Secondary Organic Aerosol Formation from Volatile Chemical Product Emissions: Model Parameters and Contributions to Anthropogenic Aerosol

Volatile chemical products (VCP) are an increasingly important source of hydrocarbon and oxygenated volatile organic compound (OVOC) emissions to the atmosphere, and these emissions are likely to play an important role as anthropogenic precursors for secondary organic aerosol (SOA). While the SOA from VCP hydrocarbons is often accounted for in models, the formation, evolution, and properties of SOA from VCP OVOCs remain uncertain. We use environmental chamber data and a kinetic model to develop SOA parameters for 10 OVOCs representing glycols, glycol ethers, esters, oxygenated aromatics, and amines. Model simulations suggest that the SOA mass yields for these OVOCs are of the same magnitude as widely studied SOA precursors (e.g., long-chain alkanes, monoterpenes, and single-ring aromatics), and these yields exhibit a linear correlation with the carbon number of the precursor. When combined with emissions inventories for two megacities in the United States (US) and a US-wide inventory, we find that VCP VOCs react with OH to form 0.8-2.5× as much SOA, by mass, as mobile sources. Hydrocarbons (terpenes, branched and cyclic alkanes) and OVOCs (terpenoids, glycols, glycol ethers) make up 60-75 and 25-40% of the SOA arising from VCP use, respectively. This work contributes to the growing body of knowledge focused on studying VCP VOC contributions to urban air pollution.

Comprehensive analysis of the air quality impacts of switching a marine vessel from diesel fuel to natural gas

New environmental regulations are mandating cleaner fuels and lower emissions from all maritime operations. Natural gas (NG) is a fuel that enables mariners to meet regulations; however, emissions data from maritime operations with natural gas is limited. We measured emissions of criteria, toxic and greenhouse pollutants from a dual-fuel marine engine running either on diesel fuel or NG as well as engine activity and analyzed the impacts on pollutants, health, and climate change. Results showed that particulate matter (PM), black carbon (BC), nitric oxides (NO_x), and carbon dioxide (CO₂) were reduced by about 93%, 97%, 92%, and 18%, respectively when switching from diesel to NG. Reductions of this magnitude provide a valuable tool for the many port communities struggling with meeting air quality standards. While these pollutants were reduced, formaldehyde (HCHO), carbon monoxide (CO) and methane (CH₄) increased several-fold. A health risk assessment of exhaust plume focused on when the vessel was stationary, and at-berth showed the diesel plume increased long-term health risk and the NG plume increased short-term health risk. An analysis of greenhouse gases (GHGs) and BC was performed and revealed that, on a hundred year basis, the whole fuel cycle global warming potential (GWP) per kWh including well-to-tank and exhaust was 50% to few times higher than that of diesel at lower engine loads, but that it was similar at 75% load and lower at higher loads. Mitigation strategies for further reducing pollutants from NG exhaust are discussed and showed potential for reducing short-term health risks and climate impacts.

Development of a Network of Accurate Ozone Sensing Nodes for Parallel Monitoring in a Site Relocation Study

