If you suffer from asthma or have seasonal allergies, an air purifier can help relieve your symptoms and increase the air quality in your home. The This Old House reviews team tested a few of the top air purifiers on the market today and pored over thousands of air purifier reviews to determine which devices are the best of the best. We did the research, so you can enjoy an allergen- and pollutant-free home.
Best Overall: Honeywell True HEPA Air Purifier with Allergen Remover
- Filters and circulates air up to 5 times an hour
- Uses certified HEPA filters to remove allergens, dust, and other microscopic particles
- Recommended for large rooms, capturing up to 99.97% of airborne particles
- More expensive than some of the other purifiers reviewed
- New units may give off a plastic smell at first
Best Value: Germ Guardian True HEPA Filter Air Purifier
- This affordable unit requires minimal maintenance, clears air, and reduces odors. It’s a great pick for pet owners, as it’s designed to remove pet dander, odors, and hair.
- Reduces pollutants in rooms up to 390 square feet
- Charcoal filter removes odors
- Optional UV-C light with Titanium Dioxide to reduce airborne bacteria, viruses, and germs
- Deodorizing filters need to be replaced weekly
- Can be a bit loud on its highest setting
Premium Pick: IQAir HealthPro Plus Air Purifier
- Hospital- and FDA-approved
- Quiet relative to other products reviewed
- Device can be easily moved from room to room
- Timer that conserves energy and prolongs filter life
- New units may give off a chemical smell at first
- Machine and filters are expensive
#4: Alen BreatheSmart Classic Large Room Air Purifier
- SmartSensor technology automatically adjusts airflow to remove impurities and reduce odors
- Covers large rooms, cleaning 1,100 sq. feet every 30 minutes
- WhisperMax technology produces a pink noise to promote better sleep
- Requires replacement filters
- New units may give off a plastic smell
#5: Whirlpool Whispure Air Purifier WP500
- Filters air 4.8 times per hour
- One of the quietest on the market
- 4 speeds for various air-cleaning needs: low, medium, high, and turbo
- One of the bulkier air purifiers we reviewed
- Some customers mentioned a plastic smell or squeaking noise
Air Purifier Reviews Guide
Poor air quality can exacerbate breathing problems and infuriate allergies. An air purifier removes irritants and toxins from the air, increasing indoor air quality levels while preventing respiratory issues like asthma and allergies.
In our comprehensive guide to buying an air purifier, we’ve outlined important factors to consider, reviewed thousands of customer testimonials, and answered frequently asked questions to ensure you get the best air purifier for your home.
Types of Air Purifiers
There are two types of air purifiers: portable and whole-home air purifiers.
Portable air purifiers
In this review, we focus on portable air purifiers. These devices are designed to clean the air in a single room. Not only are they smaller and easier to transport throughout your house, but they’re also more energy efficient and more affordable than whole-home appliances.
Whole-home air purifiers
Whole-home air purifiers attach to existing heating, ventilation, and air conditioning equipment. They can be installed as filter-based units in HVAC furnace systems, duct-based units in ductwork, or standalone systems that are installed in closets or attics. These use more energy and are more expensive than portable models.
Types of Air Purifier Filters
Below we’ve outlined the different types of filters found in an air purifier. Note: most machines will require you to replace the filter every so often. While the manufacturer will include at least one air filter with your purchase, you’ll be responsible for purchasing any additional replacement filters.
A pre-filter captures large particles that enter the device. These filters are smaller and cheaper than a HEPA filter. Check this filter every few months and replace it when it’s dirty.
A second pre-filter catches small particles not caught by the pre-filter before they hit the HEPA filter. This middle filter also targets odor molecules.
The HEPA filter removes up to 99.97% of airborne particles, making it one of the best filters to have in your unit. Though it does a good job at cleansing your air, it’s also one of the more expensive filters to replace. Check your product manual to determine how often you should change your HEPA filter. We recommend changing it every three months.
How Does an Air Purifier Work?
- The air purifier sucks in air from the room—During this step, the fan will pull air into the machine and pass it through the pre-filter. The pre-filter should capture most of the large airborne particles like dust and dirt.
