Ruptured Left Cornual Ectopic Pregnancy: A Case Report.

Cornual ectopic pregnancies are rare with a mortality rate that is significantly higher than that of other ectopic pregnancy types. Due to the cornual region's location on the fallopian tube, rupture of a cornual gestation may lead to massive maternal hemorrhage resulting in hypovolemia and shock. Here, we report a 39-year-old female who presented to Hospital Corporation of America (HCA) Florida Healthcare's emergency department (ED) in a state of hypovolemic shock. She was six weeks pregnant based on an unknown and unsure last menstrual cycle. The diagnosis of a ruptured ectopic pregnancy was suspected based on a positive urine pregnancy test and a pelvic ultrasound that revealed an empty uterus and a copious amount of free fluid within the abdomen. Significant hematoperitoneum and hemodynamic instability required emergent exploratory laparotomy with findings of a ruptured left cornual ectopic pregnancy. A left cornual resection and repair was done with an uneventful postoperative period. With cornual ectopic pregnancies being a rare entity, our case emphasizes the importance of early detection and management to help prevent fatal complications.

Should more patients be offered repair for mitral valve endocarditis? a single-centre 15-year experience.

OBJECTIVE: To describe the long-term outcomes of mitral valve repair (MVr) versus mitral valve replacement (MVR) in patients with native valve infective endocarditis (IE) at a centre with high-repair rates. METHODS: We conducted a retrospective single-centre cohort study. From 2005 to 2021, 183 patients with active or healed native valve IE were included. The primary outcome was long-term mortality. Patient status was last confirmed 31 March 2021. Secondary outcomes were post-operative MR, MV reoperation, length of post-operative intensive care stay and total hospital stay. RESULTS: 85 patients (46.4%) underwent MVr and 98 (53.6%) underwent MVR. Follow-up was 98.9% complete. Mean follow-up time was 5.3 years with 17% of patients reaching a follow-up time of over 10 years. There were 47 deaths (25.7%) within the follow-up period. MVR patients were more likely to have higher logistic EuroSCORE, active IE and were less likely to have elective surgery. In multivariate Cox proportional hazards analysis, there was no significant difference in long-term mortality between MVr and MVR groups (hazard ratio 1.09, 95% confidence interval [0.59-2.00]). In Kaplan-Meier analysis, MVR patients had a higher all-cause mortality although there was no significant difference at the endpoint. Propensity score matching analysis showed a significantly higher mortality in the replacement group instead (p = 0.002), Subgroup analysis revealed there remained no significant difference in mortality even in patients with active IE (P-interaction = 0.859) or non-elective surgery (P-interaction = 0.122). MV reoperation (odds ratio 1.00 [0.24-4.12]), post-operative intensive care stay (p = 0.9650) and total hospital stay (p = 0.9144) were comparable. CONCLUSIONS: Our data demonstrates repair was at least non-inferior to replacement in IE, supporting more aggressive use of repair. There is no reason the general principle of why repair is superior to replacement should not hold in IE, with enough operator expertise. Other experienced units should be encouraged to increase repair rates as feasible in line with current guidelines.

Fifteen-minute consultation: A structured approach to a child with primary spontaneous pneumothorax.

Primary spontaneous pneumothorax (PSP) is an uncommon presentation in children but may occur at any age and occurs in patients with no pre-existing lung disease. Management aims are to re-expand the collapsed lung, relieve pressure in the intrapleural space and avoid a tension pneumothorax. Correct management of PSP will avoid unnecessary intervention, reduce length of hospital stay and also reduce the risk of recurrence. There are no established guidelines for treating PSP in children and there is significant variation in management among centres and clinicians. This article provides a clear, evidence-based and structured approach to assessment and management of PSP in children and young people.

Management of pneumothorax in mechanically ventilated COVID-19 patients: early experience.

A significant proportion of patients infected with the novel coronavirus, now termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), require intensive care admission and subsequent mechanical ventilation. Pneumothorax, a potential fatal complication of mechanical ventilation, can further complicate the management of COVID-19 patients, whilst chest drain insertion may increase the risk of transmission of attending staff. We present a case series and a suggested best-practice protocol for how to manage and treat pneumothoraces in COVID-19 patients in an intensive care unit setting.

Spatial analysis of volatile organic compounds using passive samplers in the Rubbertown industrial area of Louisville, Kentucky, USA.

