How to Choose an Air Filter for Your Facility

The EPA lists indoor air pollution among the top five environmental health risks. Choosing the proper air filter can improve your facility’s indoor air quality and keep its occupants healthy. Here is an exploration of how air filters are categorized, and which may be appropriate for your needs.

Air Filter Classification

MERV (Minimum Efficiency Reporting Value) is a system that measures an air filter’s ability to trap airborne particles. The scale ranges from 1 to 16, with filters at MERV 16 being the best at trapping particles as little as 0.3 microns.

  • MERV 1-4: Traps larger particles like pollen and dust that reduce your facility’s indoor air quality.
  • MERV 5-8: Traps mold spores and aerosol sprays, like fabric protectors and hair spray.
  • MERV 9-12: Traps finer particles like automobile emissions and humidifier dust.
  • MERV 13-16: Traps miniscule particles like bacteria and tobacco smoke. These filters are  also proficient at trapping human-made particles, like those from sneezes.

Choosing the Right Filter

When choosing an air filter for your facility, consider the following suggestions from ASHRAE.  ASHRAE (American Society of Heating, Refrigeration and Air Conditioner Engineers) is the governing body for the MERV system, and their Standards 62.1 & 62.2 are the most prominent benchmarks for indoor air quality.

Consider your sustainable goals

The standards dictate ventilation rates and other conditions for commercial and institutional buildings, and suggests a MERV 6 filter at the very least. If your facility is seeking LEED certification, your HVAC system is required to use MERV 8 filters at a minimum for their superior protection against the recirculation of airborne dust.

Consider your building occupants

For facilities where indoor air quality is of utmost importance, such as hospitals, you’ll want to invest in a higher standard of filter for its ability to trap miniscule particulate matter such as virus-carrying bacteria. Paul Francisco, the committee chair for the 62.2 Standard, explains of the miniscule particles, “These particles have been found to be one of the most important indoor contaminants from a health perspective.” ASHRAE recommends MERV 11 to trap particles in healthcare settings, but the US Department of Energy suggests MERV 13 filters.

A study from the EPA showed that MERV 7-13 is nearly as efficient as HEPA (high-efficiency particulate air) filters, which trap 99.97% of particles as small as 0.3 micrometers. True HEPA filters perform at MERV 17-20, and are a powerful yet costly addition to an efficient HVAC system.

Consider the age of your air filter

As air filters age, they become dirty with the particles they’ve trapped. Aging filters reduce the airflow in your facility, or may recirculate those particles throughout your facility. We recommend replacing your HVAC filters every 30 days to help ensure your air filter is performing at the MERV rating it’s intended to.

Air filters are a powerful tool to improve your indoor air quality, and there are many other steps you can take to make a difference in your facility. Review our previous blog to see a dozen steps you can take to keep your facility’s occupants breathing easy this spring.

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