Risk assessment of infectious respiratory disease transmission in indoor environments

2010 ◽  
Author(s):  
Gin Nam Sze To
Keyword(s):  
Risk Assessment ◽  
Respiratory Disease ◽  
Disease Transmission ◽  
Indoor Environments

scholarly journals Risk assessment for airborne disease transmission by poly-pathogen aerosols

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0248004
Author(s):  
Freja Nordsiek ◽  
Eberhard Bodenschatz ◽  
Gholamhossein Bagheri
Keyword(s):  
Risk Assessment ◽  
Respiratory Tract ◽  
Poisson Distribution ◽  
Disease Transmission ◽  
Indoor Environments ◽  
Dose Calculations ◽  
Risk Of Infection ◽  
Response Models ◽  
Airborne Disease ◽  
Aerosol Source

In the case of airborne diseases, pathogen copies are transmitted by droplets of respiratory tract fluid that are exhaled by the infectious that stay suspended in the air for some time and, after partial or full drying, inhaled as aerosols by the susceptible. The risk of infection in indoor environments is typically modelled using the Wells-Riley model or a Wells-Riley-like formulation, usually assuming the pathogen dose follows a Poisson distribution (mono-pathogen assumption). Aerosols that hold more than one pathogen copy, i.e. poly-pathogen aerosols, break this assumption even if the aerosol dose itself follows a Poisson distribution. For the largest aerosols where the number of pathogen in each aerosol can sometimes be several hundred or several thousand, the effect is non-negligible, especially in diseases where the risk of infection per pathogen is high. Here we report on a generalization of the Wells-Riley model and dose-response models for poly-pathogen aerosols by separately modeling each number of pathogen copies per aerosol, while the aerosol dose itself follows a Poisson distribution. This results in a model for computational risk assessment suitable for mono-/poly-pathogen aerosols. We show that the mono-pathogen assumption significantly overestimates the risk of infection for high pathogen concentrations in the respiratory tract fluid. The model also includes the aerosol removal due to filtering by the individuals which becomes significant for poorly ventilated environments with a high density of individuals, and systematically includes the effects of facemasks in the infectious aerosol source and sink terms and dose calculations.

scholarly journals Risk assessment for airborne disease transmission by poly-pathogen aerosols

2020 ◽  
Author(s):  
Freja Nordsiek ◽  
Eberhard Bodenschatz ◽  
Gholamhossein Bagheri
Keyword(s):  
Risk Assessment ◽  
Respiratory Tract ◽  
Poisson Distribution ◽  
Disease Transmission ◽  
Indoor Environments ◽  
Dose Calculations ◽  
Risk Of Infection ◽  
Response Models ◽  
Airborne Disease ◽  
Aerosol Source

AbstractIn the case of airborne diseases, pathogen copies are transmitted by droplets of respiratory tract fluid that are exhaled by the infectious and, after partial or full drying, inhaled as aerosols by the susceptible. The risk of infection in indoor environments is typically modelled using the Wells-Riley model or a Wells-Riley-like formulation, usually assuming the pathogen dose follows a Poisson distribution (mono-pathogen assumption). Aerosols that hold more than one pathogen copy, i.e. poly-pathogen aerosols, break this assumption even if the aerosol dose itself follows a Poisson distribution. For the largest aerosols where the number of pathogen in each aerosol can sometimes be several hundred or several thousand, the effect is non-negligible, especially in diseases where the risk of infection per pathogen is high. Here we report on a generalization of the Wells-Riley model and dose-response models for poly-pathogen aerosols by separately modeling each number of pathogen copies per aerosol, while the aerosol dose itself follows a Poisson distribution. This results in a model for computational risk assessment suitable for mono-/poly-pathogen aerosols. We show that the mono-pathogen assumption significantly overestimates the risk of infection for high pathogen concentrations in the respiratory tract fluid. The model also includes the aerosol removal due to filtering by the individuals which becomes significant for poorly ventilated environments with a high density of individuals, and systematically includes the effects of facemasks in the infectious aerosol source and sink terms and dose calculations.

Components of a risk assessment tool for prevention and control of bovine respiratory disease in preweaned dairy calves

2020 ◽  
pp. 1-7
Author(s):  
Sharif S. Aly ◽  
Betsy M. Karle ◽  
Deniece R. Williams ◽  
Gabriele U. Maier ◽  
Sasha Dubrovsky
Keyword(s):  
Risk Factors ◽  
Risk Assessment ◽  
Risk Factor ◽  
Respiratory Disease ◽  
Scoring System ◽  
Prevention And Control ◽  
Assessment Tool ◽  
Bovine Respiratory Disease ◽  
And Control ◽  
Management Changes

Abstract Bovine respiratory disease (BRD) is the leading natural cause of death in US beef and dairy cattle, causing the annual loss of more than 1 million animals and financial losses in excess of $700 million. The multiple etiologies of BRD and its complex web of risk factors necessitate a herd-specific intervention plan for its prevention and control on dairies. Hence, a risk assessment is an important tool that producers and veterinarians can utilize for a comprehensive assessment of the management and host factors that predispose calves to BRD. The current study identifies the steps taken to develop the first BRD risk assessment tool and its components, namely the BRD risk factor questionnaire, the BRD scoring system, and a herd-specific BRD control and prevention plan. The risk factor questionnaire was designed to inquire on aspects of calf-rearing including management practices that affect calf health generally, and BRD specifically. The risk scores associated with each risk factor investigated in the questionnaire were estimated based on data from two observational studies. Producers can also estimate the prevalence of BRD in their calf herds using a smart phone or tablet application that facilitates selection of a true random sample of calves for scoring using the California BRD scoring system. Based on the risk factors identified, producers and herd veterinarians can then decide the management changes needed to mitigate the calf herd's risk for BRD. A follow-up risk assessment after a duration of time sufficient for exposure of a new cohort of calves to the management changes introduced in response to the risk assessment is recommended to monitor the prevalence of BRD.

