Indoor air quality and airborne transmission of COVID-19

Adjustments to a building's mechanical system could slow the spread.

By Salas O'Brien May 12, 2021

Precautions to prevent the transmission of coronavirus via direct and indirect contact like social distancing, handwashing, and mask wearing have become commonplace based on recommendations from the scientific community.

More may be needed. To support and maintain healthy buildings, members of the scientific community recommend that building owners and operators follow precautionary practices to:

  • Ensure sufficient and effective ventilation by supplying clean outdoor air and minimizing recirculating air.
  • Supplement general ventilation with airborne infection controls, such as local exhaust, high efficiency filtration, and germicidal ultraviolet lights.
  • Avoid overcrowding, particularly in public transport and public buildings.

What you may not know is how to make “sufficient and effective” changes in your ventilation system to diminish airborne infections. In fact, without the guidance of experts, some changes can be very costly without any benefit to the health of the occupants. That’s where we can help.

Our mechanical, electrical, plumbing, and technology team has designed and implemented measures to help clients achieve improved indoor air quality long before the pandemic hit, and we’re well-versed in strategies to address area of potential airborne viruses. We’ve identified appropriate and reasonable measures to minimize transmission in a variety of ventilation systems.

Ensuring sufficient and effective ventilation

Ventilation is the process of replacing indoor air with fresh air from outside the building. This can happen naturally through openings in the building (i.e. windows and doors) and mechanically, where airflow is distributed by fans, ductwork, terminal devices, and diffusers.

Our mechanical design experts can analyze the existing system’s performance, including its efficiency, the airflow direction, and the air change rate, which is the measure of air added and air removed from a space.

They can recommend adjustments based on their findings to minimize recirculated air, increase the air change rate, increase the outdoor air volume, or change the sequence of operations of the air handling systems, to achieve ideal ventilation.

Supplementing general ventilation with airborne infection controls

In some cases, it may be beneficial to supplement air systems with a local portable exhaust ventilation (LEV) system to achieve the desired results. A LEV captures air and transports it to a safe emission point or to a filter before reuse. The LEV reduces the quantity of airborne contaminants in the space.

The CDC suggests upgrading the efficiency – the fraction of particles removed from the air as it passes through the filter – of the system’s air filtration to slow the spread of COVID-19.

They also suggest using ultraviolet germicidal irradiation (UVGI) as a supplemental technique to inactivate potential airborne virus in the upper-room air of common occupied spaces.

This article originally appeared on Salas O’Brien’s website, Salas O’Brien is a CFE Media content partner. 

Original content can be found at

Author Bio: For more than 40 years, Salas O’Brien has been at the forefront of designing buildings that are healthy, sustainable, and cost-efficient.