Mercy Tips to Care for Earth

Air Filters 

Mercy Tips to Care for Earth

By Jason Giovannettone, Climate and Sustainability Director 

An air filter prevents air-borne contaminants (dust, pollen, bacteria and various other allergens) from entering your heating, ventilation and cooling (HVAC) system and your indoor air supply. Removing these particles from the air helps improve health and reduces the chances of particles clogging up the HVAC system, thereby increasing its efficiency and lifespan and reducing the chance of a breakdown. An air filter’s efficiency is measured by a Minimum Efficiency Reporting Value (MERV), which ranges from 1 to 16; higher numbers mean that the filter is more efficient at catching smaller particles.   

Types and Materials 

There are three major types of air filters that are typically used in an HVAC system: fiberglass, pleated and washable/reusable. 

  1. Fiberglass filters are made from glass-fiber reinforced plastic and encased in a cardboard frame.  These filters tend to be relatively inexpensive but need to be replaced every 30 days.  MERV ratings for fiberglass filters are generally lower, making them less capable of removing smaller particles.   
  1. Pleated filters are made from either polyester, paper or cotton and folded into an accordion style to create more surface area on which air-borne particles can be captured.  Pleated filters are generally more expensive than fiberglass but last longer. It is generally recommended that they be replaced every three months. These filters have MERV ratings ranging from 5 to 13, with the higher-rated filters able to effectively capture dirt, fine dust, pollen and even the smallest bacteria.  Many pleated filters are also electrostatically charged, which enables them to attract and capture an even greater number of small particles.  
  1. Washable/reusable filters are made from either synthetic fiber, aluminum mesh or both.  Though reusable filters tend to cost the most ($25 to $75 per filter), they can last up to 10 years.  MERV ratings for reusable filters typically do not exceed 8; therefore, they are not as good at removing smaller particles as a pleated filter.  These filters do require additional labor for cleaning; it is generally recommended that be cleaned every three months, a process that consists of shaking off or vacuuming loose debris and rinsing with water.    

All filter types are available in a wide range of sizes, although reusable filters cannot be customized to unique sizes based on a particular location’s needs.   

From an environmental standpoint, reusable filters are the best option.  Fiberglass and pleated filters must be disposed of after being replaced; as such, reusable filters reduce your overall carbon footprint as well as the amount of material (including plastic) being disposed.  The main drawbacks are the increased amount of labor that is needed to clean the filters and limitations on the range of sizes; this is especially an issue at larger properties that require more filters.   


If you are responsible for changing the air filters at your residence, consider getting a reusable filter. These can be easily purchased online.  If you are not responsible for changing your air filters, consult with your maintenance manager to see if it would be possible to switch to reusable filters given your location’s particular size limitations and labor requirements.