Best Air Quality Monitors, What to Measure and Why (2026)
Measure first, buy second. An air quality monitor shows you what is in your air, so you spend money on the right fix instead of guessing.
Last updated: October 2026 · By the CleanAirHomeLab team
This page compares devices from the makers' published specs. It is not medical advice.
Why You Need a Monitor Before a Purifier
Most people buy an air purifier because they sneeze, smell something, or read a scary headline about air pollution. Then they pick whatever has good Amazon reviews and hope for the best.
That is backwards. An air quality monitor tells you what is in your air. Maybe your PM2.5 is fine but your CO2 keeps climbing. Then the fix is fresh air, not a purifier. Maybe your radon is above 4 pCi/L. A purifier does not fix that; the EPA says to fix your home.
A monitor can stop a wrong purchase. And once you do buy a purifier, the monitor shows whether it is working.
The Smart Order
Buy an air quality monitor and run it for at least a week (Airthings says its CO2 and VOC readings take about 7 days to settle)
Look at the data, what is actually elevated?
If PM2.5 is high, buy a HEPA purifier sized for your room
If CO2 is high, improve ventilation (open windows, add exhaust fans)
If radon is 4 pCi/L or more, hire a qualified radon mitigation contractor
If VOCs are high, find the source (new furniture, paint, cleaners) and ventilate
What to Measure
Six readings matter for home air quality. Not every monitor tracks all six. Here is what each one tells you and why it matters.
Our Monitor Picks
#1
Airthings Wave Plus
$249.99list price
Six sensors in one device: radon, CO2, TVOC, humidity, temperature and air pressure. It runs on 2 AA batteries.
Key Specs
Sensors
Radon, CO2 (NDIR), TVOC, humidity, temperature, air pressure. No particulate sensor.
CO2 Range
400-5,000 ppm
Power
2x AA, about 16 months over Bluetooth
Connectivity
Bluetooth or Airthings SmartLink (hub required for continuous cloud sync)
What We Like
Tracks radon, CO2 and TVOC in one device
CO2 is measured with an NDIR sensor, 400 to 5,000 ppm
Runs on 2 AA batteries, about 16 months on Bluetooth
What Could Be Better
No particulate sensor, so it cannot track particles
Needs an Airthings hub for continuous cloud sync
Our Verdict
The Wave Plus tracks radon, CO2, TVOC, humidity, temperature and air pressure. It runs on AA batteries. It has no particulate sensor. If you want particle readings, pair it with a monitor that has a PM2.5 sensor.
#2
Airthings View Plus
$329.99list price
Tracks PM2.5, radon, CO2, TVOC, humidity, temperature and air pressure. It has Wi-Fi and a 2.9 inch e-paper display.
Key Specs
Sensors
PM2.5, radon, CO2 (NDIR), TVOC, humidity, temperature, air pressure
PM2.5 Range
0-1,000 ug/m3. PM10 is not measured.
Radon Range
0-500 pCi/L
CO2 Range
400-5,000 ppm
Power
6x AA batteries or USB-C
Connectivity
Wi-Fi 2.4 GHz, Airthings SmartLink, Bluetooth LE
Display
2.9 in e-paper
What We Like
Has a PM2.5 sensor, which the Wave Plus does not
2.9 inch e-paper display
Wi-Fi 2.4 GHz is built in
Runs on 6 AA batteries or USB-C
What Could Be Better
Measures PM2.5 only. It does not measure PM10
Our Verdict
The View Plus tracks radon, PM2.5, CO2, TVOC, humidity, temperature and air pressure in one device. It has Wi-Fi and a display. Its particle sensor reads PM2.5 only, not PM10.
#3
AirGradient ONE
$230list price
Open source air quality monitor. Tracks PM2.5, CO2, TVOC, NOx, temperature and humidity. The list price is $230 assembled or $138 as a kit.
