Common Mold Types Found in Homes and Their Hazard Classes

Hazard Classes of Indoor Mold

Fungi have typically been grouped into 3 hazard classes based on associated health risk.

Hazard Class A: includes fungi or their metabolic products that are highly hazardous to health. These fungi or metabolites should not be present in occupied dwellings. Presence of these fungi in occupied buildings requires immediate attention.

Hazard class B: includes those fungi which may cause allergic reactions to occupants if present indoors over a long period.

Hazard Class C: includes fungi not known to be a hazard to health. Growth of these fungi indoors, however, may cause economic damage and therefore should not be allowed.

“Hazard Class A: includes fungi or their metabolic products that are highly hazardous to health.”

Cladosporium cladosporioides (hazard class B)
Photograph via Wikipedia

Molds commonly found in kitchens and bathrooms

-Cladosporium cladosporioides (hazard class B)

-Cladosporium sphaerospermum (hazard class C)

-Ulocladium botrytis (hazard class C)

-Chaetomium globosum (hazard class C)

-Aspergillus fumigatus (hazard class A)

Molds commonly found on wallpapers

-Cladosporium sphaerospermum

-Chaetomium spp., particularly Chaetomium globosum

-Doratomyces spp (no information on hazard classification)

-Fusarium spp (hazard class A)

-Stachybotrys chartarum, commonly called ‘black mold‘ (hazard class A)

-Trichoderma spp (hazard class B)

-Scopulariopsis spp (hazard class B)

Molds commonly found on mattresses and carpets

-Penicillium spp., especially Penicillium chrysogenum (hazard class B) and Penicillium aurantiogriseum (hazard class B)

-Aspergillus versicolor (hazard class A)

-Aureobasidium pullulans (hazard class B)

-Aspergillus repens (no information on hazard classification)

-Wallemia sebi (hazard class C)

-Chaetomium spp., particularly Chaetomium globosum

-Scopulariopsis spp.

Molds commonly found on window frames

-Aureobasidium pullulans

-Cladosporium sphaerospermum

-Ulocladium spp.

Molds commonly found in basement (cellars)

-Aspergillus versicolor

-Aspergillus fumigatus

-Fusarium spp.

Molds commonly found in flower pot soil

-Aspergillus fumigatus

-Aspergillus niger (hazard class A)

-Aspergillus flavus (hazard class A)