The Best Air Purifier and Humidifier Combos, According to Our Testing

To determine the best air purifier and humidifier combo units for your money, the engineers at the Good Housekeeping Institute Home Improvement & Outdoor Lab constantly survey the marketplace to identify the models consumers are most likely to find online and in stores. After zeroing in on models for review, we begin the thorough process of reviewing technical data, owner's manuals, and consumer reviews.

We only consider combo units that feature True HEPA filtration (typically H13), which means they'll remove 99.97% of particles down to 0.3 microns in size. We also steer clear of models with ionization unless we were certain it is not a negative ion generator or that the ionization can be turned off, since these kinds of air purifiers can release ozone, and there's limited data showing the advantages of ionization versus classical filtration.

Because the point of having a two-in-one unit is to reduce the amount of space it takes up, we favor models that are more compact while still offering powerful humidification and purification. We read product reviews on major retailer websites to ensure there aren't any concerning defects and look for any potential pitfalls with the product.

We run extensive air purification tests in our Lab's airtight climate chamber. We introduced small amounts of pollutants and measured the concentrations of PM2.5, PM10 and formaldehyde prior to starting the test. We then turned on the air purifier to its maximum setting for 30 minutes and then re-measured these contaminant concentrations to get a sense of how well the purifier does at removing them.

Next, we evaluated the efficacy of the humidification feature. This included checking how easy the humidifier tank was to set up and fill, the size of the reservoir and how long it took the humidifier to reach set humidity levels in our Lab.

We also examine the fan speed, sound level using a decibel meter (pictured), and control interface to find units that were powerful, quiet, and easy to use. We also send units to consumer testers who tell us about their experiences with how the machines work in real-world conditions and give us insight into how intuitive they are to set up and operate.

✔️ Coverage area: Look for an air purifier and humidifier combo that is rated for at least one air change per hour for your desired size. We always suggest going for a combo unit that is rated for slightly larger spaces than the one you have rather than smaller for more efficacious humidification and purification.

✔️ Filtration: The best air purifier and humidifier combos feature True HEPA filters, which are the most effective at removing airborne particles, allergens, and irritants. Many combo units feature so-called "HEPA-like" filters, which won't clean your air as thoroughly.

✔️ Water tank capacity: A large reservoir means less frequent refills, letting your humidifier do the work for you. If the unit you choose has a small capacity, look for an auto-off or scheduler feature that'll prevent it from needing constant refills when not used optimally.

✔️ Ease of cleaning: It's important to clean the humidifier component of your combo unit regularly to prevent the growth of mold and other harmful microbes. Opt for a model that is easy to disassemble and reassemble and doesn't have too many nooks and crannies where bacteria can accumulate.

Air purifiers and humidifiers have different functions, so they can work together without getting in each other's way. Air purifiers remove physical pollutants from the air like small particles, whereas humidifiers add evaporated water to the air. You might be concerned that an air purifier will remove some of the humidity that a humidifier creates, but this isn't actually the case, since water molecules are measured in nanometers, which are 1,000 times smaller than the microns that an air purifier is designed to capture.

Nikolas Greenwald heads up the Good Housekeeping Institute's in-Lab testing of both air purifiers and humidifiers, regularly evaluating the top performers and newest entries in the sector to find the best ones on the market. He has a bachelor's degree in chemical engineering and applies his knowledge of fluid dynamics and filtration processes to finding strong contenders in the home HVAC space. He spent 10 hours researching and evaluating different combination air purifier and humidifier units.

For this article, Greenwald worked closely with Dan DiClerico, who has extensively tested and written about air purifiers for nearly 25 years. He has also spearheaded numerous investigative reports on the topic of indoor air quality, working with outside experts from government, industry, and the home services spaces. As director of the Home Improvement & Outdoor Lab at the Good Housekeeping Institute, DiClerico oversaw the latest round of air purifier testing in our Labs and the continuous in-home, survey-based consumer testing that allows us to evaluate these devices in real-world conditions.