Dependence on relative humidity in the formation of reactive oxygen species in water droplets

Proceedings of the National Academy of Sciences, Journal Year: 2024, Volume and Issue: 121(12)

Published: March 15, 2024

Water microdroplets (7 to 11 µm average diameter, depending on flow rate) are sprayed in a closed chamber at ambient temperature, whose relative humidity (RH) is controlled. The resulting concentration of ROS (reactive oxygen species) formed the microdroplets, measured by amount hydrogen peroxide (H 2 O ), determined nuclear magnetic resonance (NMR) and spectrofluorimetric assays after droplets collected. results found agree closely with one another. In addition, hydrated hydroxyl radical cations (•OH-H 3 + ) recorded from using mass spectrometry superoxide anions (•O − radicals (•OH) electron paramagnetic spectroscopy. As RH varies 15 95%, H shows marked rise factor about 3.5 going 50%, then levels off. By replacing water deuterium oxide (D O) but keeping gas surrounding O, spectrometric analysis demonstrates that air plays dominant role producing other ROS, which accounts for variation RH. increases, droplet evaporation rate decreases. These two facts help us understand why viruses both survive better low values, as indoor wintertime, disinfected more effectively higher summertime, thus explaining recognized seasonality airborne viral infections.

Language: Английский

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Review of factors affecting virus inactivation in aerosols and droplets

Journal of The Royal Society Interface, Journal Year: 2024, Volume and Issue: 21(215)

Published: June 1, 2024

The inactivation of viruses in aerosol particles (aerosols) and droplets depends on many factors, but the precise mechanisms are not known. system involves complex physical biochemical interactions. We reviewed literature to establish current knowledge about these identify gaps. identified 168 relevant papers grouped results by following factors: virus type structure, or droplet size, temperature, relative humidity (RH) evaporation, chemical composition droplet, pH atmospheric composition. These factors influence dynamic microenvironment surrounding a virion thus may affect its inactivation. Results indicate that experience biphasic decay as carrier aerosols undergo evaporation equilibrate with air, their final state (liquid, semi-solid solid) RH. Virus stability, RH temperature interrelated, effects multifaceted still completely understood. Studies impact stability have raised new questions require further exploration. frequent practice studying large culture media limit our understanding for transmission, so we encourage use physiologically size future research.

Language: Английский

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Seasonal influenza viruses decay more rapidly at intermediate humidity in droplets containing saliva compared to respiratory mucus

Applied and Environmental Microbiology, Journal Year: 2024, Volume and Issue: 90(2)

Published: Jan. 9, 2024

Expulsions of virus-laden aerosols or droplets from the oral and nasal cavities an infected host are important source onward respiratory virus transmission. However, presence infectious influenza in cavity during infection has not been widely considered, thus, little work explored environmental persistence expulsions. Using ferret model, we detected cavities, suggesting that can be expelled into environment both anatomical sites. We also assessed stability two A viruses (H1N1 H3N2) human saliva mucus over a range relative humidities. observed infectivity decays rapidly at intermediate humidity, while airway surface liquid retain infectivity. Virus inactivation was associated with bulk protein content, salt droplet drying time. Instead, found exhibited distinct kinetics wet dry phases residue morphology may lead to elevated first-order rate phase. Additionally, differences crystalline structure nanobead localization were between droplets. Together, our demonstrates different fluids exhibit unique profiles suggests contribute transmission low- high-humidity environments.IMPORTANCEDetermining how long persist is for mitigating risk. Expelled composed fluids, including complex mixtures, but well survive such largely unknown. Here, find present ferrets, saliva-containing expulsions play role degrades more than within mucus. Droplet composition impacts dried These results suggest sites tract could have variable environment, which will impact viral fitness.

