Research indicates 96 percent of homes have at least one type of indoor air quality issue. An indoor air quality (IAQ) monitor will report on the levels of common pollutants and other air conditions inside your home in real time.

The culprit could be anything from excessive dust to high humidity to emissions from household cleaners or building materials. The problem is, most people don’t know there’s a problem, and if they do figure it out—usually tipped off by allergy-like symptoms or more dramatic health effects—they don’t know precisely which pollutant is causing it.

Updated December 17, 2020 to add our Davis Instruments AirLink review, which is our new runner-up pick in this category. While this indoor/outdoor sensor can detect smaller particulate matter (down to PM1) than any monitor we’ve tested, it doesn’t monitor some other indoor air quality factors, such as the level of VOCs in the air.

Some indoor air quality monitors will also track outdoor air quality to provide context for your indoor readings. The measurements are then displayed on a screen on the device itself as well as in a companion app on your mobile device. Most IAQ monitors will alert you to unsafe levels via an indicator light and/or push notifications to your smartphone or tablet.

Once you’re aware something has risen to hazardous a level, you can take action to reduce it—usually by opening some windows. Some monitors will even trigger other smart appliances—such as an air purifier, a fan, or a dehumidifier—to help improve the air quality. Ultimately, a good IAQ monitor should provide enough clues for you to investigate and eliminate the source of your air quality woes.

Here are our current top picks for indoor air-quality monitors. We’ve also included a guide to the pollutants a good IAQ monitor should track. And if you scroll down to the bottom of the page, you’ll find links to all of our latest IAQ monitor reviews.

Best indoor air quality monitor

The Awair Element isn’t as pretty as the Awair 2nd Edition, which was wrapped in attractive hardwood, but this model is every bit as accurate when reporting carbon dioxide (CO2), volatile organic chemicals (VOCs), and PM2.5 (atmospheric particulate matter smaller than 2.5 microns).

Runner-up

Davis Instruments is well known for its excellent weather stations, and its AirLink air quality monitor exhibits the same precision and expert reporting. This device is unique among the monitors we’ve reviewed in that it can measure particulate matter as small as 1 micron, and it can be deployed indoors or out. But it doesn’t measure other types of air pollution, such as carbon dioxide or VOCs.