AirGradient
AirGradient ONE (I-9PSL)
- Works with HA
- Local control
- Wi-Fi
Prices verified September 2026
See more sensors picks on our Amazon storefront →Our verdict
The most Home Assistant-friendly indoor air quality monitor we've tested: open-source hardware and firmware, a native local-polling integration that Home Assistant discovers on its own, and a tick-box at setup that stops it ever talking to AirGradient's servers. It measures far more than the cheap CO2 meters — CO2, PM1/2.5/10, a VOC index, a NOx index, temperature and humidity — with named, replaceable sensor modules (SenseAir S8, Plantower PMS5003, Sensirion SGP41 and SHT40) rather than an anonymous chip. The catches are UK-specific: there is no UK retailer, so you order direct from Thailand in US dollars and pay the VAT at checkout, which lands the assembled unit at roughly £200. The 1.3in OLED is small, and the 131mm square footprint is big next to an Apollo AIR-1 or Aranet4. Buy it if you run Home Assistant and want CO2, particulate and VOC data driving real automations; buy a SwitchBot Meter Pro CO2 or IKEA Alpstuga if you only want a CO2 number on a shelf.
What can Home Assistant control on the AirGradient ONE (I-9PSL)?
| Control | Type | What it does |
|---|---|---|
| CO2 | Sensor (ppm) | NDIR CO2 reading, 400–10,000ppm range |
| PM2.5 / PM10 / PM1 | Sensor (µg/m³) | Particulate mass from the laser particle counter |
| VOC index / NOx index | Sensor (index 1–500) | Relative gas indices — 100 is the sensor's learned 24h average, not a concentration |
| Temperature / humidity | Sensor | From the isolated SHT40 sensor at the top of the case |
| LED bar mode | Select (CO2 / particulate / off) | Which pollutant the 11-LED bar colours track |
| LED bar / display brightness | Number (0–100%) | Dim or switch off the lights on a schedule from an automation |
| Calibrate CO2 sensor | Button | Forces a manual 400ppm baseline — press it outdoors or at a wide-open window |
| Share data with AirGradient | Switch | Turn off to stop the device posting readings to AirGradient's cloud |
Add it through Settings → Devices & Services: once the monitor is on your Wi-Fi, Home Assistant's discovery flow offers it as 'I-9PSL / AirGradient' with no IP entry (add by hostname if discovery doesn't cross your VLAN). The integration polls the device's local HTTP API about once a minute, so it keeps working with AirGradient's cloud switched off. Sensor entities: CO2, PM1, PM2.5, PM10, PM0.3 particle count, VOC index, NOx index, temperature, humidity, plus raw VOC/NOx/PM2.5 values for your own calibration. Configuration entities let you drive the hardware from automations — LED bar mode (CO2, particulate, off) and brightness, display brightness and units, CO2 auto-calibration interval and a one-press calibrate button, VOC/NOx learning offsets, and a switch that stops data sharing with AirGradient. Gotcha: the CO2 sensor's automatic baseline calibration assumes it sees fresh outdoor air (about 420ppm) at least once per interval, so in a sealed winter room it can drift — put it near a window you open, or press calibrate outdoors.
Specs
| Power | USB-C, 5V/2A (USB power adapter and 2m cable included) |
|---|---|
| Weight | 230g |
| Display | 1.3in 128×64 OLED plus 11-LED RGB bar |
| Sensors | SenseAir S8 CO2 (NDIR), Plantower PMS5003 (PM1/2.5/10), Sensirion SGP41 (VOC/NOx index), Sensirion SHT40 (temperature/humidity) |
| Warranty | 12 months on the assembled unit |
| Enclosure | ASA plastic, wall brackets included |
| Dimensions | 131 × 131 × 36mm |
| Open source | Hardware (KiCad) and firmware published under CC BY-SA 4.0; OSHW certified |
| Connectivity | 2.4GHz Wi-Fi (802.11 b/g/n) with local HTTP API; optional AirGradient cloud dashboard |
| Model number | I-9PSL (9th generation) |
| UK availability | Direct from airgradient.com only; ships from Thailand |
How does the AirGradient ONE (I-9PSL) compare?
| Product | From | Protocol | Local control | Integration |
|---|---|---|---|---|
| AirGradient ONE (I-9PSL) (this product) | — | Wi-Fi | Yes | Works with HA |
| Aqara Door and Window Sensor P2 | £23.99 | Matter, Thread | Yes | Works with HA |
| Aqara Motion Sensor P1 | £18.99 | Zigbee | Yes | Zigbee2MQTT / ZHA |
| Aqara Multi-State Sensor P100 | £25.49 | Zigbee, Thread, Matter | Yes | Zigbee2MQTT / ZHA |
Frequently asked questions
- Does the AirGradient ONE (I-9PSL) work with Home Assistant locally?
- Yes. The AirGradient ONE (I-9PSL) is controlled locally in Home Assistant through a certified "Works with Home Assistant" integration (airgradient), so it keeps working if your internet connection or the AirGradient cloud goes down. Control and state updates stay on your own network.
- Which protocol does the AirGradient ONE (I-9PSL) use, and do I need a hub?
- The AirGradient ONE (I-9PSL) uses Wi-Fi. To pair it with Home Assistant you need no hub — it joins your Wi-Fi network directly. AirGradient's own hub is not required when you integrate through a certified "Works with Home Assistant" integration (airgradient).