeiro, Brazil, was measured in two campaigns, total period of eight weekdays, and the VOC determination was used to calculate the average composition of the emissions of Rio de Janeiro’s LDV fleet. The United States Environmental Protection Agency (US EPA) method TO-15 was applied to determine the concentrations of VOCs C3–C12. It was found that the vehicles circulating through the tunnel were predominantly light-duty flex-fuel cars (99%). The VOC profile was constant in the monitored period. The most abundant compounds were, in order, propane, iso-pentane, n-pentane, propene, and n-butane. In addition, mono-aromatic compounds were found to be the VOC class with the highest ozone-forming potential (OFP), while propene was the main VOC contributor to ozone formation, being responsible for 27% of the troposphere ozone formed by the total VOCs monitored in the present study.

Preliminary Study of Ambiente Levels and Exposure to BTEX in the Rio de Janeiro Olympic Metropolitan Region, Brazil.

This study aims to determine BTEX concentrations in the Metropolitan Region of Rio de Janeiro (MRRJ, Brazil) and evaluate potential health risks of benzene and ethylbenzene exposure based on the collected data, in 2015, the year before the Rio 2016 Olympic Games. Samples were collected and analyzed following method TO-15 (U.S.EPA). Toluene was the most abundant compound in all samples (mean concentration 16.72 ± 15.70 µg m-3). The average benzene concentration in ambient air (3.44 ± 3.14 µg m-3) was slightly lower than the yearly average "upper assessment threshold", 3.5 µg m-3, established by EU Directive 2008/50/EC. The calculated cancer risk values were > 1 × 10-6 for all samples, clearly indicating a potential cancer risk and the importance of fixed measurements by the monitoring stations to assess ambient air quality in the urban areas of the MRRJ. Calculated ratios for the BTEX species indicate that these compounds are predominantly emitted from vehicular sources with a contribution from industrial sources.

Understanding high tropospheric ozone episodes in Bangu, Rio de Janeiro, Brazil.

This study investigates the potential factors that contribute to frequent high levels of ozone in Bangu, one of the most critical areas in the city of Rio de Janeiro, regarding ozone levels and air quality. Speciated non-oxygenated volatile organic compounds (VOCs) were measured using method TO-15 (US EPA). The measured concentrations and kinetic and mechanistic analysis of VOC reactivity showed that alkanes were the most important compounds. Ozone concentrations were simulated for a base case representing a day with high ozone levels. Simulated results and statistical multivariate analysis showed that the high ozone concentrations did not seem to be closely related to local emissions but rather were related to pollutant transport and low measured NOx levels and were triggered by photochemical activity. The differences between weekdays and weekends were also investigated, showing that ozone concentrations were also higher during weekends, mainly on Sunday, when the diesel heavy vehicle fleet was reduced and lower NO emissions were observed. The VOC/NOx ratios correspond to a VOC-limited process, which leads to higher ozone concentrations under low NOx conditions.

Application of passive sorbent tube and canister samplers for volatile organic compounds at refinery fenceline locations in Whiting, Indiana

ABSTRACTSelect volatile organic compounds (VOCs) in ambient air were measured at four fenceline sites at a petroleum refinery in Whiting, IN, using modified EPA Method 325 A/B with passive tubes and EPA Compendium Method TO-15 with canister samplers. One-week, time-integrated samplers were deployed for 8 weeks with tubes and canister samplers deployed in duplicate. Good precision was obtained from the duplicate tubes (<7%) and duplicate canisters (≤10%) for BTEX, perchloroethylene, and styrene. The tubes yielded statistically significantly higher concentrations than canisters for benzene, toluene, ethylbenzene, and m,p-xylene. However, all differences were estimated to be <0.1 ppbv. No concentration differences among the four Whiting sites were found for any of the VOCs.Implications: Recently enacted EPA Methods 325A/B use passive-diffusive tube samplers to measure benzene at refinery fenceline locations. This pilot study presents VOC data applying a modified version of EPA Method 325 A/B and its comparison to EPA Compendium Method TO-15 canister samplers at four refinery fenceline sites. The findings from this study provide additional confidence in application of the tube method at refineries to ascertain VOC source influence since tube and canister samplers were comparable and good precision was obtained from duplicate sampling for both methods. No overall difference in these reported VOC concentrations was found between Whiting sites for tubes or canisters.