Select volatile organic compounds (VOCs) were measured in the vicinity of chemical facilities and other operations in the Rubbertown industrial area of Louisville, Kentucky (USA) using modified EPA Methods 325A/B passive sampler tubes. Two-week, time-integrated passive samplers were deployed at ten sites which were aggregated into three site groups of varying distances from the Rubbertown area facilities. In comparison to canister data from 2001 to 2005, two of the sites suggested generally lower current VOC levels. Good precision was obtained from the duplicate tubes (≤ 12%) for benzene, toluene, ethylbenzene, and xylene isomers (BTEX), styrene, 1,3-butadiene, perchloroethylene, and other trace VOCs. BTEX, styrene, and 1,3-butadiene concentrations were statistically significantly higher at two site groups near Rubbertown sources than the site group farther away. As found in a similar study in South Philadelphia, BTEX concentrations were also lower for sites farther from a source, though the decline was less pronounced on a percentage basis in Rubbertown. These results suggest that EPA Methods 325A/B can be useful to assess VOC gradients for emissions from chemical facilities besides fenceline benzene levels from refineries.

Dataset of polycyclic aromatic hydrocarbon recoveries from a selection of sorbent tubes for thermal desorption-gas chromatography/mass spectrometry analysis.

This dataset contains raw area counts and percent recoveries of polycyclic aromatic hydrocarbon (PAH) standards desorbed from selected sorbent tubes and analyzed using thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). The results of this study were published in the article "Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry" in Journal of Chromatography A [1]. The sorbent tubes studied include stainless steel Carbograph 2TD/1TD, glass quartz wool-Carbograph 2TD, inert-coated stainless steel Carbograph 2TD, glass and stainless steel Tenax TA, PAH (chemical weapons), and glass and stainless steel XRO-440 sorbent tubes. Tables listing the experimental conditions, TD methods, and types of sorbent tubes are included in the manuscript. Data for experiments, including the investigation of incomplete desorption of PAHs from Carbograph 2TD/1TD and XRO-440 sorbent tubes, the comparison of PAH recoveries from three different TD methods, the analysis of PAH breakthrough from sorbent tubes, the investigation of the effect of heat on PAH percent recovery from sorbent tubes, and the formation of reaction products during PAH loading and desorption are included in Appendix A. These data can be used to guide sorbent tube selection for PAH analyses in future studies.

Rubbertown Next Generation Emissions Measurement Demonstration Project.

Industrial facilities and other sources can emit air pollutants from fugitive leaks, process malfunctions and area sources that can be difficult to understand and to manage. Next generation emissions measurement (NGEM) approaches executed near facilities are enabling new ways to assess these sources and their impacts to nearby populations. This paper describes complementary uses of emerging NGEM systems in a Louisville, KY industrial district (Rubbertown), focusing on an important area air toxic, 1,3-butadiene. Over a one-year deployment starting in September 2017, two-week average passive samplers (PSs) at 11 sites showed both geospatial and temporal trends. At 0.24 ppbv annual average 1,3-butadiene concentration, a group of PSs located near facility fence lines was elevated compared to a PS group located in the community and upwind from facilities (0.07 ppbv average). Two elevated PS periods capturing emission events were examined using time-resolved NGEM approaches as case studies. In one event a 1.18 ppbv PS reading was found to be relatively localized and was caused by a multiday emission from a yet to be identified, non-facility source. In the other event, the airshed was more broadly impacted with PS concentrations ranging from 0.71 ppbv for the near-facility group to 0.46 ppbv for the community group. This case was likely influenced by a known emission event at an industrial facility. For both case studies, air pollutant and wind data from prototype NGEM systems were combined with source location models to inform the emission events. This research illustrates the power of applying NGEM approaches to improve both the understanding of emissions near sources and knowledge of impacts to near-source communities.

Recovery and reactivity of polycyclic aromatic hydrocarbons collected on selected sorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry.

