About Cladosporium sphaerospermum
Cladosporium sphaerospermum is the most xerotolerant of the indoor Cladosporium species and the dominant Cladosporium found on indoor surfaces. Studies have shown it outcompetes Penicillium chrysogenum for surface colonization because it can re-initiate growth from hyphal tips more rapidly after drying. It is commonly found on painted wood, gypsum board, windowsills, and bathroom surfaces. Although Cladosporium species are not known to produce significant mycotoxins, they are highly allergenic and a documented trigger for allergic rhinitis, asthma, and sinusitis.
Ecology and water requirements
Cladosporium sphaerospermum is classified as a secondary colonizer with mesophilic moisture requirements: capable of growing at water activity in the range Aw 0.82 and above[2], typical of condensation surfaces and freshly damp materials. Secondary colonizers follow primary xerophilic species in the ecological succession that develops on damp building materials. Detection of elevated Cladosporium sphaerospermum on an ERMI suggests intermittent or recent moisture conditions consistent with condensation, vapor permeation, or short-lived water events: chronically cool surfaces (uninsulated walls, single-pane windows, plumbing chases) and bathrooms or kitchens with insufficient ventilation are typical contexts.
Mycotoxin biology
Cladosporium sphaerospermum is not currently documented as a significant mycotoxin producer in the indoor environment context. Its primary health relevance indoors is generally as an allergen. Fungal spores and hyphal fragments are documented triggers for allergic rhinitis, asthma exacerbation, and hypersensitivity reactions in sensitized individuals. Allergen production and inflammatory potential vary by strain, growth substrate, and environmental conditions. As with all ERMI species, a positive DNA detection in dust indicates that spore material is present in the home but does not directly measure airborne exposure or sensitization status.
Detection in dust versus visual inspection
DNA-based detection of Cladosporium sphaerospermum in settled household dust (the basis of the ERMI panel[1]) integrates spore material from current and recent growth in the home, capturing exposure history over weeks to months. A positive detection in dust does not necessarily indicate currently-active growth at the time of sampling; conversely, an active growth site can produce relatively low dust spore counts if the spores are not being aerosolized (sealed wall cavities, behind vapor barriers, or under flooring). Interpretation requires considering the dust signal alongside building inspection, occupant symptom history, and the broader pattern of species detected on the panel.
Where it’s typically found
Cladosporium sphaerospermum is documented on the following substrates and locations:
- Painted wood and walls
- gypsum board
- windowsills
- bathroom surfaces
- HVAC systems
- carpet dust
Mycotoxins
No mycotoxins documented for this species in our reference literature.
On your ERMI report
Cladosporium sphaerospermum is one of the 26 EPA water-damage indicator species used to compute the SLG1 component of the ERMI score (sometimes labeled "Group 1" in EPA documentation). Whether the level detected in any specific home is concerning depends on the broader pattern: which other species are elevated, the water-activity profile of the elevated species, the home's climate context, and (where relevant) the occupant's sensitivity history. Our interpretation report puts Cladosporium sphaerospermum in that broader pattern.