In today’s world, air quality is a growing concern. According to the Environmental Protection Agency (EPA), indoor air can be two to five times more polluted than outdoor air, and in some cases, up to 100 times more polluted (source).

Investing in an effective air purifier can make a significant difference, but with so many options available, how do you choose the right one? Here’s what you need to know when shopping for an air purifier to ensure cleaner, healthier air in your home.

Why Air Purifiers are Important

Pollutants such as dust, mold spores, pollen, pet dander, volatile organic compounds (VOCs), and even harmful gases can circulate in our homes, potentially impacting our health.

The pollutants can cause respiratory issues, exacerbate asthma, and even increase the risk of heart disease. If you're in an area prone to wildfires, smoke particles can infiltrate homes and linger, making air purifiers essential for safe breathing.

In addition, dust mites, pet dander, and mold spores are common triggers for allergies and asthma. Mold is often mistaken for allergies, but many people discover that once they address mold problems in their home, their allergy symptoms disappear entirely.

We also unknowingly contribute to our own poor air quality with everyday items like cleaning products and synthetic fragrance (assuming you are not shopping toxin-free at Ivy & Fields 😉).

Studies show that cleaner air can lead to improved sleep, better cognitive function, and overall enhanced well-being. (source) It can also keep everyone healthier when there is a sick person in the household (reduces germs in the air) and help you recover more quickly from illnesses.

How To Check Your Air Quality

Did you know you can check the air quality in your area? The EPA publishes a US Air Quality Index that tells you how clean or polluted your outdoor air is. If you are outside the US, you can use the WAQI to find the air quality index in your area.

If you live in an area with excellent outdoor air quality, doing something as simple as opening all your doors and windows for 20 minutes a day can naturally improve the air quality inside your home. However, other factors like the weather (raining, hot, cold) and insects (mosquito season!) sometimes makes this unfeasible. That's why we recommend investing in a good air purifier. 

Factors to Consider When Shopping for an Air Purifier

When you set out to purchase an air purifier, you are quickly met with lots of codes, numbers and marketing literature. In this section, I'll go through some of the specs to consider so you can make an informed choice.

Coverage Area

One of the primary reasons you may see varying price ranges among the same air purifier brands is because of the square footage they cover. Air purifiers are designed to cover specific room sizes, measured in square feet. Make sure you are purchasing a unit adequate for your space.

HEPA Ratings

Particles smaller than 2.5 microns (PM2.5) can penetrate deep into the lungs and even enter the bloodstream, posing serious health risks. HEPA (High-Efficiency Particulate Air) filters are considered the gold standard for air purifiers. A true HEPA filter can capture 99.97% of particles as small as 0.3 microns, including dust, pollen, mold spores, and pet dander. Be cautious of terms like "HEPA-like" or "HEPA-type," as these may not meet the rigorous standards of true HEPA filters.

Here is what the HEPA ratings mean:

• HEPA 10 to HEPA 12 - Captures 85–99.5% of particles at 0.3 microns. Often used in budget air purifiers or vacuum cleaners.
• HEPA 13 and HEPA 14 (Medical Grade HEPA) - Captures 99.95% to 99.995% of particles at 0.3 microns. Common in high-quality air purifiers, medical environments, and cleanrooms. 
• ULPA (Ultra-Low Penetration Air) - Captures 99.999% of particles as small as 0.12 microns. Used in highly specialized environments like labs or pharmaceutical production.
  

MERV Ratings

You may also come across MERV ratings, in particular when shopping for filters for your Central Air Conditioning system. It measures the overall efficiency of a filter in removing particles of varying sizes (0.3 to 10 microns).

• MERV 1-4: Basic filters, suitable for catching large particles like dust and lint.
• MERV 5-8: Moderate filtration, commonly used in residential HVAC systems.
• MERV 9-12: Higher filtration for allergens like mold, dust mites, and pet dander. Great for residential homes.
• MERV 13-16: Captures finer particles like bacteria and some viruses; often found in commercial buildings and hospitals.
• MERV 17-20: Comparable to HEPA, used in cleanrooms and highly controlled environments.

But be careful, a higher MERV rating does NOT always mean better. You should always follow the air filter recommendation of your Air Conditioning Unit's manual as purchasing the wrong rating can decrease your airflow efficiency and cause issues for your HVAC unit (clog, prevent airflow). 

CADR Rating

You may also see an air purifier list a CADR rating, which stands for Clean Air Delivery Rate. Unlike coverage area claims, which brands set themselves, CADR is tested and certified by an independent third party called AHAM, the Association of Home Appliance Manufacturers. That standardization is what makes it a reliable number to compare across brands.

CADR measures how much clean air a unit actually delivers, meaning it accounts for both airflow and filter efficiency together. A powerful fan paired with a mediocre filter can look impressive on airflow alone. CADR exposes any deficiencies. 

