Particle Burden Research Articles

Impact of Recent Agricultural Ammonia Increases on Fine Particulate Matter Burden over the Midwestern United States

Impact of Recent Agricultural Ammonia Increases on Fine Particulate Matter Burden over the Midwestern United States

Effects of particle size composition and burden ratio on burden segregation in the blast furnace throat based on DEM

In blast furnace charging, burden segregation affects the distribution of gas flow and the efficiency of chemical reactions, which in turn impacts the overall efficiency and quality of ironmaking. This work developed a bell-less top charging model based on the DEM to analyze burden segregation at the furnace throat under various particle size compositions, chute inclinations, and burden ratios. The results show that the burden exhibits a ring-like distribution around the furnace throat, with smaller particles concentrated in the inner ring near the center. When particle size difference of the burden is significant, adjusting the proportion of large or small particles has a more pronounced effect on particle size segregation near the center of the blast furnace. The smaller the chute inclination, the more serious the particle size segregation of the burden. Pellet tends to accumulate near the center of the blast furnace, with a segregation index reaching 0.8 in this region. Adjusting the burden ratio has a more pronounced effect on the segregation of sinter. This work provides theoretical support for charging optimization in blast furnace operation.

Resistance characteristics and particle movement behavior of a petroleum coke particle packed bed in a vertical shaft calciner under different burden distribution methods

AbstractBecause of the increasingly deteriorating quality of petroleum coke raw materials, abnormal furnace conditions, such as “firing and blasting”, frequently arise during the calcination of petroleum coke with a high powder/coke ratio in a vertical shaft calciner. This poses an urgent technical challenge that needs to be addressed. In iron and steel metallurgy, the burden distribution system is an important way to regulate blast furnace conditions and improve the permeability of a particle packed bed. In this work, advanced burden distribution concepts were introduced into the calcination process of petroleum coke in a vertical shaft calciner. Experimental devices were established to determine the resistance characteristics of a petroleum coke particle packed bed, along with a cold physical model of a 1/8 scale vertical shaft calciner. The influence of particle size and burden distribution methods on the resistance characteristics and particle motion behavior of the petroleum coke particle packed bed was systematically studied. The research findings indicate that both particle size and burden distribution methods significantly impact the resistance characteristics of petroleum coke particle packed beds. The smaller the particle size, the poorer the permeability of the bed. The layered burden distribution, symmetrical burden distribution, and dual‐particle mixed conventional burden distribution all contribute to improving the permeability of the petroleum coke particle packed bed in the vertical shaft calciner. Furthermore, employing symmetrical burden distribution in Bed‐3, which is packed with petroleum coke particles of diameters −3.2 + 2.5 mm and −1.0 + 0.8 mm, results in the smallest unit pressure drop, at only 1.7% of that of the conventional burden distribution of unscreened raw materials. This is the most effective means of improving the permeability of the bed. During the discharging process, particle size and symmetrical burden distribution have no significant impact on the motion characteristics of petroleum coke particles in the vertical shaft calciner. In general, in the calciner area, particles primarily move in a plug flow pattern and gradually transform into funnel flow in the cooling water jacket area. These research results provide the theoretical basis for addressing the technical challenges associated with powder coke calcination in vertical shaft calciners through reasonable burden distribution methods for fine and coarse particles.

Elongated particulate burden in an individual who died of mesothelioma and had an occupational history as a talc “mucker”

Introduction Tissue from a 77-year-old man diagnosed with mesothelioma was referred with a request for identification of the presence of fibrous structures in tissue samples. The individual’s work history including working as a “mucker” at a specific “industrial” talc mine. Methods Ferruginous bodies in the tissue digests as well as asbestos fibers were found. A bulk sample of a talc containing product from that mine was also analyzed. Discussions/Conclusions The correlation between the unique asbestos mineral/fibrous content of the talc to which he was exposed and findings of the same type of asbestos found in his lung is discussed. The type of asbestos found (tremolite) is a “non-commercial” type of asbestos that has been identified in some talc deposits. Tremolite, like all forms of asbestos is a causative agent for mesothelioma-the disease from which this individual suffered.

Accelerated silicosis in sandblasters: Pathology, mineralogy, and clinical correlates.

