Spark ignition vehicle contributions to atmospheric fine elemental carbon concentrations in coastal, rural and urban communities using polycyclic aromatic hydrocarbon tracers in the CMB model modified for reactivity

We apportioned the elemental carbon (EC) component of ambient PM2.5 attributable to emissions from spark ignition (SI) vehicles in samples collected over a three-year period in twelve Southern California communities, including coastal, rural, and urban areas using the chemical mass balance model (CMB8) modified for polycyclic aromatic hydrocarbon (PAH) reactivity. Selected PAH/EC ratios, measured in samples collected in the Caldecott tunnel were evaluated for use as fingerprints. PAH reactivity which occurs during atmospheric transport and affects the source contribution estimates during the summer/fall/spring months was accounted for using experimentally measured decay constants. Results showed that benzo[ghi]perylene and indeno[1,2,3-cd]pyrene can be used successfully as specific tracers of EC contributions from SI vehicles. The average EC portion of PM2.5 attributed by the model to SI emissions at these communities was 39, 58 and 62%, respectively, during the summer, spring/autumn, and winter. For all seasons, coastal community contributions represent about twice those found in the rural and urban inland communities, before December 2003 when MTBE was still in use in California

Dust removal from solar concentrators using an electrodynamic screen; Determination of the distribution of infectious viruses in aerosol particles using water-based condensational growth technology and a bacteriophage MS2 model

Inhalation of aerosols containing pathogenic viruses can result in morbidity, in some cases leading to mortality. The objective of this study was to develop a model for assessing how infectious viruses might distribute in airborne particles using bacteriophage MS2 as a surrogate for human viruses. Particle deposition in the respiratory system is size- dependent, and small virus-containing particles can be inhaled deeply into the lower lungs, potentially leading to more severe respiratory disease manifestations. Laboratory-generated virus-containing particles were size-selected by a differential mobility analyzer and then collected by the newly introduced Super-Efficient Sampler for Influenza Virus. The number of infectious and total viruses per particle as a function of particle size varied with the spraying medium: it approximated a cubic exponential value scaling for deionized (DI) water, a quartic exponential value for artificial saliva (AS), and between quadratic and cubic exponential value for beef extract solution (BES). The survivability of MS2 did not change significantly with particle size for DI water and BES, while that for AS was maximum at 120 nm. Viruses could be homogeneously distributed or aggregated inside or on the surface of the particles, depending on the composition of the spraying medium

Viable SARS-CoV-2 Delta variant detected in aerosols in a residential setting with a self-isolating college student with COVID-19

The B.1.617.2 (Delta) variant of SARS-CoV-2 emerged in India in October of 2020 and spread widely to over 145 countries, comprising over 99% of genome sequence-confirmed virus in COVID-19 cases of the United States (US) by September 2021. The rise in COVID-19 cases due to the Delta variant coincided with a return to in-person school attendance, straining COVID-19 mitigation plans implemented by educational institutions. Some plans required sick students to self-isolate off-campus, resulting in an unintended consequence: exposure of co-inhabitants of dwellings used by the sick person during isolation. We assessed air and surface samples collected from the bedroom of a self-isolating university student with mild COVID-19 for the presence of SARS-CoV-2. That virus' RNA was detected by real-time reverse-transcription quantitative polymerase chain reaction (rRT-qPCR) in air samples from both an isolation bedroom and a distal, non-isolation room of the same dwelling. SARS-CoV-2 was detected and viable virus was isolated in cell cultures from aerosol samples as well as from the surface of a mobile phone. Genomic sequencing revealed that the virus was a Delta variant SARS-CoV-2 strain. Taken together, the results of this work confirm the presence of viable SARS-CoV-2 within a residential living space of a person with COVID-19 and show potential for transportation of virus-laden aerosols beyond a designated isolation suite to other areas of a single-family home

Assessment of Scanning Mobility Particle Sizer (SMPS) for online monitoring of delivered dose in an in vitro aerosol exposure system

