strength of air pressure needed to pass through carbon filter.....????

How strong does the air pressure from a fan need to be to pass through a carbon filter???

I.e. are they relatively free-flowing???




For example, could you easily exhale through one??

I am not sure about store bought ones, but the ones in the DIY section you can breath through. You want to suck the air through the filter then out of the box. Do not push the air from the box through the filter, it will act as a cap and just put warm air back into the box