The Best Indoor Air Quality Monitors, Chosen on Their Sensors
The best indoor air quality monitors, chosen on sensor type and independent AQ-SPEC results: Airthings View Plus, Qingping Air Monitor Lite, Aranet4 and more.
Affiliate disclosure: product links on this page go to Amazon, or to the maker's own store for brands that sell only direct. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you; a link to a maker's store earns us nothing. No retailer or brand sees our picks before they are published or has any say in them. How we choose.
The best indoor air quality monitor for most homes is the Airthings View Plus. It measures radon, PM2.5, CO2, VOCs, humidity, temperature and pressure, and Airthings states it uses a laser particle sensor and a true NDIR CO2 sensor rather than an estimate. For particles and CO2 on a budget, the Qingping Air Monitor Lite did well in South Coast AQMD's independent AQ-SPEC field test, with a PM2.5 R-squared of 0.85 to 0.93 against reference instruments.
Monitors are judged on their sensors. A laser particle sensor counts particles; an NDIR sensor measures CO2 directly; a metal-oxide VOC sensor gives a relative index, not a measurement of any single chemical; and radon needs its own detector. We chose monitors that name their sensors, and where South Coast AQMD's AQ-SPEC program has tested a model, we give its result.
Our top picks at a glance
1. Best overall
Airthings View PlusMeasures: Radon, PM2.5, CO2, VOC, humidity, temperature, pressure · CO2 sensor: NDIR (Airthings) · Power: 6 AA, up to 2 years, or USB-C · Independent test: Not in AQ-SPEC's PM summary when we checked
2. Best value
Qingping Air Monitor LiteMeasures: PM2.5, PM10, CO2, temperature, humidity · CO2 sensor: Not named on the listing · Power: USB-C; 7-hour battery · Independent test: AQ-SPEC PM2.5 R² 0.85 to 0.93 field, 0.99 lab
3. Best for CO2
Aranet4 HomeMeasures: CO2, temperature, humidity, pressure · CO2 sensor: NDIR (Aranet) · Power: Batteries, up to 4 years · Independent test: Not in AQ-SPEC's PM summary (no PM sensor)
4. Best radon and CO2 without particles
Airthings Wave PlusMeasures: Radon, CO2, VOC, humidity, temperature, pressure · CO2 sensor: Listed by Airthings with ±30 ppm ±3% accuracy · Power: 2 AA, 16 to 18 months · Independent test: Not in AQ-SPEC's PM summary
5. Best for wildfire watchers
IQAir AirVisual ProMeasures: PM2.5, CO2, temperature, humidity · CO2 sensor: NDIR (IQAir) · Power: Rechargeable, plug-in · Independent test: AQ-SPEC PM2.5 R² 0.63 to 0.81 field, 0.99 lab
| Pick | Measures | CO2 sensor | Power | Independent test | Buy |
|---|---|---|---|---|---|
| Airthings View PlusBest overall | Radon, PM2.5, CO2, VOC, humidity, temperature, pressure | NDIR (Airthings) | 6 AA, up to 2 years, or USB-C | Not in AQ-SPEC's PM summary when we checked | Amazon |
| Qingping Air Monitor LiteBest value | PM2.5, PM10, CO2, temperature, humidity | Not named on the listing | USB-C; 7-hour battery | AQ-SPEC PM2.5 R² 0.85 to 0.93 field, 0.99 lab | Amazon |
| Aranet4 HomeBest for CO2 | CO2, temperature, humidity, pressure | NDIR (Aranet) | Batteries, up to 4 years | Not in AQ-SPEC's PM summary (no PM sensor) | Amazon |
| Airthings Wave PlusBest radon and CO2 without particles | Radon, CO2, VOC, humidity, temperature, pressure | Listed by Airthings with ±30 ppm ±3% accuracy | 2 AA, 16 to 18 months | Not in AQ-SPEC's PM summary | Amazon |
| IQAir AirVisual ProBest for wildfire watchers | PM2.5, CO2, temperature, humidity | NDIR (IQAir) | Rechargeable, plug-in | AQ-SPEC PM2.5 R² 0.63 to 0.81 field, 0.99 lab | Amazon |
Best overall
Airthings View Plus
Radon plus a laser PM2.5 sensor, NDIR CO2 and VOCs in one battery-powered monitor.