Optimization and evaluation of multi-bed adsorbent tube method in collection of volatile organic compounds

The feasibility of using adsorbent tubes to collect volatile organic compounds (VOCs) has been demonstrated since the 1990's and standardized as Compendium Method TO-17 by the U.S. Environmental Protection Agency (U.S EPA). This paper investigates sampling and analytical variables on concentrations of 57 ozone (O3) precursors (C2-C12 aliphatic and aromatic VOCs) specified for the Photochemical Assessment Monitoring Station (PAMS). Laboratory and field tests examined multi-bed adsorbent tubes containing a sorbate combination of Tenax TA, Carbograph 1 TD, and Carboxen 1003. Analyte stabilities were influenced by both collection tube temperature and ambient O3 concentrations. Analytes degraded during storage, while blank levels were elevated by passive adsorption. Adsorbent tube storage under cold temperatures (−10°C) in a preservation container filled with solid silica gel and anhydrous calcium sulfate (CaSO4) ensured sample integrity. A high efficiency (>99%) O3 scrubber (i.e., copper coil tube filled with saturated potassium iodide [KI]) removed O3 (i.e., <200 ppbv) from the air stream with a sampling capacity of 30h. Water vapor scrubbers interfered with VOC measurements. The optimal thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) desorption time of 8min was found at 330°C. Good linearity (R2>0.995) was achieved for individual analyte calibrations (with the exception of acetylene) for mixing ratios of 0.08–1.96 ppbv. The method detection limits (MDLs) were below 0.055 ppbv for a 3L sample volume. Replicate analyses showed relative standard deviations (RSDs) of <10%, with the majority of the analytes within <5%.

Isoprene, benzene and toluene levels at the major landmarks of Rio de Janeiro during the 2014 FIFA World Cup

Air samples were collected in the days before and during the 2014 FIFA World Cup at the major landmarks of Rio de Janeiro, Brazil. Samples were collected and analysed following Method TO-15 (US-EPA). Isoprene was selected as a marker of biogenic emissions, and benzene and toluene were selected as markers of anthropogenic emissions, primarily vehicular emissions. The isoprene, benzene, and toluene concentrations ranged from 0.39 to 2.32μg m–3, 2.27 to 10.16μg m–3, and 5.21 to 21.83μg m–3, respectively. The kinetic and mechanistic reactivities of these compounds were also calculated to estimate the actual contribution of these compounds to atmospheric oxidant formation. The benzene and toluene concentrations indicated that greener areas of the city are strongly affected by urban emissions. Levels of isoprene were similar to those previously determined in other areas with vegetation.

Air concentrations of volatile compounds near oil and gas production: a community-based exploratory study.

BackgroundHorizontal drilling, hydraulic fracturing, and other drilling and well stimulation technologies are now used widely in the United States and increasingly in other countries. They enable increases in oil and gas production, but there has been inadequate attention to human health impacts. Air quality near oil and gas operations is an underexplored human health concern for five reasons: (1) prior focus on threats to water quality; (2) an evolving understanding of contributions of certain oil and gas production processes to air quality; (3) limited state air quality monitoring networks; (4) significant variability in air emissions and concentrations; and (5) air quality research that misses impacts important to residents. Preliminary research suggests that volatile compounds, including hazardous air pollutants, are of potential concern. This study differs from prior research in its use of a community-based process to identify sampling locations. Through this approach, we determine concentrations of volatile compounds in air near operations that reflect community concerns and point to the need for more fine-grained and frequent monitoring at points along the production life cycle.MethodsGrab and passive air samples were collected by trained volunteers at locations identified through systematic observation of industrial operations and air impacts over the course of resident daily routines. A total of 75 volatile organics were measured using EPA Method TO-15 or TO-3 by gas chromatography/mass spectrometry. Formaldehyde levels were determined using UMEx 100 Passive Samplers.ResultsLevels of eight volatile chemicals exceeded federal guidelines under several operational circumstances. Benzene, formaldehyde, and hydrogen sulfide were the most common compounds to exceed acute and other health-based risk levels.ConclusionsAir concentrations of potentially dangerous compounds and chemical mixtures are frequently present near oil and gas production sites. Community-based research can provide an important supplement to state air quality monitoring programs.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-069X-13-82) contains supplementary material, which is available to authorized users.