CADR is reported separately for three pollutant types, smoke, dust, and pollen, because they represent different particle sizes. Smoke CADR is the most useful benchmark for fine particles and is the one the EPA and AHAM both recommend prioritizing when comparing units.

What is a good CADR Rating?

There is no single universally agreed "good" CADR number because it is entirely relative to room size. As a general rule of thumb, your CADR should be at least two-thirds of your room's square footage. For a 300 square foot room, look for a CADR of at least 200. The larger the space, the higher the CADR you need. For example:

What about brands that only list CFM?

CFM, or cubic feet per minute, measures raw airflow only. It tells you how much air the fan moves without any consideration for how well the filter cleans it. CADR is always lower than CFM because filtration reduces airflow. If a brand lists them as equal, that is a red flag.

AHAM testing is voluntary, so not every brand pursues it. Some skip it because of the cost. Others rely on their own internal testing instead. Either way, without a verified CADR you lose the ability to make standardized comparisons across brands, which is the main downside. When a brand lists only CFM, look for other transparency signals: detailed filter specifications, third-party lab results, and clear disclosure of what particle sizes the filter actually captures.

Types of Pollutants Targeted

Not all air purifiers address every type of pollutant. Determine the specific pollutants you want to target. Generally, HEPA filters are best for allergens, while activated carbon filters are best for neutralizing odors and chemical gases. To combat smoke smell, you'll want a HEPA filter combined with a carbon filter.

Purifiers with a UV-C light targets bacteria and viruses. 

Noise Levels

If you are purchasing an air purifier for a bedroom or workspace, consider the noise level of the air purifier. Look for units with adjustable fan speeds or sleep modes for quieter operation.

If an air purifier has a QuietMark certification, it means they are among the 20% quietest air purifier systems among those tested.

Certifications

Certifications provide consumers with peace of mind by verifying that a brand’s claims are accurate. They serve as third-party validation of the air purifier's safety, performance, and quality. While more certifications can enhance credibility, obtaining them is costly for brands, so it's rare to find a product with every certification. However, if you come across one during your research, here’s what each certification means:

• True HEPA or HEPA Certified - validates the HEPA rating.
• AHAM Verified (Association of Home Appliance Manufacturers) - validates the CADR rating.
• SGS -or- Intertek Certification - Confirms that the purifier has been independently tested for performance and safety by recognized third-party labs.
• Energy Star - certifies that it is energy-efficient and meets EPA standards.
• CARB Compliance  (California Air Resources Board) - ensures the air purifier meets strict ozone emission limits (below 0.05 parts per million).
• UL (Underwriters Laboratories) -or- ETL Listed (Electrical Testing Labs) - unit has been tested for safe electrical operation.
• Asthma & Allergy Friendly Certification - Tested by the Asthma and Allergy Foundation of America (AAFA) and Allergy Standards Limited (ASL).
• Greenguard - Confirms the air purifier has low chemical emissions (like VOCs), contributing to healthier indoor air.

Other Considerations

Here are some other specs you might consider when deciding between different air purifiers:

• Energy Consumption: Check the Energy Star certification or wattage to ensure energy efficiency.
• Cost of Ownership: there is obviously the initial investment cost, but you'll also need to keep up with the filters. Consider the cost of replacing the filters or any regular cleaning directions.
• Ease of Installation: most air purifiers are plug-and-play, while others may require more complex setup. 
• Smart Features and Connectivity: with the rise in "smart home" innovation, more and more appliances come with smart features. While we don't recommend adding to your EMF exposure 😆, some smart features can be helpful if you want to control your systems remotely or place them on a schedule to activate when you're not home.
• Aesthetic and Size: consider the space you have to place one (some systems require certain distance away from walls). You may also care about how they look and fit in with your home decor.

Air Purifiers to Consider

At Ivy & Fields we always prefer to teach you how to shop for items rather than telling you what to buy so you can feel confident that the choice you've made considers what is most important to you. As you can see, some of these features are personal decisions.

We have linked some of our favorites in our Shopping Guide. We constantly update them as we find new quality choices so there may be more there than appears on this list! However, I've quickly compared a few top choices so you can see the difference between the specs.

You will notice the less expensive options don't have a CADR rating, only a CFM rating. That of course is because CADR testing is expensive, but gives you more confidence that the unit actually works. In our house, we chose Alen Air Purifiers. We found them to be the most cost effective and they have many room sizes to match to your space! If you have a crazy large room, then Jaspr offers the higher CADR ratings. Most people, however, are buying smaller units to place in different rooms. For that scenario, our vote goes to Alen Air.

Lastly, if you have ceiling fans, check out these activated carbon stick-on filters by Barnakl you can place on top of your ceiling fan blades to clean your air. We only recommend the unscented, of course.

Check out the rest of our shopping guides here.

You might also be interested in our article, How To Shop For A Water Filter.