Aerosol Exposure Research Articles

Particulate matter in a motorcycle-dominated urban area: Source apportionment and cancer risk of lung deposited surface area (LDSA) concentrations

Source-apportioned particle concentrations are necessary to properly evaluate the health impacts of air pollution. In this study, a measurement station was established at an urban roadside in northern Taiwan to the investigate lung deposited surface area (LDSA) concentration, a relevant metric for the adverse health effects of aerosol exposure, along with PM1 and equivalent black carbon (eBC) concentrations, particle number concentration (PNC), and particle size distribution (PSD). Through positive matrix factorization and multi-linear regression analysis, we attributed 57% of LDSA to traffic emissions over the entire study. During rush hour, the motorcycle fraction increased to 0.83 and LDSA (77.6 ± 9.9 µm2/cm3) and PNC (14,000 ± 2400 particles/cm3) values peaked, while 74% of LDSA was attributed to traffic. The LDSA ratio, defined as the ratio of measured LDSA to that estimated from the particle size distribution with a spherical assumption, also increased, highlighting the greater degree of fractal morphology during rush hour. The relationship between LDSA emitted by traffic and PNC yielded a higher r2 (0.92) than the r2 between traffic LDSA and eBC (0.82). Finally, the excess lifetime cancer risk linked with traffic emission was 1.56 × 10-4 (i.e. 15.6 excess cancer cases for a population of 100,000 people) based on the LDSA apportionment results.

Efficacy of Ventilation, HEPA Air Cleaners, Universal Masking, and Physical Distancing for Reducing Exposure to Simulated Exhaled Aerosols in a Meeting Room.

There is strong evidence associating the indoor environment with transmission of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 can spread by exposure to droplets and very fine aerosol particles from respiratory fluids that are released by infected persons. Layered mitigation strategies, including but not limited to maintaining physical distancing, adequate ventilation, universal masking, avoiding overcrowding, and vaccination, have shown to be effective in reducing the spread of SARS-CoV-2 within the indoor environment. Here, we examine the effect of mitigation strategies on reducing the risk of exposure to simulated respiratory aerosol particles within a classroom-style meeting room. To quantify exposure of uninfected individuals (Recipients), surrogate respiratory aerosol particles were generated by a breathing simulator with a headform (Source) that mimicked breath exhalations. Recipients, represented by three breathing simulators with manikin headforms, were placed in a meeting room and affixed with optical particle counters to measure 0.3–3 µm aerosol particles. Universal masking of all breathing simulators with a 3-ply cotton mask reduced aerosol exposure by 50% or more compared to scenarios with simulators unmasked. While evaluating the effect of Source placement, Recipients had the highest exposure at 0.9 m in a face-to-face orientation. Ventilation reduced exposure by approximately 5% per unit increase in air change per hour (ACH), irrespective of whether increases in ACH were by the HVAC system or portable HEPA air cleaners. The results demonstrate that mitigation strategies, such as universal masking and increasing ventilation, reduce personal exposure to respiratory aerosols within a meeting room. While universal masking remains a key component of a layered mitigation strategy of exposure reduction, increasing ventilation via system HVAC or portable HEPA air cleaners further reduces exposure.

Preclinical Efficacy and Clinical Feasibility of a Novel Aerosol-Exposure Protection Mask for Esophagogastroduodenoscopy.

Background/AimsThis study aimed to assess the efficacy of a novel aerosol-exposure protection (AP) mask in preventing coronavirus disease in healthcare professionals during upper gastrointestinal endoscopy and to evaluate its clinical feasibility. MethodsIn Study 1, three healthy volunteers volitionally coughed with and without the AP mask in a cleanroom. Microparticles were visualized and counted with a specific measurement system and compared with and without the AP mask. In Study 2, 30 patients underwent endoscopic resection with the AP mask covering the face, and the SpO2 was measured throughout the procedure. ResultsIn Study 1, the median number of microparticles in volunteers 1, 2, and 3 with and without the AP mask was 8.5 and 110.0, 7.0 and 51.5, and 8.0 and 95.0, respectively (p<0.01). Using the AP mask, microparticles were reduced by approximately 92%. The median distances of microparticle scattering without the AP mask were 60, 0, and 68 in volunteers 1, 2, and 3, respectively. In Study 2, the mean SpO2 was 96.3%, and desaturation occurred in three patients.ConclusionThe AP mask could provide protection from aerosol exposure and can be safely used for endoscopy in clinical practice.

Investigations into the efficacy of a novel extubation-aerosol shield: a cough model study

SummaryBackgroundPhysicians have had to perform numerous extubation procedures during the prolonged coronavirus disease 2019 (COVID 19) pandemic. Future pandemics caused by unknown pathogen may also present a risk of exposure to infectious droplets and aerosols.AimThis study evaluated the ability of a newly developed aerosol barrier, “Extubation-Aerosol (EA)-Shield” to provide maximum protection from aerosol exposure during extubation via an aerosolised particle count and high-quality visualisation assessments.MethodsWe employed a cough model having parameters similar to humans and used micron oil aerosol as well as titanium dioxide as aerosol tracers. Aerosol barrier techniques employing a face mask (group M) and EA-Shield (group H) were compared.FindingsThe primary outcome was the difference in the number of particles contacting the physician's face before and after extubation. The maximum distances of aerosol dispersal after extubation were measured as the secondary outcomes. All aerosolised particles of the two tracers were significantly smaller in group H than in group M (p < 0.05). In addition, the sagittal and axial maximum distances and sagittal areas of aerosol dispersal for 3, 5, and 10 s after extubation were significantly smaller in group H than in group M (p < 0.05).ConclusionThis model indicates that EA-Shield could be highly effective in reducing aerosol exposure during extubation. Therefore, we recommend using it as an aerosol barrier when an infectious aerosol risk is suspected.

Aerosol exposure assessment during reclaimed water utilization in China and risk evaluation in case of Legionella

Aerosol exposure assessment during reclaimed water utilization in China and risk evaluation in case of Legionella

Impact of aerosols on liver xenobiotic metabolism: A comparison of two methods of exposure

Assessment of aerosols effects on liver CYP function generally involves aqueous fractions (AF). Although easy and efficient, this method has not been optimized recently or comparatively assessed against other aerosol exposure methods. Here, we comparatively evaluated the effects of the AFs of cigarette smoke (CS) and Tobacco Heating System (THS) aerosols on CYP activity in liver spheroids. We then used these data to develop a physiological aerosol exposure system combining a multi-organs-on-a-chip, 3D lung tissues, liver spheroids, and a direct aerosol exposure system. Liver spheroids incubated with CS AF showed a dose-dependent increase in CYP1A1/1B1, CYP1A2, and CYP2B6 activity and a dose-dependent decrease in CYP2C9, CYP2D6, and CYP3A4 activity relative to untreated tissues. In our physiological exposure system, repeated CS exposure of the bronchial tissues also caused CYP1A1/1B1 and CYP1A2 induction in the bronchial tissues and liver spheroids; but the spheroids showed an increase in CYP3A4 activity and no effect on CYP2C9 or CYP2D6 activity relative to air-exposed tissues, which resembles the results reported in smokers. THS aerosol did not affect CYP activity in bronchial or liver tissues, even at 4 times higher concentrations than CS. In conclusion, our system allows us to physiologically test the effects of CS or other aerosols on lung and liver tissues cultured in the same chip circuit, thus delivering more in vivo like data.

Simulation and evaluation of the protective barrier enclosure for cardiopulmonary resuscitation