Quantitative passive soil vapor sampling for VOCs- part 2: laboratory experiments

Controlled laboratory experiments were conducted to demonstrate the use of passive samplers for soil vapor concentration monitoring. Five different passive samplers were studied (Radiello, SKC Ultra, Waterloo Membrane Sampler, ATD tubes and 3M OVM 3500). Ten different volatile organic compounds were used of varying classes (chlorinated ethanes, ethanes, and methanes, aliphatics and aromatics) and physical properties (vapor pressure, solubility and sorption). Samplers were exposed in randomized triplicates to concentrations of 1, 10 and 100 ppmv, with a relative humidity of ∼80%, a temperature of ∼24 °C, and a duration of 30 minutes in a chamber with a face velocity of about 5 cm min(-1). Passive samplers are more commonly used for longer sample durations (e.g., 8 hour workday) and higher face velocities (>600 cm min(-1)), so testing to verify the performance for these conditions was needed. Summa canister samples were collected and analyzed by EPA Method TO-15 to establish a baseline for comparison for all the passive samplers. Low-uptake rate varieties of four of the samplers were also tested at 10 ppmv under two conditions; with 5 cm min(-1) face velocity and stagnant conditions to assess whether low or near-zero face velocities would result in a low bias from the starvation effect. The results indicate that passive samplers can provide concentration measurements with accuracy (mostly within a factor of 2) and precision (RSD < 15%) comparable to conventional Summa canister samples and EPA Method TO-15 analysis. Some compounds are challenging for some passive samplers because of uncertainties in the uptake rates, or challenges with retention or recovery.

Comparison of Sampling Probe and Thermal Desorber in HAPSITE ER for Analysis of TO-15 Compounds

The Hazardous Air Pollutants on Site (HAPSITE), a portable Gas Chromatograph-Mass Spectrometer (GCMS), has been used to detect, identify, and quantify Volatile Organic Compounds (VOCs) from environmental samples, providing on-site analysis to aid in operational risk management. HAPSITE is equipped with a hand-held sampling probe in which an air sample is delivered into a concentrator, and the VOCs collected in the concentrator are transferred, separated, and identified in the GC-MS. An upgraded version, HAPSITE ER, has recently been introduced with additional sampling capability for solid phase micro extraction and Thermal Desorption (TD). To our knowledge, however, no study has yet evaluated the performance of the thermal desorber accommodated in HAPSITE ER. In this study, therefore, we analyzed EPA Method TO-15 compounds with two different sampling methods (probe and thermal desorber for TD tubes) in a HAPSITE ER, and compared their results against each other. A major finding was that the peak intensities of the TO-15 compounds, particularly those with high Boiling Point (BP), were substantially higher in the results obtained with the thermal desorber than in those with the sampling probe. The lower peak intensities of the compounds observed in the probe analysis are likely due to the condensation of the VOCs in the probe (transfer) line that is 6 feet long and maintained at 40°C as they are delivered from the probe to the concentrator, whereas the thermal desorber is directly connected to the HAPSITE (no transfer line is used), thereby eliminating the condensation of VOCs. In conclusion, our study suggests that for the analysis of VOCs with high up to 220°C, the use of TD tubes followed by desorption in the thermal desorber offered by the newer version of HAPSITE is recommended.

Air Concentrations of Volatile Compounds Near Oil and Gas Production: A Community-Based Exploratory Study

