Recommend installing a working bathroom exhaust fan in both units.10.

I installed one above the BBQ, so it lights up the grill when someone approaches.I installed electronic count down timers for the exhaust fans.  30 minutes in the baths, 4 hours in the kitchen. 

Ultimately is the only responsible defense against government when you have exhausted talking and have still been walked-over)

That's why I added another gable vent to our house... having enough exhaust area is just as important as opening enough inlets below.

Once you've exhausted those avenues, then find a small balance commercial broker that will close it. 

If you have older, upright washers, which could use 10 usg per load, a 40 usg gas tank would be sufficient and a 40 usg electric would be fine provided it has sufficient recovery (i.e. both elements are working)Just think ... in a typical home, folks often take a shower (2.5 usg / minute on most shower heads) and then do a load of laundry without exhausting a 40usg tank.If you put in a larger (60 or 80 usg) tank you will be incurring larger stand-by losses keeping the additional volume of water at temperature.

Navigating NYC building regulations and code enforcement exhausting and very frustrating especially if you plan to GC your build.  

For rapid growth in a matter of days or weeks,  I would not have thought it was a "natural" progression.As landlords, I would suggest that all bathrooms have an exhaust fan that can turn over the air inside that room at least five times.  

I will get the help of an attorney after I have exhausted the combined knowledge on sites like these.

man this sounds exhausting and inspiring at the same time.