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On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles

The spread of SARS-CoV-2 by contact (direct or indirect) is widely accepted, but the relative importance of airborne transmission is still controversial. Probability of outdoor airborne transmission depends on several parameters, still rather uncertain: virus-laden aerosol concentrations, viability...

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Autores principales: Belosi, Franco, Conte, Marianna, Gianelle, Vorne, Santachiara, Gianni, Contini, Daniele
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier Inc. 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7833947/
https://www.ncbi.nlm.nih.gov/pubmed/33307081
http://dx.doi.org/10.1016/j.envres.2020.110603
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author Belosi, Franco
Conte, Marianna
Gianelle, Vorne
Santachiara, Gianni
Contini, Daniele
author_facet Belosi, Franco
Conte, Marianna
Gianelle, Vorne
Santachiara, Gianni
Contini, Daniele
author_sort Belosi, Franco
collection PubMed
description The spread of SARS-CoV-2 by contact (direct or indirect) is widely accepted, but the relative importance of airborne transmission is still controversial. Probability of outdoor airborne transmission depends on several parameters, still rather uncertain: virus-laden aerosol concentrations, viability and lifetime, minimum dose necessary to transmit the disease. In this work, an estimate of outdoor concentrations in northern Italy (region Lombardia) was performed using a simple box model approach, based on an estimate of respiratory emissions, with a specific focus for the cities of Milan and Bergamo (Italy). In addition, the probability of interaction of virus-laden aerosol with pre-existing particles of different sizes was investigated. Results indicate very low (<1 RNA copy/m(3)) average outdoor concentrations in public area, excluding crowded zones, even in the worst case scenario and assuming a number of infects up to 25% of population. On average, assuming a number of infects equal to 10% of the population, the time necessary to inspire a quantum (i.e. the dose of airborne droplet nuclei required to cause infection in 63% of susceptible persons) would be 31.5 days in Milan (range 2.7–91 days) and 51.2 days in Bergamo (range 4.4–149 days). Therefore, the probability of airborne transmission due to respiratory aerosol is very low in outdoor conditions, even if it could be more relevant for community indoor environments, in which further studies are necessary to investigate the potential risks. We theoretically examined if atmospheric particles can scavenge virus aerosol, through inertial impact, interception, and Brownian diffusion. The probability was very low. In addition, the probability of coagulation of virus-laden aerosol with pre-existing atmospheric particles resulted negligible for accumulation and coarse mode particles, but virus-laden aerosol could act as sink of ultrafine particles (around 0.01 μm in diameter). However, this will not change significantly the dynamics behaviour of the virus particle or its permanence time in atmosphere.
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spelling pubmed-78339472021-01-26 On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles Belosi, Franco Conte, Marianna Gianelle, Vorne Santachiara, Gianni Contini, Daniele Environ Res Article The spread of SARS-CoV-2 by contact (direct or indirect) is widely accepted, but the relative importance of airborne transmission is still controversial. Probability of outdoor airborne transmission depends on several parameters, still rather uncertain: virus-laden aerosol concentrations, viability and lifetime, minimum dose necessary to transmit the disease. In this work, an estimate of outdoor concentrations in northern Italy (region Lombardia) was performed using a simple box model approach, based on an estimate of respiratory emissions, with a specific focus for the cities of Milan and Bergamo (Italy). In addition, the probability of interaction of virus-laden aerosol with pre-existing particles of different sizes was investigated. Results indicate very low (<1 RNA copy/m(3)) average outdoor concentrations in public area, excluding crowded zones, even in the worst case scenario and assuming a number of infects up to 25% of population. On average, assuming a number of infects equal to 10% of the population, the time necessary to inspire a quantum (i.e. the dose of airborne droplet nuclei required to cause infection in 63% of susceptible persons) would be 31.5 days in Milan (range 2.7–91 days) and 51.2 days in Bergamo (range 4.4–149 days). Therefore, the probability of airborne transmission due to respiratory aerosol is very low in outdoor conditions, even if it could be more relevant for community indoor environments, in which further studies are necessary to investigate the potential risks. We theoretically examined if atmospheric particles can scavenge virus aerosol, through inertial impact, interception, and Brownian diffusion. The probability was very low. In addition, the probability of coagulation of virus-laden aerosol with pre-existing atmospheric particles resulted negligible for accumulation and coarse mode particles, but virus-laden aerosol could act as sink of ultrafine particles (around 0.01 μm in diameter). However, this will not change significantly the dynamics behaviour of the virus particle or its permanence time in atmosphere. Elsevier Inc. 2021-02 2020-12-08 /pmc/articles/PMC7833947/ /pubmed/33307081 http://dx.doi.org/10.1016/j.envres.2020.110603 Text en © 2020 Elsevier Inc. All rights reserved. Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.
spellingShingle Article
Belosi, Franco
Conte, Marianna
Gianelle, Vorne
Santachiara, Gianni
Contini, Daniele
On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title_full On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title_fullStr On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title_full_unstemmed On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title_short On the concentration of SARS-CoV-2 in outdoor air and the interaction with pre-existing atmospheric particles
title_sort on the concentration of sars-cov-2 in outdoor air and the interaction with pre-existing atmospheric particles
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7833947/
https://www.ncbi.nlm.nih.gov/pubmed/33307081
http://dx.doi.org/10.1016/j.envres.2020.110603
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