Since Biblical times, Leviticus 14:39 - 47, is has been known that indoor mold growth can be a health hazard. In the 1930s, mold was identified as the cause behind the mysterious deaths of farm animals in Russia and other countries. Stachybotrys chartarum was found growing on wet grain used for animal feed.
In the 1970s, building construction techniques changed in response to the energy crises. As a result, homes and buildings became more airtight. Also, cheaper materials such as drywall came into common use. This combination of increased moisture and suitable substrates contributed to increased mold growth inside buildings.