Language: Английский

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Adapted methods for monitoring influenza virus and respiratory syncytial virus in sludge and wastewater

The Science of The Total Environment, Journal Year: 2024, Volume and Issue: 918, P. 170636 - 170636

Published: Feb. 6, 2024

Wastewater-based surveillance constitutes a valuable methodology for the continuous monitoring of viral circulation, with capacity to function as an early warning system. It holds particular significance in scenarios where respiratory viruses exhibit overlapping clinical presentations, occurs SARS-CoV-2, influenza virus (IV), and syncytial (RSV), allows seasonal outbreaks be distinguished from COVID-19 peaks. Furthermore, sewage sludge, given it harbors concentrated human waste large population, serves substantial reservoir pathogen detection. To effectively integrate wastewater-based epidemiology into infectious disease surveillance, detection methods employed wastewater samples must adapted distinct characteristics sludge matrices. In this study, we applied protocols IV RSV comparing their performance results obtained wastewater. assess efficiency these protocols, were spiked RNA, either free or incorporated lentiviral particles. Samples using aluminum hydroxide adsorption-precipitation method before RNA extraction. Absolute quantification was carried out by RT-qPCR, including internal control monitor potential inhibitory factors. Recovery efficiencies both 60 % 75 71 respectively wastewater, whereas values particles 16 10 21 17 respectively. Additionally, protocol enabled naturally occurring collected two treatment plants during winter months, thus affirming efficacy methodologies.

Language: Английский

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Toward Standardized Aerovirology: A Critical Review of Existing Results and Methodologies

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(8), P. 3595 - 3608

Published: Feb. 14, 2024

Understanding the airborne survival of viruses is important for public health and epidemiological modeling potentially to develop mitigation strategies minimize transmission pathogens. Laboratory experiments typically involve investigating effects environmental parameters on viability or infectivity a target virus. However, conflicting results among studies are common. Herein, 34 aerovirology were compared identify links between compositional viruses. While specific experimental apparatus was not factor in variability reported results, it determined that procedure major contributed discrepancies results. The most significant contributor poorly defined initial viable virus concentration aerosol phase, causing many measure rapid inactivation, which occurs quickly after particle generation, leading Consistently, measured their reference minutes aerosolization higher at subsequent times, indicates there an loss captured these studies. composition particles carry also found be viruses; however, mechanisms this effect unknown. Temperature aerosol-phase viability, but lack directly compare temperature phase bulk phase. There need repeated measurements different research groups under identical conditions both assess degree attempt better understand already published data. Lack standardization has hindered ability quantify differences studies, we provide recommendations future These as follows: measuring using "direct method"; use equipment maximizes time resolution; all losses appropriately; perform, least, 5- 10-min sample, if possible; report clearly suspension; gas throughout experiment. Implementing will address oversights existing literature produce data can more easily quantitatively compared.

Language: Английский

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Indoor air humidity revisited: Impact on acute symptoms, work productivity, and risk of influenza and COVID-19 infection

International Journal of Hygiene and Environmental Health, Journal Year: 2023, Volume and Issue: 256, P. 114313 - 114313

Published: Dec. 27, 2023

Recent epidemiological and experimental findings reconfirm that low indoor air humidity (dry air) increases the prevalence of acute eye airway symptoms in offices, result lower mucociliary clearance airways, less efficient immune defense, deteriorate work productivity. New research also support environmental conditions for risk infection influenza COVID-19 virus is lowest Goldilocks zone 40–60% relative (RH) by decrease airways' susceptibility, which can be elevated particle exposure. Furthermore, RH generation infectious laden aerosols exhaled from infected people. In general, elevation dry health airways concomitantly with viability virus. Thus, negative effects ventilation outdoor (low absolute humidity) should assessed according to 1) weakened functionality 2) increased possible transmissibility virus, 3) evaporation containing droplets out droplet nuclei (also at high room temperature), their floating time air. The removal acid-containing ambient filtration pH, viruses, infection, synergistically may further increase dilution pollutants compared beneficial control center RH, an essential factor optimal additional positive impact on symptoms, productivity, reduced infection.