Key Specs
Sensors
PM2.5 (Plantower PMS5003), CO2 (SenseAir S8/S88 NDIR), TVOC and NOx (Sensirion SGP41), temperature and humidity (Sensirion SHT40)
CO2 Range
0-10,000 ppm, auto-calibrated every 7 days
Power
USB-C, 5V at 2A or more
Connectivity
WiFi 2.4 GHz
Display
1.3 inch OLED (128x64) plus 11 RGB LEDs
Firmware
Open source, CC-BY-SA 4.0
Model
I-9PSL
Warranty
12 months
What We Like
Open source under CC-BY-SA 4.0
CO2 is measured with a SenseAir S8/S88 NDIR sensor
The PM2.5 sensor is a Plantower PMS5003
The list price is $230 assembled or $138 as a kit
What Could Be Better
No radon sensor
Needs USB-C power at 5V and 2A or more
The OLED display is 1.3 inches
Our Verdict
The AirGradient ONE is open source. It measures PM2.5, CO2, TVOC, NOx, temperature and humidity. It has no radon sensor, so you still need a radon monitor or a test kit for radon. It needs USB-C power.
#4
Temtop M10i
Check current price
Monitor for PM2.5, formaldehyde (HCHO) and TVOC. It does not measure CO2.
Key Specs
Sensors
PM2.5 (laser), formaldehyde/HCHO (electrochemical), TVOC. No CO2.
PM2.5 Range
0-999 ug/m3, +/-10 ug/m3 from 0-100, +/-10% above
HCHO Range
0-2 mg/m3
TVOC Range
0-5 mg/m3
Power
2200 mAh battery, about 6 hours, DC 5V
Dimensions
82 x 82 x 31 mm, 200 g
Warranty
1 year
What We Like
Measures PM2.5, formaldehyde and TVOC
The 2200 mAh battery lasts about 6 hours
Weighs 200 g and measures 82 x 82 x 31 mm
What Could Be Better
Measures no CO2
Our Verdict
The Temtop M10i measures PM2.5, formaldehyde and TVOC. It measures no CO2. The battery lasts about 6 hours.
#5
PurpleAir Flex
Check current price
PM2.5 monitor with two Plantower PMS6003 laser counters. PurpleAir sells the Flex as an outdoor monitor.
Key Specs
Sensors
Dual Plantower PMS6003 laser counters plus a BME environmental module
Intended Use
Outdoor. PurpleAir sells the Flex as an outdoor PM2.5 monitor.
What We Like
Has two Plantower PMS6003 laser counters
Has a BME environmental module
What Could Be Better
PurpleAir sells the Flex as an outdoor monitor, not an indoor one
Our Verdict
The PurpleAir Flex is a PM2.5 monitor. It has two Plantower PMS6003 laser counters and a BME environmental module. PurpleAir sells it as an outdoor monitor.
Airthings vs AirGradient: Which One?
These two brands take different approaches. Airthings builds battery-powered monitors, and its Wave Plus and View Plus read radon. AirGradient builds an open-source monitor that runs on USB-C power. Here is how they compare:
Choose Airthings If...
You need radon monitoring (of these two brands, only Airthings has it)
You want battery power with no wires, for a basement or closet
You prefer a simple setup with a phone app
You want seven readings in one device (View Plus)
Choose AirGradient If...
You want a CO2 sensor rated up to 10,000 ppm (AirGradient says 0 to 10,000 ppm, NDIR)
You want NOx and TVOC readings next to PM2.5 and CO2
You like open-source hardware (AirGradient publishes it under CC-BY-SA 4.0)
You want the lowest list price of the three: AirGradient lists the ONE at $230 assembled, against $249.99 (Wave Plus) and $329.99 (View Plus) on Airthings' site
Our recommendation: If you want every reading, pair an AirGradient ONE for PM2.5 and CO2 with an Airthings Wave Plus for radon. If you can only pick one, the Airthings View Plus covers the most ground. For a closer look at a low-cost particle monitor, see Airthings vs Govee.
Feature Comparison
Feature
Wave Plus
View Plus
AirGradient
Temtop
PurpleAir
PM2.5
No
Yes
Yes
Yes
Yes
CO2
NDIR sensor
NDIR sensor
NDIR sensor
No
No
VOCs
Yes (TVOC)
Yes
Yes (TVOC, NOx)
Yes (TVOC, HCHO)
Not stated
Radon
Yes
Yes
No
No
No
Display
Glow ring only
2.9 in ePaper
1.3 in OLED
Not stated
Not stated
Power
2 AA
6 AA or USB-C
USB-C
Built-in battery
Not stated
Wi-Fi
Through a hub
Built in
Built in
Not stated
Not stated
"Not stated" means the maker's page we read did not say. Temtop's M10i page went offline on October 4, 2026; its column is from our September 2026 read.
