We have stated that there are no accepted numerical standards for mold concentrations. Several previous attempts at suggesting numerical concentrations have failed due to the enormous diversity of the thousands of mold species that naturally occur, and to the wide variability in human responses to these species. Most professional doubt that we will ever have a set of exposure limits like we have for other indoor contaminants such as radon, asbestos and lead.
This does not mean, however, that there are no standards with which to conduct a competent assessment or remediation project. Numerous public and private agencies in the US have written standards for biological contaminants, starting with the Environmental Protection Agency (EPA) and the American Conference of Governmental Industrial Hygienists (ACGIH) in the late 1980’s. The body of professional standards has grown steadily since. A sampling of the evolution of professional industry standards is shown below. [Read more…]