Airborne Transmission of COVID-19
According to the CDC, COVID-19 can be spread in tiny particles called aerosols which are produced as we breathe and are increased when talking, yelling, or singing. Aerosols can remain floating in the air for hours and can travel long distances. Because aerosols consist of water and virus, a person would need to inhale large quantities of them to get sick. However, aerosols can accumulate over time in indoor spaces if no effort is made to properly circulate and clean the air.
Controlling Airborne Transmission
- HVAC controls can be adjusted to increase the exchange of fresh air from outside a building reducing the amount of recirculated air.
- Equipment components can also be upgraded to better accommodate this functionality.
- Fixed speed fan motors can be replaced with variable speed motors to improve airflow control.
- High-tech airflow control systems are available to provide even greater control.
Ventilation with recirculated air will not reduce the risk of COVID-19 unless the air goes through a filter designed to remove tiny particles like aerosols. The EPA gives filters a MERV rating based on the size of the particles they remove. A MERV rating of 13 or higher means at least 90% of particles are removed. HEPA filters are the highest EPA-rated filter removing at least 99.97% of even smaller particles.
Common air purification methods used in commercial buildings.
- Irradiation – electromagnetic radiation (ultraviolet light) to deactivate pathogens. This technology should only be used when spaces are not occupied due to the harm the light can cause to skin and eyes.
- Ionized purifiers – whole building systems are available and can be mounted inside HVAC systems.