This article describes the optimization of methodology for extending the measurement of volatile organic compounds (VOCs) to increasingly heavier polycyclic aromatic hydrocarbons (PAHs) with a detailed focus on recent sorbent tube technology. Although PAHs have lower volatility than compounds such as benzene, toluene, ethylbenzene and xylenes, these semi-volatile compounds can be detected in air and breath samples. For this work, PAHs were captured on sorbent tubes and subsequently analyzed using automated thermal desorption gas chromatography - mass spectrometry (ATD-GC/MS). While many different sorbent tubes are commercially available, optimization for airborne PAH sampling using sorbent tubes has not been previously considered. Herein, several commercially available sorbent tubes, including Carbograph 2 TD/1TD, Tenax TA, XRO-440, and inert-coated PAH tubes are compared to determine the relative recovery for eight PAHs commonly found in the environment. Certain types of sorbent materials were found to be better suited for PAH recovery during thermal desorption, and PAH reaction products were observed on several types of sorbent tubes, including graphitized carbon black sorbents with stainless steel tube materials. As such, selection of sorbent tube media should be carefully considered prior to embarking on a PAH study.

Targeted GC-MS analysis of firefighters' exhaled breath: Exploring biomarker response at the individual level.

Biomarker measurements can provide unambiguous evidence of environmental exposures as well as the resultant biological responses. Firefighters have a high rate of occupational cancer incidence, which has been proposed to be linked in part to their increased environmental exposure to byproducts of combustion and contaminants produced during fire responses. In this article, the uptake and elimination of targeted volatile organic compounds were investigated by collecting the exhaled breath of firefighters on sorbent tubes before and after controlled structure burns and analyzing samples using automated thermal desorption-gas chromatography (ATD-GC/MS). Volatile organic compounds exposure was assessed by grouping the data according to firefighting job positions as well as visualizing the data at the level of the individual firefighter to determine which individuals had expected exposure responses. When data were assessed at the group level, benzene concentrations were found to be elevated post-exposure in both fire attack, victim search, and outside ventilation firefighting positions. However, the results of the data analysis at the individual level indicate that certain firefighters may be more susceptible to post-exposure volatile organic compounds increases than others, and this should be considered when assessing the effectiveness of firefighting protective gear. Although this work focuses on firefighting activity, the results can be translated to potential human health and ecological effects from building and forest fires.

Particulate matter, nitrogen oxides, ozone, and select volatile organic compounds during a winter sampling period in Logan, Utah, USA.

Particulate matter mass (PM), trace gaseous pollutants, and select volatile organic compounds (VOCs) with meteorological variables were measured in Logan, Utah (Cache Valley), for >4 weeks during winter 2017 as part of the Utah Winter Fine Particle Study (UWFPS). Higher PM levels for short time periods and lower ozone (O3) levels were present due to meteorological and mountain valley conditions. Nitrogenous pollutants were relatively strongly correlated with PM variables. Diurnal cycles of NOx, O3, and fine PM(PM 2.5) (aerodynamic diameter <2.5 µm [PM2.5]) suggested formation from NOx. O3 levels increased from early morning into midafternoon, and NOx and PM2.5 increased throughout the morning, followed by sharp decreases. Toluene/benzene and xylenes/benzene ratios and VOC correlations with nitrogenous and PM species were indicative of local traffic sources. Wind sector comparisons suggested that pollutant levels were lower when winds were from nearby mountains to the east versus winds from northerly or southerly origins. Implications: The Cache Valley in Idaho and Utah has been designated a PM2.5 nonattainment area that has been attributed to air pollution buildup during winter stagnation events. To inform state implementation plans for PM2.5 in Cache Valley and other PM2.5 nonattainment areas in Utah, a state and multiagency federal research effort known as the UWFPS was conducted in winter 2017. As part of the UWFPS, the U.S. Environmental Protection Agency (EPA) measured ground-based PM species and their precursors, VOCs, and meteorology in Logan, Utah. Results reported here from the EPA study in Logan provide additional understanding of wintertime air pollution conditions and possible sources of PM and gaseous pollutants as well as being useful for future PM control strategies in this area.

Non-targeted GC/MS analysis of exhaled breath samples: Exploring human biomarkers of exogenous exposure and endogenous response from professional firefighting activity.