Recent technological advances in both air sensing technology and Internet of Things (IoT) connectivity have enabled the development and deployment of remote monitoring networks of air quality sensors. The compact size and low power requirements of both sensors and IoT data loggers allow for the development of remote sensing nodes with power and connectivity versatility. With these technological advancements, sensor networks can be developed and deployed for various ambient air monitoring applications. This paper describes the development and deployment of a monitoring network of accurate ozone (O₃) sensor nodes to provide parallel monitoring in an air monitoring site relocation study. The reference O₃ analyzer at the station along with a network of three O₃ sensing nodes was used to evaluate the spatial and temporal variability of O₃ across four Southern California communities in the San Bernardino Mountains which are currently represented by a single reference station in Crestline, CA. The motivation for developing and deploying the sensor network in the region was that the single reference station potentially needed to be relocated due to uncertainty that the lease agreement would be renewed. With the implication of siting a new reference station that is also a high O₃ site, the project required the development of an accurate and precise sensing node for establishing a parallel monitoring network at potential relocation sites. The deployment methodology included a pre-deployment co-location calibration to the reference analyzer at the air monitoring station with post-deployment co-location results indicating a mean absolute error (MAE) < 2 ppb for 1-h mean O₃ concentrations. Ordinary least squares regression statistics between reference and sensor nodes during post-deployment co-location testing indicate that the nodes are accurate and highly correlated to reference instrumentation with R² values > 0.98, slope offsets < 0.02, and intercept offsets < 0.6 for hourly O₃ concentrations with a mean concentration value of 39.7 ± 16.5 ppb and a maximum 1-h value of 94 ppb. Spatial variability for diurnal O₃ trends was found between locations within 5 km of each other with spatial variability between sites more pronounced during nighttime hours. The parallel monitoring was successful in providing the data to develop a relocation strategy with only one relocation site providing a 95% confidence that concentrations would be higher there than at the current site.

Physical, chemical, and toxicological characteristics of particulate emissions from current technology gasoline direct injection vehicles

We assessed the physical, chemical and toxicological characteristics of particulate emissions from four light-duty gasoline direct injection vehicles when operated over the LA92 driving cycle. Our results showed that particle mass and number emissions increased markedly during accelerations. For three of the four vehicles tested, particulate matter (PM) mass and particle number emissions were markedly higher during cold-start and the first few accelerations following the cold-start period than during the hot running and hot-start segments of the LA92 cycle. For one vehicle (which had the highest emissions overall) the hot-start and cold-start PM emissions were similar. Black carbon emissions were also much higher during the cold-start conditions, indicating severe fuel wetting leading to slow evaporation and pool burning, and subsequent soot formation. Particle number concentrations and black carbon emissions showed large reductions during the urban and hot-start phases of the test cycle. The oxidative potential of PM was quantified with both a chemical and a biological assay, and the gene expression impacts of the PM in a macrophage model with PCR (polymerase chain reaction) and ELISA (enzyme-linked immunosorbent assay) analyses. Inter- and intra-vehicle variability in oxidative potential per milligram of PM emitted was relatively low for both oxidative assays, suggesting that real-world emissions and exposure can be estimated with distance-normalized emission factors. The PCR response from signaling markers for oxidative stress (e.g., NOX1) was greater than from inflammatory, AhR (aryl hydrocarbon receptor), or MAPK (mitogen-activated protein kinase) signaling. Protein production associated with inflammation (tumor necrosis factor alpha-TNFα) and oxidative stress (HMOX-1) were quantified and displayed relatively high inter-vehicle variability, suggesting that these pathways may be activated by different PM components. Correlation of trace metal concentrations and oxidative potential suggests a role for small, insoluble particles in inducing oxidative stress.

Characterizing emission rates of regulated pollutants from model year 2012+ heavy-duty diesel vehicles equipped with DPF and SCR systems

The regulated emissions of five 2012 and newer, low-mileage, heavy-duty Class 8 diesel trucks equipped with diesel particulate filters (DPFs) and selective catalytic reduction (SCR) systems were evaluated over test cycles representing urban, highway, and stop-and-go driving on a chassis dynamometer. NOx emissions over the Urban Dynamometer Driving Schedule (UDDS) ranged from 0.495 to 1.363g/mi (0.136 to 0.387g/bhp-hr) for four of the normal emitting trucks. For those trucks, NOx emissions were lowest over the cruise (0.068 to 0.471g/mi) and high-speed cruise (0.067 to 0.249g/mi) cycles, and highest for the creep cycle (2.131 to 9.468g/mi). A fifth truck showed an anomaly in that it had never regenerated throughout its relatively short operating lifetime due to its unusual, unladed service history. This truck exhibited NOx emissions of 3.519g/mi initially over the UDDS, with UDDS NOx emissions decreasing to 0.39g/mi after a series of parked regenerations. PM, THC, and CO emissions were found to be very low for most of the testing conditions, due to the presence of the DPF/SCR aftertreatment system, and were comparable to background levels in some cases.

