Cabin Air Filter Question

I'm not willing to say the direction of the filter doesn't matter.
I mean if it didn't? Why even bother with arrows pointing in any direction?
Just sell the filter as being being multi-directional and use it as a selling point. If a manufacturer is going to the cost and trouble of showing arrows for either filter orientation or air-flow direction, I'm assuming there is a structural reason within the composite of the filter itself.

This has been interesting because this "simple" action seems to have a lot of confusion surrounding it.

 

I'd be inclined to agree; it could well be one direction works better than the other. OTOH, if it didn't matter, I think there'd still be value in the arrows, to help re-orient the filter the same way, after an intermediate removal/replacement, to help you avoid flipping it over.

Rolls Royce for avoiding mis-orientation would be a filter that can only be put in one direction. The engine air filter's an example of this.

 

The same filter may have multiple applications.

 

Another update on this. I took out the cabin air filter from my Prius 3 2015 and my Prius C 2016 and ran the fan and put a small piece of paper in there to determine the air flow. The paper bends down showing that the air flow is from top to bottom. So with my after market filter that shows air flow arrow I installed it with the arrow pointing down.

 

if the air flowed up, all the day bree would keep falling back into the fan blades.