IntroductionThe COVID-19 pandemic has presented a significant challenge for infection prevention and control during airway management in anaesthesia and critical care. The protective barrier enclosure has been described and studied particularly for perioperative anaesthesia use. The potential use of the protective barrier enclosure during cardiopulmonary resuscitation has been poorly explored in the current literature. This work aims to demonstrate the potential of protective barrier enclosure in limiting aerosol dispersion during cardiopulmonary resuscitation delivery. MethodsA proof-of-concept simulation study was conducted to evaluate the protective properties of the protective barrier enclosure during cardiopulmonary resuscitation. Aerosol was simulated using a fluorescent dye trapped within the manikin. Three different methods of cardiopulmonary resuscitation delivery with a protective barrier enclosure applied over the manikin’s head were conducted. The first method simulated a chest compression only cardiopulmonary resuscitation, the second method also used chest compressions only, with a face mask fitted on the victim, while the third method, the victim was given chest compression and bag-valve-mask ventilation by two rescuers. ResultsIn the first method, release of aerosol from the manikin’s mouth was observed during chest compression, while in second method, most of the aerosol was trapped within the face mask, with only minor leaking. However, when bag-valve-mask ventilation was delivered, the aerosol leaked out at high speed around the bag-valve-mask seal. No aerosol condensation was found outside of the protective barrier enclosure in all scenes. ConclusionProtective barrier enclosure may reduce aerosol exposure to the rescuers during out-of-hospital cardiac arrest.

Nose-only inhalations of high-dose alumina nanoparticles/hydrogen chloride gas mixtures induce strong pulmonary pro-inflammatory response: a pilot study

Objective Solid composite propellants combustion, in aerospace and defense fields, can lead to complex aerosols emission containing high concentrations of alumina nanoparticles (Al2O3 NPs) and hydrogen chloride gas (HClg). Exposure to these mixtures by inhalation is thus possible but literature data toward their pulmonary toxicity are missing. To specify hazards resulting from these combustion aerosols, a pilot study was implemented. Materials and methods Male Wistar rats were nose-only exposed to Al2O3 NPs (primary size 13 nm, 10 g/L suspension leading to 20.0–22.1 mg/m3 aerosol) and/or to HClg aerosols (5 ppm target concentration) following two exposure scenarios (single exposures (SE) or repeated exposures (RE)). Bronchoalveolar lavage fluids (BALF) content and lungs histopathology were analyzed 24 h after exposures. Results Repeated co-exposures increased total proteins and LDH concentrations in BALF indicating alveolar–capillary barrier permeabilization and cytolysis. Early pulmonary inflammation was induced after RE to Al2O3 NPs ± HClg resulting in PMN, TNF-α, IL-1β, and GRO/KC increases in BALF. Both exposure scenarios resulted in pulmonary histopathological lesions (vascular congestions, bronchial pre-exfoliations, vascular and interalveolar septum edemas). Lung oxidative damages were observed in situ following SE. Conclusion Observed biological effects are dependent on both aerosol content and exposure scenario. Results showed an important pro-inflammatory effect of Al2O3 NPs/HClg mixtures on the lungs of rat 24 h after exposure. This pilot study raises concerns toward potential long-term pulmonary toxicity of combustion aerosols and highlights the importance for further studies to be led in order to define dose limitations and exposure thresholds for risk management at the work place.

A novel clinical method to measure skin staining reveals activation of skin damage pathways by cigarette smoke.

BackgroundLong‐term use of cigarettes can result in localised staining and aging of smokers’ skin. The use of tobacco heating products (THPs) and electronic cigarettes (ECs) has grown on a global scale; however, the long‐term effect of these products’ aerosols on consumers’ skin is unknown. This pilot clinical study aimed to determine whether THP or EC aerosol exposure results in skin staining or activation of biomarkers associated with oxidative stress.Materials and methodsEight areas were identified on the backs of 10 subjects. Two areas were used for air control, and two areas exposed to 32‐puffs of cigarette smoke (CS), THP or EC aerosols, which were delivered to the skin using a 3‐cm diameter exposure chamber and smoke engine. Skin colour was measured using a Chromameter. Squalene (SQ), SQ monohydroperoxide (SQOOH) and malondialdehyde (MDA) levels were measured in sebum samples by mass spectrometry and catalase colorimetry.ResultsCS exposure significantly increased skin staining, SQOOH and MDA levels and SQOOH/SQ ratio. THP and EC values were significantly lower than CS; EC values being comparable to air control. THP values were comparable to EC and air control at all endpoints, apart from skin staining. SQ and catalase levels did not change with exposure.ConclusionsCS stained skin and activated pathways known to be associated with skin damage. THPs and ECs produced significantly lower values, suggesting they could offer hygiene and cosmetic benefits for consumers who switch exclusively from smoking cigarettes. Further studies are required to assess longer‐term effects of ECs and THPs on skin function.

Cigarette Smoke and E-Cigarette Aerosols Lead to Clonal Expansion of Tet2 -/- and Dnmt3a R878H Cells In Vivo

Background:Environmental factors must play a significant role in the emergence of clonal hematopoiesis since only a fraction of individuals harboring clonal hematopoiesis of indeterminate potential (CHIP) mutations develop hematologic malignancy. Mouse models of chronic inflammation have demonstrated clonal expansion of Tet2 and Dnmt3a knockout hematopoietic cells while Ppm1d mutated clones exhibit clonal dominance in response to cytotoxic DNA damaging chemotherapy stress. Epidemiologic studies have associated smoking behavior with clonal hematopoiesis but the leukemogenic effects of cigarette smoke on hematopoietic stem cells (HSCs) are poorly defined. In addition, the exploding use of electronic (e)-cigarettes has led to significant concern on their detrimental health effects plus studies of E-cigarettes on the hematopoietic system are non-existent. Here, we investigated the role of cigarette smoke and E-cigarette aerosols in promoting clonal expansion of common CHIP mutations. We hypothesize that one or more specific somatic CHIP mutation displays a fitness advantage in the presence of cigarette smoke and/or e-cigarette aerosols.Methods:Competitive bone marrow transplant assays were used to determine the development of clonal expansion in response to cigarette smoke and E-cigarette aerosols using Tet2 knockout (Tet2 -/-), Dnmt3a R878H and Jak2 V617F genetically modified mice. Lethally irradiated recipient mice in the CD45.1/2 background were transplanted with whole bone marrow cells from wild type (WT) (CD45.1) and mutant (CD45.2) mice. Ratio of cells transplanted were 1:10 for Tet2 -/- and WT; 1:5 for Dnmt3a R878H and WT and 1:1 for Jak2 V617F and WT. Transplanted mice were exposed to cigarette smoke or E-cigarette aerosols using a nose-only inhalation exposures system for 2 hours/day, 4 days/week for 2 or 3 months. Control mice were exposed to room air using the nose-only inhalation approach.Results:After 2 months of exposure, we observed that Tet2 -/- cells had significantly expanded in the smoke group (paired t-test, p<0.05) while there was no significant difference in the air group (Fig. 1A). Furthermore, this increase in Tet2 -/- cells was more pronounced in the myeloid cell subset (Fig. 1B). While the knock-in mouse model of Jak2 V617F does not display a competitive advantage in a lethally irradiated bone marrow transplant setting, we observed persisting levels of Jak2 V617F mutant cells following smoke exposure but significantly reduced levels in the air group, illustrating that the mutant cells prevail in a smoke environment (Fig. 1C). During sacrifice of the Jak2 V617F transplanted and exposed mice, long-term HSCs in the bone marrow exhibited a trend towards increased bromodeoxyuridine (BrdU) incorporation and increased DNA damage as determined by H2AX staining (Fig 1D). Meanwhile, E-cigarette aerosol exposure of mice transplanted with Dnmt3a R878H cells, displayed increased levels of circulating mutant cells compared to the air group (Fig. 1E) (repeated measures, 2-way ANOVA).Conclusion:In vivo exposure of mouse models of CHIP to cigarette smoke and E-cigarette aerosols promotes mutant cell expansion over time. Our data indicate that more than one mutation is selected by environmental factors in the form of tobacco products. This data is important to guide us in preventive medicine and early detection of clonal hematopoiesis. Future research is aimed at deciphering the molecular responses of WT cells to cigarette smoke and E-cigarette aerosols and strategies to preserve WT stem cell fitness in the context of smoking and E-cigarette usage. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

In vitro hazard characterization of simulated aircraft cabin bleed-air contamination in lung models using an air-liquid interface (ALI) exposure system.