Real-time monitoring of dosimetry is critical to mitigating the constraints of offline measurements. To address this need, the use of the Scanning Mobility Particle Sizer (SMPS) to estimate the dose delivered through the Dosimetric Aerosol in Vitro Inhalation Device (DAVID) was assessed. CuO nanoparticles suspended in ethanol at different concentrations (0.01–10 mg/mL) were aerosolized using a Collison nebulizer and diluted with air at a ratio of either 1:3 (setup 1) or 1:18 (setup 2). From the aerosol volume concentrations measured by the SMPS, density of CuO (6.4 g/cm3), collection time (5–30 min), flow rate (0.5 LPM) and deposition area (0.28 cm2), the mass doses (DoseSMPS) were observed to increase exponentially over time and ranged from 0.02 ± 0.001 to 84.75 ± 3.49 μg/cm2. The doses calculated from the Cu concentrations determined by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) (DoseICP) also increased exponentially over time (0.01 ± 0.01–97.25 ± 1.30 μg/cm2). Regression analysis between DoseICP and DoseSMPS showed R2 ≥ 0.90 for 0.1–10 mg/mL. As demonstrated, the SMPS can be used to monitor the delivered dose in real-time, and controlled delivery of mass doses with a 226-fold range can be attained in ≤30 min in DAVID by adjusting the nebulizer concentration, dilution air and time.•Controlled delivery of CuO with mass doses in a 226-fold through DAVID, in ≤30 min.•Reliable dosimetry for non-steady state aerosol generation.•Correlation coefficient between DoseICP and DoseSMPS ≥ 0.9 for Cneb 0.1–10 mg/mL.•The use of SMPS for real-time monitoring of delivered dose was demonstrated

126 A CTS team approach to reliable delivery of aerosols to lung cells at the air-liquid interface (ALI), through Dosimetric Aerosol in Vitro Inhalation Device (DAVID)

OBJECTIVES/GOALS: In vitro models that mimic the human respiratory system are needed to assess the toxicity of inhaled contaminants. Therefore, our goal is to establish a Dosimetric Aerosol in-Vitro Inhalation Device (DAVID) that delivers aerosols in different patterns to human lung cells cultured at an air-liquid interface (ALI). METHODS/STUDY POPULATION: The collection unit of DAVID was modified in this study to accommodate different deposition patterns (spots, annular ring, rectangle & circle). CuO aerosols of varying concentrations were generated using a 6-jet Collison nebulizer for varying time periods to achieve different doses. To quantify the doses that were delivered to cells, the samples were digested with nitric acid & analyzed by Inductively Coupled Plasma-Optical Emission Spectrometry. Following the exposure of A549 cells to CuO aerosols, cytotoxicity and mRNA expression (i.e., HMOX1 & IL-8) will be assessed via LDH and RT-qPCR to determine the effect of regional (mass deposited/area of the pattern) and global (mass deposited/area of the cell culture insert) doses in cells. RESULTS/ANTICIPATED RESULTS: The deposition areas covered by rectangular, spot, annular ring, and circular patterns are estimated to be 6, 17, 27 and 85% of the insert’s surface area, onto which cells are cultured. Results for the patterns tested (spots and annular ring) show that both the regional and global doses were greater for spots than annular ring. Also, the regional doses were higher than global doses. Irrespective of the patterns, the global doses were the same for nebulizer suspensions of 0.1-1 mg/mL. Statistical analysis by ANOVA revealed there was no significant difference in doses between replicate inserts used in the same trial. We anticipate that regional doses with aerosol deposition to a larger surface area of the cell culture insert will correspond with higher cytotoxicity and mRNA expression of HMOX1 and IL-8 in cells. DISCUSSION/SIGNIFICANCE: There are limited in vitro exposure systems that can efficiently deliver aerosols to lung cells, while also mimicking inhalation by humans. In addition to addressing this knowledge gap, we will show the role of regional & global doses in studying cellular response & the ability of DAVID to deliver aerosols in different deposition patterns