Extended Lifetime of Respiratory Droplets in a Turbulent Vapor Puff and Its Implications on Airborne Disease Transmission

Abstract Animal models are often used to assess the airborne transmissibility of various pathogens, which are typically assumed to be carried by expiratory droplets emitted directly from the respiratory tract of the infected animal. We recently established that influenza virus is also transmissible via “aerosolized fomites,” micron-scale dust particulates released from virus-contaminated surfaces (Asadi et al., Nature Communications, 2020). Here we expand on this observation, by counting and characterizing the particles emitted from guinea pig cages using an Aerodynamic Particle Sizer (APS) and an Interferometric Mie Imaging (IMI) system. Of over 9,000 airborne particles emitted from guinea pig cages and directly imaged with IMI, none had an interference pattern indicative of a liquid droplet. Separate measurements of the particle count using the APS indicate that particle concentrations spike upwards immediately following animal motion, then decay exponentially with a time constant commensurate with the air exchange rate in the cage. Taken together, the results presented here raise the possibility that a non-negligible fraction of airborne influenza transmission events between guinea pigs occurs via aerosolized fomites rather than respiratory droplets, though the relative frequencies of these two routes have yet to be definitively determined.

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Non-respiratory particles emitted by guinea pigs in airborne disease transmission experiments

Scientific Reports ◽

10.1038/s41598-021-96678-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sima Asadi ◽

Manilyn J. Tupas ◽

Ramya S. Barre ◽

Anthony S. Wexler ◽

Nicole M. Bouvier ◽

...

Keyword(s):

Guinea Pig ◽

Disease Transmission ◽

Guinea Pigs ◽

Liquid Droplet ◽

Particle Count ◽

Air Exchange Rate ◽

Influenza Transmission ◽

Particle Sizer ◽

Airborne Disease ◽

Respiratory Droplets

AbstractAnimal models are often used to assess the airborne transmissibility of various pathogens, which are typically assumed to be carried by expiratory droplets emitted directly from the respiratory tract of the infected animal. We recently established that influenza virus is also transmissible via “aerosolized fomites,” micron-scale dust particulates released from virus-contaminated surfaces (Asadi et al. in Nat Commun 11(1):4062, 2020). Here we expand on this observation, by counting and characterizing the particles emitted from guinea pig cages using an Aerodynamic Particle Sizer (APS) and an Interferometric Mie Imaging (IMI) system. Of over 9000 airborne particles emitted from guinea pig cages and directly imaged with IMI, none had an interference pattern indicative of a liquid droplet. Separate measurements of the particle count using the APS indicate that particle concentrations spike upwards immediately following animal motion, then decay exponentially with a time constant commensurate with the air exchange rate in the cage. Taken together, the results presented here raise the possibility that a non-negligible fraction of airborne influenza transmission events between guinea pigs occurs via aerosolized fomites rather than respiratory droplets, though the relative frequencies of these two routes have yet to be definitively determined.

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Splatters and Aerosols Contamination in Dental Aerosol Generating Procedures

Applied Sciences ◽

10.3390/app11041914 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1914

Author(s):

Pingping Han ◽

Honghui Li ◽

Laurence J. Walsh ◽

Sašo Ivanovski

Keyword(s):

Particle Size ◽

Disease Transmission ◽

High Speed ◽

Low Speed ◽

Dental Procedures ◽

Dental Equipment ◽

Produce Contamination ◽

Fluorescein Dye ◽

Filter Papers ◽

Airborne Disease

Dental aerosol-generating procedures produce a large amount of splatters and aerosols that create a major concern for airborne disease transmission, such as COVID-19. This study established a method to visualise splatter and aerosol contamination by common dental instrumentation, namely ultrasonic scaling, air-water spray, high-speed and low-speed handpieces. Mock dental procedures were performed on a mannequin model, containing teeth in a typodont and a phantom head, using irrigation water containing fluorescein dye as a tracer. Filter papers were placed in 10 different locations to collect splatters and aerosols, at distances ranging from 20 to 120 cm from the source. All four types of dental equipment produced contamination from splatters and aerosols. At 120 cm away from the source, the high-speed handpiece generated the greatest amount and size (656 ± 551 μm) of splatter particles, while the triplex syringe generated the largest amount of aerosols (particle size: 1.73 ± 2.23 μm). Of note, the low-speed handpiece produced the least amount and size (260 ± 142 μm) of splatter particles and the least amount of aerosols (particle size: 4.47 ± 5.92 μm) at 120 cm. All four dental AGPs produce contamination from droplets and aerosols, with different patterns of distribution. This simple model provides a method to test various preventive strategies to reduce risks from splatter and aerosols.