Contamination of aircraft cabin air can result from leakage of engine oils and hydraulic fluids into bleed air. This may cause adverse health effects in cabin crews and passengers. To realistically mimic inhalation exposure to aircraft cabin bleed-air contaminants, a mini bleed-air contaminants simulator (Mini-BACS) was constructed and connected to an air-liquid interface (ALI) aerosol exposure system (AES). This unique "Mini-BACS+AES" setup provides steady conditions to perform ALI exposure of the mono- and co-culture lung models to fumes from pyrolysis of aircraft engine oils and hydraulic fluids at respectively 200°C and 350°C. Meanwhile, physicochemical characteristics of test atmospheres were continuously monitored during the entire ALI exposure, including chemical composition, particle number concentration (PNC) and particles size distribution (PSD). Additional off-line chemical characterization was also performed for the generated fume. We started with submerged exposure to fumes generated from 4 types of engine oil (Fume A, B, C, and D) and 2 types of hydraulic fluid (Fume E and F). Following submerged exposures, Fume E and F as well as Fume A and B exerted the highest toxicity, which were therefore further tested under ALI exposure conditions. ALI exposures reveal that these selected engine oil (0-100mg/m3) and hydraulic fluid (0-90mg/m3) fumes at tested dose-ranges can impair epithelial barrier functions, induce cytotoxicity, produce pro-inflammatory responses, and reduce cell viability. Hydraulic fluid fumes are more toxic than engine oil fumes on the mass concentration basis. This may be related to higher abundance of organophosphates (OPs, ≈2800µg/m3) and smaller particle size (≈50nm) of hydraulic fluid fumes. Our results suggest that exposure to engine oil and hydraulic fluid fumes can induce considerable lung toxicity, clearly reflecting the potential health risks of contaminated aircraft cabin air.

Non‐Marine Sources Contribute to Aerosol Methanesulfonate Over Coastal Seas

AbstractMethanesulfonate (MSA) in the marine boundary layer is commonly considered to be solely contributed by the oxidation of ocean‐derived dimethyl sulfide (DMS) and often used as an indicator of marine biogenic sources. But whether this judgment is valid in coastal seas and how the validity is affected by air mass transport history have been less discussed. Based on multi‐year observations of aerosol MSA in the coastal East China Sea (ECS) and the Gulf of Aqaba (GA), as well as the analysis of air mass transport pattern and exposure to ocean surface phytoplankton biomass, we found that terrestrial sources made a non‐negligible contribution to MSA over the ECS but not over the GA. The abundant MSA in winter over the coastal ECS was likely associated with substantial emissions of volatile organic sulfur compounds from both anthropogenic and natural sources in eastern China and significant terrestrial transport influenced by the East Asian Monsoon. Good correlations between aerosol MSA and air mass exposure to surface phytoplankton biomass were established by removing the influence of terrestrial transport and confining the air transport height within boundary layer, which makes it possible to construct parameterizations for obtaining the spatiotemporal distributions of marine biogenic aerosol components using satellite ocean color datasets.

Effect of E-cigarettes aerosol exposure during lactation in rats: Hormonal and biochemical aspects

Electronic cigarettes (e-cigarettes) have been marketed as a less lethal substitute for smoking traditional cigarettes. This study aims to investigate the impact of e-cigarettes aerosol exposure on lactating dams and pups, whose dams were exposed. Lactating dams received fresh air (control) or e-cigarettes aerosol during lactation (day 4–21). Maternal exposure to e-cigarettes aerosol during lactation induced significant reduction (P < 0.0001) in the fat content of the milk and serum Leptin level (P < 0.005) compared to control dams. Furthermore, pups whose dams were exposed to e-cigarettes during lactation showed an increased level of glucose, thyroxine and decreased level of insulin. The exposure to e-cigarettes aerosol during lactation altered the composition of milk as well as the hormonal and biochemical profile in dams and pups. This result, if observed in women using e-cigarettes, suggests that e-cigarettes’ use during lactation may have consequences on the milk production and hormonal and biochemical profile in breastfeeding mothers and nursing babies.

Controlling risk of SARS-CoV-2 infection in essential workers of enclosed food manufacturing facilities.

