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100+ Free CMR Practice Questions

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In mold remediation, a 'negative air machine' (NAM) performs which primary function within the containment?

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Sample CMR Practice Questions

Try these sample questions to test your CMR exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under the ANSI/IICRC S520 Standard, a Condition 1 environment is defined as which of the following?
A.Normal fungal ecology in which mold is not expected to be amplified indoors.
B.A settled-dust reservoir that contains elevated concentrations of mold spores.
C.Visible mold growth on surfaces with active colonization of structural materials.
D.A previously remediated area that is pending post-remediation verification.
Explanation: Condition 1 (Normal Fungal Ecology) describes an indoor environment with no abnormal mold contamination — indoor fungal levels are equivalent to or lower than outdoor reference levels. No remediation is required. Condition 2 involves settled dust reservoirs, and Condition 3 involves actual mold growth.
2The ANSI/IICRC S520 Condition 3 classification applies when which situation is present?
A.Mold spore counts indoors are identical to outdoor reference samples.
B.There is actual mold growth — visible colonies, hidden growth, or active amplification.
C.Settled dust contains mold spores but no surface growth is visible.
D.A clearance test detects trace spore counts below action-level thresholds.
Explanation: Condition 3 (Actual Mold Growth) is the most severe S520 category. It includes visible surface mold, hidden growth (e.g., behind walls), or any active amplification of mold in the building. Condition 3 requires full remediation protocols including source removal and appropriate containment.
3Which category of remediation under ANSI/IICRC S520 addresses small isolated areas of mold growth not exceeding 10 square feet?
A.Category 1 — Small, Isolated Mold Contamination
B.Category 2 — Mid-Sized, Isolated Mold Contamination
C.Category 3 — Extensive Mold Contamination
D.Category 4 — HVAC System Mold Contamination
Explanation: S520 Category 1 covers small, isolated mold contamination areas of 10 square feet or less. This category typically allows limited containment and can often be handled by trained building maintenance personnel with appropriate PPE. Categories 2 and 3 address progressively larger and more complex contamination scenarios.
4A remediator discovers mold contamination covering approximately 150 square feet on drywall in a commercial building. Which S520 remediation category applies?
A.Category 1 — Small, Isolated
B.Category 2 — Mid-Sized, Isolated
C.Category 3 — Extensive
D.Category 4 — HVAC System
Explanation: S520 Category 3 (Extensive Mold Contamination) applies to areas greater than 100 square feet. At 150 square feet, this exceeds the Category 2 threshold. Category 3 requires a full containment barrier system, engineering controls (HEPA-filtered negative air, decontamination chamber), appropriate PPE, and documentation by a qualified professional.
5What is the minimum negative air pressure differential that must be maintained inside a full containment barrier relative to adjacent unaffected areas, per industry guidelines?
A.−1 Pa (0.004 in w.c.)
B.−5 Pa (0.02 in w.c.)
C.−10 Pa (0.04 in w.c.)
D.−25 Pa (0.10 in w.c.)
Explanation: The industry standard minimum negative air pressure differential for mold remediation containment is −5 Pascals (0.02 inches of water column). This negative pressure prevents mold-laden air from escaping the containment zone into clean areas. Pressure is measured with a manometer and verified throughout the remediation.
6HEPA filtration, as used in mold remediation air scrubbers and vacuums, is defined by its ability to capture at least what percentage of particles at the most penetrating particle size?
A.95% of particles ≥ 0.3 μm
B.99.97% of particles ≥ 0.3 μm
C.99.97% of particles ≥ 1.0 μm
D.99.99% of particles ≥ 0.5 μm
Explanation: By definition, a HEPA (High-Efficiency Particulate Air) filter must capture at least 99.97% of airborne particles that are 0.3 micrometers or larger. This threshold is critical because 0.3 μm is the most penetrating particle size (MPPS) — the size at which filter efficiency is lowest. Mold spores, which typically range from 2 to 100 μm, are well above this threshold.
7What is the minimum number of air changes per hour (ACH) recommended for a mold remediation containment zone to maintain adequate negative pressure and particulate control?
A.2 air changes per hour
B.4 air changes per hour
C.8 air changes per hour
D.12 air changes per hour
Explanation: The general industry recommendation for mold remediation containment zones is a minimum of 4 air changes per hour (ACH). This rate, achieved through HEPA-filtered negative air machines, ensures adequate particle removal and maintains the negative pressure differential. More ACH may be warranted for heavily contaminated or larger spaces.
8Which type of containment is characterized by using 6-mil polyethylene sheeting to completely seal an entire room or area, a decontamination chamber, and an airlock entry?
A.Limited containment
B.Regulated areas containment
C.Full containment
D.Portable enclosure containment
Explanation: Full containment (also called full-scale containment or PEC — primary engineering containment) uses 6-mil poly sheeting to enclose the entire affected area, with a double-entry decontamination (decon) chamber and an airlock. It is used for Category 3 (extensive) mold contamination and situations involving vulnerable building occupants. The decon chamber allows workers to remove and bag contaminated PPE before exiting the clean area.
9A decontamination chamber in a full containment setup serves which primary purpose?
A.To store clean PPE and tools before entering the remediation area.
B.To act as an airlock where workers remove contaminated PPE and bag it before exiting to the clean area.
C.To provide a staging area for waste bags before disposal.
D.To house the HEPA air scrubber unit to maximize airflow efficiency.
Explanation: The decontamination (decon) chamber is an intermediate space between the contaminated work area and the clean building. Workers remove their outer layer of contaminated PPE (Tyvek suit, gloves, booties) in the decon chamber and bag it before proceeding through to the clean side. This prevents cross-contamination of building surfaces and personnel.
10The principle of 'source removal' in mold remediation means which of the following?
A.Applying an EPA-registered antimicrobial coating over all visible mold growth.
B.Physically removing mold-contaminated materials rather than encapsulating them.
C.Drying out the moisture source before allowing mold to self-desiccate and die.
D.Using HEPA vacuuming alone to remove spores from porous building materials.
Explanation: Source removal is the S520 and industry standard principle that mold-contaminated materials — especially porous materials like drywall and insulation — must be physically removed and properly disposed of. Mold cannot be effectively cleaned from porous substrates; the material itself must be discarded. Encapsulation is not an acceptable substitute for source removal when active mold growth is present.

