How to Make the Indoors Safer During COVID-19

Indoor Air Quality

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As schools prepare to resume and more individuals are heading back to their workplaces and shared work areas, Syracuse University Professor Jianshun “Jensen” Zhang uses a three-step strategy to enhance indoor air quality (IAQ) and assist avoid the spread of COVID inside your home.

Zhang’s strategy is detailed in a current editorial released in the journal “Science and Technology for the Built Environment” called “Integrating IAQ control strategies to reduce the risk of asymptomatic SARS CoV-2 infections in classrooms and open plan offices.”

“Classrooms and open-space offices present a special challenge because of their relatively large occupant density, which can lead to a higher chance of person-to-person cross infection in the space via airborne transmission as well as through direct or indirect contacts,” Zhang states. “As schools and businesses are making plans to reopen, how can the risk of such cross infection be minimized or prevented?”

The coronavirus illness is a breathing health problem that can spread out from individual to individual. The infection that triggers COVID-19 spreads, generally through breathing beads from coughing, sneezing, or talking. Some individuals without signs have the ability to spread out the illness without understanding that they have it.

Dr. Zhang, a teacher in the Department of Mechanical and Aerospace Engineering and Director of the Building Energy and Environmental Systems Laboratory, composes that source control, ventilation and air cleansing — and mixes of all 3 — can use essential tools in avoiding the spread of COVID within indoor areas.

Here’s a take a look at his three-step strategy:

Source Control

Source control is the very first and essential amongst all IAQ techniques. For avoiding the spread of the coronavirus, that implies spotting, tracking, and separating contaminated individuals; and avoiding transmission from asymptomatic infection providers.

“The latter is more challenging in open space office or classroom settings in which air is typically well mixed,” Zhang composes. “To reduce the number of virus-containing aerosols emitted to the space from any possible virus carriers present, universal face masking, as well as hand sanitizing before entering the space is essential.”


The next action in air quality is ventilation with a concentrate on providing sufficient tidy outside air to spaces and workplaces and efficiently watering down the concentration of toxins.

“Mechanically ventilated classrooms and offices typically have about 20 percent of their air supplied from outdoors, and the rest is recirculated air. This is done to save heating and cooling energy while maintaining acceptable levels of IAQ,” Zhang states. “To reduce the risk of the SARS CoV-2 virus infection, the outdoor ventilation rate should be increased to the maximum operational capacity of the building ventilation system, which can be two or more times of that under the normal operation mode per the existing standard.”

He likewise composes that any recirculated air requirements to be filtered with HEPA filters or MERV 14 filters, to lessen cross-contamination.

Zhang states that appropriate air circulation is important for ensuring the filtered air is reaching individuals where they are. He states, “this is an area so far has been largely neglected in existing guidelines or recommended practices for reducing the SARS CoV-2 virus infection.”

He explains that a lot of class and open strategy workplaces in the United States utilize blending ventilation (MV) for fresh air shipment. Air diffusers in MV are generally situated near the ceiling level, however Zhang suggests that air supply ought to be generated through ground ventilation. The distinction is that filtered air from the ceiling blends with the breathed out breath of individuals who might be asymptomatic providers of COVID.

He stated to avoid filtered air ending up being infected, it needs to be pumped into a space through ground-level vents. Zhang suggests utilizing “displacement ventilation,” which just provides the air supply at the flooring level however tires it through vents in the ceiling.

Air cleansing

Air cleansing techniques include using air purification or filtration within a structure, spaces, or at an individual level, such as a correctly used mask. But amongst all 3, there should be high-efficiency filters and enough air flow, composes Zhang.

At the structure level, high-efficiency particle (HEPA) filters in the recirculated or blended duct can lower the cross contamination in between spaces and increase the overall tidy air shipment rate (outside plus filtered air) for watering down the infection concentration in the aerated area.

Standalone space air cleaners with HEPA filters can likewise be utilized as an extra procedure to even more lower the concentration of infection in the occupied area. Research has revealed a variety of tidy air shipment rate (CADR) from 170 to 800?m3/h (or 100 to 470 CFM) with a typical expense of $361 based upon an extensive study of off-the-shelf air cleaners readily available from the most popular online shopping websites. The outcomes followed an earlier lab research study in which 6 portable air cleaners were checked for both particle and unstable natural substances elimination efficiency. Zhang states that an air cleaner with a CADR of 722?m3/h (425 CFM) can double the tidy air supply for 25 individuals in a class or open strategy workplace.

Zhang states this can be thought about as an affordable supplemental procedure for spaces where overall ventilation air flow rate is inadequate. However, for areas with displacement ventilation (DV), a space air cleaner ought to just be utilized with care so that the preferable air flow pattern of DV is not interrupted.


Zhang composes that these IAQ techniques can be utilized and executed throughout numerous scales from a whole structure to a space to a person’s cubicle or individual area. In his editorial, Dr. Zhang likewise consists of a table that reveals the performance of various mixes of IAQ techniques and the associated expenses.


Reference: “Integrating IAQ control strategies to reduce the risk of asymptomatic SARS CoV-2 infections in classrooms and open plan offices” by Jensen Zhang, 17 July 2020, Science and Technology for the Built Environment.
DOI: 10.1080/23744731.2020.1794499
Zhang is Professor and Director of Building Energy and Environmental Systems Laboratory, Department of Mechanical and Aerospace Engineering at Syracuse University (SU), New York, U.S.A., and a Visiting Professor and Chief Researcher of the School of Architecture and Urban Planning at Nanjing University, China.Zhang is a co-leader of the Syracuse University research study cluster in Energy and Environment that promotes and collaborates multi-disciplinary research study on the school. He is a professional in space air and impurity circulation, product emissions, air filtration, developing enclosure efficiency, and combined heat, air, wetness and contaminant simulations (CHAMPS) for integrative style and smart controls of structures.

Much of this work occurs in the Total Indoor Environmental Quality Laboratory (TIEQ Lab) at the Syracuse Center of Excellence in Environmental and Energy Systems. The TIEQ Lab can replicate numerous indoor workplace settings such as heating, ventilation, and cooling, and set up to evaluate the incorporated control and management techniques.

Zhang has actually authored/co-authored over 200 technical documents and 3 American nationwide requirements. He is Associate Editor of Journal of Science and Technology for the Built Environment (STBE, previously ASHRAE HVAC&R Research Journal) and The International Journal of Ventilation, and acts as a Member of the Editorial Boards of Building Simulations–a global Journal, International Journal of High-Rise Buildings, and the International Journal of Architectural Frontier Research. He is Fellow of ISIAQ and ASHRAE, and existing Chairman of the International Association of Building Physics.

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