If you have a cat or dog, you should not be surprised to find elevated pet allergens in your home. But did you know that you can find pet allergens in the dust of essentially every single home?

Cat and dog allergens are stickier than other allergens and are passively transported.  A child with a cat or dog will likely shed some pet allergens at school.  A classmate without pets may pick up that pet allergen at school, bring it home, and expose siblings. In this article, I will highlight strategies to reduce pet allergens, whether or not you have a pet in the home.

Is Pet Allergen Airborne?

Before we can come up with a strategy to reduce pet allergens in the home, we need to establish if they are predominantly found in the air or settled on surfaces.  Unfortunately, with cat and dog allergens, they can be found both in the air and settle on surfaces.

Most cat allergens are found in relatively large particles greater than 10 microns in diameter.  These larger particles settle out of the air via gravity and collect in the house dust. There is a percent of allergen, however, that is smaller than 5 microns that tends to stay airborne for long periods of time.

Some people start reacting to pet allergens by simply stepping foot in a home with cats or dogs. They are likely reacting to small airborne particles containing allergens.  Other people may not react until they stir up settled dust or have direct contact with the allergen.

You need a double strategy to remove pet allergen: air filters to remove the airborne allergen and strategic cleaning to remove settled dust.

Removing Airborne Allergen

To remove the airborne pet allergen, the best strategy is air filtration.  You can filter the air with a portable air cleaner or with a centralized filter that is part of your heating and cooling system such as a furnace, air conditioner, or heat pump.

If you don’t have a central air system, a portable air cleaner is the best strategy.  There are many technologies available, but the most trustworthy utilizes HEPA filtration. Although several companies make disparaging remarks about HEPA, they are mostly false claims. In fact, many HEPA alternatives produce harmful by-products such as ozone.  HEPA is at least 99.97% efficient at all sized particles (and for particles both larger and smaller than 0.3 µm, the removal efficiency is even higher).

If you have a central air system, you can improve the efficiency of your home’s filter to help remove airborne allergens. However, there are many pitfalls to purchasing a high-efficiency filter at the hardware store and installing it in your central air system.  Filters create a restriction to airflow and can inadvertently damage the equipment. You want to get the highest efficiency filter that doesn’t affect performance. If you put in a new filter and there is a noticeable reduction in the airflow coming out of the registers, you should reduce the efficiency.

I recommend purchasing filters that have been testing using the ASHRAE 52.2 standard, which provides a MERV rating between 1 (least efficient) and 16 (most efficient before getting into HEPA filter range).  A filter with a MERV 8 efficiency is a good starting point for most systems.


Removing Settled Allergen

Not all allergens are airborne and in fact, most will be settled onto surfaces.  To remove allergens from hard surfaces, the best option is electrostatic cloths (e.g. Swiffer®). These can be used to remove dust off of hard flooring, bookshelves, and countertops.

What about allergens that have accumulated in carpeting?  Not all vacuum cleaners are created equal.  Some vacuums are specifically designed to remove pet allergen.  They contain a HEPA filter to reliably trap small allergenic particles, whereas normal vacuums may shoot particles back out into the room.

The absolute best vacuum is a centralized vacuuming system with exhaust.  If the filtering mechanism misses anything, it gets exhausted to the outdoors.  These systems are very expensive and are best installed when a home is under construction.

What if the offending pet is in the home?

Of course, the best way to reduce pet allergen in a home is to remove the pets. That is a highly personal decision and one that is not easy to make.  I have a friend who cannot part with her cat despite being allergic to it. The cat is confined to certain rooms and her husband does most of the pet care and cleaning.

With a pet in your home, you will always be fighting an uphill battle against allergens.  If no one in your home is allergic, there may be minimal concern.  In fact, growing up with pets may reduce the likelihood of allergic disease in children.  Just be careful with visitors that are already sensitized to pets.

By filtering your air and strategically cleaning surfaces, you will be better equipped to reduce cat and dog allergens in your home.


About the Author

Ian Cull, PE, CIH is the owner of Indoor Science, a Chicago-based air quality consulting company.  He and his team investigate air quality issues in homes, offices, and schools including mold inspections and indoor air quality testing. Mr. Cull previously served as the Technical Director of the Indoor Air Quality Association.  With over 20 years of experience, Mr. Cull has been invited to speak around the world including Asia, Europe, South America, and Australia.