International Scientific Forum on Home Hygiene

Home Hygiene & Health

The Leading Source of Scientific, Professional & Consumer Information
International Scientific Forum on Home Hygiene

Home Hygiene & Health

The Leading Source of Scientific, Professional & Consumer Information

Indoor airborne risk assessment in the context of SARS-CoV-2. Description of airborne transmission mechanism and method to develop a new standardized model for risk assessment

The SARS-CoV-2 virus can spread through zoonotic transmission, direct and indirect contact transmission, direct deposition transmission, and inhalation or airborne transmission. Evidence suggests that it is transmitted through infectious fluids released from an infected individual as particles of different sizes and quantities, during breathing, speaking, coughing and sneezing. While the largest particles travel downwards quite rapidly, smaller ones remain suspended in the air for longer periods and travel farther distances. When people are in close proximity, transmission of infectious particles can occur through direct inhalation (short-range) and deposition onto the mucous linings of the respiratory tract and ocular membranes of a susceptible host particularly in the absence of face covers and ventilation. ‘Long-range’ transmission can occur in enclosed settings when infectious particles accumulate over time in a given volume, where the concentration of virions is sufficient enough to cause infection once infectious particles are inhaled

Methods

Development airborne transmission modelling included several stages: defining the mechanism of airborne transmission, identifying questions and outcomes, retrieving, assessing, synthesizing the evidence, formulating and testing the model. The process required the establishment of the Airborne Risk Indoor Assessment (ARIA) Technical Advisory Group which constituted an ad-hoc advisory panel supporting WHO’s World Health Emergencies preparedness, readiness and response to COVID-19 and included the Global Infection Prevention and Control Network, Environment and Engineering Control Expert Advisory Panel (ECAP) for COVID-19, the European Organization for Nuclear Research (CERN), technical experts from ministries of health and similar institutions  and WHO .

Outcomes

This process resulted in a new multi-box model to quantify the risk of SARS-CoV-2 airborne transmission that incorporates additional knowledge of factors related to inhalation transmission.. Based on this model an online, user-friendly tool to assess SARS-CoV-2 airborne transmission risk in residential, public and health care settings was developed. Its application by Infection Prevention and Control specialists, building managers, health care facility managers and the general public will inform risk reduction measures and enable informed decisions by end-users.

 

Resource Link:

https://iris.who.int/bitstream/handle/10665/376346/9789240090576-eng.pdf?sequence=1&isAllowed=y