What is the Best MERV Rating for COVID-19 Protection?

In this article we discuss what type of air filter is best for protecting against COVID-19 and why you should upgrade your HVAC system to at least a MERV 13 rating.

What is the Best MERV Rating for COVID-19 Protection?

In the wake of the coronavirus pandemic, many outdated systems have been forced to improve. Health systems have been tested and a lot of data has been gathered to help us learn and grow. One of the most important changes that has been recommended is to upgrade air filters to a MERV 13 or higher. But what does this mean and is it enough to protect against COVID-19?A MERV 13 filter is a step in the right direction as it captures more particles than a typical MERV 8 filter.

However, it's not as effective at capturing small virus-sized particles as a HEPA filter. A MERV 13 will trap less than 75% of air particles that are 0.3-1.0 microns in size (coronavirus is 0.1 microns). It can also be difficult for many existing HVAC systems to adopt a MERV 13 due to the increased fan load from finer filter media, which can actually reduce airflow if your system is not designed to handle it. On average, many installations are limited to one type of MERV 8 or MERV 9 filter. So, can building air filtration protect you from contracting COVID-19? The answer is yes, but it's important to understand what type of filter you should use and why you shouldn't use the most efficient filter you can find.

Hospitals have specially designed mechanical systems that can adapt to the levels of filtration they need, but these are often based on other control systems and strategies (most importantly, they have dedicated staff who operate and maintain this equipment). For residential or commercial use, HEPA filters are the most efficient, followed by MERV 13-16 filters. Portable air filters also come with multiple filters to trap harmful particles and remove a large amount of COVID particles from indoor air. MERV 16 is the tallest filter you can buy, but your air conditioning system may not be able to do it. Alternatively, you can upgrade the ventilation system itself, making it suitable for at least MERV 13 filters.

As part of a comprehensive indoor air quality strategy, filtration provides an additional level of protection against many of the harmful pollutants floating in the air. To help protect against the COVID-19 virus, ASHRAE changed its recommendation from MERV 8 filters to MERV 13+. A HEPA filter is essentially the ultimate solution in the world of air filters and far exceeds what a MERV 13 can do. An additional benefit of MERV 13+ filters are the points they provide for achieving Green Building Leadership in Energy and Environmental Design (LEED) certification in the air filtration efficiency criteria part of the certification. Considering the threat posed by the spread of COVID-19 and other germs, upgrading a building's air filter to a HEPA is a much more effective step than just a MERV 13 considering the small size of a virus (0.06-0.12 microns); the more efficient the filter, the better. Follow ASHRAE indoor air quality recommendations to reduce aerosol transmission of the COVID-19 variant of Omicron. Ultraviolet (UV) lamps may also be used as part of an indoor air quality strategy, as well as other air cleaning technologies such as ionizers, ozone generators and plasma.

For more information on these technologies and how they can help protect against COVID-19, visit your local health center or contact an HVAC professional.

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