The SARS-CoV-2 global pandemic poses significant health risks to workers who are essential to maintaining the food supply chain. Using a quantitative risk assessment model, this study characterized the impact of risk reduction strategies for controlling SARS-CoV-2 transmission (droplet, aerosol, fomite-mediated) among front-line workers in a representative indoor fresh fruit and vegetable manufacturing facility. We simulated: 1) individual and cumulative SARS-CoV-2 infection risks from close contact (droplet and aerosols at 1–3 m), aerosol, and fomite-mediated exposures to a susceptible worker following exposure to an infected worker during an 8 h-shift; and 2) the relative reduction in SARS-CoV-2 infection risk attributed to infection control interventions (physical distancing, mask use, ventilation, surface disinfection, hand hygiene, vaccination). Without mitigation measures, the SARS-CoV-2 infection risk was largest for close contact (droplet and aerosol) at 1 m (0.96, 5th – 95th percentile: 0.67–1.0). In comparison, risk associated with fomite (0.26, 5th – 95th percentile: 0.10–0.56) or aerosol exposure alone (0.05, 5th – 95th percentile: 0.01–0.13) at 1 m distance was substantially lower (73–95%). At 1 m, droplet transmission predominated over aerosol and fomite-mediated transmission, however, this changed by 3 m, with aerosols comprising the majority of the exposure dose. Increasing physical distancing reduced risk by 84% (1–2 m) and 91% (1–3 m). Universal mask use reduced infection risk by 52–88%, depending on mask type. Increasing ventilation (from 0.1 to 2–8 air changes/hour) resulted in risk reductions of 14–54% (1 m) and 55–85% (2 m). Combining these strategies, together with handwashing and surface disinfection, resulted in <1% infection risk. Partial or full vaccination of the susceptible worker resulted in risk reductions of 73–92% (1 m risk range: 0.08–0.26). However, vaccination paired with other interventions (ACH 2, mask use, or distancing) was necessary to achieve infection risks <1%. Current industry SARS-CoV-2 risk reduction strategies, particularly when bundled, provide significant protection to essential food workers.

Front lines of the COVID-19 pandemic: what is the effectiveness of using personal protective equipment in health service environments?-a systematic review.

PurposeThis systematic review aimed to evaluate the effectiveness of the use of personal protective equipment (PPE) in closed environments, similar to waiting or exam rooms of healthcare facilities, in the face of exposure to a bioaerosol.MethodsCombinations of words were selected for six electronic databases and for the gray literature. To consider the eligibility of the studies to be included/excluded, the acronym “PECOS” was used: humans and/or experimental models that simulate aerosol (Population); aerosol exposure and the use of masks/respirators (exposition/intervention); controlled or not controlled (comparison); effectiveness of PPE and the receiver exposure (outcomes); and randomized clinical studies or not, observational or laboratory simulation studies (Studies design).ResultsA total of 4820 references were retrieved by the search strategy. Thirty-five articles were selected for complete reading, of which 13 articles were included for qualitative synthesis. A surgical mask or N95 respirator reduced the risk of transmission, even over short distances. The use of masks, even those with less filtering power, when used by all individuals in the same environment is more effective in reducing risk than the use of respirators with high filtering power for only some of the individuals present.ConclusionThe use of mask in closed environments is effective in reducing the risk of transmission and contagion of a contaminated bioaerosol, with greater effectiveness when these devices are used by the source and receiver, regardless of the equipment’s filtering power. (PROSPERO 2020 CRD 42020183759).Supplementary InformationThe online version contains supplementary material available at 10.1007/s00420-021-01775-y.

