Mold Building Profile
The Mold Building Profile quantifies multiple fungal species in settled indoor dust, including water-damage indicators such as Stachybotrys chartarum and Aspergillus versicolor. Results guide environmental remediation and support clinical assessment of mould-related respiratory and systemic symptoms.
7
Biomarkers
Dust
Sample
10–14 business days
Turnaround
No
Fasting
What is the Mold Building test?
The Mold Building Profile quantifies multiple fungal species in settled dust collected from indoor environments, providing practitioners with objective evidence of mould contamination when patients present with symptoms potentially linked to water-damaged buildings. Mould exposure is implicated in a spectrum of respiratory, allergic, and systemic complaints, yet clinical diagnosis is challenging because symptoms overlap with other conditions and direct causation is difficult to prove. This profile bridges the clinical and environmental domains, offering species-specific data that guide remediation priorities and support clinical decision-making in cases of suspected mould-related illness. Settled dust is a time-integrated reservoir of airborne spores, reflecting chronic exposure better than short-duration air sampling. The panel targets species commonly associated with water-damaged indoor environments — Stachybotrys chartarum, Aspergillus versicolor, Chaetomium, and others — alongside ubiquitous genera whose indoor enrichment signals moisture problems. Results are expressed as spores per milligram of dust, enabling comparison to published reference data and outdoor baselines, and each detected species contributes to the overall environmental risk assessment.
What does the Mold Building test measure?
Aspergillus versicolor is a xerophilic mould species capable of growth on damp building materials, particularly gypsum board, cellulose insulation, and ceiling tiles. It produces sterigmatocystin, a mycotoxin structurally related to aflatoxin, and has been isolated from water-damaged buildings associated with occupant complaints of respiratory and systemic symptoms.
Detection of A. versicolor in indoor dust samples indicates water intrusion or chronic moisture problems. Occupants of buildings with elevated A. versicolor may report upper-airway irritation, exacerbation of asthma, fatigue, and cognitive complaints; the species is a recognised marker of dampness-related health risk in indoor air quality investigations.
Stachybotrys chartarum is a cellulose-degrading mould requiring sustained high moisture (>90% relative humidity) and is typically found on wet gypsum wallboard, ceiling tiles, and paper-faced materials after flooding or chronic leaks. It produces trichothecene mycotoxins, which inhibit protein synthesis and disrupt cellular membranes.
S. chartarum is the most studied 'black mould' in relation to indoor air quality. Although causal links between exposure and specific diseases remain contested, detection in dust samples confirms significant water damage and is correlated with respiratory symptoms, asthma exacerbations, mucous-membrane irritation, and systemic inflammatory complaints in occupants.
Penicillium is a ubiquitous genus of moulds found on decaying vegetation, soil, and food, as well as damp indoor surfaces including wallpaper, carpet, and insulation. Various species produce secondary metabolites including penicillin and a range of mycotoxins; indoor species often reflect water damage or elevated humidity.
Penicillium is one of the most frequently detected genera in indoor environments. Low levels are common background flora, but concentrations above background suggest moisture problems and are associated with allergic rhinitis, asthma, and hypersensitivity pneumonitis in sensitised individuals.
Chaetomium is a cellulose-digesting genus that colonises wet cellulose-rich materials such as drywall, paper, and textiles. It requires sustained moisture and is a late-stage coloniser following prolonged water damage. Some species produce chaetoglobosins and other secondary metabolites.
Chaetomium detection is a strong indicator of chronic water damage. It is less common than Aspergillus or Penicillium but its presence correlates with prolonged dampness. Occupants may report musty odour, respiratory irritation, and worsening of pre-existing airway disease.
Cladosporium is one of the most abundant outdoor mould genera and is commonly found indoors on damp surfaces, textiles, and ventilation systems. It grows across a wide range of temperatures and moisture conditions and is a frequent sensitiser in atopic individuals.
Because Cladosporium is ubiquitous outdoors, indoor detection must be interpreted relative to outdoor levels. Indoor concentrations significantly exceeding outdoor levels suggest moisture problems or ventilation deficiencies. It is a common trigger of allergic rhinitis and asthma.
Alternaria is a plant pathogen and saprophyte abundant in outdoor air, particularly during warm months. Indoors it colonises damp windowsills, showers, and textiles. Its spores are large and readily trapped in nasal passages, making Alternaria a potent allergen.
Alternaria is one of the most allergenic outdoor moulds and is associated with severe asthma exacerbations. Indoor detection above outdoor baseline suggests moisture issues or poor ventilation. Sensitised patients may require avoidance strategies and environmental remediation.
Total mould count aggregates all culturable and non-culturable fungal spores and fragments recovered from a dust sample, providing a measure of overall fungal burden. It reflects the cumulative impact of outdoor infiltration, indoor amplification, and moisture-related growth.
An elevated total mould count indicates excessive fungal burden in the indoor environment and is used as a screening tool. It must be interpreted alongside speciation data and outdoor baselines, but consistently high counts correlate with occupant complaints of respiratory and systemic symptoms.
Why is the Mold Building test ordered?