- Measures
- Radon, PM2.5, CO2, VOC, humidity, temperature, pressure
- CO2 sensor
- NDIR (Airthings)
- Power
- 6 AA, up to 2 years, or USB-C
- Independent test
- Not in AQ-SPEC's PM summary when we checked
Pros
- Only pick here that also measures radon
- Cable-free placement
- Five-year warranty with free registration
Cons
- Most expensive pick
- VOC and CO2 sensors take up to 7 days to calibrate
Airthings' product sheet describes a laser optical particle counter for PM2.5, an NDIR CO2 sensor and a metal-oxide VOC sensor, plus its alpha-spectrometry radon chamber, rated at about 10% accuracy on a 7-day average and 5% on a 2-month average at 5.4 pCi/L. Radon is the reason to choose it over cheaper monitors; the EPA recommends testing every home. Our View Plus review has the details.
Best value
Qingping Air Monitor Lite
PM2.5, PM10 and CO2 with strong independent field results, for a fraction of the View Plus's price.
- Measures
- PM2.5, PM10, CO2, temperature, humidity
- CO2 sensor
- Not named on the listing
- Power
- USB-C; 7-hour battery
- Independent test
- AQ-SPEC PM2.5 R² 0.85 to 0.93 field, 0.99 lab
Pros
- Strong AQ-SPEC field result for PM2.5
- Apple HomeKit and app
- Refreshes every second
Cons
- No VOC or radon
- Needs to stay plugged in
AQ-SPEC tests monitors side by side with reference instruments outdoors and in a lab chamber. The Qingping Air Monitor Lite's PM2.5 R-squared of 0.85 to 0.93 in the field is among the better results for consumer monitors in its summary. Read our Qingping review.
Best for CO2
Aranet4 Home
An NDIR CO2 monitor with an e-ink display and up to four years of battery life.
- Measures
- CO2, temperature, humidity, pressure
- CO2 sensor
- NDIR (Aranet)
- Power
- Batteries, up to 4 years
- Independent test
- Not in AQ-SPEC's PM summary (no PM sensor)
Pros
- True NDIR CO2
- Very long battery life
- Portable
Cons
- No particles or VOCs
- App history limited to 90 days on the phone
If the question is ventilation, whether a bedroom or office gets stuffy, CO2 is the number to watch, and the Aranet4 does that one job well. See our best CO2 monitors.
Best radon and CO2 without particles
Airthings Wave Plus
Radon, CO2 and VOCs in a battery-powered wall or shelf unit, cheaper than the View Plus.
- Measures
- Radon, CO2, VOC, humidity, temperature, pressure
- CO2 sensor
- Listed by Airthings with ±30 ppm ±3% accuracy
- Power
- 2 AA, 16 to 18 months
- Independent test
- Not in AQ-SPEC's PM summary
Pros
- Radon and CO2 for less
- Long battery life
- Wave-to-check display
Cons
- No PM2.5
- Bluetooth only without a hub
For a basement or bedroom where radon and stuffiness are the questions, the Wave Plus covers both without paying for a particle sensor. Read the Wave Plus review.
Best for wildfire watchers
IQAir AirVisual Pro
PM2.5 and CO2 with a large screen and outdoor-data pairing, from the company behind the AirVisual map.
- Measures
- PM2.5, CO2, temperature, humidity
- CO2 sensor
- NDIR (IQAir)
- Power
- Rechargeable, plug-in
- Independent test
- AQ-SPEC PM2.5 R² 0.63 to 0.81 field, 0.99 lab
Pros
- Pairs indoor and outdoor data
- Clear display
- Custom alerts
Cons
- Weaker AQ-SPEC field result than the Qingping
- Expensive
The AirVisual Pro is useful if you want indoor readings shown next to outdoor air from IQAir's network or your own outdoor sensor. Its AQ-SPEC field results were more modest. See the AirVisual Pro review.
How we chose air quality monitors
We required each maker to name what its monitor measures and, for CO2, whether it uses an NDIR sensor or estimates CO2 from a VOC sensor. Where South Coast AQMD's AQ-SPEC program has evaluated a model's PM2.5 against reference instruments, we report its R-squared: how closely the monitor tracked the reference (1.0 is a perfect match). We did not use Amazon ratings. Several popular monitors, including Airthings' home models and Awair, were not in AQ-SPEC's PM summary when we read it, so for those we rely on the makers' sensor descriptions.
