Enough to be able to breathe.

But this being my first experience of a rental property owner, I took a breath, and figured out how this could work.

Take a breath and vent here, not at the tenant. 

Give yourself breathing room.

Breath....

All my ducks are in a row, I just need an Agent (motivated, who loves their job) and who lives and breathe's commercial real-estate (experience will do to..) in the Connecticut (Hartford, West Hartford, Manchester, South Windsor, East Windsor, Enfield, etc. and Western MA, East Long Meadow, Springfield, Chicopee, South Hadley, North Hampton, etc.)

a couple of box fans + 20x20 filters.... run continuously 1-2 days. dump the filters directly into a trash bag. replace and re-run.have the ac/heat ducts (if any) professionally cleaned... you don't want to breath the nasties again....also i would check for cold/humid sections of walls. also crumbly (drywall/plaster) around baseboards. if you have those, (respectfully sorry) you are in for a surprise if you open the walls.....now, what is the source of humidity?

One day, I'll live in a forest in Oregon or in the mountains in Colorado, but for now, this will do...Any other things you can do to breathe cleaner air in a city?

So don't critic everything and breath down their back.

Don't hold your breath.