Nitrous oxide level changed

The Nitrous oxide level changed trigger fires after the nitrous oxide (N2O) reading on one or more air quality sensors changes by a meaningful amount. Nitrous oxide is a potent greenhouse gas produced by agricultural activities, industrial processes, and combustion of fossil fuels. While it is less commonly monitored at home than other pollutants, specialized sensors track it in greenhouses, workshops near agricultural operations, and laboratory or medical settings.

Imagine your greenhouse ventilation fans spinning up automatically when N2O shifts after a round of fertilizing, keeping the growing environment healthy without an extra trip outside. Use this trigger to log environmental data, activate ventilation, or send alerts whenever your N2O 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 Nitrous oxide 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.n2o_changed. A basic example looks like this:

trigger: air_quality.n2o_changed
target:
  entity_id: sensor.greenhouse_n2o
options:
  threshold: 5

This fires whenever the greenhouse N2O sensor reading changes by at least 5 ppb.

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

• Nitrous oxide is a potent greenhouse gas with roughly 300 times the warming potential of carbon dioxide. Monitoring it is valuable for environmental tracking.
• The trigger fires on any change that meets the threshold, whether the level goes up or down.
• To react only when N2O crosses a specific concentration in one direction, use Nitrous oxide 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 the greenhouse on N2O change

After fertilizing, N2O levels in a greenhouse tend to climb. This automation turns on the ventilation fans when N2O levels shift, keeping the growing environment healthy for your plants without an extra trip outside to check.

• Trigger: Nitrous oxide level changed
• Target: Greenhouse N2O sensor
• Threshold type: 5
• Action: Turn on fan

alias: "Ventilate greenhouse on N2O change"
triggers:
  - trigger: air_quality.n2o_changed
    target:
      entity_id: sensor.greenhouse_n2o
    options:
      threshold: 5
actions:
  - action: fan.turn_on
    target:
      entity_id: fan.greenhouse_ventilation

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:

• Nitrous oxide level crossed threshold - Triggers after one or more nitrous oxide levels cross a threshold.