Insights on the methodology for indoor microbial aerosol studies

Covid-19 has highlighted the need for reliable methods for airborne microbe control. Different microbes are suitable for different purposes, and the microbes are sensitive to collection methods used. We identified three safe-to-use microbes suitable for airborne microbial studies: MS2-bacteriophage virus, Staphylococcus simulans and Bacillus atrophaeus bacterial spores. We found that the sensitive microbes (MS2 and S. simulans) survive better, when collected directly in a liquid media. © 2022 17th International Conference on Indoor Air Quality and Climate, INDOOR AIR 2022. All rights reserved.

Simultaneous detection of SARS-CoV-2, influenza A, respiratory syncytial virus, and measles in wastewater by multiplex RT-qPCR.

A multiplex quantitative reverse transcription polymerase chain reaction (RT-qPCR)-based method was designed for the simultaneous detection of influenza A, SARS-CoV-2, respiratory syncytial virus, and measles virus. The performance of the multiplex assay was compared to four monoplex assays for relative quantification using standard quantification curves. Results showed that the multiplex assay had comparable linearity and analytical sensitivity to the monoplex assays, and the quantification parameters of both assays demonstrated minimal differences. Viral reporting recommendations for the multiplex method were estimated based on the corresponding limit of quantification (LOQ) and the limit of detection at 95 % confidence interval (LOD) values for each viral target. The LOQ was determined by the lowest nominal RNA concentrations where %CV values were ≤35 %. Corresponding LOD values for each viral target were between 15 and 25 gene copies per reaction (GC/rxn), and LOQ values were within 10 to 15 GC/rxn. The detection performance of a new multiplex assay was validated in the field by collecting composite wastewater samples from a local treatment facility and passive samples from three sewer shed locations. Results indicated that the assay could accurately estimate viral loads from various sample types, with samples collected from passive samplers showing a greater range of detectable viral concentrations than composite wastewater samples. This suggests that the sensitivity of the multiplex method may be improved when paired with more sensitive sampling methods. Laboratory and field results demonstrate the robustness and sensitivity of the multiplex assay and its applicability to detect the relative abundance of four viral targets among wastewater samples. Conventional monoplex RT-qPCR assays are suitable for diagnosing viral infections. However, multiplex analysis using wastewater provides a fast and cost-effective way to monitor viral diseases in a population or environment.

Multiple Monitoring Stations in Big Cities: First Example of Three Spore Traps in Rome

(1) Background: Rome is a municipality with an area of 1287 km2 and presents floristic-vegetational complexity that is reflected in the composition of aerospora, which are responsible for pollinosis. The presence of airborne pollen can be detected by pollen monitoring. The large extent of the city's territory makes it possible to verify possible changes in pollen composition in different sites of the city. With this in mind, a study was conducted to assess the differences in airborne pollen concentration, considering phenological and production indicators at three different sites in the city. (2) Methods: Pollen data of eight taxa were considered, Alnus spp., Castanea sativa Miller, Cupressaceae-Taxaceae, Olea europaea L., Platanaceae, Poaceae, Quercus spp., and Urticaceae, during 2020 and 2021, using three monitoring samplers. The airborne pollen concentration and the seasons of the three centers were calculated and compared with each other. (3) Results: The diversity between the three samplers shows a phenological succession in accordance with the microclimatic diversity present in the city. The heterogeneity of the airborne pollen concentration reflects the floristic-vegetational diversity, while qualitative and quantitative parameters indicate a homogeneous flowering trend reflecting the seasonality of the various species. (4) Conclusions: The present work and the Italian geographic context suggest the need for a greater number of sampling points to guarantee a true localization of the data. Having several sampling stations also contributes to the protection of health and green areas, which are difficult to manage, conserve, and maintain.

Statistical Inference to the Parameter of the Inverse Power Ishita Distribution under Progressive Type-II Censored Data with Application to COVID-19 Data

The goal of the article is the inference about the parameters of the inverse power ishita distribution (IPID) using progressively type-II censored (Prog–II–C) samples. For IPID parameters, maximum likelihood and Bayesian estimates were obtained. Two bootstrap “confidence intervals” (CIs) are also proposed in addition to “approximate confidence intervals” (ACIs). In addition, Bayesian estimates for “squared error loss” (SEL) and LINEX loss functions are provided. The Gibbs within Metropolis–Hasting samplers process is used to provide Bayes estimators of unknown parameters also “credible intervals” (CRIs) of them by using the “Markov Chain Monte Carlo” (MCMC) technique. Then, an application of the suggested approaches is considered a set of real-life data this data set COVID-19 data from France of 51 days recorded from 1 January to 20 February 2021 formed of mortality rate. To evaluate the quality of the proposed estimators, a simulation study is conducted.

