From a9b61a3a7334899bdb0be8076160b2f937fa6a9e Mon Sep 17 00:00:00 2001 From: Andre Henriques Date: Fri, 5 Nov 2021 15:45:27 +0100 Subject: [PATCH] Update about --- cara/apps/templates/about.html.j2 | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) diff --git a/cara/apps/templates/about.html.j2 b/cara/apps/templates/about.html.j2 index e0b517f9..c4c414a8 100644 --- a/cara/apps/templates/about.html.j2 +++ b/cara/apps/templates/about.html.j2 @@ -9,7 +9,6 @@ Currently, the existing public health measures point to the importance of proper This pandemic clearly raised increased awareness on airborne transmission of respiratory viruses in indoor settings. Out of the main modes of viral transmission, the airborne route of SARS-CoV-2 seems to have a significant importance to the spread of COVID-19 infections world-wide, hence proper guidance to building engineers or facility managers, on how to prevent on-site transmission, is essential.
For information on the Airborne Transmission of SARS-CoV-2, feel free to check out the HSE Seminar: https://cds.cern.ch/record/2743403.
-Slides available in https://indico.cern.ch/event/968258/.

What is CARA?


CARA stands for COVID Airborne Risk Assessment and was developed in the spring of 2020 to better understand and quantify the risk of long-range airborne spread of SARS-CoV-2 virus in workplaces. CARA comes with different applications that allow more or less flexibility in the input parameters: @@ -19,18 +18,19 @@ CARA stands for COVID Airborne Risk Assessment and was developed in the spring o The mathematical and physical model simulate the long-range airborne spread of SARS-CoV-2 virus in a finite volume, assuming a homogenous mixture, and estimates the risk of COVID-19 airborne transmission therein. The results DO NOT include short-range airborne exposure (where the physical distance plays a factor) nor the other known modes of SARS-CoV-2 transmission. Hence, the output from this model is only valid when the other recommended public health & safety instructions are observed, such as adequate physical distancing, good hand hygiene and other barrier measures.
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The methodology, mathematical equations and parameters of the model are described here in the CERN Report: CERN-OPEN-2021-004.

+

The methodology, mathematical equations and parameters of the model are described here in the CARA paper: CERN-OPEN-2021-004.

The model used is based on scientific publications relating to airborne transmission of infectious diseases, virology, epidemiology and aerosol science. It can be used to compare the effectiveness of different airborne-related risk mitigation measures. -The tool helps assess the potential dose of infectious airborne viruses in indoor gatherings, with people seated, standing, moving around, while breathing, speaking or shouting/singing. The model is based on the Wells-Riley model of aerosol disease transmission, which assumes a fixed value for the average infectious dose. The dose-response models for respiratory diseases is more accurate, although since this parameter for SARS-CoV-2 is not known so far, the Wells-Riley method is recommended in the health science community (see References). -The methodology of the model is divided into three parts: +The tool helps assess the potential dose of infectious airborne viruses in indoor gatherings, with people seated, standing, moving around, while breathing, speaking or shouting/singing. The model is based on the exponential dose-response of disease transmission, which assumes a fixed value for the average infectious dose. +The methodology of the model is divided into five parts:
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  1. Estimating the emission rate of virions.
    2. -
  2. Modeling the concentration evolution of viruses within a given volume and consequent inhalation dose during the exposure time.
    3. -
  3. Estimating the probability of a COVID-19 infection, the expected number of new cases arising from the transmission event and the basic reproduction rate (R0).
    4. +
  4. Estimating the emission rate of virions;
    5. +
  5. Estimating the removal rate of virions;
    6. +
  6. Modeling the concentration of virions within a given volume, as a function of time;
    7. +
  7. Absorbed dose of infectious viruses, inhaled during the exposure time;
    8. +
  8. Estimating the probability of a COVID-19 infection (or secondary transmission) and the expected number of new cases arising from the event
-Parts #1 and #3 are mainly based on methods published in scientific papers (see References), and cover the medical aspects, which is not the core competencies of the authors. The ‘heart and soul’ of CARA lies within the Part #2 and the concentration modelling, which is based on a mass-balance differential equation solved for a constant emission rate and time-dependent exchange rate (e.g. natural ventilation flow rate). Other aspects, e.g., the biological decay of the virus in the air, gravitational settlement of the aerosols, mechanical supply of fresh air, effect of HEPA filtration, among others, are also included.

What is the aim of CARA?


Although the user is able to calculate the infection probability of a stand-alone event with a pre-defined set of protection measures, the main utility of CARA is to compare the relative impact of different measures and/or combination of measure. For example: