Stachybotrys chartarum

Health: Produces trichothecene mycotoxins linked to respiratory distress, chronic fatigue, neurological symptoms, and immune suppression. Highest-risk species for vulnerable occupants.

Found in: Chronically wet materials — drywall, cellulose ceiling tiles, paper-backed insulation, and OSB behind slow plumbing leaks or post-flood walls that stayed wet 48+ hours.

Aspergillus

Health: Can cause aspergillosis in immunocompromised individuals, allergic bronchopulmonary reactions, and sinus infections. Some species produce aflatoxins.

Found in: HVAC systems, air handlers, dust-laden ducts, damp wall cavities, and stored materials. One of the most common indoor molds in humid Florida homes.

Cladosporium

Health: Strong allergen — triggers asthma, hay fever, rhinitis, and skin irritation. Less toxic than Stachybotrys but far more widespread indoors.

Found in: Bathroom ceilings, window sills, HVAC duct interiors, painted surfaces, and the underside of roof sheathing in poorly ventilated attics.

Penicillium

Health: Common allergen causing asthma and respiratory reactions. Some species produce mycotoxins; prolonged exposure worsens indoor air quality significantly.

Found in: Water-damaged materials, wallpaper glue, carpet padding, insulation, and behind cabinets with undetected moisture. Spreads rapidly in 24–72 hours after water intrusion.

Alternaria

Health: Major outdoor allergen that moves indoors; strongly associated with asthma onset in children and severe allergic rhinitis.

Found in: Window frames, showers, under sinks, and anywhere with condensation. Thrives in Florida's year-round humidity even without an active leak.

Fusarium

Health: Can cause infections and produces mycotoxins. Less common indoors but significant when present — often signals a chronic moisture source.

Found in: Wet drywall, water-damaged carpet, and HVAC drain pans. Often found alongside other species after a flood or plumbing failure.

Chaetomium

Health: Produces mycotoxins associated with skin and neurological effects. Its presence almost always indicates advanced, long-standing water damage.

Found in: Damp drywall, paper products, and water-damaged building materials that have been wet for extended periods. A red flag for hidden structural moisture.

Aureobasidium

Health: Allergenic; causes hay fever, asthma, and hypersensitivity pneumonitis in sensitive individuals.

Found in: Window sills, caulk lines, bathroom grout, and any surface with recurring condensation — very common in coastal and canal-front homes.