The AirVisual Pro's PM2.5 and CO2 measurements are displayed side by side on the same screen (as shown in the below image), either when the Pro is not connected to Wi-Fi, or when no outdoor station is selected.
When you select an outdoor air quality monitoring station for your Pro to follow via Wi-Fi, this will be displayed next to your device's immediate PM2.5 readings on the first screen to clearly display the comparison.
To deselect an outdoor station, go to the Pro's settings menu > Location > Locations list > Remove outdoor location.
^Example of an AirVisual Pro displaying PM2.5 and CO2 readings side by side