Many building materials used in construction today are toxic.  With conventional construction there is very little emphasis placed on the health of those constructing the buildings or the health of the occupants.  As a builder who started out apprenticing on spec houses, it is easy for me to recognize the disregard for health that occurs in most of what is built today.  As the cost of quality-natural materials has risen, building materials have become more synthetic and less healthy.  Plastics, fungicides on  lumber, formaldehyde based additives in plywood and finishing products, vinyl products and adhesives are just a few of the obvious sources for unhealthy indoor air.  It is unwise to construct a home with products like these.  As our structures have become more airtight to comply with our stricter energy code the result has been an increase in indoor air quality related diseases.

Rammed earth is nontoxic.  It is essentially stone.  It does not support the growth of mildew or mold because there is nothing for them to eat.  There are no hidden toxic substances off gassing into the structure. Rammed earth walls are a good start to creating a building with clean indoor air.  They may be treated with a nontoxic sealer or not.  The walls are tight, and if the connective detailing is done correctly, there will be very little air leakage.  This means that in order to maintain a healthy indoor environment air will have to be exchanged via an HRV or some other tempering system.