Adsorption of SARS-CoV-2 onto granular activated carbon (GAC) in wastewater: Implications for improvements in passive sampling.

Based on recent studies, passive sampling is a promising method for detecting SARS-CoV-2 in wastewater surveillance (WWS) applications. Passive sampling has many advantages over conventional sampling approaches. However, the potential benefits of passive sampling are also coupled with apparent limitations. We established a passive sampling technique for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater using electronegative filters. Though, it was evident that the adsorption capacity of the filters constrained their use. This work intends to demonstrate an optimized passive sampling technique for SARS-CoV-2 in wastewater using granular activated carbon (GAC). Through bench-scale batch-adsorption studies and sewershed deployments, we established the adsorption characteristics of SARS-CoV-2 and two human feacal viruses (PMMoV and CrAssphage) onto GAC. A pseudo-second-order model best-described adsorption kinetics for SARS-CoV-2 in either deionized (DI) water and SARS-CoV-2, CrAssphage, and PMMoV in wastewater. In both laboratory batch-adsorption experiments and in-situ sewershed deployments, the maximum amount of SARS-CoV-2 adsorbed by GAC occurred at ~60 h in wastewater. In wastewater, the maximum adsorption of PMMoV and CrAssphage by GAC occurred at ~60 h. In contrast, the adsorption capacity was reached in DI water seeded with SARS-CoV-2 after ~35 h. The equilibrium assay modeled the maximum adsorption quantity (qmax) in wastewater with spiked SARS-CoV-2 concentrations using a Hybrid Langmuir-Freundlich equation, a qmax of 2.5 × 109 GU/g was calculated. In paired sewershed deployments, it was found that GAC adsorbs SARS-CoV-2 in wastewater more effectively than electronegative filters. Based on the anticipated viral loading in wastewater, bi-weekly sampling intervals with deployments up to ~96 h are highly feasible without reaching adsorption capacity with GAC. GAC offers improved sensitivity and reproducibility to capture SARS-CoV-2 RNA in wastewater, promoting a scalable and convenient alternative for capturing viral pathogens in wastewater.

Use of Low-Cost Sensors to Characterize Occupational Exposure to PM2.5 Concentrations Inside an Industrial Facility in Santa Ana, CA: Results from a Worker- and Community-Led Pilot Study

PM2.5 is an air contaminant that has been widely associated with adverse respiratory and cardiovascular health, leading to increased hospital admissions and mortality. Following concerns reported by workers at an industrial facility located in Santa Ana, California, workers and community leaders collaborated with experts in the development of an air monitoring pilot study to measure PM2.5 concentrations to which employees and local residents are exposed during factory operating hours. To detect PM2.5, participants wore government-validated AtmoTube Pro personal air monitoring devices during three separate workdays (5 AM–1:30 PM) in August 2021. Results demonstrated a mean PM2.5 level inside the facility of 112.3 µg/m3, nearly seven-times greater than outdoors (17.3 µg/m3). Of the eight workers who wore personal indoor sampling devices, five showed measurements over 100 μg/m3. Welding-related activity inside the facility resulted in the greatest PM2.5 concentrations. This study demonstrates the utility of using low-cost air quality sensors combined with employee knowledge and participation for the investigation of workplace air pollution exposure as well as facilitation of greater health-related awareness, education, and empowerment among workers and community members. Results also underscore the need for basic measures of indoor air pollution control paired with ongoing air monitoring within the Santa Ana facility, and the importance of future air monitoring studies aimed at industrial facilities.

Monitoring of SARS-CoV-2 in sewersheds with low COVID-19 cases using a passive sampling technique.

