Home can be a sanctuary from the hectic world, but if the air indoors triggers allergies and other health problems, it can become an unfortunate situation. Common indoor air pollutants—such as mold, pollen, dust, pet dander, formaldehyde, particulate matter, and volatile organic compounds (VOCs)—result from typical indoor sources and activities like cooking, cleaning, smoking, building materials, consumer products, and home furnishings.
According to the U.S. Environmental Protection Agency, using a portable air purifier is an effective tool for improving indoor air quality. And the best air purifiers for allergies or smoke with HEPA filters can make the needed difference to improve indoor air quality. The trick is to recognize the best place to put an air purifier so that it maximizes filtration and airflow throughout the room to keep everyone as healthy and safe as possible.
The following are a few tips to keep in mind so you know where to place air purifiers in your home to maximize their benefits.
Put an air purifier near the problem.
“If you can, place the purifier close to things that make the air worse,” suggests Josh Mitchell, HVAC technician and owner of Air Conditioner Lab. “This could be near the kitchen to tackle cooking smells or where your pets hang out, since they can bring in a lot of dust and dander.” The most advantageous part about portable air purifiers is that they can easily be moved and placed near the air quality issue.
I’ve found that keeping a purifier near my kitchen island really helps when I’m whipping up something smoky like stir-fry. It’s amazing how fast it clears out those lingering cooking odors. To add to Mitchell’s point, targeting the source of pollutants can significantly boost a purifier’s efficiency. For instance, pet dander can carry allergens that trigger asthma or allergies in about 10-20% of people, according to the American Lung Association. Placing the unit near your pet’s favorite lounging spot can trap those particles before they spread. If you’re dealing with VOCs from fresh paint or new furniture, try moving the purifier to that room for a few days—it makes a noticeable difference.
Keep it off the ground.
Mitchell also recommends placing a room air purifier at breathing height, at about 3 to 5 feet off the ground. “Placing the purifier at a breathing level, either on a table or a stand, can be more effective. It works well when it’s closer to where we breathe because it can catch more of the dust and particles we might breathe in.”
I learned this the hard way after keeping my purifier on the floor for weeks and wondering why it wasn’t helping my allergies as much as I’d hoped. Once I moved it onto a side table, I could literally feel the difference in the air. Scientifically, this makes sense because many airborne particles, like dust and pollen, tend to float at chest level rather than settle immediately. HEPA filters, which capture 99.97% of particles as small as 0.3 microns, work best when positioned where air circulates naturally at the height you’re breathing. A sturdy table or shelf about 3 feet high is usually perfect for this.
Give air purifiers clearance.
Air purifiers need plenty of space around them to work at maximum performance. They need to easily take in tainted air and then push filtered air back into the room. It is important to avoid air purifier placement that is in a corner or up against the wall, and keep other objects away from the unit.
“Portable air purifiers should be placed in areas where they can effectively circulate and clean the air,” says Brad Roberson, president of Aire Serv, a Neighborly company. “Ideally, position the air purifier in a central location with good airflow, avoiding obstructions that may hinder its performance.” HVAC brand Carrier recommends placing an air purifier on a flat surface with at least 12 inches of breathing area around the four sides of the unit.
I once tucked my purifier behind a sofa to keep it out of sight, and it barely made a dent in the air quality. After moving it to an open spot, it was like night and day. To maximize airflow, think of your purifier like a fan—it needs room to “breathe.” Studies show that poor placement can reduce a purifier’s efficiency by up to 20%. A good trick is to place it in the center of the room or at least a foot away from walls or furniture. If you’re tight on space, even a small gap can help, but don’t cram it into a corner!
Avoid placing it near heat or moisture sources.
To ensure that the air purifier works to the best of its ability, do not set it in rooms with high heat or humidity. According to Samsung, the maker of consumer electronics that includes air solutions, an air purifier in a moist area will require more energy to generate airflow. This will ultimately reduce how the air is filtered. Also, moisture can cause the unit to malfunction. Therefore, avoid using air purifiers in bathrooms and other areas that tend to have high humidity levels.
