AirGradient One

Quick verdict

The gold standard for local air quality monitoring in Home Assistant. Real NDIR CO2 sensing (not VOC guesswork), PM2.5 particulate tracking, plus temperature and humidity, all running on open-source ESPHome firmware. Flash it with your own config or use it out of the box. The built-in display is a nice touch for rooms where you want at-a-glance readings. If you care about what you are breathing and want the data to stay local, this is the one to get.

Standout: Open-source indoor air quality monitor with true NDIR CO2 sensing and ESPHome compatibility.

Last checked: 2026-03-22

Compatibility snapshot

Why it stands out

• true NDIR CO2 sensor alongside PM2.5, temperature, and humidity, not just VOC estimation
• open-source and ESPHome-compatible, giving full control over firmware and data
• built-in display shows readings at a glance without needing a phone or dashboard

Reasons to hesitate

• larger form factor than basic Zigbee environmental sensors
• WiFi-only. Requires a stable wireless connection
• premium pricing compared to simpler air quality sensors

Best for

• Home Assistant users who want accurate, local indoor air quality data with CO2 readings
• open-source enthusiasts who value ESPHome compatibility and firmware flexibility

Avoid if

• you just need a basic temperature and humidity sensor. This is overkill for that
• you want a tiny, discreet sensor. The AirGradient One has a visible display and footprint

Privacy and local-control notes

Open-source hardware running ESPHome firmware. Fully local, no cloud account required. Can be flashed with custom firmware for complete control.

Home Assistant support: supported · integration path: AirGradient / ESPHome.

Buying reality check

Price notes: Mid-range for a multi-sensor air quality monitor. The NDIR CO2 sensor alone justifies the price over cheaper VOC-only devices.

Compare side by side: see sensor comparisons →