Home Assistant Air Quality: Monitor CO2, PM2.5, and VOC for a Healthier Home

Better Focus and Sleep

High CO2 makes you drowsy and unfocused. Automated ventilation keeps levels below 800 ppm so you sleep deeper and think clearer.

Lung Health

PM2.5 particles are small enough to enter your bloodstream. Monitoring lets you run HEPA filters only when needed, protecting your lungs without wasting energy.

Chemical Detection

VOC sensors catch off-gassing from new furniture, paint fumes, and cleaning product residue. Get an alert before chemicals build up to uncomfortable levels.

Energy Savings

Instead of running ventilation 24/7, trigger it only when air quality actually needs it. Demand-controlled ventilation can cut heating and cooling costs by 20 to 40%.

The reference standard for consumer CO2 monitoring. NDIR sensor with proven accuracy, e-ink display, 2+ year battery life, Bluetooth connection to HA. The only downside is the price: around 150 euros. But you get lab-grade accuracy in a pocket-sized device.

Same NDIR technology as the Aranet4, but you build it yourself. A SenseAir S8 module (around 20 euros) on an ESP32 with ESPHome gives you accurate CO2 readings over Wi-Fi, fully local, for a fraction of the price. Add a BME280 for temperature and humidity in the same box.

A compact all-in-one sensor from Xiaomi's ecosystem. Measures CO2, PM2.5, PM10, temperature, and humidity. Connects via Bluetooth. The CO2 accuracy is decent but not quite Aranet4 level. Great if you want multiple metrics in one device for around 60 to 80 euros.

IKEA's air quality sensor measures PM2.5, VOC, temperature, and humidity. It connects to Home Assistant directly via Zigbee (pair it with your existing coordinator, skip the IKEA hub). For around 35 euros, you get a lot of sensor coverage with a nice display. Possibly the best bang for your buck in air quality monitoring.

The Plantower PMS5003 is the sensor inside most commercial PM2.5 monitors, including PurpleAir. Wire it to an ESP32 with ESPHome for PM1.0, PM2.5, and PM10 readings. Very accurate for its price. Runs about 15 euros for the sensor module alone.

If you already have a Xiaomi/Smartmi air purifier, it has a built-in PM2.5 sensor. The Xiaomi Miot HACS integration exposes the PM2.5 reading as a sensor entity. You get monitoring and purification in one device with no extra hardware.

Open-source hardware that measures CO2 (SenseAir S8), PM2.5 (PMS5003), VOC (SGP41), temperature, and humidity. Runs ESPHome out of the box, so it connects locally to Home Assistant with zero cloud. Available as a pre-built kit or DIY. One of the most popular air quality monitors in the HA community.

Build your own combo sensor with an ESP32 board, SenseAir S8 (CO2), PMS5003 (PM2.5), SGP30 or SGP41 (VOC), and BME280 (temp, humidity, pressure). Total cost around 45 euros. You choose exactly which sensors to include and can add more later. ESPHome makes configuration simple.

The only consumer sensor that measures radon along with CO2, VOC, temperature, humidity, and pressure. Connects to HA via Bluetooth. Battery powered (1.5 years). At around 200 euros it is not cheap, but if radon is a concern in your area, this is the go-to device.

Connect Your Sensors

ESPHome devices auto-discover in HA. Bluetooth sensors (Aranet4, Airthings) need a BLE proxy or the built-in Bluetooth integration. Zigbee sensors (VINDSTYRKA) pair through ZHA or Zigbee2MQTT.

Create Air Quality Zones

Group sensors by room using areas in HA. Name them consistently: "Bedroom CO2", "Bedroom PM2.5", etc. This makes automations and dashboards much cleaner to build and maintain.

Set Up Thresholds

Create template sensors that categorize air quality as Good, Fair, or Poor. Use CO2 below 800 for good, 800 to 1200 for fair, above 1200 for poor. Same for PM2.5: below 12 good, 12 to 35 fair, above 35 poor.

Build Your Dashboard

Use gauge cards for current levels (color-coded green/yellow/red), history graphs for trends over 24 hours, and a mini graph card (HACS) for a compact overview. See the dashboard section below for examples.

Add Automations

Start simple: a notification when bedroom CO2 exceeds 1000 ppm. Then add ventilation control, air purifier triggers, and window-open reminders. See the automations section below for ready-to-use YAML.

Placement Matters

Mount sensors at breathing height (1 to 1.5m), away from windows, doors, and HVAC vents. Do not put a CO2 sensor right next to your bed head, your breath will spike it. Keep it 2 meters away for an accurate room average.

1. Bedroom Ventilation Alert

Get a notification on your phone when bedroom CO2 rises above 1000 ppm. Simple, but life-changing for sleep quality. Only triggers once per night to avoid alarm fatigue.

automation:
  - alias: "Bedroom CO2 Alert"
    trigger:
      - platform: numeric_state
        entity_id: sensor.bedroom_co2
        above: 1000
        for:
          minutes: 5
    condition:
      - condition: time
        after: "22:00:00"
        before: "08:00:00"
    action:
      - service: notify.mobile_app
        data:
          title: "Bedroom air is stuffy"
          message: "CO2 is at {{ states('sensor.bedroom_co2') }} ppm. Open a window or turn on ventilation."