With increasing reports of accelerated and acute silicosis, PMF, and autoimmune disease among coal miners and silica-exposed countertop workers, we present previously incompletely-described pulmonary pathology of accelerated silicosis and correlations with mineralogy, radiography, and disease progression in 46 Texas oilfield pipe sandblasters who were biopsied between 1988 and 1995. Worker examinations included pulmonary function tests, chest X-ray (CXR), high-resolution computed tomography (HRCT), and Gallium-67 scans. Quantitative mineralogic analysis of pulmonary parenchymal burden of silica, silicates, and metal particles used scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM EDS). Workers had clinical deterioration after <10 years exposure in dusty workplaces. Althoughinitial CXR was normal in 54%, Gallium-67 scans were positive in 68% of those with normal CXR, indicating pulmonary inflammation. The histology of accelerated silicosis is diffuse interstitial infiltration of macrophages filled with weakly birefringent particles with or without silicotic nodules or alveolar proteinosis. Lung silica concentrations were among the highest in our database, showing a dose-response relationship with CXR, HRCT, and pathologic changes (macrophages, fibrosis, and silicotic nodules). Radiographic scores and diffusing capacity worsened during observation. Silica exposure was intensified, patients presented younger, with shorter exposure, more severe clinical abnormalities, higher lung particle burdens, and more rapid progression in a subset of patients exposed to recycled blasting sand. Accelerated silicosis may present with a normal CXR despite significant histopathology. Multivariable analyses showed silica, and not other particles, is the driver of observed radiologic, physiologic, and histologic outcomes. Eliminating this preventable disease requires higher physician, public health, and societal awareness.

Microplastic ingestion by fish with different feeding habits in the Ob and Yenisei Rivers

Microplastic particles in the size range 0.15 to 5.00 mm were quantified and characterised in the gastrointestinal tracts of three wild freshwater fish (n = 141) from the Ob and Yenisei rivers, including common ruffe (Gymnocephalus cernua L.), Siberian dace (Leuciscus baicalensis Dybowski) and European perch (Perca fluviatilis L.). Microplastics were found in the gastrointestinal tract of 62% of the fish examined, ranging from 18.5% in the Yenisei perch sample to 92.6% in the Ob ruffe sample. The vast majority of microplastics in all fish species were fibres (up to 99.7% of all particles detected in perch), followed by irregularly shaped fragments (up to 22.7% in ruffe), with no preference between the three species. Spheres and films were found exclusively in dace and ruffe, with proportions of 3.7% and 1.2% respectively. Particles consisted of polyethylene terephthalate, polypropylene, polyamide and other synthetic polymers with a significant proportion of highly degraded polymers. The mean MP content in fish GITs ranged from 0.44 ± 0.25 items per individual in Yenisei perch to 3.81 ± 0.55 items per individual in Ob ruffe. Particle burdens in fish were significantly higher in the Ob than in the Yenisei (p &lt; 0.05), which may reflect the common level of plastic contamination in these two rivers. MP ingestion varied in species with different feeding habits as ruffe (benthivorous) &gt; dace (omnivorous) &gt; perch (hunter) in both rivers (p &lt; 0.01). This study was the first to quantify MP consumption by freshwater fish of different species in the Ob and Yenisei rivers and to identify patterns associated with different feeding habits.

Analysing the interplay of environmental virology, public health, and sanitation: a comprehensive review from a Kenyan perspective.

This comprehensive review examines the interplay between environmental virology, public health, and sanitation in the unique context of Kenya. The review sheds light on the specific viral threats faced by the country, including waterborne viruses, zoonotic infections, and emerging viral diseases, and their implications for public health. It explores the prevailing public health challenges in Kenya associated with environmental viromics, such as infectious viral diseases, and the rising burden of other infectious particles. The role of sanitation in mitigating viral infections is highlighted, emphasising the importance of clean water supply, proper waste management, and hygienic practises. The review also presents strategies for strengthening environmental virology research in Kenya, including enhancing laboratory capacities and leveraging technological advancements. Furthermore, the policy implications and recommendations derived from the review emphasise the need for multi-sectoral collaboration, evidence-based decision-making, and long-term investments in infrastructure and behaviour change interventions. Implementing these strategies can enhance the understanding of environmental virology, improve public health outcomes, and ensure sustainable sanitation practises in Kenya, ultimately contributing to the well-being of the population and sustainable development.