Continuous Inhalation Exposure to Fungal Allergen Particulates Induces Lung Inflammation While Reducing Innate Immune Molecule Expression in the Brainstem

Continuous exposure to aerosolized fine (particle size ≤2.5 µm) and ultrafine (particle size ≤0.1 µm) particulates can trigger innate inflammatory responses in the lung and brain depending on particle composition. Most studies of manmade toxicants use inhalation exposure routes, whereas most studies of allergens use soluble solutions administered via intranasal or injection routes. Here, we tested whether continuous inhalation exposure to aerosolized Alternaria alternata particulates (a common fungal allergen associated with asthma) would induce innate inflammatory responses in the lung and brain. By designing a new environmental chamber able to control particle size distribution and mass concentration, we continuously exposed adult mice to aerosolized ultrafine Alternaria particulates for 96 hr. Despite induction of innate immune responses in the lung, induction of innate immune responses in whole brain samples was not detected by quantitative polymerase chain reaction or flow cytometry. However, exposure did trigger decreases in Arginase 1, inducible nitric oxide synthase, and tumor necrosis factor alpha mRNA in the brainstem samples containing the central nervous system respiratory circuit (the dorsal respiratory group, ventral respiratory group, and the pre-Bötzinger and Bötzinger complexes). In addition, a significant decrease in the percentage of Toll-like receptor 2-expressing brainstem microglia was detected by flow cytometry. Histologic analysis revealed a significant decrease in Iba1 but not glial fibrillary acidic protein immunoreactivity in both the brainstem and the hippocampus. Together these data indicate that inhalation exposure to a natural fungal allergen under conditions sufficient to induce lung inflammation surprisingly causes reductions in baseline expression of select innate immune molecules (similar to that observed during endotoxin tolerance) in the region of the central nervous system controlling respiration.

Validation of an oncoplastic breast simulator for assessment of technical skills in wide local excision

Background

Simulation enables safe practice and facilitates objective assessment of technical skills. However, simulation training in breast surgery is rare and assessment remains subjective. The primary aim was to evaluate the construct validity of technical skills assessments in wide local excision (WLE).

Methods

Surgeons of different grades performed a WLE of a 25-mm palpable tumour on an in-house synthetic breast simulator. Procedures were videotaped (blinded), reviewed retrospectively, and independently rated against a procedure-specific global rating scale by two consultant breast surgeons. Specimen radiographs were obtained and the macroscopic distance from the ‘tumour’ edge to the resection margin was recorded in four cardinal directions. Expert consensus was used to construct an Oncoplastic Deviation Score (ODS), assigning points for excessively wide (more than 10 mm) and, conversely, close (less than 5 mm) macroscopic margins.

Results

Thirty-four surgeons (12 consultant surgeons, 12 specialty trainees and 10 core trainees) participated in the study. Video-based rating scores varied hierarchically with operator expertise (P &lt; 0·050). Inter-rater reliability was excellent (α ≥ 0·80, P &lt; 0·050 for all scales), and inter-rater agreement was moderate (κ = 0·132–0·361, P &lt; 0·050 for all scales). Statistically significant differences were observed on pairwise comparisons between each grade of surgeon in scores for ‘exposure’, ‘skin flap development’, ‘glandular remodelling’, ‘skin closure’ and ‘final product review’ (P &lt; 0·050). Consultants received significantly fewer ODS points than specialty trainees (P = 0·012) and core trainees (P = 0·028). Compared with experts (median 9·0 mm), wider margins were observed amongst specialty trainees (median 12·0 mm) and narrower margins amongst core trainees (median 7·1 mm) (P = 0·001).

Conclusion

Video ratings of performance and a proposed ODS differentiate surgeons based on technical skills in WLE and may be useful for objective assessment of breast surgery trainees.

