Minimum Efficiency Reporting Values, or MERV, reports a filter's ability to capture particles. Filters with MERV-13 or higher ratings can trap smaller particles, including viruses. Many home HVAC systems will have a MERV-8 filter installed as the default. Upgrading to a MERV-13 rated filter, or the highest-rated filter that your HVAC system fan and filter slot can accommodate, could improve the system’s efficacy in removing viruses from circulated air. Before making any changes to the air filter in an HVAC system, users should consult their HVAC manual or an HVAC professional.
Be sure the HVAC filter is correctly in place. Also consider running the system fan for longer times, or continuously, as HVAC systems filter the air only when the fan is running. Many systems can be set to run the fan even when no heating or cooling is taking place. Another measure that will help is opening the outside air intake, if your system has one. However, this is not common for home systems.
By itself, using an upgraded HVAC filter is not enough to protect people from COVID-19. When used along with other best practices recommended by the Centers for Disease Control and Prevention, an upgraded HVAC filter can be part of a plan to protect yourself and your family.