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HVAC filtration for controlling infectious airborne disease transmission in indoor environments: Predicting risk reductions and operational costs

Building and Environment ◽

10.1016/j.buildenv.2013.08.025 ◽

2013 ◽

Vol 70 ◽

pp. 150-160 ◽

Cited By ~ 41

Author(s):

Parham Azimi ◽

Brent Stephens

Keyword(s):

Disease Transmission ◽

Indoor Environments ◽

Operational Costs ◽

Airborne Disease

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Assessment of Airborne Disease Transmission Risk and Energy Impact of HVAC Mitigation Strategies

10.1101/2021.11.15.21266233 ◽

2021 ◽

Author(s):

Michael J. Risbeck ◽

Martin Z. Bazant ◽

Zhanhong Jiang ◽

Young M. Lee ◽

Kirk H. Drees ◽

...

Keyword(s):

Disease Transmission ◽

Significant Risk ◽

Mitigation Strategies ◽

Transmission Risk ◽

Disease Spread ◽

Particle Removal ◽

Outdoor Air ◽

Common Basis ◽

Air Ventilation ◽

Airborne Disease

The COVID-19 pandemic has focused renewed attention on the ways in which building HVAC systems may be operated to mitigate the risk of airborne disease transmission. The most common suggestion is to increase outdoor-air ventilation rates so as to dilute the concentrations of infectious aerosol particles indoors. Although this strategy does reduce the likelihood of disease spread, it is often much more costly than other strategies that provide equivalent particle removal or deactivation. To address this tradeoff and arrive at practical recommendations, we explain how different mitigation strategies can be expressed in terms of equivalent outdoor air (EOA) to provide a common basis for energy analysis. We then show the effects of each strategy on EOA delivery and energy cost in simulations of realistic buildings in a variety of climates. Key findings are that in-duct filtration is often the most efficient mitigation strategy, while significant risk reduction generally requires increasing total airflow to the system, either through adjusted HVAC setpoints or standalone disinfection devices.

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Knowledge and awareness about airborne pathogens and its prevention among the general public

International Journal of Research in Pharmaceutical Sciences ◽

10.26452/ijrps.v11ispl3.2927 ◽

2020 ◽

Vol 11 (SPL3) ◽

pp. 279-286

Author(s):

Ashritha M ◽

Geetha R V ◽

Jayalakshmi Somasundaram

Keyword(s):

General Public ◽

Health Workers ◽

Control Measures ◽

Dust Particles ◽

Protective Measures ◽

The People ◽

Airborne Disease ◽

Protection And Control ◽

And Control ◽

Respiratory Droplets

The airborne disease is mainly caused by the pathogens, which spread through respiratory droplets while coughing, sneezing or talking. Infection protection and control measures are taken to prevent the possible spread of , which also spreads through respiratory droplets. Discharged microbes are suspended in the air as dust particles and even in the form of droplets. The Middle East respiratory syndrome is caused by wherein the health workers are at a higher risk. Hence, awareness must be created in order to reduce a number of cases. The preventive measures are mainly taken in health care as patients are susceptible to diseases. It is essential for all the people to become aware and take steps according. The survey was distributed online to around 100 participants of various places of Tamil regarding the awareness of airborne pathogens. From this above study, it could be noticed that around 85% of the people are aware of the airborne pathogen whereas 15% of the people are not aware of. 64% of people have a good knowledge of the symptoms of any type of airborne disease. the protective measures that must be taken, about 65% of the people are conscious of doing it. The study concludes that there is awareness of airborne pathogens and its prevention among the general public.

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