Language: Английский

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Stability of influenza A virus in droplets and aerosols is heightened by the presence of commensal respiratory bacteria

Journal of Virology, Journal Year: 2024, Volume and Issue: 98(7)

Published: June 13, 2024

ABSTRACT Aerosol transmission remains a major challenge for control of respiratory viruses, particularly those causing recurrent epidemics, like influenza A virus (IAV). These viruses are rarely expelled alone, but instead embedded in consortium microorganisms that populate the tract. The impact microbial communities and inter-pathogen interactions upon stability transmitted is well-characterized enteric pathogens, under-studied niche. Here, we assessed whether presence five different species commensal bacteria could influence persistence IAV within phosphate-buffered saline artificial saliva droplets deposited on surfaces at typical indoor air humidity, airborne aerosol particles. In droplets, individual or mixed bacterial community resulted 10- to 100-fold more infectious remaining after 1 h, due bacterial-mediated flattening drying early efflorescence. Even when no efflorescence occurred high humidity bacteria-induced changes droplet morphology were abolished by aerosolization deposition well plate, remained protective. Staphylococcus aureus Streptococcus pneumoniae most stabilizing compared other commensals equivalent density, indicating composition an individual’s microbiota previously unconsidered factor influencing persistence. IMPORTANCE It known infections such as coronavirus disease 2019 release virus-containing aerosols larger infected host. survival time into environment can vary depending temperature, room UV exposure, composition, suspending fluid. However, few studies consider fact not alone tract—we constantly colonized plethora our noses, mouth, lower system. gut, be stabilized against inactivation environmental decay gut bacteria. Despite similarly complex tract, have investigated viral stabilization occur this address question investigating range systems representing droplets.

Language: Английский

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Persistence of Phi6, a SARS-CoV-2 surrogate, in simulated indoor environments: Effects of humidity and material properties

PLoS ONE, Journal Year: 2025, Volume and Issue: 20(1), P. e0313604 - e0313604

Published: Jan. 6, 2025

The SARS-CoV-2 virus caused the COVID-19 pandemic and brought major challenges to public health. It is transmitted via aerosols, droplets, fomites. Among these, viral transmission through fomites not well understood although it remains a very important route. This motivated us study how play role in within controlled indoor environments. To achieve this, we investigated aerosol persistence on under different humidity levels mimic built environment. We developed protocol effect of infectivity using full-scale environmental chamber. results show that aerosolized Phi6 air decreased by ≥ 1 log 10 as relative (RH) increased from 25% 75% but then RH further 85%, resulting characteristic V-shape curve which varied with exposure time. Consistently, material properties may impact persistence, changes local more significantly influence These provide new insights into fomite-mediated conditions. findings will help guide design effective strategies for control

Language: Английский

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Mucin Colocalizes with Influenza Virus and Preserves Infectivity in Deposited Model Respiratory Droplets

Environmental Science & Technology, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 17, 2025

The stability of influenza virus in respiratory particles varies with relative humidity (RH) and protein content. This study investigated the decay, or loss infectivity, A (IAV) 1-μL droplets deposited on a surface varying concentrations mucin, one most abundant proteins mucus, examined localization virions within droplets. IAV remained stable at 0.1% 0.5% mucin phosphate-buffered saline (PBS) over 4 h 20%, 50%, 80% RH, maximum decay 1.2 log10/mL. In contrast, pure PBS droplets, decayed by least 2.6 log10/mL after 50% RH. Mucin's protective effect was independent its concentration, except RH h. Confocal microscopy revealed that 20% led to thicker coffee rings dendritic patterns where colocalized mucin. At no morphological difference observed between PBS-only mucin-containing but still center Analysis digital droplet PCR showed helped maintain integrity. To our knowledge, this is first localize model results suggest mucin's colocalization may protect from environmental stressors, enhancing stability.

Language: Английский

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Factors Affecting Reduction of Infectious Aerosols by Far-UVC and Portable HEPA Air Cleaners

ACS ES&T Air, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 20, 2025

Language: Английский

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