About Cladosporium cladosporioides 2
The second sequence variant (seqvar 2) of Cladosporium cladosporioides represents a closely related genetic lineage of the same species, separated in the ERMI panel because molecular detection differentiates between them. Its ecology, health effects, and indoor significance are essentially identical to seqvar 1. The combined interpretation of both seqvars gives a more complete picture of total C. cladosporioides burden in the sample.
Ecology and water requirements
Cladosporium cladosporioides 2 is classified as a secondary colonizer with mesophilic moisture requirements: capable of growing at water activity in the range Aw 0.87 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 cladosporioides 2 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 cladosporioides 2 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 cladosporioides 2 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 cladosporioides 2 is documented on the following substrates and locations:
- Same as seqvar 1: ubiquitous indoors and outdoors on damp surfaces
- plant debris
- HVAC systems
Mycotoxins
No mycotoxins documented for this species in our reference literature.
On your ERMI report
Cladosporium cladosporioides 2 is one of the 10 EPA environmental reference species used to compute the SLG2 component of the ERMI score (sometimes labeled "Group 2" in EPA documentation). Group 2 species are commonly found in outdoor air; their levels are subtracted from the indicator-species sum, which means high outdoor-reference detections actually reduce the final ERMI. A low-level detection of Cladosporium cladosporioides 2 is common, because these species are also found in outdoor air. Our interpretation report reads its level alongside the indicator species.