The same can be said for installing a ventilation, just because you have one/it doesnt mean your air is good either.

Anyways, my house 62.2 2010 ventilation rate in tectite is 82 cfm. I ran 120 cfm for 24 hours and my bedroom reading this morning, door not closed but cracked open overnight was 625, outside was at 410 ppm. I think ill let it go back up to 900 ish, ventilate same cfm with data logging and look at the graph and see if its gradual decline or short decline then stabilized.