PM2.5 value

The PM2.5 value condition passes when a PM2.5 sensor’s reading meets a specific level. PM2.5 is the most widely used indicator of air quality, and for good reason: these fine particles (smaller than 2.5 micrometers) come from traffic, wildfires, and everyday cooking, and they affect respiratory health at surprisingly low concentrations. This condition gives your automation precision, closing the windows only when outdoor PM2.5 is above a safe limit or holding off on opening them until the reading drops back down.

Using this condition from the user interface

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

To use this condition in an automation:

1. Go to Settings > Automations & scenes.
2. Open an existing automation, or select Create automation > Create new automation.
3. In the And if section, select Add condition.
4. Select what you want to check. 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 conditions shown for that target, select PM2.5 value.
6. Under Threshold type, set the PM2.5 level the condition checks against.
7. Under Condition passes if (see Behavior), pick Any or All.
8. Select Save.

Options in the UI

Using this condition 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 condition as air_quality.is_pm25_value. A basic example looks like this:

condition: air_quality.is_pm25_value
target:
  entity_id: sensor.living_room_pm25
options:
  threshold: 35
  behavior: any

This passes when the living room PM2.5 sensor reads at or above 35 µg/m³.

Options in YAML

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

Targets

This condition supports targets. A target tells Home Assistant what the condition should check. 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 evaluates 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 condition. For example, combine a specific entity with an area to check both at once.

Behavior with multiple targets

When you target more than one entity (or select an area, floor, or label that contains several), the Condition passes if option controls how the results combine:

• Any (default): the condition passes if at least one of the targeted entities matches. For example, if you check three smoke sensors and only one of them detects smoke, the condition still passes. This is useful for questions like “is there smoke anywhere in the house?”
• All: the condition passes only when every targeted entity matches. For example, if you check the same three smoke sensors, the condition passes only once all three report cleared. This is useful for “is the entire house safe now?” checks, so your automation does not send an all-clear while one room still has a reading.

Good to know

• Sensors that are unavailable (unavailable) or have an unknown state (unknown) are skipped for Any and fail for All.
• The World Health Organization recommends keeping 24-hour average PM2.5 exposure below 15 μg/m3.
• For other particle sizes, see
  • PM1 value
  • PM4 value
  • PM10 value

Try it yourself

Ready to test this? Go to Settings > Automations & scenes, open an automation, and add this condition. Trigger the automation with and without the condition met, and watch whether it continues or stops.

More examples

Real scenarios where this condition gates an automation. Copy any example and adapt it to your setup.

Automation: check outdoor PM2.5 before opening the windows each morning

During wildfire season, outdoor PM2.5 readings spike overnight while you sleep. This automation triggers when you open the living room window cover and checks the outdoor PM2.5 reading first. If the level is at or above 35 μg/m3, the cover closes right back and you get a notification letting you know the air outside is not safe for ventilation. On clear mornings, nothing happens and you enjoy the fresh air.

• Trigger: State: Living room window cover opened
• Condition: Air Quality: PM2.5 value
• Target: Outdoor PM2.5 sensor
• Threshold type: 35
• Condition passes if: Any
• Action: Cover: Close cover, then notify

alias: "Close windows if outdoor PM2.5 is high"
triggers:
  - trigger: state
    entity_id: cover.living_room_window
    to: open
conditions:
  - condition: air_quality.is_pm25_value
    target:
      entity_id: sensor.outdoor_pm25
    options:
      threshold: 35
      behavior: any
actions:
  - action: cover.close_cover
    target:
      entity_id: cover.living_room_window
  - action: notify.mobile_app_phone
    data:
      title: "PM2.5 is high outside"
      message: >
        Outdoor PM2.5 is above 35. The window
        has been closed to keep the air clean.

Still stuck?

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

Related conditions

These conditions work well alongside this one:

• PM1 value - Tests the PM1 level of one or more entities.

• PM4 value - Tests the PM4 level of one or more entities.

• PM10 value - Tests the PM10 level of one or more entities.