I made the mistake of putting a purifier in my bathroom during a mold scare, and it started acting up after a week of steamy showers. Humidity can clog filters and even damage internal components, which isn’t cheap to fix. For context, high humidity (above 60%) can reduce a purifier’s efficiency because wet air is harder to move through filters. If you live in a humid area, consider a dehumidifier alongside your purifier to keep things in check. For example, in coastal regions, where humidity often exceeds 70%, combining these tools can make your purifier last longer and work better.
Put air purifiers in rooms you use most.
Be strategic by placing air purifiers in the rooms most frequented. Mitchell suggests, “Focus on high traffic areas. It’s a good idea to put your air purifier in places where you and your family spend the most time. These areas typically have higher air pollutants due to frequent use.” This is often the living room, family room, bedrooms, kitchen, or home office if someone works from home. Having a dedicated kitchen air purifier may be particularly beneficial.
My living room and bedroom are where I keep my purifiers since that’s where I’m usually hanging out or sleeping. It’s a game-changer for nighttime allergies. Data from the EPA shows that indoor air can be 2-5 times more polluted than outdoor air, especially in high-traffic areas where dust and dander accumulate. If you work from home, a purifier in your office can help with focus, too—clean air reduces that foggy feeling. A practical tip: if you’re on a budget, start with one purifier in your bedroom, since you spend about a third of your life sleeping there.
Be mindful of nearby electronics.
The best location for an air purifier is far away from electronic devices. Avoid putting portable air purifiers close to electronics, such as televisions, microwaves, and stereos. Because these devices may run on similar wavelengths as the purifier, they could interfere with how the purifier operates. A good rule of thumb is to keep an air purifier at least 6 feet away from electronic devices in the room.
I had my purifier right next to my TV for a while, and it seemed to struggle—turns out, electromagnetic interference was the culprit. Keeping it 6 feet away cleared things up. This interference happens because some electronics emit signals on similar frequencies as purifiers, which can mess with their sensors or motors. If your room is packed with gadgets, try to carve out a clear zone for the purifier. A quick tip: if you notice your purifier making odd noises or shutting off randomly, move it away from nearby devices to see if that fixes it.
Place them in the correct sized room.
While whole house air purifiers can help reduce respiratory irritants and minimize allergy symptoms throughout the home, portable units are most effective when the room is the right size for its capability. “Select a purifier that is appropriate for the square footage of the room,” advises Roberson. Since the size of a room is one of the most important factors in determining an air purifier’s effectiveness, check the label and manufacturer’s instructions for the maximum square footage rating in order to choose the best unit for the space. This will help determine if a small room air purifier, like this highly rated option available at Amazon—the “best bang for the buck” pick in our tested buyer’s guide, or a large room air purifier, like this one, is necessary.
I once used a small purifier in my oversized living room and was disappointed with the results until I checked the specs—it was rated for half the square footage! Matching the purifier to the room size is critical because a unit that’s too small won’t cycle the air effectively. For example, a purifier rated for 300 square feet in a 600-square-foot room might only clean half the air volume in a given time. A quick way to measure your room is to pace it out (one step is roughly 3 feet) or check your home’s floor plan. Always go slightly above the room’s square footage for best results, especially in high-pollution areas like kitchens.
Keep doors and windows closed.
Finally, to ensure that an air purifier works effectively to improve indoor air quality, keep doors and windows closed while the air purifier is running. “Do not place [the air purifier] near openings such as doorways or open windows,” recommends Dr. James Langer, air filter expert and president and co-founder of Colorfil. “While they can still be useful in other contexts, air movement through openings or doorways lessen the impact of an air purifier when used in open living spaces or kitchens,” says Langer. This helps prevent smoke and other air pollutants from entering the home from outdoors.
I used to leave my windows cracked for “fresh air,” but my purifier was working overtime with no real impact. Closing them made a huge difference in how clean the air felt. Outdoor pollutants like pollen or vehicle exhaust can sneak in and overload your purifier, especially in urban areas where air quality can be poor. For instance, the EPA notes that PM2.5 (fine particulate matter) levels can spike near busy roads. If you must ventilate, run the purifier for a few hours after closing windows to clear out any sneaky pollutants that slipped in.