When PM2.5 levels become unhealthy, set Lennox iComfort fan to On -

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If your home's PM levels are too high, this sets your Lennox iComfort fan to on, allowing more air to be filtered by your central system. Note: Use a second applet to turn off the device once levels are healthy again.

This Trigger fires whenever the measured Particulate Matter of 2.5 microns in size (PM2.5) is above or below the threshold.

This Action will set my thermostat's fan to On indefinitely. Note: does not work when the thermostat is in Away mode.