For those using an FA helmet, I have some questions about options on cooling:

1.) ambient air through an air filter
2.) water filtered/cooled
3.) dry ice

On 1, it seems like the easiest by far but I am wondering if the outside air really brings down temps - I am sure there is a 20 to 30 temp difference cooler than just roasting in the car (great, that gets me down to 90 degree air) but the added expense of the helmet for that doesn't seem like that big of a benefit.

On 2, how much moisture is getting into the helmet and in the case of a long race (we've been running 1.5 hour enduros - 45 minutes a stint minimum), could it possibly lead to fogging as the ice water turns to warm water?

On 3, how are others doing this? I've heard of running through piping in a cool box with dry ice but a.) is this a messy pita? b.) do you still have the same condensation problems as you would with (2) and how do you filter?

FWIW, I have been mentally leaning toward (2) but I had this thought this morning that I might be saturating the helmet with the moist air. The idea was to run a NACA duct into some 3" to 1" tubing into a cooler at the bottom. Take a 1" outlet from the top with a high speed computer fan (or something of that size) pushing air into the outlet tubing and thus filtering the incoming air through the ice water - call it the Pot Head Cooling System This was the thought but I got a bit leary at the thought of trashing the liner of a xhundred dollar FA helmet due to pumping a ton of moisture into it.

Thanks in advance.