Thermodynamical framework for effective mitigation of high aerosol loading in the Indo-Gangetic Plain during winter

The Indo-Gangetic Plain (IGP) experiences severe air pollution every winter, with ammonium chloride and ammonium nitrate as the major inorganic fractions of fine aerosols. Many past attempts to tackle air pollution in the IGP were inadequate, as they targeted a subset of the primary pollutants in an environment where the majority of the particulate matter burden is secondary in nature. Here, we provide new mechanistic insight into aerosol mitigation by integrating the ISORROPIA-II thermodynamical model with high-resolution simultaneous measurements of precursor gases and aerosols. A mathematical framework is explored to investigate the complex interaction between hydrochloric acid (HCl), nitrogen oxides (NOx), ammonia (NH3), and aerosol liquid water content (ALWC). Aerosol acidity (pH) and ALWC emerge as governing factors that modulate the gas-to-particle phase partitioning and mass loading of fine aerosols. Six "sensitivity regimes" were defined, where PM1 and PM2.5 fall in the "HCl and HNO3 sensitive regime", emphasizing that HCl and HNO3 reductions would be the most effective pathway for aerosol mitigation in the IGP, which is ammonia-rich during winter. This study provides evidence that precursor abatement for aerosol mitigation should not be based on their descending mass concentrations but instead on their sensitivity to high aerosol loading.

144 Occupational Exposure to Particles Measured by Nanoparticles Tracking Analysis (NTA) in Exhaled Breath Condensate (EBC).

Abstract The production of paints, coatings and construction materials may generate nanoparticles (NP) with potential adverse health effects. We carried out a study aimed at investigating exposure biomarkers reflecting the internal dose of inhaled particles and NP. NTA was used to quantify particle number concentration and size in EBC collected at the end of shift in 81 workers employed in companies producing technological materials. External exposure was characterized in terms of particle number concentration, size and lung deposited surface area (LDSA) in the near operational field by using a set of DiSCmini. Three subgroups were identified: Low-Exposure (LE, n=30), High-Exposure (HE n=35), and non-occupationally exposed (UC, n=16). Comparisons between groups were made using non-parametric analyses. LE and HE workers showed significantly higher number of NP in EBC (p=0.024, p=0.041, respectively) as compared to UC. The HE groups showed higher levels of inflammatory biomarkers, such as IL-1β and IL-10 as compared to LE and UC (p=0.02, p&amp;lt;0.01, respectively). Positive correlations were observed between particle number concentration recorded by DiscMini and NTA data (Rho=0,225, p=0.04) and between the NTA and IL-10 and IL-1β (Rho=0.246, p=0.012; Rho=0.223, p=0.022, respectively). In contrast, LDSA did not correlate with NTA data. These findings provide evidence of the relationship between increasing exposure to NP and the burden of particles in the airways which, in turn, results in sustained inflammation. Given the lack of exposure biomarkers for dusts, these results are promising to investigate the relationship between internal dose of particles and changes in lung pathobiology.

Derivation of first-order dissolution rates to estimate particle clearance and burden in the human respiratory tract

Inhalation is a portal-of-entry for aerosols via the respiratory tract where particulate burden accumulates depending on sites of particle deposition, normal clearance mechanisms, and particle solubility. The time available for dissolution of particles is determined by the balance between the rate of particle clearance from a region and their solubility in respiratory solvents. Dissolution is a function of particle surface area divided by particle volume or mass (i.e., dissolution is inversely proportional to the physical diameter of particles). As a conservative approach, investigators commonly assume the complete and instantaneous dissolution of metals from particles depositing in the alveolar region of the respiratory tract. We derived first-order dissolution rate constants to facilitate biokinetic modeling of particle clearance, dissolution, and absorption into the blood. We then modeled pulmonary burden and total dissolution of particles over time as a function of particle size, density, and solubility. We show that assuming poorly soluble particle forms will enter the blood as quickly as highly soluble forms causes an overestimation of concentrations of the compound of interest in blood and other extrapulmonary tissues while also underestimating its pulmonary burden. We conclude that, in addition to modeling dose rates for particle deposition into the lung, physiologically based pharmacokinetic modeling of pulmonary and extrapulmonary tissues concentrations of moderately and poorly soluble materials can be improved by including estimates of lung burden and particle dissolution over time.

Larger operating rooms have better air quality than smaller rooms in primary total knee arthroplasty.

