Why your HEPA air filter might not be doing what you think

hepa air filter

With the onset of the COVID pandemic, people have become far more conscious of the air pollution they are inhaling on a constant basis. The most common solution people arrive at is to purchase an air purification system, especially one that is labeled as a High Efficiency Particulate Air (HEPA) filter. While this solution may work well for some, what many do not realize is that a basic HEPA air filter is not always enough to effectively clean the air.

HEPA air filters do offer a range of benefits and are touted to be able to remove dust, bacteria and even viruses like COVID from the air. For these reasons they’ve become popular in places like restaurants, hospitals, and schools.  The CDC even recommends the use of HEPA air filter systems to combat the spread of COVID-19.

HEPA is effective… in the right setting

HEPA air filter units, unfortunately, are not a one size fits all solution. When selecting an air purifier, it is critical to consider the location, size of the room, and fan speed.  These factors determine the effectiveness of your purification unit, and ultimately determines if your air purification unit will serve its purpose of keeping you and your family safe.

A traditional HEPA air filter unit can struggle to a remarkable degree when placed in too large of a room. Despite being a high efficiency filter, down to 0.1 microns, the air is not being filtered because it is not moving through the HEPA enough, leaving you with all the same problems as before, needing to buy multiple HEPA units to ensure consistent performance. This means plenty of cost for far too little performance.

Choosing the Right Air Filtration System

If you’re in the market for a portable air filtration system, it’s important to consider the needs of your facility before jumping into a purchasing decision. Consider the following:

  • Room size and ceiling height
  • Desired (or required) air changes per hour
  • Maintenance requirements

Why Room Size Matters

If you multiply the length and width of the area in which you intend to operate the air purification unit, you will get the size of the room area in square feet. Many portable HEPA air filters will make a recommendation for a room size in square feet. While this type of filter may meet the requirements for your room, a better alternative may be to buy an air filter system that can handle a variable room size.  One of the many advantages of a portable unit is, in fact, its ability to be moved around.  So why invest in a filter system that restricts where you are able to use it effectively?

For example, the ProGuard Mobile Air Purifier can accommodate a variety of room sizes using a fan capable of multiple air changes per hour.

How Many Air Changes Per Hour?

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration systems design and construction. ASHRAE recommends 6 air changes per hour for optimal air purification.  To achieve this amount of air turnover, a powerful system that accounts for various room sizes is required.  Below is an example of a table that demonstrates how air changes per hour can change dependent on the room size.

proguard air changes per hour


Maintaining any air filter system can be a cumbersome task.  Systems that rely on HEPA filters often require frequent filter changes to functionally operate.  Manufacturers typically recommend filter replacements every 6 to 9 months.  With this in mind, a HEPA air filter that is already above and beyond its room size capabilities may need even more frequent filter replacements.

The New Standard for Clean Air

Mobile air purification systems set a new standard for achieving clean indoor air while significantly reducing the risk of spreading harmful viruses and bacteria. The ProGuard Mobile Air Purifier goes beyond the traditional filter-only units and compensates for insufficient ventilation. The ProGuard unit purifies indoor air better than standard HEPA filter systems. Air quality is more important than ever before.  Get in touch with us to learn more about how to improve indoor air quality in your facility.