A non-targeted analysis workflow was applied to analyze exhaled breath samples collected from firefighters pre- and post-structural fire suppression. Breath samples from firefighters functioning in attack and search positions were examined for target and non-target compounds in automated thermal desorption-GC/MS (ATD-GC/MS) selected ion monitoring (SIM)/scan mode and reviewed for prominent chemicals. Targeted chemicals included products of combustion such as benzene, toluene, xylenes, and polycyclic aromatic hydrocarbons (PAH) that serve as a standard assessment of exposure. Sixty unique chemical features representative of exogenous chemicals and endogenous compounds, including single-ring aromatics, polynuclear aromatic hydrocarbons, volatile sulfur-containing compounds, aldehydes, alkanes, and alkenes were identified using the non-targeted analysis workflow. Fifty-seven out of 60 non-targeted features changed by at least 50% from pre- to post-fire suppression activity in at least one subject, and 7 non-targeted features were found to exhibit significantly increased or decreased concentrations for all subjects as a group. This study is important for (1) alerting the firefighter community to potential new exposures, (2) expanding the current targeted list of toxicants, and (3) finding biomarkers of response to firefighting activity as reflected by changes in endogenous compounds. Data demonstrate that there are non-targeted compounds in firefighters' breath that are indicative of environmental exposure despite the use of protective gear, and this information may be further utilized to improve the effectiveness of personal protective equipment.

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

Select 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.

Calibration and performance of synchronous SIM/scan mode for simultaneous targeted and discovery (non-targeted) analysis of exhaled breath samples from firefighters.

Traditionally, gas chromatography-mass spectrometry (GC/MS) analysis has used a targeted approach called selected ion monitoring (SIM) to quantify specific compounds that may have adverse health effects. Due to method limitations and the constraints of preparing duplicate samples, the information that could be obtained from separately collecting the full scan chromatogram of the sample has often been sacrificed. However, the hybrid technique called synchronous SIM/scan mode alternates between the two acquisition modes, maintaining the accuracy and sensitivity of SIM for targeted analysis while also providing the full scan chromatogram for discovery of non-target compounds. This technology was assessed using calibration data and real-world breath samples from a joint EPA/NIOSH collaboration that investigated the safety of firefighters' protective gear during controlled structure burns. Collecting field samples is costly and must be performed strategically to ensure that time points and replicates are accurate and representative of the intended population. This is difficult to accomplish with firefighters who are working under volatile conditions. The synchronous SIM/scan method decreases the number of field samples that need to be collected by half and reduces error in trying to recreate time points since a breath sample from a single sorbent tube can be used to collect both the SIM and scan data simultaneously. As a practical demonstration of the method, we investigate thirty-six firefighter breath samples, document organic compounds of interest, and identify additional non-target compounds.

Inception of the 'endocarditis team' is associated with improved survival in patients with infective endocarditis who are managed medically: findings from a before-and-after study.

Objective: Despite improvements in its management, infective endocarditis (IE) is associated with poor survival. The aim of this study was to evaluate the impact of a multidisciplinary endocarditis team (ET), including a cardiologist, microbiologist and a cardiac surgeon, on the outcome of patients with acute IE according to medical or surgical treatment strategies. Methods: We conducted an observational before-and-after study of 196 consecutive patients with definite IE, who were treated at a tertiary reference centre between 2009 and 2015. The study was divided into two periods: period 1, before the formation of the ET (n=101), and period 2, after the formation of the ET (n=95). The role of the ET included regular multidisciplinary team meetings to confirm diagnosis, inform the type and duration of antibiotic therapy and recommend early surgery, when indicated, according to European guidelines. Results: The patient demographics and predisposing conditions for IE were comparable between the two study periods. In the time period following the introduction of the ET, there was a reduction in both the time to commencement of IE-specific antibiotic therapy (4.0±4.0 days vs 2.5±3.2 days; P=0.004) and the time from suspected IE to surgery (7.8±7.3 days vs 5.3±4.2 days; P=0.004). A 12-month Kaplan-Meier survival for patients managed medically was 42.9% in the pre-ET period and 66.7% in the post-ET period (P=0.03). The involvement of the ET was a significant independent predictor of 1-year survival in patients managed medically (HR 0.24, 95% CI 0.07 to 0.87; P=0.03). Conclusions: A standardised multidisciplinary team approach may lead to earlier diagnosis of IE, more appropriate individualised management strategies, expedited surgery, where indicated, and improved survival in those patients chosen for medical management, supporting the recent change in guidelines to recommend the use of a multidisciplinary team in the care of patients with IE.

Sample integrity evaluation and EPA method 325B interlaboratory comparison for select volatile organic compounds collected diffusively on Carbopack X sorbent tubes.

