Types of toxic mold,
by genus

Stachybotrys

Common name: Black mold.

Grows on: Damp cellulose, wood, ceiling tiles, gypsum, cardboard.

Health effects: Particularly harmful to infants, elderly, and immunocompromised occupants. Causes infections and respiratory inflammation when fragments and mycotoxins become airborne.

Memnoniella

Common name: Also called black mold; closely related to Stachybotrys.

Distinguishing feature: Releases spores in chains under the microscope; Stachybotrys releases in clumps.

Health effects: Effectively identical to Stachybotrys.

Penicillium

Notes: Some species are beneficial (cheese, antibiotics); indoor species in damp buildings are problematic.

Health effects: Triggers allergies. Significant problem for people with weakened immune systems.

Alternaria

Notes: Widespread; many indoor species are toxic at elevated exposure.

Health effects: Inhaling spores commonly causes hay fever and asthma exacerbations.

Trichoderma

Appearance: White with green patches.

Grows in: Damp areas, particularly chronic-leak environments.

Health effects: Triggers allergies. Some subspecies cause pulmonary and liver infections.

Geotrichum

Appearance: White, powdery.

Grows in: Mild climates, damp environments.

Health effects: Pulmonary infections, tuberculosis-like symptoms, fatigue, itchy eyes, severe headaches.

Chaetomium

Notes: Strong musty smell. Allergen.

Grows on: Water-damaged drywall, under carpets, on wallpaper backings, baseboards.

Health effects: Can cause neurological damage, autoimmune effects, conjunctivitis, breathing difficulties.

Ulocladium

Appearance: Black.

Grows in: Water-damaged homes, kitchens, basements, bathrooms.

Health effects: Severe allergen. Skin infections, chronic allergic reactions, respiratory symptoms resembling asthma.

Bipolaris

Appearance: Grayish-brown or whitish, becoming dark olive; fluffy.

Grows on: Soil, grass; indoors on water-damaged hardwood, houseplants, carpets.

Health effects: Wheezing, asthma, coughing, blocked nostrils.