Background: Horizontal drilling, hydraulic fracturing, and other drilling and well stimulation technologies are now used widely in the United States and increasingly in other countries. They enable increases in oil and gas production, but there has been inadequate attention to human health impacts. Air quality near oil and gas operations is an underexplored human health concern for five reasons: (1) prior focus on threats to water quality; (2) an evolving understanding of contributions of certain oil and gas production processes to air quality; (3) limited state air quality monitoring networks; (4) significant variability in air emissions and concentrations; and (5) air quality research that misses impacts important to residents. Preliminary research suggests that volatile compounds, including hazardous air pollutants, are of potential concern. This study differs from prior research in its use of a community-based process to identify sampling locations. Through this approach, we determine concentrations of volatile compounds in air near operations that reflect community concerns and point to the need for more fine-grained and frequent monitoring at points along the production life cycle.Methods: Grab and passive air samples were collected by trained volunteers at locations identified through systematic observation of industrial operations and air impacts over the course of resident daily routines. A total of 75 volatile organics were measured using EPA Method TO-15 or TO-3 by gas chromatography/mass spectrometry. Formaldehyde levels were determined using UMEx 100 Passive Samplers.Results: Levels of eight volatile chemicals exceeded federal guidelines under several operational circumstances. Benzene, formaldehyde, and hydrogen sulfide were the most common compounds to exceed acute and other health-based risk levels.Conclusions: Air concentrations of potentially dangerous compounds and chemical mixtures are frequently present near oil and gas production sites. Community-based research can provide an important supplement to state air quality monitoring programs.

Flexible Polyurethane Foams: A Comparative Measurement of Toxic Vapors and Other Toxic Emissions in Controlled Combustion Environments of Foams With and Without Fire Retardants

Abstract A series of experiments were performed to measure the toxic vapor emissions of fires involving flexible polyurethane foams (FPUF) with and without flame retardants (FR). FPUF were covered with FR and non-FR fabrics to simulate cushion conditions. Testing was performed to both maximize detection of gases in small scale testing and measurement of exposure concentrations in realistic fire conditions in a room sized enclosures. A standard smoke box with load cell, open flame ignition source and Fourier transform infra-red spectrometer (FTIR) fit with a 2 m gas cell was used to monitor gas emission real time during testing with filter samples analyzed for acid gases and chloro-dioxins and furans. An NFPA 286 room was used to measure realistic smoke emissions from three seat furniture mock-ups with non-combustible frames. Oxygen consumption calorimetry, smoke opacity and smoke toxicity were measured during these tests. FTIR and grab sampling were performed during the room fires. Grab sampling using evacuated metal canisters were used to collect combustion gasses at various stages of the fire followed by analysis using EPA method TO-15 indoor air pollutants. In addition chloro-dioxins and furans were measured using a particulate filter collection system. The results of the study indicated that both FR and non-FR FPUF gave very similar results for smoke toxicity and both were less than what would be produced by an equivalent mass of wood. Use of fire barrier materials increased the toxicity of smoke produced from non-FR FPUF due to the creation of oxygen limited conditions. Use of fire barrier materials with FR FPUF would not sustain ignition and ended up producing less toxic smoke for up to 19 kW ignition source.

Vapor Intrusion Investigation at a Site in New Jersey: A Field Study

AbstractA vapor intrusion investigation was conducted at a New Jersey site contaminated with tetrachloroethene (PCE) and trichloroethene (TCE). Several residential and commercial buildings are nearby and may be impacted, including a middle school, a learning center, and a church. Groundwater water samples were collected from the site and analyzed for volatile organic compounds (VOCs). Based on the results of the groundwater samples, subslab soil gas and indoor samples were collected from the buildings located in the area surrounding the site and analyzed for VOCs by using the U.S. Environmental Protection Agency Method TO-15. The analytical data were compared against background ambient air data and the soil gas and indoor air data were compared against New Jersey state screening levels. Both PCE and TCE were found above screening levels in groundwater and subslab soil gas samples. It is recommended that further groundwater and vapor intrusion investigations be performed at the nearby buildings and an appr...

Determination of Volatile Organic Compounds in Air by GC/MS: Italian Proficiency Tests

Three national proficiency scheme rounds on the analysis of volatile organic compounds (VOCs) in air have been organized; the first between April and June 2007, the second between May and July 2008, and the third between April and June 2010. A group of about 10 Italian laboratories used the U.S. Environmental Protection Agency Method TO-15 for the determination of VOCs in air collected in canisters. A canister containing a VOC mixture, prepared by dynamic dilution from certified reference materials, was shipped to each participating laboratory; VOC concentrations were between 2 and 50 parts per billion by volume. Homogeneity of the samples prepared was tested and considered adequate according to ISO 13528:2005(E); stability was also checked. The canisters were analyzed by the laboratories within 30 days by GC/MS. The data were analyzed by robust statistics. Good accordance among laboratory results was obtained.