Operating room air quality can be affected by several factors including temperature, humidity, and airborne particle burden. Our study examines the role of operating room (OR) size on air quality and airborne particle (ABP) count in primary total knee arthroplasty (TKA). We analyzed all primary, elective TKAs performed within two ORs measuring 278 sq ft. (small) and 501 sq ft. (large) at a single academic institution in the United Statesfrom April 2019 to June 2020. Intraoperative measurements of temperature, humidity, and ABP count were recorded. p values were calculated using t test for continuous variables and chi-square for categorical values. 91 primary TKA cases were included in the study, with 21 (23.1%) in the small OR and 70 (76.9%) in the large OR. Between-groups comparisons revealed significant differences in relative humidity (small OR 38.5% ± 7.24% vs. large OR 44.4% ± 8.01%, p = 0.002). Significant percent decreases in ABP rates for particles measuring 2.5μm (- 43.9%, p = 0.007) and 5.0μm (- 69.0%, p = 0.0024) were found in the large OR. Total time spent in the OR was not significantly different between the two groups (small OR 153.09 ± 22.3 vs. large OR 173 ± 44.6, p = 0.05). Although total time spent in the room did not differ between the large and small OR, there were significant differences in humidity and ABP rates for particles measuring 2.5μm and 5.0μm, suggesting the filtration system encounters less particle burden in larger rooms. Larger studies are required to determine the impact this may have on OR sterility and infection rates.

TiO2–Ag–NP adhesive photocatalytic films able to disinfect living indoor spaces with a straightforward approach

TiO2–Ag doped nanoparticulate (TiO2–Ag–NP) adhesive photocatalytic films were used to assess the ability in dropping down the burden of indoor microbial particles. The application of an easy-to use photocatalytic adhesive film to cleanse indoor living spaces from microbial pollution, represents a novelty in the field of photocatalytic devices. Reduction was attained by photocatalysis in selected spaces, usually with overcrowding (≥ 3 individuals) in the common working daily hours, and upon indoor microclimate monitoring. TiO2–Ag doped nanoparticulate (TiO2–Ag–NP) adhesive photocatalytic films were applied within five types of living spaces, including schools and job places. The microbial pollution was assessed at time 0 (far from routine clean, ≥ 9 h) and throughout 2–4 weeks following the photocatalyst application by relative light unit (RLU) luminometry and microbial indirect assessment (colony forming units per cubic meter, CFU/m3). TiO2–Ag–NP photocatalyst reduced RLU and CFU/m3 by rates higher than 70% leading to RLU ≤ 20 and microbial presence ≤ 35 CFU/m3. The described TiO2–Ag–NP is able to reduce microbial pollution to the lowest RLU threshold (≤ 20) within 60 min in open daylight in a standardized test room of 100 m2. The correlation between RLU and CFU/m3 was positive (r = 0.5545, p < 0.05), assessing that the microbial reduction of indoor areas by the TiO2–Ag–NP adhesive film was real. Titania photocatalysts represent promising tools to ensure air cleaning and sanitization in living indoor microclimates with a low cost, feasible and straightforward approach. This approach represents an easy to handle, cost effective, feasible and efficacious approach to reduce microbial pollution in indoor spaces, by simply attaching a TiO2–Ag–NP adhesive film on the wall.

Role of Operating Room Size on Air Quality in Primary Total Hip Arthroplasty

BackgroundAirborne biologic particles (ABPs) can be measured intraoperatively to evaluate operating room (OR) sterility. Our study examines the role of OR size on air quality and ABP count in primary total hip arthroplasty (THA). MethodsWe analyzed primary THA procedures done within 2 ORs measuring 278 ft2 and 501 ft2 at a single academic institution from April 2019 to June 2020. Temperature, humidity, and ABP count per minute were recorded with a particle counter intraoperatively and cross-referenced with surgical data from the electronic health records using procedure start and end times. Descriptive statistics were used to evaluate differences in variables. P-values were calculated using t-test and chi-squared test. ResultsA total of 116 primary THA cases were included: 18 (15.5%) in the “small” OR and 98 (84.5%) in the “large” OR. Between-group comparisons revealed significant differences in temperature (small OR: 20.3 ± 1.23 C versus large OR: 19.1 ± 0.85 C, P < .0001) and relative humidity (small OR: 41.1 ± 7.24 versus large OR: 46.9 ± 7.56, P < .001). Significant percent decreases in ABP rates for particles measuring 2.5 um (−125.0%, P = .0032), 5.0 um (−245.0%, P = .00078), and 10.0 um (−413.9%, P = .0021) were found in the large OR. Average time spent in the OR was significantly longer in the large OR (174 ± 33 minutes) compared to the small OR (151 ± 14 minutes) (P = .00083). ConclusionTemperature and humidity differences and significantly lower ABP counts were found in the large compared to the small OR despite longer average time spent in the large OR, suggesting the filtration system encounters less particle burden in larger rooms. Further research is needed to determine the impact this may have on infection rates.

