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Integrating IAQ Control Strategies to Reduce the Risk of Asymptomatic SARS-CoV-2 Infections

Integrating IAQ Control Strategies to Reduce the Risk of Asymptomatic SARS-CoV-2 Infections

From ASHRAE Journal Newsletter, July 28, 2020

Asymptomatic individuals’ breathing and speaking are considered responsible for a large portion of the spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through airborne transmission, says the new research from ASHRAE’s Science and Technology for the Built Environment.

As businesses and schools are making plans to reopen, engineers are assessing how the risk of cross infection can be minimized and prevented. Because of their relatively large occupant density, classrooms and open-space offices present a special challenge.

“Integrating IAQ Control Strategies to Reduce the Risk of Asymptomatic SARS-CoV-2 Infections in Classrooms and Open Plan Offices” evaluates the potential of various indoor air quality control strategies for decreasing the risk of infection through airborne transmission.

Jianshun "Jensen” Zhang, Ph.D., Fellow ASHRAE, discussed his research with ASHRAE Journal: 

1. What is the significance of this research? 

Zhang: The research evaluates the potential of various indoor air quality control strategies for reducing the risk  of contracting the SARS-CoV-2 virus via airborne transmission. It shows the importance of integrating source control, ventilation and air cleaning/filtration to reduce infection risk.

Universal masking is identified as the most effective source control strategy for reducing the virus generation rate from asymptomatic virus carriers and for providing good protection for individuals. Combining masking with an increased ventilation rate (i.e., supply air flow rate of fresh outdoor air to the building), effective room air distribution and semi-open partitions and air cleaning, it is possible to reduce the risk of infection by a factor of 8.5 to over 500 for classrooms and open-plan offices beyond the typical space conditions designed according to ANSI/ASHRAE Standard 62.1, Ventilation for Acceptable Indoor Air Quality. 

2. How does this research further the industry's knowledge on this topic?

Zhang: Semi-open partitions integrated with effective room/space air distribution has been identified as an effective strategy for reducing the risk of cross infection but has not been sufficiently emphasized and applied in most existing guidance for combating the spread of SARS-CoV-2. 

This is an area that needs more attention from the industry as well as academia. Estimating the potential for various control strategies can help the industry focus on the most effective technologies and their integration for infectious disease control, as well as for improving IAQ and energy efficiency.

3. In your research, you list areas that need research and development. How does this research set up those next steps?

Zhang: The research indicates that many of the IAQ control principles and strategies developed in the past can be applied to reduce the risk of SARS-CoV-2 infection with more emphasis on minimizing cross contamination in and between rooms. It also discusses some specific problems that need to be further investigated on the subject and recommends 10 areas for further research and development.

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