Monitoring SARS-CoV-2 RNA in sewer systems, upstream of a wastewater treatment plant, is an effective approach for understanding potential COVID-19 transmission in communities with higher spatial resolutions. Passive sampling devices provide a practical solution for frequent sampling within sewer networks where the use of autosamplers is not feasible. Currently, the design of upstream sampling is impeded by limited understanding of the fate of SARS-CoV-2 RNA in sewers and the sensitivity of passive samplers for the number of infected individuals in a catchment. In this study, passive samplers containing electronegative membranes were applied for at least 24-h continuous sampling in sewer systems. When monitoring SARS-CoV-2 along a trunk sewer pipe, we found RNA signals decreased proportionally to increasing dilutions, with non-detects occurring at the end of pipe. The passive sampling membranes were able to detect SARS-CoV-2 shed by >2 COVID-19 infection cases in 10,000 people. Moreover, upstream monitoring in multiple sewersheds using passive samplers identified the emergence of SARS-CoV-2 in wastewater one week ahead of clinical reporting and reflected the spatiotemporal spread of a COVID-19 cluster within a city. This study provides important information to guide the development of wastewater surveillance strategies at catchment and subcatchment levels using different sampling techniques.

Development of passive samplers for the detection of SARS-CoV-2 in sewage and seawater: Application for the monitoring of sewage.

Recent studies have shown that passive sampling is a promising tool for SARS-CoV-2 detection for wastewater-based epidemiology (WBE) application. We have previously developed passive sampling of viruses using polymer membranes in seawater. Even though SARS-CoV-2 was not detected yet in seawater, passive sampling could be optimized for future application in coastal areas close to wastewater treatment plant (WWTP). The aim of this study was to optimize passive sampling of SARS-CoV-2 in sewage and seawater by selecting a suitable membrane, to determine whether the quantities of virus increase over time, and then to determine if passive sampling and traditional sampling are correlated when conducted in a wastewater treatment plant. Nylon and Zetapor allowed the detection of heat inactivated SARS-CoV-2 and of the Porcine Epidemic Diarrhea Virus (PEDV), a coronavirus surrogate, in wastewater and seawater spiked with these 2 viruses, showing an increase in detection between 4 h and 24 h of immersion and significantly higher recoveries of both viruses with nylon in seawater (15%) compared to wastewater (4%). On wastewater samples, both membranes detected the virus, the recovery rate was of about 3% for freshly collected samples, and no significant difference was found between SARS-CoV-2 genome concentration on Zetapor and that in water. In sewage spiked seawater, similar concentrations of genome were found on both membranes, with a mean recovery rate of 16% and 11% respectively for nylon and Zetapor. A 3-weeks monitoring with passive sampler allowed the detection of viruses in the influent of a WWTP with a frequency of 100% and 76% for SARS-CoV-2 and norovirus GII respectively. Passive and traditional sampling gave the same evolution of the SARS-CoV-2 concentration over time. All these results confirmed the interest of passive sampling for virus detection and its potential application for monitoring in the wastewater system for targeted public health actions.

Development of Quantitative Real-Time PCR for Detecting Environmental DNA Derived from Marine Macrophytes and Its Application to a Field Survey in Hiroshima Bay, Japan

The sequestration and storage of carbon dioxide by marine macrophytes is called blue carbon;this ecosystem function of coastal marine ecosystems constitutes an important countermeasure to global climate change. The contribution of marine macrophytes to blue carbon requires a detailed examination of the organic carbon stock released by these macrophytes. Here, we introduce a quantitative real-time polymerase chain reaction (qPCR)-based environmental DNA (eDNA) system for the species-specific detection of marine macrophytes. and report its application in a field survey in Hiroshima Bay, Japan. A method of qPCR-based quantification was developed for mangrove, seagrass, Phaeophyceae, Rhodophyta and Chlorophyta species, or species-complex, collected from the Japanese coast to investigate their dynamics after they wither and die in the marine environment. A trial of the designed qPCR system was conducted using sediment samples from Hiroshima Bay. Ulva spp. were abundant in coastal areas of the bay, yet their eDNA in the sediments was scarce. In contrast, Zostera marina and the Sargassum subgenus Bactrophycus spp. were found at various sites in the bay, and high amounts of their eDNA were detected in the sediments. These results suggest that the fate of macrophyte-derived organic carbon after death varies among species.

