Mold Spore Release during Simulated Flooding and High Humidity

Peter Pityn, PhD, James J. Anderson, MLT


Rationale: Two one-month simulations were performed in a chamber to measure mold spore release from deteriorating building materials caused by flooding and excessive dampness.  

Methods: Penicillium chrysogenum was implanted on the backside of a typical wooden frame gypsum wall inside of an environmental chamber. The wall cavity was sealed. Water was fed slowly into the wall cavity, emulating a leaky foundation.  One inch of water flooded the bottom of the chamber producing 100% RH continuously. Spore release inside the wall cavity and on the front side of the wall was measured and compared.  Aspergillus fumigatus was implanted in the second study with conditions maintained at 75-85% RH and no flooding.

Results: Many other molds produced heavy growth in equal or greater abundance. Sustained heavy growth during one month of flooding and later elimination of water did NOT release spores into air, until stripped by high velocity air.

With sustained high humidity (no flooding) surface mold and spore releases within the wall cavity increased gradually, but not in front. Near the end, different spores were eventually released into the front airspace, but in far lesser amounts. 

Conclusions: The wall is an effective barrier against molds released from the wall cavity.  Spore release is inhibited by very high humidity conditions.  High air contamination does not necessarily accompany findings of extensive mold on building surfaces, as is often assumed or insinuated, until wall integrity is disrupted. The mold colonization process appears to be selective, modulated by environmental conditions.


abstract No: 


Full conference title: 

The American Academy of Allergy, Asthma & Immunology 2017
    • AAAAI 2017 (73rd)