The customer is responsible for making decisions such as which filter to buy, how many to install and where to install them. AiroTrust, LLC. Is not responsible for the misuse of our products. But we are here to make your buying process as simple, straightforward, and safe as possible. With our testing and experience installing Building Masks in many different sized buildings with different applications, we can make great recommendations to help you choose the most effective filters and install them correctly. If you are concerned about how the AiroTrust Building Masks and filter selection will affect your HVAC system, it is always a good idea to consult with your HVAC company before installing for long term.

Where to Install

The AiroTrust Building Mask attaches to any air vent on a ceiling that features 2’ x 2’ ceiling tiles like the ones found in office spaces all over the world. If your ceiling tile frame is made from a metal construction, the Building Mask with its strong neodymium magnets will snap on over the vent with minimal effort.

Although you could install an AiroTrust Building Mask onto either the cold air returns or supply vents, we have found that the most effect and safe way is to cover all supply vents for a system. While covering the cold air returns would keep your ducts and HVAC units clean, covering the supply vents is far more effective at increasing the indoor air quality in your building. This will ensure that all the air coming from your HVAC unit has an extra layer of filtration to immensely cut down on the number of particles in the air directly before reaching your common spaces. The reason we recommend covering ALL the supply vents is to keep the pressure constant over all vents. Comparing your building to the Air Conditioning in your car, if you close all the vents besides one, all of the air will be directed to the vent that is still open. Similarly, if you restrict the air flow with a filter on only half of the supply vents, the bulk of the airflow will be directed through the path of least resistance which would be the un-filtered vents.

Safety Considerations

A main concern that our customers have when installing an air filter directly to their system at the ceiling is the added airflow restriction of these filters. Many are worried that with the added airflow restriction, the evaporation coils on their AC unit could freeze. Our findings, that have been backed up by HVAC testing companies, have determined that this is very rarely an issue. Especially since most modern HVAC motors are ECM's (Electronically Controlled Motor) allowing the motor to automatically run faster when it detects a restriction in airflow. With an ECM motor, our testing showed that the airflow over the coils is nearly the same even with our most restrictive filters covering all of the cold air return vents. Even for customers without ECM motors who are concerned, an AiroTrust Building Mask with a high efficiency filter are typically very low risk. For customers who need to be as safe as possible, AiroTrust Building Mask's can be used as a seasonal solution during flu and allergy seasons. Furthermore, choosing one of our least restrictive, yet highly effective, filters such as the 30/30 Dual 9 would be a great choice for anyone with concerns. Lastly, choosing a thicker 4" filter (when there are no obstructions) causes much less restriction by increasing the surface area of the filter without loosing the filtration efficiency.

How to Choose the best filter for your application


  • 55% average particle reduction in a single pass!
  • Great for removing air-born particles such as lint, dust, pollen, dust mites, and mold.
  • Excellent airflow efficiency and low pressure drop.


  • 30% average particle reduction in a single pass!
  • Removes many of the larger air-born particles like the MERV 8 filter.
  • Removes odors such as animal, chemical, waste, food, smoking and more.
  • Contains 323 gsm of activated carbon to attract and capture odors.

MERV 11:

  • Middle of the road particle reduction compared to MERV 8 and MERV 13 filters.
  • Reduces all the particles that a MERV 8 filter does, plus allergy irritating particles including dust, mold spores, pet dander, dust mites, and more.
  • Works well for those with allergies looking to increase indoor air quality.
  • High capacity filter provides a good balance of filtration and airflow.

MERV 13:

  • More than 90% average particle reduction in a single pass!
  • Removes all of the particles of the MERV 8 plus aerosols, virus carriers, bacteria, smog, and pet dander.
  • Great for those with bad allergies or pet owners.
  • Most restrictive on airflow, but offers the best filtration to make up for it.

When do I need to replace the filters in my Building Masks?

There is no correct answer to this question. Since every environment and every filter is different, it is very difficult to accurately estimate the life of the filters. The easiest way to tell when the filters need to be changed is to simply look up. Our filters will get visibly dirty signaling that it is time to replace them. We have seen filters last only 2 weeks in some especially dirty environments, while they can last many months in very clean settings. If the filters develop a darker color, it is best to change them. 

Leaving dirty filters in for too long could potential damage your system so it is best to check them regularly. If your filters are extremely dirty causing a large reduction in airflow, it may be best to remove the filters until you receive replacements.

Why do I need to replace the filters in my Building Masks?

It is extremely important for you to regularly check your filters and replace them when necessary. Leaving dirty filters on your vents can cause problems for your HVAC system.

  • A dirty filter restricts the air flow for your HVAC system causing it to work harder in order to cool or heat your air and potentially cause problems with the system.
  • As a filter becomes dirty, it will loose its effectiveness at cutting down on particles and filtering your air. 
  • Dirty, unchanged filters could make your HVAC system fail completely. Repairing a broken system is far more expensive than regularly replacing dirty filters.