air quality

Qingping CGS1

Qingping Air Detector (AKA ClearGrass Air Detector) is one of the best portable devices reviewed yet.

Impressive tech specs and design. Can be used both: as portable and not portable. And in a mixed way too. Good sensors for tvoc, t/rh, co2. High-resolution touch screen, Wi-Fi (that remember all Wi-Fi you were connected to), ambient light sensors, android and ios mobile app. And all that for a bit more than 100$ (incl. Delivery). For this price tag, it is a kind of flawless device. So the minor issues are not critical at all. Like it might have a different CO2 sensor (SenseAir S8 instead of Sensirion SDC30 for example) inside. But since S8 is not bad. It is still ok.


  • 1800 mAh battery (~4 hours of battery life)
  • Compact (9x9x7cm, 218g)
  • Calibration (tvoc, CO2) may be done manually
  • Correct t/RH and CO2 measurements
  • High resolution display with good viewangles
  • Touchscreen and good UI usablility
  • Keep multiple Wi-Fi AP settings
  • Weather and time sync from Internet
  • Ambient light sensor
  • Good thermal design and active airflow
  • Mobile App and 3-rd party app support
  • Wireless (OTA) update w/o app needed


  • CO2 high level is starting 2000ppm.
  • Disassemble is not trivial.
  • There might be other sensors inside.
  • No alarm clock (but should it be there?)

Device inside:

Device App:

Device Thermal:

Manufacturer link:

AliExpress price ~110$

air quality

AWAIR Element

A new device from one of the best manufacturer of home air quality monitors – AWAIR Element (AWAIR REV3E)

This one is less expensive, but keep best feature of AWAIR 2.

What changed in Awair Element (in compare to Awair 2)?

  • Plastic case
  • Little bit smaller
  • No microphone and no speaker (no sound)
  • No Sub-1GHz wireless
  • Integrated antennas
  • Less expensive

So I would say nothing critical was removed to achieve better price. It is still a good design, both internal and external. Same air quality sensors:

  • t/RH (Sensirion SHT30)
  • TVOC (Sensirion SGP30)
  • PM2.5 (Honeywell HPMA115S0)
  • CO2 (Telaire T6703-5K)

Automatic firmware update, fast new device setup, ambient light sensor, 24h clock mode, and other good features are still in place.

Device support some integrations like: IFTT, Amazon alexa, Google Assistance (not tested).

See what is inside Awair element.

Amazon: 149$ (~175$ with taxes custom and forwarding to Ukraine)

Awair site: 149$

air quality

Air Quality monitors

It is several years already I trying some Air Quality monitors. And I think it is time to post some of the results. So here it is. Overview of some Air Quality monitors tested so far.

For me perfect device is the one:

  1. measure correctly
  2. measure multiple parameters
  3. display information locally
  4. has a battery and can be used as a mobile tool
  5. is an IoT device with Wi-Fi connectivity and mobile app
  6. not cost a fortune
  7. quiet

Some of the requirements are cannot (or at least not easy to) be met simultaneously. A lot of advanced sensors with Wi-Fi connectivity and good mobile application make the device expensive. Battery and battery charging circuits usually affect temperature and relative humidity measurements. Active airflow improves measurement speed and quality but makes devices noisy. So there is no single perfect device yet to cover all Air Quality Monitor use cases. That is why I choose some devices I like more by category.

IoT Air Quality Monitors

Best IoT Air Quality Monitor “award” goes to AWAIR 2

  • ✔️Good design
  • ✔️Local data display
  • ✔️IoT device with a nice mobile application
  • ✔️Good hardware design (airflow, antennas, etc.)
  • ✔️ CO2, PM2.5, VOC, temperature, humidity
  • ❌Not all sensors are perfect
  • ❌No iPad application
  • ❌No battery
  • ❌Noise
  • 170-200$

So as you can see above the device is not perfect. It is noisy, that is how good airflow and better measurement quality and speed achieved. Some Sensors are not the best in class, that is how the price is lower than 200$. For more details see AWAIR 2 Review.

