Best air quality sensors for Home Assistant

Air quality is one of those smart home metrics that’s easy to ignore until you have a problem. But once you start tracking it, you realize how much your home environment affects sleep, focus, and health. The good news: Home Assistant plays well with a wide range of air quality sensors, and many of the best options work entirely locally without any cloud dependence.

What actually matters

Before diving into products, let’s clarify what you’re actually measuring. The most useful metrics for a smart home are:

• PM2.5 – Fine particulate matter that penetrates deep into the lungs
• CO₂ – Carbon dioxide, a good proxy for ventilation adequacy (look for true NDIR sensors, not estimated “eCO₂”)
• TVOC – Total volatile organic compounds, off-gassing from furniture, paint, and cleaning products
• Temperature and humidity – Basic but important for comfort and mold prevention

Most people don’t need all of these. A single sensor covering PM2.5 and CO₂ in your bedroom or living room gives you most of the value. The trick is finding sensors that actually work locally with Home Assistant rather than requiring a cloud account. If cost is your main constraint, see the best air quality sensor for the money.

Best overall: AirGradient ONE

The AirGradient ONE is the clear winner if you want professional-grade air quality data without the professional price tag. It measures PM1/PM2.5/PM10 (Plantower PMS5003), true CO₂ (SenseAir S8 NDIR), TVOC and NOx index (Sensirion SGP41), and temperature/humidity (SHT4x) in one package that connects to Home Assistant over Wi-Fi.

What makes it stand out: no cloud required. The firmware is open source, and you can pull readings locally via its built-in local API (and on to MQTT if you like). The sensor is accurate enough that AirGradient sells it to schools and offices. It’s not the cheapest option, but it’s the most capable single device that works entirely locally.

The tradeoffs: it’s larger than most consumer sensors (about the size of a paperback), and Wi-Fi setup takes a bit more work than a Zigbee pairing. But once it’s running, it’s rock solid.

If you need outdoor or garage monitoring, the AirGradient Open Air is the weather-resistant sibling. It’s a different (outdoor) enclosure rather than a cheaper version of the ONE—same open firmware and local integration, focused on PM2.5, CO₂, TVOC/NOx, temperature and humidity for outside use.

Best ESPHome option: Apollo AIR-1

If you’d rather have an ESPHome node than a vendor device, the Apollo AIR-1 is a compact, fully local Wi-Fi sensor running ESPHome, so Home Assistant discovers it automatically. The standard unit (Sensirion SEN55) covers PM1–PM10, VOC index, NOx index, temperature and humidity; an optional SCD40 module adds true CO₂. It’s an easy, low-cost way to get broad coverage on a local-first setup—just remember to order the CO₂ variant if you want CO₂.

Best Zigbee option: Frient Air Quality Sensor

If you already run a Zigbee network in Home Assistant, the Frient Air Quality Sensor is a small, battery-powered pick. It measures VOC, temperature, and humidity over Zigbee and pairs with ZHA or Zigbee2MQTT (and works with Hubitat too). Note it does not measure CO₂ or PM2.5—it’s a VOC trend sensor, not a full air-quality monitor. The upside is simple setup and no Wi-Fi congestion; the downside is limited US availability and a narrower feature set than AirGradient.

Also worth considering for Apple households: Eve Room. It’s HomeKit-native and measures VOC (Sensirion SGP30), temperature, and humidity (no PM2.5, no CO₂). Recent versions use Thread, so it runs locally with low latency, and you can bring it into Home Assistant via the HomeKit Controller integration—the data stays on your local network rather than routing through a cloud.

Budget picks and alternatives

The SwitchBot Meter Pro CO2 is worth a look if you want true NDIR CO₂ on a budget, alongside temperature and humidity. It works locally with Home Assistant through the SwitchBot Bluetooth integration over BLE—no SwitchBot hub required; you just need a Bluetooth adapter or an ESPHome Bluetooth proxy in range. At well under the price of an AirGradient, it’s a reasonable single-metric entry point.

For basic temperature, humidity, and VOC tracking, the Aqara TVOC Air Quality Monitor measures TVOC, temperature, and humidity via Zigbee (pairs directly to ZHA or Zigbee2MQTT; no Aqara hub required). It’s a supplement, not a replacement for a PM2.5 or CO₂ sensor.

The Zooz ZSE44 Temp Humidity Sensor is a solid Z-Wave option for basic temperature and humidity. Zooz makes good Z-Wave hardware, and it integrates cleanly with Home Assistant—just note it’s temp/humidity only, not air quality.

One thing to avoid: cheap “7-in-1” air quality gadgets from marketplaces that promise everything for $30. Many use uncalibrated VOC modules that drift fast and report meaningless numbers. Stick with brands that publish their actual sensor part numbers (Plantower, Sensirion, SenseAir). One hazard these general monitors do not cover is radon, so if that is a concern in your area see the best smart radon monitors with Home Assistant.

Integration considerations

The most important factor isn’t the sensor itself—it’s how it connects to Home Assistant. Here’s how the options stack up:

Wi-Fi / ESPHome sensors (AirGradient, Apollo AIR-1): Most flexible. AirGradient exposes a local API; the Apollo runs ESPHome’s native API. Both are fully local. Downside: they need power near an outlet.

Zigbee sensors (Frient, Aqara): Need a Zigbee coordinator (e.g. Sonoff ZBDongle-E, the Home Assistant Connect ZBT-2, or ConBee III). More setup friction but stable, and Zigbee mains-powered devices act as mesh repeaters (note: battery sensors like the Frient do not repeat).

Bluetooth sensors (SwitchBot Meter Pro CO2): Local via BLE with a Bluetooth adapter or ESPHome proxy; no vendor hub needed for readings.

Thread + HomeKit sensors (Eve Room): the Eve Room runs over Thread and works locally via HomeKit Controller - note it is HomeKit-only, not Matter. Dedicated air-quality sensors over Matter are still uncommon in 2026, though IKEA’s ALPSTUGA is a cheap exception: Matter over Thread, reporting CO2, PM2.5, temperature and humidity, and it acts as a Thread router since it runs on USB-C power.

For most people the right starting point is one AirGradient ONE (or an Apollo AIR-1 with SCD40) in your main living space, then adding cheaper Zigbee temperature/humidity sensors in other rooms.

Quick verdict

Go with the AirGradient ONE if you want the best local-only air quality monitoring available—accurate PM, true NDIR CO₂, VOC/NOx, and clean Home Assistant integration with no cloud. Prefer ESPHome? The Apollo AIR-1 (with the CO₂ option) is the local-first alternative.

Add cheaper Zigbee temp/humidity sensors for broader coverage—just don’t expect a VOC-only or temp-only sensor to replace a proper air-quality monitor. The bottom line: one good sensor in your primary living space tells you more than a dozen cheap ones that give misleading readings. Start simple, expand if the data proves useful.