Applied Microbial Remediation
Technician
Final Test Review
(Questions & Solutions)
2025
1
,Section I: Advanced Mold Remediation Principles
1. A property manager discovers extensive mold growth behind
vinyl wallpaper in a second-floor bathroom. Moisture meter on
the gypsum board reads 24% MC. Which metric most accurately
predicts when mold growth will cease after drying?
A. Surface relative humidity (RH) below 60%
B. Equilibrium relative humidity (ERH) below 75%
C. Moisture content (MC) below 17%
D. Water activity (aₓ) below 0.95
ANS: C
Rationale: Gypsum-board mold stops growing when its MC falls
below ~17%. ERH and aₓ correlate, but direct MC <17% is the industry
threshold.
2. During remediation of active mold growth (Condition 3), when
should a registered biocide be applied?
A. Prior to demolition to kill spores in place
B. Immediately after bulk removal and HEPA-vacuuming
C. As the first step in the remediation sequence
D. Mixed into drywall compound during reconstruction
ANS: B
Rationale: Biocides are used only after physical removal and HEPA
cleaning to reduce residual organisms on remaining materials, then
followed by verification testing.
3. A remediation technician plans to remove moldy wood studs
using abrasive methods. Which technique aligns with S520
recommendations for heavy fungal colonization?
A. Sponge wiping with detergent alone
B. Dry sandblasting within containment
C. Wet-ice blasting under negative pressure
D. Application of surface sealant
ANS: C
2
,Rationale: Wet or dry ice blasting under negative-pressure
containment effectively removes heavy Condition 3 growth on
structural wood without excessive dust.
4. In a crawlspace remediation, hidden mold is suspected under
concrete piers. Which inspection method most reliably locates
concealed fungal reservoirs?
A. Infrared thermal imaging
B. Bulk sampling of concrete shards
C. Spore-trap air sampling only
D. Visual inspection under UV light
ANS: A
Rationale: Thermal imaging identifies moisture pockets behind
surfaces, guiding targeted destructive inspection; air sampling alone
cannot locate hidden reservoirs.
5. A restoration crew encounters hydrophobic mold growth in a
wall cavity. Which penetration enhancer improves biocide
efficacy?
A. Add detergent surfactant to the solution
B. Increase pH above 10
C. Switch to pure hydrogen peroxide
D. Use an alcohol-based formulation
ANS: A
Rationale: Nonionic surfactants lower surface tension, allowing
biocide to penetrate hydrophobic spores and hyphae; pH and carrier
adjustments have limited effect on surface wetting.
6. After removing mold-damaged material, clearance spore counts
remain elevated. Which action should you take first?
A. Reapply biocide to all remaining surfaces
B. Expand containment and repeat HEPA vacuuming
C. Increase negative-pressure differential
D. Switch to a smaller-pore HEPA filter
ANS: B
Rationale: Elevated counts typically indicate residual dust or spores;
additional HEPA vacuuming within containment corrects this before
3
, altering controls or biocide use.
7. Which mold species requires continuous saturation for 7–12
days before colonization and poses high mycotoxin risk?
A. Aspergillus niger
B. Penicillium chrysogenum
C. Stachybotrys chartarum
D. Cladosporium sphaerospermum
ANS: C
Rationale: Stachybotrys chartarum is a high-cellulose, low-nitrogen
xerophilic mold that grows only with water activity >0.90 for at least a
week and produces potent mycotoxins.
8. A multi-unit complex tests background air in an unaffected
corridor at 500 spores/m³ (Condition 1). Post-remediation
hallway sampling registers 450 spores/m³. Has clearance been
achieved?
A. Yes, because post-remediation count is ≤ background
B. No, because total counts must be <100 spores/m³
C. No, because a ≥20% reduction is required
D. Yes, if settlement plate counts are zero
ANS: A
Rationale: Clearance criterion is post-remediation spore count at or
below unaffected-area baseline; fixed thresholds are not specified in
S520.
Section II: Sewage Remediation Strategies
9. A Category 3 (black) water backup floods an unfinished
basement. Which content is salvageable?
A. Particleboard shelving
B. Uncarpeted concrete floor
C. Laminate drywall knee-wall
D. Exposed insulation
ANS: B
Rationale: Porous and semi-porous materials contaminated with
black water must be discarded. Non-porous surfaces like concrete
4
Technician
Final Test Review
(Questions & Solutions)
2025
1
,Section I: Advanced Mold Remediation Principles
1. A property manager discovers extensive mold growth behind
vinyl wallpaper in a second-floor bathroom. Moisture meter on
the gypsum board reads 24% MC. Which metric most accurately
predicts when mold growth will cease after drying?
A. Surface relative humidity (RH) below 60%
B. Equilibrium relative humidity (ERH) below 75%
C. Moisture content (MC) below 17%
D. Water activity (aₓ) below 0.95
ANS: C
Rationale: Gypsum-board mold stops growing when its MC falls
below ~17%. ERH and aₓ correlate, but direct MC <17% is the industry
threshold.
2. During remediation of active mold growth (Condition 3), when
should a registered biocide be applied?
A. Prior to demolition to kill spores in place
B. Immediately after bulk removal and HEPA-vacuuming
C. As the first step in the remediation sequence
D. Mixed into drywall compound during reconstruction
ANS: B
Rationale: Biocides are used only after physical removal and HEPA
cleaning to reduce residual organisms on remaining materials, then
followed by verification testing.
3. A remediation technician plans to remove moldy wood studs
using abrasive methods. Which technique aligns with S520
recommendations for heavy fungal colonization?
A. Sponge wiping with detergent alone
B. Dry sandblasting within containment
C. Wet-ice blasting under negative pressure
D. Application of surface sealant
ANS: C
2
,Rationale: Wet or dry ice blasting under negative-pressure
containment effectively removes heavy Condition 3 growth on
structural wood without excessive dust.
4. In a crawlspace remediation, hidden mold is suspected under
concrete piers. Which inspection method most reliably locates
concealed fungal reservoirs?
A. Infrared thermal imaging
B. Bulk sampling of concrete shards
C. Spore-trap air sampling only
D. Visual inspection under UV light
ANS: A
Rationale: Thermal imaging identifies moisture pockets behind
surfaces, guiding targeted destructive inspection; air sampling alone
cannot locate hidden reservoirs.
5. A restoration crew encounters hydrophobic mold growth in a
wall cavity. Which penetration enhancer improves biocide
efficacy?
A. Add detergent surfactant to the solution
B. Increase pH above 10
C. Switch to pure hydrogen peroxide
D. Use an alcohol-based formulation
ANS: A
Rationale: Nonionic surfactants lower surface tension, allowing
biocide to penetrate hydrophobic spores and hyphae; pH and carrier
adjustments have limited effect on surface wetting.
6. After removing mold-damaged material, clearance spore counts
remain elevated. Which action should you take first?
A. Reapply biocide to all remaining surfaces
B. Expand containment and repeat HEPA vacuuming
C. Increase negative-pressure differential
D. Switch to a smaller-pore HEPA filter
ANS: B
Rationale: Elevated counts typically indicate residual dust or spores;
additional HEPA vacuuming within containment corrects this before
3
, altering controls or biocide use.
7. Which mold species requires continuous saturation for 7–12
days before colonization and poses high mycotoxin risk?
A. Aspergillus niger
B. Penicillium chrysogenum
C. Stachybotrys chartarum
D. Cladosporium sphaerospermum
ANS: C
Rationale: Stachybotrys chartarum is a high-cellulose, low-nitrogen
xerophilic mold that grows only with water activity >0.90 for at least a
week and produces potent mycotoxins.
8. A multi-unit complex tests background air in an unaffected
corridor at 500 spores/m³ (Condition 1). Post-remediation
hallway sampling registers 450 spores/m³. Has clearance been
achieved?
A. Yes, because post-remediation count is ≤ background
B. No, because total counts must be <100 spores/m³
C. No, because a ≥20% reduction is required
D. Yes, if settlement plate counts are zero
ANS: A
Rationale: Clearance criterion is post-remediation spore count at or
below unaffected-area baseline; fixed thresholds are not specified in
S520.
Section II: Sewage Remediation Strategies
9. A Category 3 (black) water backup floods an unfinished
basement. Which content is salvageable?
A. Particleboard shelving
B. Uncarpeted concrete floor
C. Laminate drywall knee-wall
D. Exposed insulation
ANS: B
Rationale: Porous and semi-porous materials contaminated with
black water must be discarded. Non-porous surfaces like concrete
4