Comparison, association, and risk assessment of phthalates in floor dust at different indoor environments in Delaware, USA

2015 ◽  
Vol 50 (14) ◽  
pp. 1428-1439 ◽  
Author(s):  
Xiaolong Bi ◽  
Shoujun Yuan ◽  
Xiaojun Pan ◽  
Cherese Winstead ◽  
Qiquan Wang
Keyword(s):  
Risk Assessment ◽  
Indoor Environments ◽  
Floor Dust

scholarly journals Aerosol transport measurements and assessment of risk from infectious aerosols: a case study of two German cash-and-carry hardware/DIY stores

2021 ◽  
Author(s):  
eberhard Bodenschatz ◽  
Gholamhossein Bagheri ◽  
Bardia Hejazi ◽  
Birte Thiede ◽  
Oliver Schlenczek
Keyword(s):  
Upper Bound ◽  
Disease Transmission ◽  
Face Mask ◽  
Indoor Environments ◽  
Aerosol Dynamics ◽  
Direct Exposure ◽  
Decay Times ◽  
Dominant Feature ◽  
Aerosol Dispersion ◽  
Cash And Carry

We report experimental results on aerosol dispersion in two large German cash-and-carry hardware/DIY stores to better understand the factors contributing to disease transmission by infectious human aerosols in large indoor environments. We examined the transport of aerosols similar in size to human respiratory aerosols (0.3μm-10μm) in representative locations, such as high-traffic areas and restrooms. In restrooms, the observed decay of aerosol concentrations was consistent with well-mixed air exchange. In all other locations, fast decay times were measured, which were found to be independent of aerosol size (typically a few minutes). From this, we conclude that in the main retail areas, including at checkouts, rapid turbulent mixing and advection is the dominant feature in aerosol dynamics. With this, the upper bound of risk for airborne disease transmission to a susceptible is determined by direct exposure to the exhalation cloud of an infectious. For the example of the SARS-CoV-2 virus, we find when speaking without a face mask and aerosol sizes up to an exhalation (wet) diameter of 50μm, a distance of 1.5me to be unsafe. However, at the smallest distance between an infectious and a susceptible, while wearing typical surgical masks and for all sizes of exhaled aerosol, the upper bound of infection risk is only ∼ 5% and decreases further by a factor of 100 (∼ 0.05%) for typical FFP2 masks for a duration of 20 min. This upper bound is very conservative and we expect the actual risk for typical encounters to be much lower. The risks found here are comparable to what might be expected in calm outdoor weather.

scholarly journals Pilot evaluation of risk assessment and enhanced protocols regarding contacts at an international professional golf event

2021 ◽  
Vol 7 (3) ◽  
pp. e001127
Author(s):  
Patrick G Robinson ◽  
Andrew Murray ◽  
Volker Sheer ◽  
Graeme Close ◽  
Denis F Kinane
Keyword(s):  
Risk Assessment ◽  
Pilot Study ◽  
High Risk ◽  
Disease Transmission ◽  
Low Risk ◽  
Contact Tracing ◽  
Sporting Events ◽  
Medical Surveillance ◽  
Rt Pcr ◽  
Antigen Testing

ObjectivesThe aim of this study was to assess whether a risk assessment and managed risk approach to contact tracing was practical and feasible at the Gran Canaria Lopesan Open 2021 and could inform further pilot work regarding disease transmission during elite sporting events.MethodsThis prospective cohort study included all international attendees. All participants required a minimum of one negative reverse transcriptase PCR (RT-PCR) test prior to travelling to each tournament. High-risk contacts were isolated for 10 days. Moderate-risk contacts received education regarding enhanced medical surveillance, had daily rapid antigen testing for 5 days, with RT-PCR day 5, mandated mask use and access to outside space for work purposes only. Low-risk contacts received rapid antigen testing every 48 hours and PCR testing on day 5.ResultsA total of 550 persons were accredited and were required to undergo RT-PCR testing before the event. Two of these tests were positive (0.36%). Of these, case 1 had 1 high, 23 moderate and 48 low-risk contacts. Case 2 did not have any significant travel history within 2 days of positive test and had one high-risk contact. There were no further positive tests on site in the wider cohort of attendees, from a total of 872 RT-PCR and 198 rapid antigen tests.ConclusionsThis pilot study showed it is practical, feasible and well accepted to provide enhanced (daily) virus testing and risk-mitigating measures at a professional golf event. Further study is required to assess the efficacy of these interventions; however, no transmission was found in this pilot study.

scholarly journals Device for Suppression of Aerosol Transfer in Close Proximity Settings

COVID ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 394-402
Author(s):  
Yicheng Bao ◽  
Loïc Anderegg ◽  
Sean Burchesky ◽  
John M. Doyle
Keyword(s):  
Respiratory Disease ◽  
Disease Transmission ◽  
Potential Application ◽  
Small Space ◽  
Large Space ◽  
Face To Face ◽  
Close Proximity ◽  
Optically Transparent ◽  
Filter Unit ◽  
University Setting

Here we present a device that suppresses transfer of aerosol between nearby seating areas through the use of optically transparent, sound transmitting barriers and HEPA fan filter unit (FFU). A potential application of this device is to lower the risk of respiratory disease transmission in face-to-face, maskless meetings between individuals in a university setting. We evaluate overall aerosol transmission between users of the device. This is done for two different physical settings: a large space, such as a library, and a small space, such as an enclosed study room. We find that the device can provide lower aerosol transmission compared to the typical transmission between two individuals wearing surgical face masks separated by six feet.

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