These new systems are so advanced, and they are sensitive to chemicals, such as bleach.

You may forget that they used chemical weapons on their own people.

Who wants to admit they are inhaling poisonous chemicals? 

Chemicals sold as ready to use are a huge rip off.

If the topcoat is truly a polyurethane, that stuff cures in way that nothing will ever chemically bond with it.

This type of wood when burning gives off toxic gases and chemicals and is not meant to be thrown in the fireplace just like certain types of trees aren't as well.Try getting the tenants to understand that.It's a miracle by their own ignorance that they haven't done something to kill themselves yet early in life.Common sense escapes them in many cases.

Of course, its with highly toxic chemicals but I did this to one house, all tile floor, cabinets, vanities, tubs showers, the whole dang thing it took a week and no normal person could tell anything was paint.

This is a new one to me.I have a house on the edge if town for sale and I had a gal come out and enthuse that it was just right because she had chemical sensitivity and yadda yadda yadda.

It's one of the big three chemicals used to keep the water balanced.

You might want to consider an industrial hygenist.a company called Modec (web addy is deconsolutions dot com) sells cleanup chemicals for meth labs.