Monitor buying guide
What each sensor can and cannot tell you
| Measurement | Sensor | How much to trust it |
|---|---|---|
| PM2.5 | Laser (optical) particle counter | Good for trends; accuracy varies by model; see AQ-SPEC results |
| CO2 | NDIR (non-dispersive infrared) | Good; measures CO2 directly |
| "eCO2" | Estimated from a VOC sensor | Not a CO2 measurement; avoid if CO2 matters |
| TVOC | Metal-oxide sensor | Relative index for trends, not a measurement of specific chemicals |
| Radon | Diffusion chamber with alpha detection | Good for long-term averages; needs days to weeks |
| Formaldehyde | Electrochemical, in some monitors | Often unreliable at the low levels found in homes |
Our guide to how accurate consumer monitors are goes deeper into the AQ-SPEC results.
Decide what you need to know
- Is my purifier working, or is wildfire smoke getting in? PM2.5. Any good laser-sensor monitor.
- Is the bedroom or office stuffy? CO2 from an NDIR sensor. See why CO2 matters.
- Does my house have a radon problem? A radon detector, ideally run for months. See our radon guide.
- Is a new home or renovation off-gassing? A VOC sensor shows trends. See our VOC guide.
Placement changes the reading
Put a monitor at breathing height in the room you use, away from windows, vents, the kitchen stove and your own breath on a desk. Our placement guide explains why.
What to skip
- Monitors that show "CO2" from a VOC sensor. Look for NDIR.
- Exact-looking VOC numbers in ppb from metal-oxide sensors; treat them as relative.
- Combination CO and smoke claims. An air quality monitor is not a carbon monoxide alarm; fit a UL-listed CO alarm.
Monitoring an office rather than a home? See our Awair Omni review of Awair's commercial monitor.
Frequently asked questions
What is the best indoor air quality monitor?
The Airthings View Plus for most homes: it measures radon, PM2.5, CO2, VOCs, humidity, temperature and pressure, with a laser particle sensor and NDIR CO2 as Airthings describes. The Qingping Air Monitor Lite is the best value for particles and CO2.
Are home air quality monitors accurate?
For particles, the better ones track reference instruments closely; South Coast AQMD's AQ-SPEC found field R-squared values from about 0.6 to over 0.9 for consumer PM2.5 monitors. NDIR CO2 sensors are reliable; VOC readings are relative.
What should an air quality monitor measure?
PM2.5 for particles and smoke, CO2 for ventilation, and radon if your home has never had a radon test. VOCs are useful for trends; humidity helps with mold prevention.
What is NDIR CO2?
Non-dispersive infrared: the sensor measures how much infrared light CO2 absorbs, giving a direct CO2 reading. Cheaper monitors sometimes estimate CO2 from a VOC sensor instead, which is much less reliable.
Do air quality monitors detect carbon monoxide?
Most do not, and none of our picks is a substitute for a carbon monoxide alarm. Fit a UL-listed CO alarm on every level of the home.
Do I need a radon detector if I have an air quality monitor?
Only if your monitor measures radon; most do not. The EPA recommends testing every home, and the Airthings View Plus and Wave Plus include radon sensors.
Sources
- AQ-SPEC Sensor Evaluations: Summary of PM Sensors, South Coast Air Quality Management District
- View Plus product sheet, Airthings
- Airthings Wave Plus, Airthings
- A Citizen's Guide to Radon, US Environmental Protection Agency
- Volatile Organic Compounds' Impact on Indoor Air Quality, US Environmental Protection Agency
Related guides
Air Quality Monitor for a Nursery: What to Track and Which to Choose
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Air Quality Monitors Explained: Sensors, Readings and What They Can Miss
A home monitor is a bundle of small sensors, each good at one thing. Knowing which sensor sits behind each number tells you which readings to trust and which to treat as a trend.
Airthings View Plus Review: Radon, PM2.5 and NDIR CO2 in One Monitor
The View Plus is the most complete home air monitor Airthings makes: radon plus particles, CO2 and VOCs, on batteries or USB-C. It is expensive, and worth it mainly if you want radon too.