72 A One-health Perspective on S. aureus Induced Mastitis

Abstract Bovine mastitis, commonly caused by bacteria, is one of the most devastating diseases for the dairy industry worldwide, with high economic, social, and public health impacts. Among the pathogenic bacteria, Staphylococcus aureus is one of the leading pathogens in most countries. Success rate of antibiotic treatment is low such that effective control of S. aureus induced mastitis is currently only possible through prevention of new infections and culling of infected animals. The infection is usually subclinical, causing elevated somatic cell counts but no detectable changes in milk or the udder. S. aureus persists in mammary glands, teat canals, and teat lesions of infected cows and is transmitted to other cows during milking. The direct evidence of cross-species transmission of S. aureus is still scarce. Nevertheless, accumulating indirect evidence supports the zoonotic potential for S. aureus from bovine mastitis to humans. In addition to direct contact, aerosol exposures may also be an important mechanism for the transmission. While animal-adapted livestock-associated methicillin-resistant S. aureus has been known for many years, most S. aureus isolated from mastitic milk in Canada are methicillin-sensitive. S. aureus induced mastitis is a common reason for therapeutic and/or prophylactic use of antibiotics on dairy farms. Occurrence of multidrug resistant, especially methicillin-resistant, S. aureus has been a major public health concern. In this talk, we will address the pathogenesis and strain spectrum of S. aureus induced bovine mastitis, review existing evidence for inter-species transmission, and discuss possible transmission of methicillin-resistance determinants. This talk aims to emphasize the need for the one-health approach for prevention and treatment of S. aureus induced mastitis, in order to provide safe and nutritious milk and milk products to consumers.

Sensitivity analysis of SARS-CoV-2 aerosol exposure.

As vaccination campaigns are in progress in most countries, hopes to win back more normality are rising. However, the exact path from a pandemic to an endemic virus remains uncertain. While in the pre-vaccination phase many critical indoor situations were avoided by strict control measures, for the transition phase a certain mitigation of the effect of indoor situations seems advisable. To better understand the mechanisms of indoor airborne transmissions, we present a new time-discrete model to calculate the level of exposure towards infectious SARS-CoV-2 aerosol and carry out a sensitivity analysis for the level of SARS-CoV-2 aerosol exposure in indoor settings. Time limitations and the use of any kind of masks were found to be strong mitigation measures, while how far the effort for a strict use of professional face pieces instead of simple masks can be justified by the additional reduction of the exposure dose remains unclear. Very good ventilation of indoor spaces is mandatory. The definition of sufficient ventilation in regard to airborne SARS-CoV-2 transmission follows other rules than the standards in ventilation design. This means that especially smaller rooms most likely require a significantly greater fresh air supply than usual. Further research on 50% group models in schools is suggested. The benefits of a model in which the students come to school every day, but for a limited time, should be investigated. In terms of window ventilation, it has been found that many short opening periods are not only thermally beneficial, they also reduce the exposure dose. The fresh air supply is driven by the temperature gradient and wind speed. However, the sensitivity towards these parameters is not very high and in times of low wind and temperature gradients, there are no arguments against keep windows open in order to make up for the reduced air flow rate. Long total opening periods and large window surfaces will strongly reduce the exposure. Additionally, the results underline the expectable fact that exposure doses will increase when hygiene and control measures are reduced. It seems advisable to investigate what this means for the infection rate and the fatality of infections in populations with partial immunity. Very basic considerations suggest that the value of aerosol reduction measures may be reduced with very infectious variants such as delta.

Paper-in-Facemask Device for Direct Mass Spectrometry Analysis of Human Respiratory Aerosols and Environmental Exposures via Wearable Continuous-Flow Adsorptive Sampling: A Proof-of-Concept Study.

Facemasks are considered safe and wearable devices that cover the human mouth and nose for filtering exhaled aerosols and inhaled environmental exposures; various chemical and environmental residues thus can remain in facemasks. Therefore, direct analysis of residues in facemasks can be used to investigate the wearer's health and behavior. Here, we developed a simple paper-in-facemask sampling method for adsorbing a wearer's respiratory aerosol and environmental exposures by fixing paper strips at the outside and inside surfaces of facemasks, and the paper strips were then analyzed by paper spray mass spectrometry (PSMS) for directly detecting adsorbed analytes without any sample pretreatment. The applicability of this device was demonstrated by directly analyzing exhaled aerosolized saliva, breath metabolites, and inhalable environmental exposures. The technical aspects, including sampling time, sampling position, paper property, and spray solvent, were investigated. The sampling process was revealed to involve a continuous-flow adsorptive mechanism. These findings motivated us to extend this work and build a wearable sampling device that is capable of simultaneously monitoring both exhaled and inhaled biomarkers in situ to investigate human health and environmental exposure. This work highlights that facemasks are promising platforms for aerosol collection and direct MS analysis, which is expected to be a promising method for monitoring human health, diseases, and behaviors.

