Volatile organic compounds level changed

The Volatile organic compounds level changed trigger fires after the VOC reading on one or more air quality sensors changes by a meaningful amount. Volatile organic compounds are gases released by paints, cleaning products, adhesives, new furniture, cooking, and many building materials. That “new furniture smell” or the sharp scent of a freshly cleaned bathroom? Those are VOCs. Elevated levels affect indoor air quality and comfort, and prolonged exposure is a health concern.

Imagine the exhaust fan in your freshly painted room switching on automatically as fumes build up, clearing the air so you don’t have to keep checking. Use this trigger to boost ventilation, turn on an air purifier, or log air quality changes whenever your VOC sensor reports a significant shift.

Using this trigger from the user interface

If you prefer building automations visually, Home Assistant walks you through this trigger step by step. You pick what to watch, tweak a few options, and save. No YAML knowledge required.

To use this trigger in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the When section, select Add trigger.
4. Select what you want to monitor. Under By target (see Targets), pick the area your air quality sensor is in (like your living room or bedroom). You can also select a floor, a device, a specific entity, or a label.
5. From the triggers shown for that target, select Volatile organic compounds level changed.
6. Under Threshold type, set how much the level has to change before the trigger fires.
7. Select Save.

Options in the UI

Using this trigger in YAML

If you work directly in YAML, or you want to know exactly what Home Assistant does under the hood, this section has the technical reference. It lists the field names you use in YAML, their types, and which ones are required.

In YAML, refer to this trigger as air_quality.voc_changed. A basic example looks like this:

trigger: air_quality.voc_changed
target:
  entity_id: sensor.kitchen_voc
options:
  threshold: 50

This fires whenever the kitchen VOC sensor reading changes by at least 50 micrograms per cubic meter.

Options in YAML

YAML sometimes provides additional options for more complex use cases that are not available through the UI.

Targets

This trigger supports targets. A target tells Home Assistant what the trigger should watch. You can point it at a single entityAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more], a device, an area, a floor, or a label, and Home Assistant watches every matching air_quality entity behind that target.

• Entity: one specific air_quality entity, such as air_quality.living_room.
• Device: every air_quality entity that belongs to a device.
• Area: every air_quality entity in a room or area.
• Floor: every air_quality entity on a floor.
• Label: every air_quality entity that shares a label.

You can also mix target types in one trigger. For example, combine a specific entity with an area to watch both at once.

Good to know

• VOC sensors are especially useful in kitchens, bathrooms, and newly renovated rooms where off-gassing is common.
• The trigger fires on any change that meets the threshold, whether the level goes up or down.
• To react only when VOC levels cross a specific concentration in one direction, use Volatile organic compounds level crossed threshold instead.

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, create a new automation, and add this trigger. Save the automation, then change the state of the targeted entity to watch the trigger fire on your actual entitiesAn entity represents a sensor, actor, or function in Home Assistant. Entities are used to monitor physical properties or to control other entities. An entity is usually part of a device or a service. [Learn more].

More examples

Real scenarios where this trigger fires in automations and scripts. Copy any example and adapt it to your setup.

Automation: ventilate after painting

A freshly painted room smells exciting at first, but those fumes are VOCs you don’t want to breathe for hours. This automation turns on the exhaust fan when VOC levels shift, helping clear the fumes faster so the room is ready to enjoy sooner.

• Trigger: Volatile organic compounds level changed
• Target: Workshop VOC sensor
• Threshold type: 100
• Action: Turn on fan

alias: "Ventilate on VOC change"
triggers:
  - trigger: air_quality.voc_changed
    target:
      entity_id: sensor.workshop_voc
    options:
      threshold: 100
actions:
  - action: fan.turn_on
    target:
      entity_id: fan.workshop_exhaust

Still stuck?

The Home Assistant community is quick to help: join Discord for real-time chat, post on the community forum with the trigger you’re using and what you expected to happen, or share on our subreddit /r/homeassistant.

Related triggers

These triggers work well alongside this one:

• Volatile organic compounds level crossed threshold - Triggers after one or more volatile organic compounds levels cross a threshold.