Applications of Hadamard transform-gas chromatography/mass spectrometry for the detection of hexamethyldisiloxane in a wafer cleanroom

The Hadamard transform-gas chromatography/mass spectrometry (HT-GC/MS) technique was successfully employed for the detection of hexamethyldisiloxane (HMDSO, C(6)H(18)OSi(2)) at the sub-nL/L level in a semiconductor wafer cleanroom. Indoor air samples were collected from the room, according to EPA Method TO-17 using a Tedlar bag where the air samples were allowed to pass through an absorption tube for 24 h. The condensed components were then heated and simultaneously injected into a GC column through a Hadamard-injector, which was operated in accordance with the Hadamard codes. Compared to the single injection used in most GC/MS systems, the signal-to-noise (S/N) ratios were substantially improved after the inverse Hadamard transformation of the encoded chromatogram. Under optimized conditions, when cyclic S-matrix orders of 255, 1023 and 2047 were used, the S/N ratios of the HMDSO signals were substantially improved by 7.4-, 15.1- and 20.1-fold, respectively. These improvements are in good agreement with theoretically calculated values (8.0-, 16.0- and 22.6-fold, respectively). We found that when the HT-GC/MS technique was applied, HMDSO could be detected at the 0.1 nL/L level.

Source apportionment of benzene downwind of a major point source

In the United States, the Emergency Planning and Community Right–to–Know Act requires sources that emit more than their Threshold Planning Quantity (TPQ) must publically report their total annual emissions. Because these values are aggregated over an entire year, high total emissions are often reported in the toxic release inventory. The Akwesasne Mohawk Reservation in rural Northern New York State lies downwind of an industrial source that reported annual benzene emissions of approximately 29 000 pounds. To assess if these emissions contributed significantly to the ambient concentrations, 24 hour canister samples were collected every 6th day from May 30 2007 to July 12 2008 at 9 locations on the Reservation. The samples were analyzed for benzene, toluene, ethyl benzene, and xylenes (BTEX) by GC/FID/MS using EPA Method TO15 procedures. In addition, gasoline samples (6 regular unleaded, 2 midgrade unleaded and 2 super unleaded) were collected in December 2007, May 2008 and July 2008 from five gas stations. The concentrations of BTEX in each gasoline sample were determined by headspace analysis. Vehicle tailpipe sampling was conducted by directly collecting samples from the tailpipe into Tedlar bags on 5 days: March 26, 2008, April 24, 2008, May 8, 2008, May 29, 2008 and June 12, 2008. Three samples were collected from each of the 22 vehicles that were fueled with unleaded regular gasoline from the reservation. Using these measured source profiles and ambient concentrations, the Chemical Mass Balance model was applied to each sample to assess the source contributions of BTEX. The results show that the predominant benzene source is vehicular exhaust with a small contribution from gasoline volatilization. The industrial plant has little or no impact on the ambient benzene concentrations in this community.

Health risk assessment of BTEX emissions in the landfill environment

This study focuses on a health risk assessment related to benzene, toluene, ethylbenzene, and m,p,o-xylene (xylenes) (BTEX) exposure via inhalation for workers at a landfill (LF) site. First, the landfill gas (LFG) samples were collected and analyzed accordance with US EPA method TO-17. The mean concentrations of benzene, toluene, ethylbenzene, and xylenes were determined as 140.3, 1271.7, 239.9, and 341.3 μg/m 3, respectively. Then, a risk assessment methodology was employed to evaluate the potential adverse health effects of the individual BTEX compounds according to their carcinogenicities. The corresponding mean cancer risk for benzene was estimated to be 6.75E−05 that is lower than the designated acceptable risk level of 1.0E−04. With respect to mean non-carcinogenic risks for toluene, ethylbenzene, and xylenes, both individually and cumulatively, they were lower than the specified level of 1.0. These findings reveal that landfill BTEX emissions do not pose a health threat to workers at the landfill site. In addition, as far as the risks are concerned for the population in the neighborhood area of the landfill, air dilution of BTEX emitted from LF site is widely sufficient to guarantee their protection.