Frequent replacement of A/C system or refrigerator components (such as air coils)
DANGER: If you have experienced loss of “Freon” or refrigerant from your A/C system, it may have leaked into your home from sulfur eaten pinholes in your equipment.

   The Chinese made drywall is known to produce foul smelling-odors (resembling rotten eggs), which may be caused by hydrogen sulfide or other sulfide gases being emitted from the defective Chinese drywall. Air quality tests have been administered in several homes built in South Florida, and results have found at least three different sulfide gases in the air: carbon disulfide, carbonyl sulfide, and dimethyl sulfide among others.

   Hydrogen sulfide, the compound that causes the rotten egg smell, was not found in the air quality reports. However, tests administered directly from the Chinese drywall material itself, by Environ Corp an air quality management organization, revealed that hydrogen sulfide was indeed present. Knauf Tianjin, a Chinese drywall manufacturer who has had reports of problems with their drywall, reported that tests administered on the drywall in 2006 also found hydrogen sulfide.

I am pretty certain that any chemical in the house capable of corroding metal that fast isn't healthy to breath.