Product: AirGradient ONE, 9th generation (I-9PSL)
| Research date: 2026-09-23 | Worker C, air-quality monitors | DESK RESEARCH — no hands-on testing; owner evidence attributed. |
|---|
Overview
Maker: AirGradient (based in Chiang Mai, Thailand; monitors made in Thailand). Fully open-source indoor monitor (open hardware + open firmware; designs on GitHub). Ships as a self-assembly kit or fully assembled/tested. Positioned as the tinkerer's alternative to closed ecosystems, with local Home Assistant support and auto-discovery.
Social standing
- Independent owner review #1: thehomeassistantblog.com (https://thehomeassistantblog.com/2025/10/15/airgradient-one-review/, snippet-derived 2026-09-23) — owner ran TWO I-9PSL units (one fully assembled/certified, one kit) for 6 months, compared them to each other and to his Airthings View Plus, and documented Home Assistant integration. Key owner findings (paraphrased): kit is the exact same hardware at a large discount (~$138 vs $230) and takes ~10 minutes to assemble, but you get no warranty or certifications (CE/FCC/RoHS) and no test report — "you basically imported the parts yourself."
- Independent review #2: lesterchan.net (https://lesterchan.net/blog/2025/10/20/airgradient-one-indoor-monitor-i-9psl-review/, snippet-derived) — four sensors inside (S8/S88 CO2, PMS5003 PM, SGP41 TVOC/NOx, SHT-series T/H).
- Community-maintained comparison (terkea GitHub README, snippet-derived): AirGradient ONE ~£155–235, 8 params, "more expensive than DIY, defaults to cloud".
- 2026 Changchun field study (ResearchGate, snippet-derived): AirGradient showed "the most consistent agreement with reference measurements, with minimal systematic bias" across IQAir/PurpleAir/AirGradient — the strongest independent accuracy signal found for any monitor in this corpus, though it tested the platform's PM sensing generally.
- Threads search ("AirGradient ONE monitor", threads-cli) launched 2026-09-23 — held for security review, pending. No Facebook group venue found for AirGradient owners in this pass.
Social validation: Tier 2
Named sources: (1) thehomeassistantblog 6-month owner review (snippet, 2026-09-23); (2) lesterchan independent review (snippet); (3) terkea community table (snippet). Weakness: no Facebook group or Threads owner discussion directly observed this pass.
Key specs (manufacturer spec sheet, https://www.airgradient.com/indoor/, snippet-derived — bias noted)
| Spec | Detail | Measured vs estimated |
|---|---|---|
| PM1.0 / PM2.5 / PM10 | Plantower PMS5003 (laser scattering). Manufacturer-claimed accuracy PM2.5: ±4µg/m³ @0–100µg/m³, ±8% @100–500 (assembled/tested); ±10µg/m³ / ±10% (kit) | Measured (laser); PM1/PM10 lower accuracy per manufacturer |
| CO2 | SenseAir S8 or S88 (NDIR), 0–10,000ppm; ±40ppm ±3% of reading (400–2000/3000ppm ranges). 7-day auto baseline calibration — "needs a few days to become accurate" | Direct NDIR measurement |
| TVOC / NOx | Sensirion SGP41; TVOC index <±15 @ 0–500 index (also ppb); NOx <±50 @ 0–500 | Index, not speciated concentrations |
| Radon | None | — |
| Temp / humidity | Sensirion SHT40; ±0.2°C, ±2%RH | Direct |
| Display | 1.3" OLED 128×64 + 11 RGB LEDs | — |
| Connectivity | WiFi 2.4GHz; Bluetooth LE; local Home Assistant auto-discovery; I2C/GPIO/UART broken out | — |
| Power | USB-C (2m cable included; >2A 5V plug NOT included) | — |
| Indoor/outdoor | Indoor (ASA enclosure is UV-resistant/weatherproof per spec, but positioned as indoor) | — |
| Certifications | CE, FCC, RoHS, REACH, RESET Air (assembled only; kit has none) | — |
Pricing (dated 2026-09-23)
- Kit USD 138 / fully assembled USD 230 — manufacturer page (snippet-derived, 2026-09-23). BreatheSafeAir table lists "$138 (DIY)/$195" — conflicting assembled figure; treat $195–230 as the band, UNVERIFIED which is current.
- Cellular version (I-9PSL-CE) also exists — price not observed.
What is included / what else is needed
Kit: PCB v9, PMS5003 (pre-mounted), S8/S88 module, SHT4x module, SGP41 module, USB-C cable, ASA enclosure + stands + screws. Needs own 5V/2A USB plug. Assembled: same + test report + warranty.
Support reality
- 12-month warranty on assembled (manufacturer). Kit: no warranty (per owner review).
- Open-source: full schematics/firmware on GitHub; community self-support. Company is small (Thailand-based) — longevity is a buyer consideration, UNVERIFIED beyond public presence.
Accuracy (attribution only)
- Manufacturer claims (above) — not independently verified by us.
- Owner (thehomeassistantblog, snippet-derived): 6-month side-by-side of kit vs assembled vs Airthings View Plus — read as comparative owner evidence, not lab data.
- 2026 Changchun study (snippet-derived): AirGradient minimal systematic bias vs reference among the three platforms tested.
Buyer questions
- Which pollutants does it NOT measure? Radon. (PM10/NOx present but lower-confidence/index.)
- Is the data trustworthy vs reference? Best independent signal in corpus for PM (Changchun 2026); CO2 is true NDIR; kit-vs-assembled accuracy differs per manufacturer (±10 vs ±4).
- Subscription/paywall features? Dashboard "free for now" per airgradient.com comparison (stale); terkea notes "defaults to cloud" — current terms UNVERIFIED.
Community verdict
The most sensor-complete indoor monitor under ~$200 in kit form, with the strongest independent PM-accuracy signal found, but buyers must choose between the cheap kit (no warranty/certifications) and the assembled unit — and accept a small open-source vendor plus a cloud-default dashboard.
UNVERIFIED / gaps
- Current assembled price ($195 vs $230 conflict); dashboard subscription terms; long-term sensor drift reports; direct owner social discussion.
Sources (observed 2026-09-23)
- SNIPPET: browser.search → https://www.airgradient.com/indoor/ (specs, prices; manufacturer).
- SNIPPET: browser.search → https://thehomeassistantblog.com/2025/10/15/airgradient-one-review/ (6-month owner review).
- SNIPPET: browser.search → https://lesterchan.net/blog/2025/10/20/airgradient-one-indoor-monitor-i-9psl-review/.
- SNIPPET: browser.search → https://github.com/terkea/air-quality-monitor (community table).
- SNIPPET: browser.search → ResearchGate Changchun 2026 study (accuracy).
- Private: full recovery log in ../_source-ledger.md (never ships).