About the CMR Exam

The Council-certified Microbial Remediator (CMR) is an ANSI-accredited credential from the American Council for Accredited Certification validating competence in executing mold and microbial remediation projects per the ANSI/IICRC S520 Standard. The exam is delivered at computer-based testing centers or via remote-proctored online testing.

Questions

100 scored questions

Time Limit

2 hours

Passing Score

70%

Exam Fee

$345 (American Council for Accredited Certification (ACAC))

CMR Exam Content Outline

20%

Microbial Contamination Assessment (ANSI/IICRC S520)

Conditions 1, 2, and 3 classification, water damage categories, fungal ecology, and assessment principles.

25%

Engineering Controls and Containment

Source containment, full containment, negative air pressure, HEPA filtration, air changes per hour, and decontamination chambers.

25%

Remediation Execution and Source Removal

HEPA vacuuming, damp wiping, antimicrobial use, removal of porous materials, and demolition techniques.

15%

Personal Protective Equipment (PPE)

Respiratory protection levels, OSHA 1910.134 requirements, fit testing, and skin/eye protection selection.

15%

Post-Remediation Verification and Clearance

Visual inspection, moisture verification, sampling protocols, and IEP coordination for clearance criteria.

How to Pass the CMR Exam

What You Need to Know

  • Passing score: 70%
  • Exam length: 100 questions
  • Time limit: 2 hours
  • Exam fee: $345

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

Frequently Asked Questions

What is the ACAC CMR certification?

The Council-certified Microbial Remediator (CMR) is an ANSI-accredited certification from the American Council for Accredited Certification (ACAC) for hands-on workers performing mold and microbial remediation per the ANSI/IICRC S520 Standard.

How many questions are on the CMR exam?

The CMR exam contains 100 multiple-choice questions with four answer options. Candidates need to score 70% or higher to pass. The exam is offered at computer-based testing centers or via remote-proctored online delivery.

What does the CMR exam cost?

The CMR application and examination fee is approximately $345 through ACAC. Annual recertification fees apply once certified, and continuing education or retesting is required every 5 years.

What experience do I need to sit for the CMR?

ACAC requires documented experience in mold remediation work plus a passing score on the exam. Candidates without sufficient experience may earn the entry-level CMRC (Certified Microbial Remediation Contractor) and upgrade to CMR after gaining qualifying experience.

Is the CMR the same as IICRC certification?

No. ACAC CMR is a personnel certification grounded in the ANSI/IICRC S520 Standard, but it is administered by ACAC, not IICRC. Many practitioners hold both ACAC CMR and IICRC AMRT (Applied Microbial Remediation Technician) credentials.