Environmental conditions influence mold growth and mycotoxin production. Such things as water activity (aw), temperature, pH and atmosphere can strongly affect and profoundly alter patterns of growth and mycotoxin production. Generally, maintenance of low temperatures will prevent aflatoxin production in stored products, whereas other toxins such as penicillic acid, patulin, zearolenone and T-2 toxin may be produced at low temperatures. Toxic Penicillium and Fusarium species are generally more capable of growth at low temperatures than are toxic species of Aspergillus. Temperature interacts with aw to influence mold growth and mycotoxin production. Aflatoxin B1 can be produced at conditions of aw and temperature which are close to the minimum aw and temperature for growth.
Class of water damage is determined by the probable rate of evaporation based on the type of materials affected, or wet, in the room or space that was flooded. Determining the class of water damage is an important first step, and will determine the amount and type of equipment utilized to dry-down the structure. Class 1 - Slow Rate of Evaporation. Affects only a portion of a room. Materials have a low permeance/porosity. Minimum moisture is absorbed by the materials. **IICRC s500 2016 update adds that class 1 be indicated when <5% of the total square footage of a room (ceiling+walls+floor) are affected ** Class 2 - Fast Rate of Evaporation. Water affects the entire room of carpet and cushion. May have wicked up the walls, but not more than 24 inches. **IICRC s500 2016 update adds that class 2 be indicated when 5% to 40% of the total square footage of a room (ceiling+walls+floor) are affected ** Class 3 - Fastest Rate of Evaporation. Water generally comes from overhead, affecting the entire area; walls, ceilings, insulation, carpet, cushion, etc. **IICRC s500 2016 update adds that class 3 be indicated when >40% of the total square footage of a room (ceiling+walls+floor) are affected ** Class 4 - Specialty Drying Situations. Involves materials with a very low permeance/porosity, such as hardwood floors, concrete, crawlspaces, gypcrete, plaster, etc. Drying generally requires very low specific humidity to accomplish drying.