Characterization of the elemental and particle load of patient exhaled breath condensate and comparison with pulmonary lavages

In the field of biomonitoring, exhaled breath condensate (EBC) is described as a potentially useful matrix for assessing inhalation exposure biomarkers in a non-invasive way. However, it is still unclear to what extent EBC is representative of the deep lung. To address this knowledge gap, EBC, bronchial washes (BWs), and bronchoalveolar lavages (BALs) were collected from 82 patients suffering from interstitial lung diseases (ILDs). The particulate contents and elemental composition of EBC, BW, and BAL were then compared in the same patients. The size distribution of particles in EBC was assessed with dynamic light scattering while inductively coupled plasma mass spectrometry was used to quantify its elemental composition. In addition, transmission electron microscopy coupled with energy dispersive x-ray spectrometry were used to further characterize samples of interest. EBC was found to be representative of both the sub-micron and nano-sized particle fractions of BAL and BW, with lower overall levels of elements in EBC than in BW and BAL. Silicon (Si) was the main component for all respiratory matrices with median levels of 2525 µg l−1, 5643 µg l−1 and 5169 µg l−1 in the nano/ion fractions of EBC, BAL and BW, respectively. Moreover, Si levels in EBC from patients in this study were elevated compared to the levels reported in the literature for healthy subjects. Interestingly, Si levels in the EBC of ILD patients were inversely related to those in BAL and BW. In conclusion, the particulate content of EBC is associated with the lung particle burden and potentially correlates with pathologies, rendering it a relevant biomonitoring technique for the occupational and clinical fields.

Effect of the Tubing Material Used in Peristaltic Pumping in Tangential Flow Filtration Processes of Biopharmaceutics on Particle Formation and Flux

Tangential flow filtration (TFF) is a central step in manufacturing of biopharmaceutics. Membrane clogging leads to decreased permeate flux, longer process time and potentially complete failure of the process. The effect of peristaltic pumping with tubings made of three different materials on protein particle formation during TFF was monitored via micro flow imaging, turbidity and photo documentation. At low protein concentrations, pumping with a membrane pump resulted in a stable flux with low protein particle concentration. Using a peristaltic pump led to markedly higher protein particle formation dependent on tubing type. With increasing protein particle formation propensity of the tubing, the permeate flux rate became lower and the process took longer. The protein particles formed in the pump were captured in the cassette and accumulated on the membrane leading to blocking. Using tubing with a hydrophilic copolymer modification counteracted membrane clogging and flux decrease by reducing protein particle formation. In ultrafiltration mode the permeate flux decrease was governed by the viscosity increase rather than by the protein aggregation; but using modified tubing is still beneficial due to a lower particle burden of the product. In summary, using tubing material for peristaltic pumping in TFF processes which leads a less protein particle formation, especially tubing material with hydrophilic modification, is highly beneficial for membrane flux and particle burden of the product.

Reduction in Operating Room Airborne Particle Burden and Time-Dependent Contamination of Sterile Instrument Trays With the Use of a Novel Air Filtration System.

