Air pressure in the grow room

[MegaOctane12]

I noticed itâ??s extremely hard to have a perfect balance of air coming in from outside and air getting out. Iâ??m especially afraid of the negative air flow condition (more is coming in and less going out) as it will disperse the smell trough out the house.

So I was thinking of trying to get a little more air going out than coming in to make sure the smell stays in the grow room. Is this a bad idea and if so, how can I get the exact pressure/ratio (in to out) ?

Thanks

If you look around there are forumlas for the exact amount of air that should be exchanged.