its ok to have the car set on recirculate but only use this mode for a short period of time,
using this mode to demist with AC on is good,and in the summer having recirculate turned
on will help to cool the car quicker, the tell tale signs that recirc has been on for too long
is that your windscreen will slowly start to mist at the bottom and / or the rear window will
mist up as soon as you see these signs turn the recirc off.