IntroductionPostoperative infections represent a substantial burden to patients and healthcare systems. To improve patient care and reduce healthcare expenditures, interventions to reduce surgical infections must be employed. The crystalline C-band ultraviolet (UV-C) air filtration technology (Aerobiotix Inc., Miamisburg, OH, USA) has been designed to reduce airborne bioburden through high-quality filtration and germicidal irradiation. The purpose of this study was to assess the ability of a novel UV-C air filtration device to reduce airborne particle counts and contamination of surgical instrument trays in an operating room (OR) setting.Materials and methodsThirty sterile instrument trays were opened in a positive-air-flow OR. The trays were randomly assigned to one of two groups (UV-C or control, n=15 per group). In the UV-C group, the UV-C filtration device was used and in the control, it was not. All trays were opened with the use of a sterile technique and left exposed in the OR for four hours. Air was sampled by a particle counter to measure the numbers of 5µm and 10µm particles. Culture specimens were obtained from the trays to assess for bacterial contamination. Outcome data were collected at 30-minute intervals for the duration of the four-hour study period.ResultsUse of the UV-C device resulted in statistically significant reductions in the numbers of 5µm (average of 64.9% reduction when compared with the control, p<0.001) and 10µm (average of 65.7% reduction when compared with the control, p<0.001)-sized particles detectable in the OR. There was no significant difference in the overall rates of contamination (33.3% in the control group vs. 26.7% in the UV-C group, p=1.0) or the time to contamination (mean survival of 114 minutes in the control group vs. 105 minutes in the UV-C group, p=0.72) of surgical instrument trays with the use of the UV-C device.ConclusionsThe results demonstrate that the UV-C filtration device can successfully reduce airborne bioburden in standard ORs, suggesting that it may have the potential to reduce the risk for wound and hardware infections. Further clinical trials are necessary to better determine the effect of this air filtration system on postoperative infection rates.

LA-ICP-MS and Immunohistochemical Staining with Lanthanide-Labeled Antibodies to Study the Uptake of CeO2 Nanoparticles by Macrophages in Tissue Sections

Due to the increasing use and production of CeO2 nanoparticles (NPs), the likelihood of exposure especially via the air rapidly grows. However, the uptake of CeO2 NPs via the lung and the resulting distribution into various cell types of remote organs are not well understood because classical analytical methods provide limited spatial information. In this study, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) was combined with immunohistochemical (IHC) staining with lanthanide-labeled antibodies to investigate the distribution of intratracheally instilled CeO2 NPs from the rat lung to lymph nodes, spleen, and liver after 3 h, 3 days, and 21 days. We selected regions of interest after fast imaging using LA-ICP-MS in low-resolution mode and conducted high-resolution LA-ICP-MS in combination with IHC for cellular localization. The lanthanide labeling, which was largely congruent with conventional fluorescent labeling, allowed us to calculate the association rates of Ce to specific cell types. Major portions of Ce were found to be associated with phagocytic cells in the lung, lymph nodes, spleen, and liver. In the lung, almost 94% of the Ce was co-localized with CD68-positive alveolar macrophages after 21 days. Ce was also detected in the lymph nodes outside macrophages 3 h post instillation but shifted to macrophage-associated locations. In the liver, Ce accumulations associated with Kupffer cells (CD163-positive) were found. Ce-containing populations of metallophilic and marginal zone macrophages (both CD169-positive) as well as red pulp macrophages (CD68-positive) were identified as major targets in the spleen. Overall, high-resolution LA-ICP-MS analysis in combination with IHC staining with lanthanide-labeled antibodies is a suitable tool to quantify and localize Ce associated with specific cell types and to estimate their particle burden under in vivo conditions.

Assessing alternatives to HEPA air purification requirements to reduce viral pathogen transmission in healthcare HVAC systems

Background: High-efficiency particulate air (HEPA) filters are currently recommended when using recirculated air to eliminate the risk of pathogen transmission such as SARS-CoV-2 from one patient care area to the next. We tested the efficacy of lower-grade air filters in eliminating airborne virus transmission. Methods: We conducted an experiment in 2 adjacent exam rooms in an unoccupied hospital emergency unit. The HVAC system contained a 15,000-cubic-feet-per-minute rooftop air handler. All outside air and exhaust dampers were closed during the trial (full air recirculation). We conducted experiments in 3 tests arms with varying grades of MERV filters (AAF Flanders, Louisville, KY): (1) control without filters, (2) MERV8+14 filters, and (3) MERV8+16 filters. We repeated 20-minute virus challenge runs 3 times per test arm. Live attenuated influenza vaccine (2 mL LAIV, FluMist Quadrivalent 2020/21, AstraZeneca, Wilmington, DE), was aerosolized into the HVAC system via a commercial nebulizer. Air was sampled using 3 six-stage Andersen air samplers placed in the center of the adjacent room. Environmental particle counts were collected using a particle counter (PEC-PCO-1, PCE Americas). Results: Concentrations of viral RNA were determined by qPCR, and viral concentrations (vg/mL) in each stage of each arm were compared directly. Pairwise comparisons of the virus and particle burdens across each stage of each test arm were made using a general linear model. LAIV was detected in the control arm at a virus burden of 2,277 vg/mL, indicating a &gt;6.5 log reduction of the virus released in the HVAC system (8.8×109 total vg). In the second arm, the MERV8+MERV14 filters demonstrated in a 13-fold decrease in viral burden compared to the control arm (mean virus burden: 169 vg/mL, p Our study demonstrates that viral containing particles can be transported via a hospital HVAC system from one patient room to the next. Considering the decrease in detectable virus within the HVAC system, the combination of MERV8+MERV16 filters reduced the virus burden reaching an adjacent room to levels well below the human infectious dosages for influenza and other highly infective viruses. Conclusions: Our findings indicate that MERV8+MERV16 filters provide protection against virus transmission through HVAC systems and are a cost-conscious alternative to HEPA filters.Funding: NoneDisclosures: None