What the Numbers Mean
Your monitor gives you numbers. Here is what the EPA and ASHRAE actually say about each one.
Reading
What the source says
PM2.5
EPA daily AQI breakpoints (2024): Good 0.0 to 9.0, Moderate 9.1 to 35.4, Unhealthy for Sensitive Groups 35.5 to 55.4, Unhealthy 55.5 to 125.4 ug/m3.
CO2
ASHRAE Standard 62.1 sets no indoor CO2 limit. A 1,000 ppm limit was in the 1989 edition and was later removed. Read CO2 as a sign of fresh air.
VOCs (TVOC)
The EPA pages we read set no home limit. The EPA says many VOCs are up to ten times higher indoors than outdoors.
Radon
EPA: fix your home at 4 pCi/L or more. Consider fixing between 2 and 4 pCi/L.
Humidity
EPA: keep it below 60 percent, ideally between 30 and 50 percent.
The PM2.5 breakpoints are for the EPA's daily outdoor Air Quality Index. A reading from a home monitor is not an official AQI, so use them as a rough guide.
Do I need an air quality monitor if I have an air purifier?
It helps. A monitor shows you whether your purifier is doing its job. A PM2.5 monitor shows you the real number. You might find that your purifier's auto mode is not strong enough, or that cooking pushes PM2.5 higher than you thought.
Should I buy an all-in-one monitor or separate sensors?
An all-in-one monitor like the Airthings View Plus is the easiest option. It reads radon, PM2.5, CO2, VOCs, humidity, temperature and air pressure. Another setup: an AirGradient ONE for PM2.5, CO2, TVOC and NOx, plus an Airthings Wave Plus for radon. Two devices, every reading covered.
How accurate are consumer air quality monitors?
It depends on the maker, and not all of them say. Airthings rates the Wave Plus CO2 sensor at plus or minus 30 ppm plus 3%, and the View Plus at plus or minus 50 ppm plus 3%. For radon, Airthings says accuracy at 5.4 pCi/L is about 10% after 7 days and about 5% after 2 months. Govee publishes no accuracy figure for its H5106.
Where should I place an air quality monitor?
In the room where you spend the most time. Airthings says to keep its monitors at least 3 feet from vents, fans, windows and doors, because those can skew readings. It also says never to put one outdoors or in a room over 85% humidity, like a bathroom. For radon, the EPA says to test in the lowest lived-in level of your home.
How is CO2 actually measured, and does the sensor type matter?
NDIR (non-dispersive infra-red) sensors measure CO2 directly with infra-red light. Every monitor on this page that reads CO2 uses one. Airthings specifies NDIR on both the Wave Plus and the View Plus, over a 400 to 5,000 ppm range. AirGradient rates the NDIR sensor in the ONE from 0 to 10,000 ppm. Correction, September 2026: this page previously described Airthings CO2 as estimated. That was wrong.
Ready to Clean Your Air?
Once you know what is in your air, the next step is picking the right purifier. We size every pick by the maker's published CADR.
Affiliate Disclosure:Some links on this page are affiliate links and may earn us a commission at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. Amazon links on this page are affiliate links. Links to Airthings, AirGradient or other makers' own sites are plain links that pay us nothing. Our picks are based on the makers' published figures, not commission rates. Full disclosure.
Sources and last review
Specifications on this page are taken from the documents below, on the dates shown. We do not physically test products; read our methodology. Page last reviewed .
Correction, September 2026: this page previously described Airthings CO2 as an estimate derived from VOC readings. Airthings specifies an NDIR sensor on both the Wave Plus and the View Plus. Correction, October 2026: the disclosure said Airthings and AirGradient were partners; they are not. CO2, VOC and humidity bands with no source, the pre-2024 PM2.5 breakpoints, a WHO reference and old prices were removed.