IoT Alternatives


✔️ quiet, more parameters (CO, O3, NO2), iPad app
❌ expensive (330$), cheaper sensors, no local display

AirVisual Pro (Node)

✔️ large display, outdoor data for PM2.5, battery, iPad app
❌ more expensive (280$), fewer parameters (no VOC)

Netatmo Smart Home Weather Station (Urban Weather)

✔️ quiet, weather station (external t/RH module), iPad app, 180$
❌ fewer parameters (no PM2.5, no VOC), poor CO2 sensor

Air Mentor 2s

✔️ quiet, more parameters (HCHO), iPad app
❌ Bluetooth or additional hub, single color status LED, 330$

Airthings Wave Plus

✔️ quiet, Radon sensor, work from 2xAA, iPad app, 200-270$
❌ fewer parameters (no PM2.5)

Portable Monitors

Best Portable Air Quality Monitor “award” goes to K6-D

  • ✔️Several hours of battery life
  • ✔️Good Sensors
  • ✔️ CO2, PM2.5, VOC, temperature, humidity
  • ✔️ Low price ~100$
  • ❌Humidity measurements not perfect
  • ❌No connectivity
  • ❌Noise

Again, as it was with the best IoT device, this one is not perfect. It is noisy, it has no Wi-Fi/Bluetooth/etc, humidity measurements may show -10% RH on high humidity tests, but still, it is better than some others and good for the price.

Portable Alternatives


✔️ additional HCHO Sensor
❌ less temperature/humidity accuracy, 110$

AirVisual Pro (Node)

✔️ less noisy, large display, outdoor data for PM2.5, battery, IoT
❌ more expensive (280$), fewer parameters (no VOC)


✔️ large display
❌ wrong temperature and humidity, cheaper sensors, ~110$


✔️ small
❌ CO2 only, ~124$ , battery sold separately, auto power-off


✔️ PC app for data logging
❌ wrong temperature and humidity, no VOC, no PM2.5 ~80$

Airthings wave plus

✔️ quiet, Radon sensor, months of work from 2xAA
❌ fewer parameters (no PM2.5), 200-270$, single LED local status display.

Other Air Quality Monitors

Best in Most Trusted device category is Green Day AZ7788

  • ✔️Correct measurements
  • ✔️Old, but a good type of sensors
  • ✔️ Relay output
  • ❌Only C02
  • ❌No connectivity
  • ❌No battery
  • ~110$

Old school device with separate analog temperature and humidity sensors, Old model of CO2 sensor. No other air quality sensors present. Need to be always plugged. But still one of the best in measurement quality.

air quality


Dienmern DM601 is a portable air quality monitor with two options available DM601A and DM601B. The difference is in additional HCHO sensors. Model DM601A has no HCHO sensor onboard.

The device has SHT30 temperature and humidity sensor but measures temperature wrongly due to device self-heating and poor thermal design (see thermal photos of DM601A). The battery is 3000 mAh that gives about 5 hours of both charging time and battery life (see details).

Most of the sensors inside DM601 are unbranded. No Wireless connectivity. Usability is average. Measurements (except temperature) are more or less ok.

Aliexpress price: 70$-100$

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Air Mentor 2s

Update from April 2023:

  • Air Mentor Site got expired certificate since March 2022
  • iOS application is not available any more for download
  • Android app is still in the store (but Air Cloud not work)
  • Cloud synchronization not work for already installed app

Original post:

Multi-sensor (CO2, PM2.5, TVOC, HCHO) air quality monitor with Bluetooth and Wi-Fi.

Applications are available for iPhone, iPad, Android phones.

Air Mentor 2 iPad application

By its design Air Mentor is not a portable IoT device. It has no battery. It has no display. So it is an alternative to uHoo (and to some extent to Netatmo). If compare Air Mentor 2s to uHoo: Air Mentor 2s have HCHO sensor. But uHoo measures CO, O3, NO2, pressure instead. Netatmo is actually a weather station with an external t/RH sensor, that also measures air quality by CO2 parameter only. Air Mentor 2s got a more expensive CO2 and t/RH sensors than both Netatmo and uHoo.

Temperature and Humidity sensor (SHT30) is both good itself and placed correctly on the bottom of the device with some gap from the mainboard. More or less as it is recommended by the Sensirion guide.

There are some issues with the current versions of mobile applications. For example, you cannot connect the device to Wi-Fi access points using iOS devices (it works using the Android version). Russian localization is not complete. Trend data from cloud not always loading (for both iOS and Android).

air quality

Hti HT-401 CO2 Meter

Hti HT-401 is the most portable CO2 meter I have. It is small and simple. It is only 75 mm in diameter and 25 mm in depth. Weight is 62 g. That is including 14250 (1/2AA) 300 mAh battery. Its only button is power. It count 30 seconds before actually show the CO2 level. And it automatically power off after 30 minutes.

