Over the last few months, the Omicron variant of Covid-19 has caused a significant rise in daily case numbers.
Numerous studies have been performed on Covid-19 transmission since Covid-19 was declared a global pandemic in 2019 by the World Health Organization. Over the last two years, scientists have learned through extensive research that the most likely route of transmission is through exposure to virus particles in respiratory fluids.
Every time that building occupants cough, sneeze, laugh, talk, sing, exercise, or exhale they expel respiratory droplets into the air, many of which are invisible to the naked eye. Airborne transmission is much more likely to occur indoors where expelled viral particles are suspended in the air.
These smaller respiratory droplets can contain Covid-19, and depending on the size of these particles, they can remain suspended in the air from minutes to hours. Viral particles dilute throughout the building depending on their size, building airflow, and building ventilation.
The Center for Disease Control (CDC) has provided resources for building operators to help them safely regulate the airflow of an indoor environment by using air scrubbers.
In its guidelines on Ventilation of Buildings last updated on June 2, 2021, the CDC recommends “the use of portable high-efficiency particulate air (HEPA) fan/filtration systems to enhance air cleaning (especially in higher risk areas such as a nurse’s office or areas frequently inhabited by people with a higher likelihood of having COVID-19 and/or an increased risk of getting COVID-19).”
The CDC states in this article that “HEPA filters are no less than 99.97% efficient at capturing human-generated viral particles associated with SARS-CoV-2.”
Things to consider when choosing an air filter:
When it comes to choosing the proper air scrubbers for your building, there are numerous factors to consider.
The Environmental Protection Agency (EPA) has put together a free PDF that guides a building operator through selecting the right one.
There are two major points to consider: “In order to select an air cleaner that effectively filters viruses from the air, choose: 1) a unit that is the right size for the space you will be using it in (this is typically indicated by the manufacturer in square feet), 2) a unit that is designated a HEPA unit, or specifically indicates that it filters particles in the 0.1-1 um size range.”
In summary, you want to select air scrubbers that have high filtration efficiency, high airflow, and low-pressure drop.
For a great overview of how air scrubbers work you can view this helpful document.
Other Safety Recommendations
As always there are preliminary steps that you can take as a building operator.
The CDC continues to recommend masks, social distancing, and lower occupancy rates as the best primary means available for controlling transmission.
Although people are less likely to be infected with Covid-19 through fomite transmission, disinfecting surfaces and clean hands remain best practices to diminish the chances of viral contact transmission.