Abstract P2-18-18: Improving training in breast surgical oncology: The development and preliminary validation of a simulator for wide local excision

Background

Simulation training has the potential to increase resident confidence in basic procedural tasks prior to operating room (OR) refinements, offsets a reduction in mentoring opportunities, avoids the use of patients for skills practice, and facilitates objective assessment of technical skills. Despite a multitude of benefits, adoption of simulation training and assessment in breast surgical oncology has not been forthcoming.

Aims

To develop and validate a high-fidelity surgical simulator for the practice, training and assessment of technical skills in wide local excision (WLE) of a palpable breast tumour.

Methods

Subjects (attendings and residents with an interest in breast surgery, and novice trainees) were invited to perform a WLE of 25mm palpable breast lesion located 30mm from the nipple areolar complex in the 3o clock position, on a synthetic breast simulator developed at Imperial College London as part of the London Deanery Skills Programme. Procedures were videotaped (blind) and were retrospectively reviewed and independently rated against procedure-specific ratings of performance (VAS 0-100) by two expert breast surgeons (&gt;10 years experience). Specimen radiographs were performed (BioVision, Faxitron, USA) and margin of clearance (mm) were calculated from the edge of the “tumour” to the limits of surrounding breast tissue excised in 4 cardinal directions (i.e. N, S, E W). Specimen weights were recorded (g). Subjects completed a comprehensive questionnaire to determine simulator content and face validity.

Results

21 subjects participated (5 attendings, 13 registrars, and 3 junior trainees). Data was analysed according to experience (high = &gt;100 independent wide local procedures; low = no independent wide local procedures). Statistically significant (p ≤ 0.05) differences in performance were observed between high and low experience surgeons [for each category data are VAS score medians±IQR; ‘exposure’: low = 70.0±50.0, high = 80.0±20.0; ‘skin flap development’: low = 70.0±50.0, high = 80.0±40.0; ‘resection skills’: low = 60.0±55.0, high = 80.0±45.0; ‘glandular remodelling’: low = 70.0±25.0; high = 80.0±50.0, ‘skin closure’: low = 70.0±25.0, high = 90.0±20.0]. Resection margin width and specimen weight (MWU = 52.5, p = 1.0) did not discriminate high-low experience surgeons. The majority of participants believed that training on the model simulated the same steps as a real WLE (94.7%) and was useful for real practice (84.2%).

Discussion

Preliminary data on a WLE simulator suggests that the model is face and construct valid, and may be useful to supplement early stage practice prior to skills development in the OR. Video performance ratings whilst time consuming appear to distinguish high-low experience surgeons better than do specimen weight or radiographic margin width.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-18-18.

JP-8 Jet Fuel Can Promote Auditory Impairment Resulting From Subsequent Noise Exposure in Rats

We report on the transient and persistent effects of JP-8 jet fuel exposure on auditory function in rats. JP-8 has become the standard jet fuel utilized in the United States and North Atlantic Treaty Organization countries for military use and it is closely related to Jet A fuel, which is used in U.S. domestic aviation. Rats received JP-8 fuel (1000 mg/m(3)) by nose-only inhalation for 4 h and half of them were immediately subjected to an octave band of noise ranging between 97 and 105 dB in different experiments. The noise by itself produces a small, but permanent auditory impairment. The current permissible exposure level for JP-8 is 350 mg/m(3). Additionally, a positive control group received only noise exposure, and a fourth group consisted of untreated control subjects. Exposures occurred either on 1 day or repeatedly on 5 successive days. Impairments in auditory function were assessed using distortion product otoacoustic emissions and compound action potential testing. In other rats, tissues were harvested following JP-8 exposure for assessment of hydrocarbon levels or glutathione (GSH) levels. A single JP-8 exposure by itself at 1000 mg/m(3) did not disrupt auditory function. However, exposure to JP-8 and noise produced an additive disruption in outer hair cell function. Repeated 5-day JP-8 exposure at 1000 mg/m(3) for 4 h produced impairment of outer hair cell function that was most evident at the first postexposure assessment time. Partial though not complete recovery was observed over a 4-week postexposure period. The adverse effects of repeated JP-8 exposures on auditory function were inconsistent, but combined treatment with JP-8 + noise yielded greater impairment of auditory function, and hair cell loss than did noise by itself. Qualitative comparison of outer hair cell loss suggests an increase in outer hair cell death among rats treated with JP-8 + noise for 5 days as compared to noise alone. In most instances, hydrocarbon constituents of the fuel were largely eliminated in all tissues by 1-h postexposure with the exception of fat. Finally, JP-8 exposure did result in a significant depletion of total GSH that was observable in liver with a nonsignificant trend toward depletion in the brain and lung raising the possibility that the promotion of noise-induced hearing loss by JP-8 might have resulted from oxidative stress.

