55 research outputs found
Chemical and Biological Characterization of Particulate Matter (PM 2.5) and Volatile Organic Compounds Collected at Different Sites in the Los Angeles Basin
Background: Most studies on air pollution (AP) exposure have focused on adverse health effects of particulate matter (PM). Less well-studied are the actions of volatile organic compounds (VOCs) not retained in PM collections. These studies quantified chemical and biological properties of both PM2.5 and VOCs. Methods: Samples were collected near the Port of Los Angeles (Long Beach, LB), railroads (Commerce, CM), and a pollution-trapping topography-site (San Bernardino, SB). Quantitative assays were conducted: (1) chemical—prooxidant and electrophile content, (2) biological—tumor necrosis factor-α (TNF-α) and heme oxygenase-1 (HO-1) expression (3), VOC modulation of PM effects and (4), activation of the antioxidant response element (ARE) using murine RAW 264.7 macrophages. Results: SB site samples were the most potent in the chemical and biological assays, followed by a CM railroad site. Only PM2.5 exhibited significant proinflammatory responses. VOCs were more potent than PM2.5 in generating anti-inflammatory responses; further, VOC pretreatment reduced PM-associated TNF-α expression. VOCs significantly increased ARE activation compared to their corresponding PM2.5 which remained at background levels. Conclusion: Ambient VOCs are major contributors to adaptive responses that can modulate PM effects, in vitro, and, as such, need to be included in comprehensive assessments of AP
An online monitor of the oxidative capacity of aerosols (o-MOCA)
The capacity of airborne particulate matter to generate reactive oxygen
species (ROS) has been correlated with the generation of oxidative stress
both in vitro and in vivo. The cellular damage from oxidative stress, and by
implication with ROS, is associated with several common diseases, such as
asthma and chronic obstructive pulmonary disease (COPD), and some neurological
diseases. Yet currently available chemical and in vitro assays to
determine the oxidative capacity of ambient particles require large samples,
analyses are typically done offline, and the results are not immediate.Here we report the development of an online
monitor of the oxidative capacity of
aerosols (o-MOCA) to provide online, time-resolved assessment of
the capacity of airborne particles to generate ROS. Our approach combines
the Liquid Spot Sampler (LSS), which collects particles directly into small
volumes of liquid, and a chemical module optimized for online measurement
of the oxidative capacity of aerosol using the dithiothreitol (DTT) assay.
The LSS uses a three-stage, laminar-flow water condensation approach to
enable the collection of particles as small as 5 nm into liquid. The DTT
assay has been improved to allow the online, time-resolved analysis of
samples collected with the LSS but could be adapted to other collection
methods or offline analysis of liquid extracts.The o-MOCA was optimized and its performance evaluated using the
9,10-phenanthraquinone (PQ) as a standard redox-active compound. Laboratory
testing shows minimum interferences or carryover between consecutive
samples, low blanks, and a reproducible, linear response between the DTT
consumption rate (nmol min−1) and PQ concentration (µM). The calculated
limit of detection for o-MOCA was 0.15 nmol min−1. The system was validated
with a diesel exhaust particle (DEP) extract, previously characterized and
used for the development, improvement, and validation of the standard DTT
analysis. The DTT consumption rates (nmol min−1) obtained with the o-MOCA were
within experimental uncertainties of those previously reported for these DEP
samples. In ambient air testing, the fully automated o-MOCA was run
unattended for 3 days with 3 h time resolution and showed a diurnal and
daily variability in the measured consumption rates (nmol min−1 m−3)
Design and Laboratory Evaluation of a Sequential Spot Sampler for Time-Resolved Measurement of Airborne Particle Composition
Residential biofuels in south Asia: Carbonaceous aerosol emissions and climate impacts
High concentrations of pollution particles, including "soot" or black carbon,,exist over the Indian Ocean, but their sources and geographical origins are not well understood. We measured emissions from the combustion of biofuets, used widely in south Asia for cooking, and found that large amounts of carbonaceous aerosols are emitted per kilogram of fuel burnt. We calculate that biofuel combustion is the largest source of black carbon emissions in India, and we suggest that its control is central to climate change mitigation in the south Asian region
Effective area in slotted high Tc dc washer superconducting quantum interference devices
Ambient vapor samples activate the Nrf2-ARE pathway in human bronchial epithelial BEAS-2B cells
Ambient air pollutants have been reported to induce oxidative stress based inflammatory responses in humans and experimental animals. However, most of these reports describe the actions of the particulate phase of ambient and exhaust samples. We describe here results of studies investigating the actions of the vapor phase of ambient air samples collected in the midtown area of Los Angeles on human bronchial epithelial BEAS-2B cells using DNA microarray analysis. Among 26 genes whose expression increased fourfold or more, four genes were associated with detoxifying genes regulated by the transcription factor Nrf2. Consistent with these results, the vapor samples activate the Nrf2-ARE pathway, resulting in up-regulation of heme oxygenase-1 (HO-1), glutamate cysteine ligase modifier subunit, and cystine transporter (xCT) mRNA and proteins. No appreciable increases in pro-inflammatory genes were observed. These results suggest that ambient vapor samples activate the Nrf2-ARE pathway but not an inflammatory response. Also, treatment of the vapor samples with glutathione resulted in reduction in the Nrf2 activation and HO-1 induction, suggesting that electrophiles in vapor samples contribute to this Nrf2-dependent antioxidant or adaptive response
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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
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The BioCascade impactor: A novel device for direct collection of size-fractionated bioaerosols into liquid medium
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