Operational Constraints of Detecting SARS-CoV-2 on Passive Samplers using Electronegative Filters: A Kinetic and Equilibrium Analysis

In developing an effective monitoring program for the wastewater surveillance of SARS-CoV-2 ribonucleic acid (RNA), the importance of sampling methodology is paramount. Passive sampling has been shown to be an effective tool to detect SARS-CoV-2 RNA in wastewater. However, the adsorption characteristics of SARS-CoV-2 RNA on passive sampling material are not well-understood, which further obscures the relationship between wastewater surveillance and community infection. In this work, adsorption kinetics and equilibrium characteristics were evaluated using batch-adsorption experiments for heat-inactivated SARS-CoV-2 (HI-SCV-2) adsorption to electronegative filters. Equilibrium isotherms were assessed or a range of total suspended solids (TSS) concentrations (118, 265, and 497 mg L-1) in wastewater, and a modeled q(max) of 7 X 10(3) GU cm(-2) was found. Surrogate adsorption kinetics followed a pseudo-first-order model in wastewater with maximum concentrations achieved within 24 h. In both field and isotherm experiments, equilibrium behavior and viral recovery were found to be associated with wastewater and eluate TSS. On the basis of the results of this study, we recommend a standard deployment duration of 24-48 h and the inclusion of eluate TSS measurement to assess the likelihood of solids inhibition during analysis.

Investigation of Sources, Diversity, and Variability of Bacterial Aerosols in Athens, Greece: A Pilot Study

We characterized the composition, diversity, and potential bacterial aerosol sources in Athens’ urban air by DNA barcoding (analysis of 16S rRNA genes) during three seasons in 2019. Air samples were collected using the recently developed Rutgers Electrostatic Passive Sampler (REPS). It is the first field application of REPS to study bacterial aerosol diversity. REPS samplers captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, we detected 793 operational taxonomic units (OTUs), which were fully classified into the six distinct taxonomic categories (Phylum, Class, Order, etc.). These OTUs belonged to Phyla Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Fusobacteria. We found a complex community of bacterial aerosols with several opportunistic or potential pathogens in Athens’ urban air. Referring to the available literature, we discuss the likely sources of observed airborne bacteria, including soil, plants, animals, and humans. Our results on bacterial diversity are comparable to earlier studies, even though the sampling sites are different or geographically distant. However, the exact functional and ecological role of bioaerosols and, even more importantly, their impact on public health and the ecosystem requires further air monitoring and analysis.

SARS-CoV-2 Detection in air samples from inside heating, ventilation, and air conditioning (HVAC) systems- COVID surveillance in student dorms.

BACKGROUND: The COVID-19 pandemic affected universities and institutions and caused campus shutdowns with a transition to online teaching models. To detect infections that might spread on campus, we pursued research towards detecting SARS-CoV-2 in air samples inside student dorms. METHODS: We sampled air in 2 large dormitories for 3.5 months and a separate isolation suite containing a student who had tested positive for COVID-19. We developed novel techniques employing 4 methods to collect air samples: Filter Cassettes, Button Sampler, BioSampler, and AerosolSense sampler combined with direct qRT-PCR SARS-CoV-2 analysis. RESULTS: For the 2 large dorms with the normal student population, we detected SARS-CoV-2 in 11 samples. When compared with student nasal swab qRT-PCR testing, we detected SARS-CoV-2 in air samples when a PCR positive COVID-19 student was living on the same floor of the sampling location with a detection rate of 75%. For the isolation dorm, we had a 100% SARS-CoV-2 detection rate with AerosolSense sampler. CONCLUSIONS: Our data suggest air sampling may be an important SARS-CoV-2 surveillance technique, especially for buildings with congregant living settings (dorms, correctional facilities, barracks). Future building designs and public health policies should consider implementation of Heating, Ventilation, and Air Conditioning surveillance.

Passive sampling, a practical method for wastewater-based surveillance of SARS-CoV-2.

In search of practical and affordable tools for wastewater-based surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), three independent field experiments were conducted using three passive sampler sorbents (electronegative membrane, cotton bud, and gauze) in Guelph, Ontario, Canada. Total daily cases during this study ranged from 2 to 17/100,000 people and 43/54 traditionally collected wastewater samples were positive for SARS-CoV-2 with mean detectable concentrations ranging from 8.4 to 1780 copies/ml. Viral levels on the passive samplers were assessed after 4, 8, 24, 48, 72, and 96 hrs of deployment in the wastewater and 43/54 membrane, 42/54 gauze, and 27/54 cotton bud samples were positive. A linear accumulation rate of SARS-CoV-2 on the membranes was observed up to 48 hours, suggesting the passive sampler could adequately reflect wastewater levels for up to two days of deployment. Due the variability in accumulation observed for the cotton buds and gauzes, and the pre-processing steps required for the gauzes, we recommend membrane filters as a simple cost-effective option for wastewater-based surveillance of SARS-CoV-2.