- Patients with new-onset or worsening asthma, allergic rhinitis, or chronic cough in whom building exposure is suspected based on temporal correlation with symptom onset
- Individuals reporting persistent fatigue, cognitive complaints, or systemic inflammatory symptoms temporally associated with occupancy of a specific building, particularly following water damage or flooding
- Children or immunocompromised patients residing in buildings with visible mould, musty odour, or documented water intrusion where health effects are a concern
- Adults with hypersensitivity pneumonitis or recurrent respiratory infections in whom environmental mould is a plausible contributing factor
- Occupants of buildings with known water damage, roof leaks, or plumbing failures who wish to document environmental exposure before or after remediation
- Clinical settings where objective environmental data will inform shared decision-making about avoidance, remediation, or relocation and support disability or housing claims
Sample collection and turnaround
Sample type
Dust
Fasting required
No
Collection method
At-home collection kit
Turnaround
10–14 business days
Collection notes
The kit includes a dust collection swab or vacuum-filter cassette with instructions for sampling settled dust from high-contact surfaces such as bedroom floors, furniture tops, or windowsills. Patients collect approximately 1–5 grams of dust using the supplied swab or by vacuuming a standardised area (e.g., 1 square metre for 2 minutes) and transferring the sample into the provided container. Multiple sampling sites within the home improve representativeness. The sample is returned to US BioTek by post in the pre-addressed shipping envelope.
Specimen requirements
Minimum 1 gram settled dust; 5 grams preferred for comprehensive analysis. Sample should be dry and free of gross contamination (food particles, pet hair should be minimised). Store at room temperature and ship promptly to preserve spore viability and antigen integrity.
What can affect Mold Building results?
Dust composition varies by room, surface type, and foot traffic. Samples collected from high-traffic floors or ventilation registers reflect different exposure profiles than bedroom dust; standardised sampling from multiple sites improves representativeness.
Indoor mould levels are influenced by outdoor spore counts, which peak in warm, humid months. Elevated indoor counts should be compared to concurrent outdoor baselines to distinguish infiltration from amplification.
Cleaning or remediation lowers detectable mould in dust. Sampling immediately after intervention may underestimate chronic exposure; baseline sampling before remediation documents pre-intervention burden.
Increased ventilation dilutes indoor bioaerosols and reduces settled dust accumulation. Poorly ventilated spaces concentrate spores and dust, elevating measured counts.
Relative humidity above 60% and uncontrolled leaks promote mould growth and spore release. Ongoing moisture intrusion sustains elevated counts even after partial remediation.
Spore viability and antigen integrity decline over time. Samples should be shipped promptly and stored dry; delays or moisture exposure can alter culturable counts and antigen detection.
What do Mold Building results mean?
Elevated
Elevated counts of water-damage indicators (Stachybotrys, Aspergillus versicolor, Chaetomium) confirm significant moisture intrusion and support a diagnosis of mould-related environmental exposure. High total mould counts or indoor enrichment of Penicillium, Cladosporium, or Alternaria suggest dampness, poor ventilation, or ongoing amplification. Clinical correlation is essential — elevated environmental mould may contribute to respiratory symptoms, asthma exacerbation, allergic rhinitis, hypersensitivity pneumonitis, or systemic inflammatory complaints, but environmental testing does not establish causation. Results guide remediation priorities and support avoidance strategies, and post-remediation re-sampling documents clearance.
Normal
Normal levels — defined as indoor counts comparable to or below outdoor baselines and absence of water-damage indicators — suggest that the tested environment is not a significant source of mould exposure. However, normal results in one location do not exclude contamination elsewhere in the building, and negative results do not rule out mould-related illness if sampling was not representative of the patient's primary exposure area.
Reduced
Low or undetectable mould levels in dust suggest that indoor fungal burden is minimal and comparable to outdoor background. This does not exclude mould growth in concealed spaces (wall cavities, subfloors) or exclude other environmental triggers (dust mites, volatile organic compounds, particulate matter). If clinical suspicion remains high despite low dust counts, consider air sampling, inspection of hidden reservoirs, or testing for mycotoxins.
Note: Environmental testing for mould is a tool to inform clinical decisions, not a stand-alone diagnostic. Results depend on sample location, timing, and representativeness; single-site sampling may miss localised contamination. Outdoor baseline data, recent weather, and season should inform interpretation. Some species are ubiquitous and only pathological when present at elevated levels; others (Stachybotrys, Chaetomium) indicate significant water damage at any detectable concentration. The profile does not measure mycotoxins directly; elevated spore counts suggest potential mycotoxin exposure, but clinical toxicity remains a contested and complex area. Remediation of identified sources should be pursued regardless of symptom attribution, and post-remediation clearance testing is advisable.
Frequently asked questions
It quantifies multiple mould species in settled indoor dust, including Stachybotrys chartarum, Aspergillus versicolor, Penicillium, Chaetomium, Cladosporium, and Alternaria, plus a total mould count. Each species is reported as spores per milligram of dust.
How to access the Mold Building test
The Mold Building reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.
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Published: October 7, 2026
Last reviewed: October 7, 2026
- World Health Organization. WHO guidelines for indoor air quality: dampness and mould. (2009)
- Institute of Medicine (US) Committee on Damp Indoor Spaces and Health. Damp indoor spaces and health. (2004)
- Bush RK, et al. The medical effects of mold exposure. J Allergy Clin Immunol. (2006)
- Mendell MJ, et al. Respiratory and allergic health effects of dampness, mold, and dampness-related agents: a review of the epidemiologic evidence. Environ Health Perspect. (2011)
- Vesper SJ, et al. Development of an Environmental Relative Moldiness Index for homes in the U.S. J Occup Environ Med. (2007)
This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.