A sample integrity evaluation and an interlaboratory comparison were conducted in application of U.S. Environmental Protection Agency (EPA) Methods 325A and 325B for diffusively monitoring benzene and other selected volatile organic compounds (VOCs) using Carbopack X sorbent tubes. To evaluate sample integrity, VOC samples were refrigerated for up to 240 days and analyzed using thermal desorption/gas chromatography-mass spectrometry at the EPA Office of Research and Development laboratory in Research Triangle Park, NC, USA. For the interlaboratory comparison, three commercial analytical laboratories were asked to follow Method 325B when analyzing samples of VOCs that were collected in field and laboratory settings for EPA studies. Overall results indicate that the selected VOCs collected diffusively on sorbent tubes generally were stable for 6 months or longer when samples were refrigerated. This suggests the specified maximum 30-day storage time of VOCs collected diffusively on Carbopack X passive samplers and analyzed using Method 325B might be able to be relaxed. Interlaboratory comparison results were in agreement for the challenge samples collected diffusively in an exposure chamber in the laboratory, with most measurements within ±25% of the theoretical concentration. Statistically significant differences among laboratories for ambient challenge samples were small, less than 1 part per billion by volume (ppbv). Results from all laboratories exhibited good precision and generally agreed well with each other.

South Philadelphia passive sampler and sensor study.

UNLABELLED: From June 2013 to March 2015, in total 41 passive sampler deployments of 2 wk duration each were conducted at 17 sites in South Philadelphia, PA, with results for benzene discussed here. Complementary time-resolved measurements with lower cost prototype fenceline sensors and an open-path ultraviolet differential optical absorption spectrometer were also conducted. Minimum passive sampler benzene concentrations for each sampling period ranged from 0.08 ppbv to 0.65 ppbv, with a mean of 0.25 ppbv, and were negatively correlated with ambient temperature (-0.01 ppbv/°C, R(2) = 0.68). Co-deployed duplicate passive sampler pairs (N = 609) demonstrated good precision with an average and maximum percent difference of 1.5% and 34%, respectively. A group of passive samplers located within 50 m of a refinery fenceline had a study mean benzene concentration of 1.22 ppbv, whereas a group of samplers located in communities >1 km distant from facilities had a mean of 0.29 ppbv. The difference in the means of these groups was statistically significant at the 95% confidence level (p < 0.001). A decreasing gradient in benzene concentrations moving away from the facilities was observed, as was a significant period-to-period variation. The highest recorded 2-wk average benzene concentration for the fenceline group was 3.11 ppbv. During this period, time-resolved data from the prototype sensors and the open-path spectrometer detected a benzene signal from the west on one day in particular, with the highest 5-min path-averaged benzene concentration measured at 24 ppbv. IMPLICATIONS: Using a variation of EPA's passive sampler refinery fenceline monitoring method, coupled with time-resolved measurements, a multiyear study in South Philadelphia informed benzene concentrations near facilities and in communities. The combination of measurement strategies can assist facilities in identification and mitigation of emissions from fugitive sources and improve information on air quality complex air sheds.

In patients with acute flail chest does surgical rib fixation improve outcomes in terms of morbidity and mortality?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was: In patients with acute flail chest does surgical rib fixation improve outcomes in terms of morbidity and mortality? Using the reported search criteria, 137 papers were found. Of these, 11 papers (N = 1712) represent the best evidence to answer the clinical question, and include one meta-analysis, two randomized, controlled trials (RCTs), five retrospective cohort studies and two case-control series. In-hospital mortality was lower for the surgical group in the meta-analysis [n = 582, odds ratio (OR) 0.31 (0.20-0.48), risk difference (RD) 0.19 (0.13-0.26), number needed to treat (NNT) 5] as well as significant decreases in ventilator days [mean 8 days, 95% confidence interval (CI) 5-10 days] and intensive care unit stay (mean 5 days, 95% CI 2-8 days). A reduction was found for septicaemia [n = 345, OR 0.36 (0.19-0.71), RD 0.14 (0.56-0.23), NNT 7], pneumonia [n = 616, OR 0.18 (0.11-0.32), RD 0.31 (0.21-0.41), NNT 3, P = 0.001], tracheostomy (OR 0.06, 95% CI 0.02-0.20) and chest wall deformity [n = 228, OR 0.11 (0.02-0.60), RD 0.30 (0.00-0.60), NNT 3]. Eight studies (n = 1015) had a shorter duration of mechanical ventilation following surgery. A reduction in intensive care unit stay was demonstrated in four papers (n = 389, 3.1-9.0 days), whereas a further three papers described a reduction in the duration of hospitalization (n = 489, 4-10.6 days). Three studies (n = 166) showed a lower risk for tracheostomy. One retrospective cohort study estimated lower total treatment costs in surgically treated patients ($32 300 vs $37 100) although not statistically significant. One retrospective case-control study described a lower risk for reintubation (n = 50, P = 0.034) and home oxygen requirements (n = 50, P = 0.034). One cohort study showed a better APACHE II score 14 days after trauma in the surgical group (P = 0.02). Surgical stabilization of flail chest in thoracic trauma patients has beneficial effects with respect to reduced ventilatory support, shorter intensive care and hospital stay, reduced incidence of pneumonia and septicaemia, decreased risk of chest deformity and an overall reduced mortality when compared with patients who received non-operative management.