Contrasting Stratospheric Smoke Mass and Lifetime From 2017 Canadian and 2019/2020 Australian Megafires: Global Simulations and Satellite Observations

AbstractStratospheric injections of carbonaceous aerosols and combustion gases by extreme wildfires have become increasingly common. Recent “megafires,” particularly large and intense fires, delivered particulate burdens to the lower stratosphere comparable to those of moderate volcanic eruptions. The 2017 Canadian megafire generated four large Pyrocumulonimbi (pyroCbs), injecting up to ≈0.3 Tg of smoke in the lower stratosphere. Even more extreme, the 2019/2020 Australian event produced a pyroCb activity resulting in stratospheric smoke intrusions of ≈1 Tg. To understand their contrasting behavior, we present global climate simulations of the atmospheric response to these events, applying smoke burdens informed by remote observations. Model outcomes, compared to satellite data of smoke transport, reproduce reasonably well the initial plume rise, at 0.2–0.3 km/day, attaining heights of ≈20 km in Canada and above 30 km in Australia. Global dispersal of the plume occurs within about 3 weeks in both cases, consistent with observations. Smoke removal timescales, ≈5 months for the Canadian megafire, agree with remote measurements. During the Australian megafire, observations indicate stratospheric injections three times as large, and models predict comparatively longer smoke lifetimes, ≈16 months. After the latter event, atmospheric optical depths and radiative cooling achieved values close to those measured following the Pinatubo eruption. Sensitivity tests of model assumptions indicate, in accord with prior studies, that smoke burden, injection heights, and black carbon content can determine plume evolution and possible climate impacts. An empirical relation between peak heights of stratospheric plumes and lifetimes is derived that can help assess megafire impacts on the stratosphere, climate and the Earth system.

Strategies for the Control of Visible Particles in Sterile Devices

Abstract Currently, limited guidance is available for the contamination control of visible particles for the manufacture of sterile devices; thus, a comprehensive guidance is warranted. Sterile devices require stringent control of visible particulates to ensure proper functionality, performance assurance of sterility, reliability, patient safety, efficacy, and product quality. This paper outlines practical and science-based strategies to prevent/minimize visible particle contamination from non-process related extrinsic and process related intrinsic sources. Witness plates are proposed as a comprehensive strategy for the real time detection of visible particles, sources of extrinsic and intrinsic visible particles, and methods to identify particle types. Implementing the control measures described herein, which include air ionization units for the control and neutralization of static charges, would maximize device yield and quality, thus reducing rework and leading to increased profitability. Installing validated air ionization systems at appropriate manufacturing and processing locations, storage, product transfer areas, and gown-up rooms can significantly reduce visible particle contamination accumulation, dispersion, and yield losses. Implementing effective material transfer practices can further minimize the risk of introduction of unwanted particles and particle dispersion within classified areas. Also described are additional control measures, such as material systems and supply chain controls, good facility design, gowning practices, manufacturing equipment and tool controls, and manual visual inspections which would further contribute to the overall reduction of particle burden. Crucial elements of an effective particle removal process are the dry and wet cleaning processes and the facility surveillance program. Process-product-particle traceability matrices can serve as effective tools to promptly identify trends and reduce device conformity defects. For this paper, the meaning of the term particle only includes particulates and particulate matter. Microbial contamination control approaches, including facility decontamination, are outside the scope of this paper.