2. Automatic Fan Speed Based on CO2

Control your ERV, HRV, or bathroom fan speed based on CO2 levels. Low speed below 800 ppm, medium at 800 to 1200, high above 1200. This is demand-controlled ventilation, the same strategy commercial buildings use.

automation:
  - alias: "Demand Controlled Ventilation"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_co2
        above: 1200
    action:
      - service: fan.set_percentage
        target:
          entity_id: fan.ventilation
        data:
          percentage: 100
  - alias: "Ventilation Medium"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_co2
        above: 800
        below: 1200
    action:
      - service: fan.set_percentage
        target:
          entity_id: fan.ventilation
        data:
          percentage: 50
  - alias: "Ventilation Low"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_co2
        below: 800
    action:
      - service: fan.set_percentage
        target:
          entity_id: fan.ventilation
        data:
          percentage: 25

3. Air Purifier on High PM2.5

Turn on your air purifier when PM2.5 spikes (cooking, wildfires, dusty day) and turn it off when levels drop back to safe. Works perfectly with Xiaomi purifiers via Xiaomi Miot, or any smart plug controlling a dumb HEPA filter.

automation:
  - alias: "Air Purifier On - High PM2.5"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_pm25
        above: 35
        for:
          minutes: 2
    action:
      - service: fan.turn_on
        target:
          entity_id: fan.air_purifier
      - service: fan.set_percentage
        target:
          entity_id: fan.air_purifier
        data:
          percentage: 80
  - alias: "Air Purifier Off - Clean Air"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_pm25
        below: 10
        for:
          minutes: 10
    action:
      - service: fan.turn_off
        target:
          entity_id: fan.air_purifier

4. Kitchen Cooking Alert

PM2.5 spikes dramatically when you cook, especially when frying or grilling. This automation sends a reminder to turn on the range hood and opens a smart window or activates the kitchen fan.

automation:
  - alias: "Kitchen Cooking - PM2.5 Spike"
    trigger:
      - platform: numeric_state
        entity_id: sensor.kitchen_pm25
        above: 50
    action:
      - service: notify.mobile_app
        data:
          title: "Range hood reminder"
          message: "Kitchen PM2.5 is {{ states('sensor.kitchen_pm25') }} µg/m³. Turn on the range hood!"
      - service: switch.turn_on
        target:
          entity_id: switch.kitchen_fan

5. VOC Alert After Cleaning or Painting

After using cleaning products or painting, VOC levels can stay elevated for hours. This automation alerts you and opens windows or cranks up ventilation until levels drop back to normal.

automation:
  - alias: "High VOC Alert"
    trigger:
      - platform: numeric_state
        entity_id: sensor.living_room_voc
        above: 500
        for:
          minutes: 5
    action:
      - service: notify.mobile_app
        data:
          title: "High VOC detected"
          message: "VOC is {{ states('sensor.living_room_voc') }} ppb. Open windows to ventilate."
      - service: fan.set_percentage
        target:
          entity_id: fan.ventilation
        data:
          percentage: 100

Gauge Cards

Use gauge cards for CO2 and PM2.5 with color-coded severity zones. Green below 800 ppm, yellow from 800 to 1200, red above 1200. One gauge per room for an instant overview.

type: gauge
entity: sensor.bedroom_co2
min: 400
max: 2000
severity:
  green: 0
  yellow: 800
  red: 1200
name: Bedroom CO2

History Graphs

24-hour history graphs reveal patterns: does CO2 spike every night in the bedroom? Does PM2.5 jump every evening when you cook dinner? Stack multiple rooms on one graph to compare.

type: history-graph
entities:
  - sensor.bedroom_co2
  - sensor.living_room_co2
  - sensor.office_co2
hours_to_show: 24
title: CO2 Trends

🃏 Mushroom Cards

Mushroom chips (HACS) work great for a compact air quality bar at the top of any dashboard. Show CO2, PM2.5, humidity, and temperature as small colored chips. Tap to expand.

type: custom:mushroom-chips-card
chips:
  - type: entity
    entity: sensor.bedroom_co2
    icon: mdi:molecule-co2
  - type: entity
    entity: sensor.bedroom_pm25
    icon: mdi:blur
  - type: entity
    entity: sensor.bedroom_humidity
    icon: mdi:water-percent

Bedroom (Priority 1)

CO2 sensor. Mount at nightstand height but at least 2 meters from the bed head. CO2 from your breath concentrates near your pillow, so placing it too close gives falsely high readings. One per bedroom that people sleep in.

Kitchen (Priority 2)

PM2.5 sensor. Place it 2 to 3 meters from the stove. Directly above the stove will trigger constantly while cooking. You want to measure the ambient kitchen air, not the direct exhaust from your pan.

Home Office (Priority 3)

CO2 + VOC sensor. Small rooms with closed doors get stuffy fast. A CO2 sensor here keeps you productive. VOC is useful if you have new furniture or carpet off-gassing in the office.

Living Room

All-in-one sensor. The main living area benefits from a multi-sensor (CO2 + PM2.5 + temp + humidity). Place it on a shelf at about 1.5 meters height, away from windows and heating vents.

Starter

~€35

• 1x IKEA VINDSTYRKA (PM2.5 + VOC + temp + humidity)
• Place in bedroom or living room
• Connects via your existing Zigbee coordinator

Best for: testing the waters, seeing if air quality monitoring is useful for you.

Complete

~€125

• 1x AirGradient ONE (CO2 + PM2.5 + VOC) for living room
• 1x IKEA VINDSTYRKA for kitchen
• All local, all automated

Best for: meaningful coverage of the rooms that matter most. CO2 for ventilation, PM2.5 for cooking.

Whole Home

~€250

• 2x DIY multi-sensor (bedrooms)
• 1x AirGradient ONE (living room)
• 1x IKEA VINDSTYRKA (kitchen)
• Full coverage: CO2, PM2.5, VOC, temp, humidity in every room

Best for: complete picture. Every occupied room has data. Demand-controlled ventilation that actually works.