December 01, 2025

Clean the air when air quality drops

Indoor air quality fluctuates throughout the day from cooking, outdoor pollution, pet dander, and more. Automate air purification when quality drops below healthy thresholds for better health and comfort.

Use cases

Indoor Sources

Cooking Smoke - Air quality drops when cooking creates smoke or strong odors
Pet Odors - Dander and smells accumulating in living spaces

External Factors

Seasonal Allergies - Outdoor pollen affecting indoor air quality
Poor Outdoor AQI - Wildfire smoke or pollution entering home
Health Maintenance - Proactive air quality management for respiratory health

Products needed

Essential Equipment - Option 1: Smart Air Purifier

Air Quality Sensor

Popular brands: Awair, IQAir, Aqara, PurpleAir
PM2.5 detection • WiFi connectivity • Measures AQI or PM2.5

Smart Air Purifier

Brands: Coway, Levoit, Dyson, Winix
WiFi-enabled OR regular purifier on smart plug (simpler option)

Essential Equipment - Option 2: HVAC-Based

Air Quality Sensor + Smart Thermostat

Brands: Ecobee, Honeywell
Smart thermostat with air filter/circulation mode

Optional Enhancements

Multiple Sensors

Track air quality in different rooms

Outdoor Air Quality Monitor

Compare indoor vs outdoor conditions

Basic automation setup

IF air quality poor (AQI > 100) THEN turn on air purifier to high AND send notification "Poor air quality detected"

Triggers

Air quality (AQI) drops below 35
OR PM2.5 concentration above 50 μg/m³
OR VOC (Volatile Organic Compounds) exceeds threshold

Conditions (optional)

Note: Air quality is health-critical and should be addressed immediately
Optional: Only during occupied hours

Actions

Turn on air purifier at high speed
OR activate HVAC fan with filter
Optional: Close smart windows/vents
Optional: Send notification with current air quality reading

Platform-specific examples

Home Assistant

Trigger Air quality sensor drops below 35 AQI

Action Turn on air purifier at 100%, send notification

Alternative: Use PM2.5 sensor above 50 μg/m³

SmartThings

IF Air quality sensor reports AQI below 35

THEN Turn on air purifier smart plug, send notification

Hubitat

Trigger AQI sensor drops below 35

Action Turn on air purifier at high, send notification

Setup: Use Rule Machine with air quality device

Apple HomeKit

When Air quality sensor detects poor air quality

Condition AQI below threshold (if supported)

Do Turn on air purifier

Alexa

When Air quality sensor value below 35 AQI

Action Turn on air purifier, send notification

Google Home

Starter Air quality sensor detects poor quality

Action Turn on air purifier, announce status

Advanced features

Automatic purifier shutoff

Turn off when air quality improves:

Create automation with these elements:

Trigger: Air quality rises above 50 AQI for 30 minutes
Condition: Purifier is currently on
Action:
- Turn off purifier
- Send notification: “Air quality improved ([current AQI]) - Purifier turned off”

Graduated speed control

Adjust purifier speed based on air quality level:

Create automation triggered by air quality sensor state change:

Good air (AQI above 50): Set fan to 25% (low/auto)
Moderate (AQI 35-50): Set fan to 50% (medium)
Unhealthy (AQI below 35): Set fan to 100% (high)

Use conditional logic to check current AQI and set appropriate fan speed.

No purifier? Alternative actions

If you don’t have an air purifier:

Send mobile notification: “Air quality poor ([current AQI]). Consider opening windows or improving ventilation.”
Create persistent notification on dashboard with current AQI and suggestion to check outdoor air quality before opening windows

Air quality levels reference

AQI scale

Good (0-50 AQI):

No action needed
Air quality satisfactory

Moderate (51-100):

Turn on purifier at low speed
Sensitive individuals may experience minor effects

Unhealthy for Sensitive Groups (101-150):

Purifier on medium to high
People with respiratory conditions should limit outdoor activity

Unhealthy (151-200):

Purifier on maximum
Notify household members
Everyone may experience health effects

Very Unhealthy (201-300):

Purifier maximum
Urgent notification
Health warnings for everyone

Hazardous (301+):

Purifier maximum
Emergency notification
Seal windows/doors
Consider evacuation if outdoor air (wildfire)

Troubleshooting

Issue: Purifier doesn’t turn on

Causes:

Air quality sensor not reporting correctly
Threshold too low (never reaches trigger point)
Smart plug or purifier not responding
Automation disabled or has errors

Solutions: ✅ Check air quality sensor battery and connectivity ✅ View current sensor reading in app - is it updating? ✅ Adjust threshold based on typical readings (try 45-50 instead of 35) ✅ Test purifier control manually - verify smart plug works ✅ Check automation logs to see if triggers are firing ✅ Verify automation is enabled

Issue: Purifier runs constantly

Causes:

Air quality sensor placed poorly (near kitchen, litter box, etc.)
Outdoor air quality consistently poor
Purifier not actually improving air (filter needs replacement)
Threshold set too high (always triggers)
No shutoff automation created

Check:

✅ Review sensor placement - away from heat, humidity, direct sources
✅ Check outdoor AQI - if outdoor is poor, indoor will be affected
✅ Inspect purifier filter - replace if dirty or old
✅ Monitor air quality trends - is it improving when purifier runs?
✅ Create companion shutoff automation (see Advanced Features above)

Fix:

Move sensor to central location away from direct pollution sources
Lower threshold (trigger at 30 instead of 35)
Add time delay: Only turn on if quality stays poor for 5+ minutes
Set maximum run time: Turn off after 2 hours, reassess air quality
Add shutoff automation with 30-minute “quality stable” delay

Issue: False triggers from cooking

Causes:

Sensor too close to kitchen
Cooking creates brief air quality spikes
No delay to differentiate temporary vs sustained poor quality

Solutions: ✅ Move sensor away from kitchen or add delay before triggering ✅ Add condition: Only trigger between certain hours (not dinner time) ✅ Use “for: 5 minutes” delay to ignore brief spikes ✅ Install separate kitchen hood fan automation ✅ Add condition: Don’t trigger if stove is in use (if smart) ✅ Use higher threshold for cooking hours (trigger at 30 instead of 35)

Related automations: