ACAC Council-certified Microbial Investigator (CMI)

Which ANSI consensus standard is the primary reference for professional mold remediation in the United States?

• AANSI/IICRC S500
• BANSI/IICRC S520
• CASTM D7338
• DASTM E2418

Which ASTM standard provides a guide specifically for the assessment of fungal growth in buildings?

• AASTM D7338
• BASTM E1527
• CASTM D6245
• DASTM E2418

Stachybotrys chartarum is best characterized as:

• AA xerophilic mold that grows readily on dry surfaces
• BA hydrophilic mold requiring prolonged wetness on cellulose substrates
• CA common outdoor mold rarely found indoors
• DA yeast rather than a filamentous mold

Which mycotoxin is most commonly associated with Aspergillus versicolor?

• AAflatoxin B1
• BSterigmatocystin
• CTrichothecenes
• DOchratoxin A

An Air-O-Cell spore trap cassette is typically operated at what flow rate?

• A5 L/min
• B10 L/min
• C15 L/min
• D28.3 L/min

When using an Air-O-Cell cassette at 15 L/min for 5 minutes, what is the sampled air volume?

• A15 L
• B30 L
• C75 L
• D150 L

The Andersen N6 single-stage impactor is most appropriate for which type of sampling?

• ANon-viable spore trap analysis
• BViable (culturable) bioaerosol sampling
• CSurface tape lift collection
• DBulk material sampling

Under ANSI/IICRC S520, which condition describes an indoor environment with actual mold growth and associated spores?

• ACondition 1
• BCondition 2
• CCondition 3
• DCondition 4

An indoor air spore trap shows Penicillium/Aspergillus at 4,500 spores/m³ while the simultaneous outdoor sample reads 200 spores/m³. What is the most appropriate initial interpretation?

• ANormal — indoor counts always exceed outdoor
• BIndoor amplification likely; investigate further
• CSample is invalid because Pen/Asp is a single genus
• DThe lab made an error; reject the result

Which water activity (aw) threshold is generally considered the lower limit for most mold growth on building materials?

• A0.50
• B0.65
• C0.75
• D0.95

Which sampling method is most appropriate to confirm whether discoloration on a drywall surface is mold growth?

• AAir-O-Cell cassette
• BTape lift surface sample
• CAndersen N6 impactor
• DBulk sampling of HVAC supply air

ERMI (Environmental Relative Moldiness Index) is based on which analytical method?

• ADirect microscopy of spore traps
• BQuantitative PCR (qPCR) of dust DNA
• CCulture on MEA agar
• DATP bioluminescence

What is the primary purpose of a field blank when collecting spore-trap samples?

• ATo calibrate the pump flow rate
• BTo detect background contamination during transport and handling
• CTo replace a sample that fails analysis
• DTo allow the lab to skip QA/QC

Under ANSI/IICRC S520, the minimum respiratory protection for workers in a Condition 3 environment (heavy mold growth, >100 sq ft) is typically:

• AN95 filtering facepiece
• BHalf-face air-purifying respirator with P100
• CFull-face air-purifying respirator with P100
• DSurgical mask

Which of the following is the MOST defensible justification for collecting an indoor air sample inside a sealed wall cavity?

• AClients always request cavity samples
• BThere is suspected hidden mold growth and visual evidence is inconclusive
• CIt is the standard for every CMI investigation
• DCavity samples are required by S520 for every assessment

Per ANSI/IICRC S500, Category 2 water is defined as water that:

• AOriginates from a sanitary source and poses no harm
• BContains significant contamination and has potential to cause discomfort or sickness
• CIs grossly contaminated and contains pathogenic agents
• DHas been standing more than 72 hours

Under ANSI/IICRC S500, untreated Category 1 water can typically be reclassified to Category 2 after approximately:

• A24 hours
• B48-72 hours
• C7 days
• D30 days

An IR (infrared) thermal camera identifies a cool spot on a wall. What does this most likely indicate in a mold investigation?

• AActive mold growth behind the wall
• BSurface temperature anomaly that may indicate moisture
• CAn electrical fault inside the wall
• DConfirmation that mold spores are present

Which moisture meter type penetrates materials with two metal pins and reads electrical resistance?

• APinless capacitance meter
• BPin-type resistance meter
• CThermohygrometer
• DAnemometer

Which fungal genus is most commonly used as an indicator of chronic indoor water damage in ERMI Group 1?

• ACladosporium
• BAlternaria
• CAspergillus versicolor
• DEpicoccum

ACAC certifications, including the CMI, are valid for what initial period before recertification is required?

• A1 year
• B2 years
• C3 years
• D5 years

An investigator notices a strong musty odor in a basement but no visible mold. The most appropriate first step is:

• AImmediately recommend full demolition
• BConduct a moisture survey and visual inspection before sampling
• CApply biocide throughout the basement
• DTake a single air sample and report negative if low

Which OSHA standard governs respiratory protection that applies to mold remediation employers?

• A29 CFR 1910.134
• B29 CFR 1910.1200
• C29 CFR 1926.62
• D40 CFR Part 763

Which of the following is a key principle of ACAC's Code of Ethics applicable to inspectors?

• AInspectors should also perform the remediation to maintain control
• BAssessment and remediation should generally be performed by independent parties to avoid…
• CInspectors should not disclose conflicts of interest if they affect business
• DInspectors may take referral fees from labs in exchange for sample volume

Which color description most accurately reflects Stachybotrys chartarum colonies under typical conditions?

• APink/orange
• BGreenish-black to dark olive
• CBright yellow
• DWhite cottony

Why is comparing indoor to outdoor spore counts an essential step in a CMI investigation?

• AOutdoor counts have no relationship to indoor air
• BOutdoor counts establish the natural background against which indoor amplification is jud…
• COutdoor sampling replaces the need for indoor sampling
• DOutdoor air is more contaminated than indoor air, so it is always the worst case

Which document is the most appropriate U.S. federal guidance for mold remediation in schools and commercial buildings (non-regulatory)?

• AOSHA 1910.134
• BEPA 402-K-01-001 'Mold Remediation in Schools and Commercial Buildings'
• CNIOSH 7400
• DAIHA Z9.4

Which of the following best describes 'dew point' in the context of building science and mold investigation?

• AThe temperature at which the air can hold no more moisture and condensation occurs
• BThe boiling point of water at a given pressure
• CA measurement of the indoor odor threshold
• DThe temperature at which mold spores die

An attic shows widespread Aspergillus/Penicillium growth on the underside of roof sheathing. The MOST likely root cause is:

• APoor lawn drainage
• BInadequate attic ventilation combined with bath fans venting into the attic
• CTermite activity
• DAsbestos contamination of the insulation

Which of the following is the most appropriate documentation practice for a CMI on-site investigation?

• ATake no photos to protect client privacy
• BPhotograph all observations with location, date, and scale references; maintain a written…
• CRecord only verbal narratives without written notes
• DSubmit samples without chain-of-custody to reduce paperwork

What is the design selection sieve count in the original Andersen six-stage viable impactor?

• A100
• B200
• C400
• D1000

Per ANSI/IICRC S520, which type of containment is typically required for Condition 3 remediation in occupied buildings?

• ANo containment necessary
• BSource containment (limited barrier and HEPA vacuum only)
• CFull containment with negative pressure and decontamination chamber
• DOpen-air remediation with fans

HERTSMI-2 differs from ERMI in that HERTSMI-2:

• ATests for 100 species
• BUses culture instead of qPCR
• CIs a focused 5-species subset of ERMI's Group 1 with a simpler score
• DReplaces ERMI for all clinical decisions

Which Aspergillus species in the Aspergillus fumigatus group is best known for causing invasive pulmonary infections in immunocompromised individuals?

• AAspergillus fumigatus
• BAspergillus niger
• CAspergillus versicolor
• DAspergillus flavus

In the assessment-remediation workflow, what is the role of the Indoor Environmental Professional (IEP) per S520?

• APerform demolition and removal of contaminated materials
• BAssess the extent of contamination, establish project criteria, and conduct post-remediat…
• CManage the contractor's payroll
• DProvide medical care to occupants

Which fungal genus typically produces large pigmented multi-celled conidia (often called 'club-shaped' or 'snowshoe-shaped') and is one of the most common allergenic outdoor molds?

• ACladosporium
• BAlternaria
• CAspergillus
• DPenicillium

What is the typical purpose of MEA agar in viable mold sampling?

• ASelective medium for bacteria only
• BGeneral-purpose medium for cultivating most fungi
• CMedium specific to mycobacteria
• DMedium for thermophilic actinomycetes

Which scenario most strongly supports the use of an ERMI dust sample rather than an Air-O-Cell air sample?

• AInvestigating an active visible leak with current water intrusion
• BCharacterizing the chronic mold burden of a home for a sensitized occupant over time
• CDetermining whether a wall cavity is currently growing mold
• DMeasuring respiratory exposure during a remediation

Which best describes 'chain of custody' (COC) in environmental sampling?

• AAn optional record that some labs request
• BDocumentation tracing each sample from collection through analysis, signed at each transf…
• CA list of approved labs the inspector may use
• DA QA/QC plan only for federal sites

Penicillium and Aspergillus are reported together as 'Pen/Asp' on spore-trap analysis because:

• AThey are the same genus
• BTheir non-viable conidia look nearly identical under direct microscopy
• CLabs are not legally allowed to separate them
• DERMI requires aggregation

Which of the following best describes 'mycotoxins'?

• ASpores produced by molds for reproduction
• BSecondary metabolites produced by some fungi that may exert toxic effects on humans or an…
• CBacteria that colonize mold surfaces
• DA type of allergenic protein only

An indoor air sample collected during cold weather shows much lower outdoor Cladosporium counts than expected for warm-weather sampling. What is the most likely explanation?

• ALaboratory error
• BCladosporium has strong seasonal variation, with lower outdoor counts during cold/snowy c…
• CCladosporium does not exist in winter
• DThe pump was miscalibrated

The minimum filtration recommended for the exhaust from a mold remediation containment is:

• AMERV 8
• BMERV 13
• CHEPA (99.97% at 0.3 µm)
• DCharcoal only

An inspector measures relative humidity (RH) of 75% and temperature of 72°F in a finished basement. The most defensible conclusion is:

• AConditions are well within ASHRAE thermal-comfort range
• BSustained RH at or above 75% supports mold growth on many surfaces; dehumidification is w…
• CRH cannot affect mold growth in basements
• DTemperature must be raised to 90°F to suppress mold

Which is a key strength of viable (culturable) sampling that non-viable (spore trap) sampling lacks?

• AProvides total spore count irrespective of viability
• BAllows speciation to specific Aspergillus and Penicillium species
• CIs faster (results in 24 hours)
• DRequires no laboratory analysis

Which type of mold growth is generally considered diagnostic of chronic, sustained water damage (versus a transient single event)?

• ACladosporium on a window sill during seasonal humidity
• BStachybotrys chartarum on paper-faced drywall and Chaetomium globosum on cellulose substr…
• COutdoor Alternaria on a doormat
• DPenicillium on a small produce item

Which is the BEST approach when an inspector observes visible mold during a routine indoor air quality assessment?

• ASkip visual documentation and rely only on air samples
• BDocument the visible mold thoroughly (location, extent, photo), use sampling to character…
• CSanitize the area immediately
• DRecommend tearing down the entire building