- Air filters through the second pre-filter—Before hitting the HEPA filter, the air and any remaining particles and odors will go through the second pre-filter.
- Air goes through the HEPA filter and cycles back into the room—In this last step, the air filters through the HEPA filter and is pushed back into the room. The more times the air passes through the HEPA filter, the cleaner the air becomes.
How to Get the Most out of Your Air Purifier
Though air purifiers can be a big investment up front, there are still ways you can use them and save money in the long run. Here are a few tips on how to save money with your air purifier.
- Clean the house regularly—The more dust and airborne contaminants you remove from your home, the better your air purifier will work. Dust countertops and shelves with a microfiber cloth every couple of weeks and vacuum your floors at least twice a month.
- Minimize use of candles—Your candles emit carbon dioxide and can make an air purifier work harder.
- Invest in an energy-efficient purifier—ENERGY STAR-certified units may be a bit more costly, but they can conserve energy costs and save you money over time.
- Purchase washable filters—Replacement filters cost around $50 to $500. By using reusable, washable filters, you won’t have to buy a new filter every time the filter gets dirty.
- Change your filter every time it gets dirty—You may be tempted to change the filter less often than the manufacturer recommends to save money—we highly advise against this. Operating an air purifier with a dirty filter reduces efficiency and can lead to mechanical failure. Replace the filter or invest in a reusable option.
Buying an Air Purifier: 6 Major Factors to Consider
Indoor air quality needs
If you’re someone who suffers from allergies, consider choosing a machine designed for allergy relief—these models include HEPA filters which can remove 99.97% of most airborne particles sized 0.3 microns or larger (for reference, the average cross-section of a human hair is 50 microns).
If you suffer from asthma, consider purchasing an asthma air purifier that includes a HEPA filter as well as odor and chemical filtration. If you’re sensitive to chemicals, go for an air purifier that has multiple chemical sensitivities (MCS). These contain more powerful filtration for odors and chemicals than other models and are often manufactured with materials that will not off-gas chemicals into the air.
To choose the right size air purifier, calculate the square footage of the room you want to purify by measuring the length and width of the space. Select a unit that has a coverage rating higher than the room in which it will reside (about two times the area of the space)—this ensures that the air purifier will be able to handle its load. You can find coverage information under the air purifier manufacturer specifications.
Air change per hour (ACH) reflects how often an air purifier will filter the entire volume of air in the treatment space each hour. For example, an air purifier with an ACH rating of four would pull air through the machine and clean it at least four times per hour.
Some models will come with a programmable timer that allows you to schedule when the purifier runs. Portable purifiers have a carrying handle so you can easily transport it from room to room. A remote control is handy for adjusting settings from across the room. Various fan speeds lend noise control and reusable filters lower maintenance costs.
If you want to make sure your purifier is working to the best of its ability at all times, look for one that has a service indicator light—this lets you know when it’s time to clean or replace your air filter.
Air purifiers can be noisy, especially when they operate on the highest setting. If you’re planning on leaving the appliance in your bedroom or home office, look for the decibel level before buying. This can be found in the product specifications. We recommend choosing a larger unit and running it on a lower speed to minimize noise and save on energy costs.
Air Purifier FAQs
What is the best air purifier on the market?
While there are plenty of top air purifiers that do an excellent job at removing impurities from the air, the reviews team believes the Honeywell air purifier is the best air purifier on the market. It filters and circulates air up to five times an hour and uses certified HEPA filters to remove all types of airborne contaminants in your home, including dust, dirt, and allergens.
What is the best air purifier for mold?
The best air purifier for mold is the Alen BreatheSmart Customizable Air Purifier. With four filter options tailored to your specific needs, this device targets allergies, mold, dust, bacteria, VOCs, and odors. It also has a Laser Smart Sensor that targets the smallest airborne particles down to 0.3 microns. Plus, if you’re not satisfied with this purifier, Alen offers a lifetime guarantee.
Can air purifiers make you sick?
HEPA air purifiers don’t add anything to the air in your home, so they can’t make you sick—they actually remove harmful airborne contaminants like mold spores, dust, and allergens. However, ozone generator products sold as air purifiers can cause dizziness, headaches, and lung irritation.