COVID-19 ISO Insights

Indoor Airflow Model May Help Mitigate SARS-CoV-2 Laden Aerosols

June 29, 2020

By: Christopher Sirota, CPCU

Combating airborne viruses indoors may have gotten a bit easier. Researchers at the National Institute of Standards and Technology (NIST) have released new software that can model airflow to help reduce the concentration of contaminated aerosols that may be floating around near people and objects.

We previously posted that there is reportedly a risk that the novel coronavirus (SARS-CoV-2), which causes COVID-19, may be transmitted through the air as an aerosol emitted from an infected person. For example, a related April 2020 National Health Institute report regarding healthcare worker exposure to SARS-CoV-2 noted that "[s]neezing and coughing are effective aerosol generators, but all forms of expiration produce particles across a range of sizes."

Now, NIST reports that it has modified one of its airflow analysis models, called CONTAM, to develop the newly released software called Fate and Transport Indoor Microbiological Aerosols (FaTIMA). FaTIMA can reportedly simulate how much aerosol might be expelled by people indoors, and how long that potentially contaminated air might linger or dissipate depending on various factors.

Per the announcement, building managers and engineers could input the following factors to generate a simulation to help evaluate the risk of various sized rooms within a building:

  • the room dimensions
  • the number of people within a room and their rate of exhaling aerosols
  • the number of infected patients within a room
  • the rate of fresh air introduced by the ventilation system
  • the efficiency of air contaminant filtration
  • the size of the virus-containing aerosols and the speed at which they fall on to surfaces

The announcement notes that the FaTIMA software default settings are based on previous studies of influenza-containing aerosols.

After better understanding the airflow of a room, the risk of allowing a high concentration of aerosol to form within a room can reportedly be mitigated by various means, such as adjusting the number of occupants, increasing the amount of fresh or filtered air introduced, or increasing the rate of air filtration.

Of note, the announcement highlights that the range of adjustments to the model can help evaluate specific scenarios such as:

an individual’s exposure for up to 24 hours even if the person only enters the room periodically […] In the case of a caregiver scheduled to check on a patient every hour during a 12-hour shift, the [FaTIMA] tool would be able to predict the person’s average, peak and total exposure in the patient’s room over the course of the entire shift. The tool would also estimate the number of aerosols that had landed on the floors, walls and other surfaces in the room.

The full NIST report is available here.