Spatial analysis of volatile organic compounds in South Philadelphia using passive samplers.

UNLABELLED: Select volatile organic compounds (VOCs) were measured in the vicinity of a petroleum refinery and related operations in South Philadelphia, Pennsylvania, USA, using passive air sampling and laboratory analysis methods. Two-week, time-integrated samplers were deployed at 17 sites, which were aggregated into five site groups of varying distances from the refinery. Benzene, toluene, ethylbenzene, and xylene isomers (BTEX) and styrene concentrations were higher near the refinery's fenceline than for groups at the refinery's south edge, mid-distance, and farther removed locations. The near fenceline group was significantly higher than the refinery's north edge group for benzene and toluene but not for ethylbenzene or xylene isomers; styrene was lower at the near fenceline group versus the north edge group. For BTEX and styrene, the magnitude of estimated differences generally increased when proceeding through groups ever farther away from the petroleum refining. Perchloroethylene results were not suggestive of an influence from refining. These results suggest that emissions from the refinery complex contribute to higher concentrations of BTEX species and styrene in the vicinity of the plant, with this influence declining as distance from the petroleum refining increases. IMPLICATIONS: Passive sampling methodology for VOCs as discussed here is employed in recently enacted U.S. Environmental Protection Agency Methods 325A/B for determination of benzene concentrations at refinery fenceline locations. Spatial gradients of VOC concentration near the refinery fenceline were discerned in an area containing traffic and other VOC-related sources. Though limited, these findings can be useful in application of the method at such facilities to ascertain source influence.

Volatile organic compounds at two oil and natural gas production well pads in Colorado and Texas using passive samplers.

UNLABELLED: A pilot study was conducted in application of the U.S. Environmental Protection Agency (EPA) Methods 325A/B variant for monitoring volatile organic compounds (VOCs) near two oil and natural gas (ONG) production well pads in the Texas Barnett Shale formation and Colorado Denver-Julesburg Basin (DJB), along with a traffic-dominated site in downtown Denver, CO. As indicated in the EPA method, VOC concentrations were measured for 14-day sampling periods using passive-diffusive tube samplers with Carbopack X sorbent at fenceline perimeter and other locations. VOCs were significantly higher at the DJB well pad versus the Barnett well pad and were likely due to higher production levels at the DJB well pad during the study. Benzene and toluene were significantly higher at the DJB well pad versus downtown Denver. Except for perchloroethylene, VOCs measured at passive sampler locations (PSs) along the perimeter of the Barnett well pad were significantly higher than PSs farther away. At the DJB well pad, most VOC concentrations, except perchloroethylene, were significantly higher prior to operational changes than after these changes were made. Though limited, the results suggest passive samplers are precise (duplicate precision usually ≤10%) and that they can be useful to assess spatial gradients and operational conditions at well pad locations over time-integrated periods. IMPLICATIONS: Recently enacted EPA Methods 325A/B use passive-diffusive tube samplers to measure benzene at multiple fenceline locations at petrochemical refineries. This pilot study presents initial data demonstrating the utility of Methods 325A/B for monitoring at ONG facilities. Measurements revealed elevated concentrations reflective of production levels and spatial gradients of VOCs relative to source proximity at the Barnett well pad, as well as operational changes at the DJB well pad. Though limited, these findings indicate that Methods 325A/B can be useful in application to characterize VOCs at well pad boundaries.