Promotion of Noise-Induced Cochlear Injury by Toluene and Ethylbenzene in the Rat

Ethylbenzene + toluene are known individually to have ototoxic potential at high exposure levels and with prolonged exposure times generally of 4-16 weeks. Both ethylbenzene + toluene are minor constituents of JP-8 jet fuel; this fuel has recently been determined to promote susceptibility to noise-induced hearing loss. Therefore, the current study evaluates the ototoxic potential of combined exposure to ethylbenzene + toluene exposure in a ratio calculated from the average found in three laboratories. Rats received ethylbenzene + toluene by inhalation and half of them were subjected simultaneously to an octave band of noise (OBN) of 93-95 dB. Another group received only the noise exposure which was designed to produce a small, but permanent auditory impairment while an unexposed control group was also included. In two separate experiments, exposures occurred either repeatedly on 5 successive days for 1 week or for 5 days on 2 successive weeks to 4000 mg/m(3) total hydrocarbons for 6 h based upon initial pilot studies. The concentration of toluene was 400 ppm and the concentration of ethylbenzene was 660 ppm. Impairments in auditory function were assessed using distortion product otoacoustic emissions and compound action potential testing. Following completion of these tests, the organs of Corti were dissected to permit evaluation of hair cell loss. The uptake and elimination of the solvents was assessed by harvesting key organs at two time points following ethylbenzene + toluene exposure from additional rats not used for auditory testing. Similarly, glutathione (GSH) levels were measured in light of suggestions that oxidative stress might result from solvent-noise exposures. Ethylbenzene + toluene exposure by itself at 4000 mg/m(3) for 6 h did not impair cochlear function or yield a loss of hair cells. However, when combined with a 93-dB OBN exposure combined solvent + noise did yield a loss in auditory function and a clear potentiation of outer hair cell death that exceeded the loss produced by noise alone. No evidence was found for a loss in total GSH in lung, liver, or brain as a consequence of ethylbenzene + toluene exposure.

Enantiomeric separation of R,S-naproxen by conventional and nano-liquid chromatography with methyl-beta-cyclodextrin as a mobile phase additive

Chiral separations of R,S-naproxen mixtures were obtained on an achiral column (ODS) with methyl-beta-cyclodextrin as a mobile phase additive using conventional and nano-LC. The optimised mobile phase composition was 20 mmol l(-1) methyl-beta-cyclodextrin, 20% (v/v) acetonitrile, and 50 mmol l(-1) sodium acetate buffer at pH 3 using hydrochloric acid for pH adjustment. In addition to UV detection at 232 nm, amperometric detection was also investigated. Without using any internal standard, the reproducibility of amperometric detection (+1.05 V vs. Ag/AgCl) over a long analysis cycle in LC was greatly improved by choosing the peak area ratio between R- and S-naproxen as the analytical readout (the relative standard deviation was 2.11%) and enantiomeric purity could be assessed directly. This method was successfully employed for enantiomeric purity assessment in commercial naproxen tablets. Finally, successful transfer from conventional LC to nano-LC was realised, resulting in over 1000-fold reduction in reagent consumption.