Investigation of the potential of aerosolized Salmonella Enteritidis on colonization and persistence in broilers from day 3 to 21

The presence of Salmonella in air of poultry houses has been previously confirmed. Therefore, it is important to investigate the entry of Salmonella into broilers through air. The present study aimed to evaluate different levels of Salmonella Enteritidis aerosol inoculations in broiler chicks for colonization of ceca, trachea, and liver/spleen and persistence over time. In 3 independent trials, 112 one-day-old birds were randomly divided into 4 groups (n = 28/group). On d 1 of age, one group was exposed to an aerosol of sterile saline and the remaining three groups were exposed to an aerosol generated from one of 3 doses (103, 106, or 109 CFU/mL) of S. Enteritidis inoculum. Aerosol exposure time was 30 min/group and was performed using a nebulizer. On d 3, 7, 14, and 21 of age, ceca, trachea, and liver/spleen were aseptically removed. Ceca were cultured for Salmonella counts (log10 CFU/g) and all tissues were cultured for Salmonella prevalence. All tissues from the control group were Salmonella negative for all sampling days. On sampling d 3 and 7, ceca Salmonella counts were highest (5.14 and 5.11, respectively) when challenged with 109Salmonella (P ≤ 0.0281). Ceca Salmonella counts increased from d 3 (2.43) to d 7 (4.43), then remained constant when challenged at 103Salmonella, and counts decreased over time for all other groups. Tissue Salmonella prevalence increased with increasing challenge levels at all sampling timepoints (P ≤ 0.0213). Salmonella prevalence was low (0/18 to 4/18) and did not change over time following 103Salmonella challenge (P ≥ 0.2394). Prevalence decreased over time in ceca and trachea following 106 and 109Salmonella challenge (P ≤ 0.0483). Liver/spleen Salmonella prevalence increased from d 3 (13/18) to d 14 (18/18) and then decreased at d 21 (10/18) in birds exposed to an aerosol of 109Salmonella but remained constant over time for rest of the Salmonella inoculated groups. Overall, this study demonstrated the Salmonella colonization and persistence in different tissues in broilers following exposure to aerosolized Salmonella.

Neutralizing Concentrations of Anti-Botulinum Toxin Antibodies Positively Correlate with Mouse Neutralization Assay Results in a Guinea Pig Model.

Botulinum neurotoxins (BoNT) are some of the most toxic proteins known and can induce respiratory failure requiring long-term intensive care. Treatment of botulism includes the administration of antitoxins. Monoclonal antibodies (mAbs) hold considerable promise as BoNT therapeutics and prophylactics, due to their potency and safety. A three-mAb combination has been developed that specifically neutralizes BoNT serotype A (BoNT/A), and a separate three mAb combination has been developed that specifically neutralizes BoNT serotype B (BoNT/B). A six mAb cocktail, designated G03-52-01, has been developed that combines the anti-BoNT/A and anti-BoNT/B mAbs. The pharmacokinetics and neutralizing antibody concentration (NAC) of G03-52-01 has been determined in guinea pigs, and these parameters were correlated with protection against an inhalation challenge of BoNT/A1 or BoNT/B1. Previously, it was shown that each antibody demonstrated a dose-dependent mAb serum concentration and reached maximum circulating concentrations within 48 h after intramuscular (IM) or intraperitoneal (IP) injection and that a single IM injection of G03-52-01 administered 48 h pre-exposure protected guinea pigs against an inhalation challenge of up to 93 LD50s of BoNT/A1 and 116 LD50s of BoNT/B1. The data presented here advance our understanding of the relationship of the neutralizing NAC to the measured circulating antibody concentration and provide additional support that a single IM or intravenous (IV) administration of G03-52-01 will provide pre-exposure prophylaxis against botulism from an aerosol exposure of BoNT/A and BoNT/B.