HT-401 CO2 Meter

Four-digits LED display only shows CO2 level and 3 emoticons ?<600ppm ?600-1200ppm ?>1200. That is it. No settings for emoticons limits. No setting for the power-off timer. Not display temperature and humidity, nor time and date. Just one sensor inside and that is well known SenseAir S8 LP. That provides correct readings. Changing the environments not impact accuracy. The device is relatively cheap (I bought it for about 75$ without battery on Aliexpress)

air quality

D9 Air Quality Detector

This time OCRKJ D9-H. Which also can be found in some shops as unbranded LCD Digital Air Quality Monitor (AKA monllac, AgoHike, Robincure). Similar to OCRKJ K6-D from the previous review. It was bought for about 100$. Yet another portable device with 10 hours battery life and correct CO2 measurements.

D9 Air Quality detector


  • 3000 mAh battery ( 10 hours of battery life)
  • additional sensors (HCHO, VOC and PM2.5)
  • 16 different screens including trends
  • Active airflow with the relatively quiet fan
  • quality design and schematic inside (no glues, connectors, replaceable sensors)
  • good CO2 sensor inside – SenseAir S8 LP


  • slow charging – 8 hours (in operation mode)
  • no connectivity (Bluetooth, wi-fi, USB mass storage)
  • no ambient light sensor
  • unconfigurable high CO2 limits (GOOD is up to 1000 ppm)
  • wrong temperature and RH measurements (+3C, -10%RH)

It looks like relatively cheap SHT20 temperature and humidity sensor inside make it sort of a lottery if you will get correct measurements or not.

See device insides:

SALE Price was: 102$

air quality

K6 Air Quality Detector

I was not expecting much ordering KKMOON K6 (and receiving actually OCRKJ K6). Which also known as CAFU K6. Because most of the portable air quality monitors I got before have at least one major issue with measurements (AiRead M3 – all measurements wrong, HT-501 – wrong temperature, AirRadio A6 – issues with CO2 measurement after outdoor use and wrong humidity measurements). AirVisual Node was the only exception that both portable and show correct numbers. But it just too big to put it in your pocket. So there was a long history of portable CO2 monitors with issues. And it was kind of a surprise that the device I bought for 83$ is both portable and displays more or less correct numbers.

OCRKJ K6 Air Quality Detector


  • 3000 mAh battery ( 10 hours of battery life)
  • additional sensors (VOC, PM2.5)
  • correct t, RH and CO2 measurements (not sure about other)
  • 16 different screens including trends
  • Active airflow with the relatively quiet fan
  • quality design and schematic inside (no glues, connectors, replaceable sensors)
  • good CO2 sensor inside – SenseAir S8 LP


  • some noise from the PM2.5 sensor fan
  • slow charging – 8 hours (in operation mode)
  • no connectivity (Bluetooth, wi-fi, USB mass storage) – nothing
  • no ambient light sensor
  • unconfigurable high CO2 limits (GOOD is up to 1000 ppm)

See device insides:

Price: ~100$ (sale price was 83$)

air quality

Awair 2

Awair 2-nd edition is a better version of Awair, that fix some known issues of first edition

Awair 2
Awair 2-nd edition

What was fixed and added

  • 24h time format
  • USB Type-C standard 5v power connector
  • USB 5v 2A standard power supply
  • Better display (resolution, no backlight)
  • Ambient light sensor (display auto brightness)
  • Microphone (not sure if it is good to have it on IoT device)
  • Better PM2.5 sensor
  • New buttons to switch the display mode
  • Better wireless connectivity (new antennas)
  • Better (active) airflow
air quality

XINTEST HT-501 CO2 Meter

Portable CO2 meter and data logger with battery and good CO2 sensor inside.

Xintest HT-501

The only really wrong thing about this device is it always show temperature higher than it is for about 2°C (for example 28.0°C instead of 26.0°C) and it is not something related to wrong sensor placement.


  • Portable
  • 20h work from a battery
  • LCD Color zoning
  • Datalogger
  • Setup time and alarms from PC
  • Sensair S8 CO2 sensor


  • Incorrect temperature measurements
  • No time and date on the screen
  • 30 sec warmup time