cool vs warm mist humidifier?

I know this is a silly question, but does anyone know if it is better to use a cool or warm mist humidifier for a cat with a URI? I have both types and was thinking of putting one in my sick kitty's room but I don't want to use the wrong type...or does it matter? I was just a bit concerned about hot steam burning him if he got too hot but I don't want to chill him either--I worry so much about the cats, I never go through this with the humans in my house!!

I have a cat that struggles with URI's and I have a warm mist humidifier that I use. I believe the warm moisture helps open up the nasal passages more so then the cool mist. Another trick is to shut kitty in the bathroom with you while you shower and close all the doors. The steam/humidity from the shower really helps also. I keep mine running just about all winter long.