- What the Council-certified Microbial Consultant Credential Actually Is
- Why "CMC" Causes Confusion
- Who Issues It and Who Oversees the Program
- Eligibility: Three Education-and-Experience Pathways
- The Application Package and Approval Process
- Exam Format and Test-Day Logistics
- The Six Official Exam Domains
- Reference Books the Exam Assumes You Know
- Reading the Pass-Rate Data Correctly
- Cost, Validity and Renewal
- Who Uses the Credential and What About Salary
- Sequencing Your Preparation Around the Domains
- Frequently Asked Questions
- CMC here means Council-certified Microbial Consultant, issued by the American Council for Accredited Certification (ACAC), not any other credential sharing the...
- The exam has 120 multiple-choice questions, three hours, closed book, with a 75% passing score.
- Eligibility requires documented microbial sampling experience plus degree or credit pathways, four project sheets and verification.
- The initial two-year term costs $500 total; renewal is $400 and requires 40 recertification credits.
What the Council-certified Microbial Consultant Credential Actually Is
The Council-certified Microbial Consultant credential is a professional certification for people who design, conduct and interpret microbial sampling regimens in the built environment. Think of the consultant who is called after a water loss, a complaint about indoor air quality or a suspected mold problem, and who must decide what to sample, how to sample it, how to read the results and what a defensible remediation and clearance process looks like.
That focus matters because the credential is not a classroom certificate. It is a peer-reviewed professional designation: candidates document real project work, submit it for board review and then sit a proctored written exam. If you are searching for a quick overview of what the designation is, this article covers the essentials. For a deeper look at the acronym itself, see our companion pieces on what CMC stands for and what CMC is.
Why "CMC" Causes Confusion
Several unrelated professional credentials in other fields abbreviate to "CMC." Search results blend them together, and some third-party pages describe the wrong one. Practice material written for management, nursing or pharmaceutical credentials will not help you here, and neither will a provider's own mold-inspector exam.
Everything on this page refers only to the Council-certified Microbial Consultant credential from ACAC. A useful sanity check: if a study resource does not mention microbial sampling, bioaerosols, remediation or the ACAC, it is probably about something else. Our CMC meaning and what does CMC mean pages walk through the naming issue in more detail.
Who Issues It and Who Oversees the Program
The credential is issued by the American Council for Accredited Certification (ACAC) through its CMC Certification Board. The program carries accreditation from the Council for Engineering and Scientific Specialty Boards (CESB), which is a meaningful quality signal because accreditation of the program, not just the organization, speaks to how the exam and certification process are governed. The written exam is delivered through Kryterion, Inc.
ACAC also administers a related credential, the CMI, and publishes a joint domain chart for both exams. If you are weighing the two, keep in mind that they share a published objectives document but are distinct certifications. Use ACAC's own materials to confirm which one fits your role.
Eligibility: Three Education-and-Experience Pathways
ACAC does not let you simply register and test. You must show a combination of education and documented microbial sampling experience. There are three published pathways:
| Pathway | Education | Documented Experience |
|---|---|---|
| Pathway 1 | Related four-year postsecondary degree, or 30 qualifying college credits | Four years of microbial sampling |
| Pathway 2 | Related two-year degree, or 15 qualifying credits | Six years of microbial sampling |
| Pathway 3 | High school diploma or GED | Eight years of consulting experience in microbial sampling |
Qualifying fields include microbiology, engineering, science, architecture and industrial hygiene. ACAC's FAQ defines which college coursework counts and excludes the social sciences, so check it before assuming a transcript qualifies. Candidates must also demonstrate the ability to design, conduct and interpret sampling regimens, which is why generic "assistant" experience may not carry the same weight as hands-on consulting work.
The candidate handbook says experience should come from building sciences, microbiology and microbial risk analysis. That wording describes where experience should originate; it should not be read as a mandatory three-area checklist. No mandatory preparation course or minimum training-hour count is published. For the full breakdown, see our guide to CMC requirements.
The Application Package and Approval Process
The application is more involved than a typical exam registration. Expect to assemble:
- Four project sheets documenting your sampling work
- Applicable college transcripts
- Experience verification
- Online forms with required email verifications
Approval requires unanimous board approval. ACAC's current application page says the full process runs about six months including the examination, and that the board meets every four to six weeks. The candidate handbook, however, describes a 90-day timeline and mentions notarized forms and employer affidavits. This is an unresolved conflict between ACAC sources, so confirm current requirements directly with ACAC before you start gathering documents.
Timing matters when you are planning around board meetings, so also review our notes on CMC exam dates and scheduling.
Exam Format and Test-Day Logistics
- Questions: 120 multiple-choice items, each with at least four answer options
- Time: three hours, computer-delivered
- Book policy: closed book
- Passing score: 75%, set using the Modified Angoff method
- Scoring detail: the scored versus unscored split is not published
- Practical component: none is described
The handbook describes randomized question and answer order, immediate electronic scores and emailed results. Adaptive testing is not described, and calculator permission is unverified, so do not assume you can bring one. Confirm with ACAC and your test provider.
Testing center or online
You can test at a center or via online video proctoring, scheduled through ACAC. Testing-center candidates need two government-issued IDs, including one with a photo. Online candidates need their own computer, an approved webcam, a private location and a connection of at least 2 Mbps upload and download; phones and tablets are not allowed. ACAC's exam page asks for arrival 15 minutes early, while the handbook says 30, so plan for the longer window to be safe.
The 75% bar is a score threshold, not a pass rate; those are different ideas, covered in our passing score guide. For a candid look at the difficulty, read how hard the CMC exam is.
The Six Official Exam Domains
ACAC's formal domain chart for the CMC and CMI examinations (approved February 21, 2024) lists six domains. These are official exam objectives, not a provider's curriculum. ACAC does not publish percentage weights, so no domain can be called the heaviest. Treat all six as testable. Our complete guide to all six content areas goes deeper; here is the orientation.
Domain 1: Scientific knowledge of biological agents
The biology underneath the work: what fungi, bacteria and other agents are, how they grow, what they need and how they behave in buildings.
- Growth conditions and moisture relationships
- Distinguishing organism groups and their typical indicators
- Why a lab result means different things for different organisms
Domain 2: Potential health effects and risks associated with exposure
How exposure relates to health outcomes, and how to communicate risk responsibly without overstating what sampling can show.
- Exposure pathways and susceptible populations
- The limits of inferring health effects from environmental data
Domain 3: Principles of Microbial Investigation
How to scope a building investigation: gathering history, forming hypotheses, inspecting for moisture and deciding whether sampling is warranted at all.
- Visual assessment and moisture source identification
- Linking findings to a defensible investigative narrative
Domain 4: Principles of Microbial Sampling
The core consulting skill: designing a sampling regimen, choosing methods, controlling quality and interpreting results with their limitations.
- Sampling strategy, controls and equipment calibration
- Data limitations and interpretation
- Matching the method to the question being asked
Domain 5: Principles of Microbial Remediation
Containment, removal, documentation and verification that remediation actually worked.
- Remediation planning and documentation
- Post-remediation verification concepts
Domain 6: Health & Safety
Protecting workers and occupants, including respiratory protection. The handbook's shorter five-topic outline omits Health & Safety as a standalone topic, but the formal domain chart includes it, so do not skip it.
- Respirator selection and the respiratory protection standard
- Hazard controls during investigation and remediation
Key Takeaway
The handbook's body of knowledge and the formal domain chart do not match perfectly. Build your study plan from the six-domain chart, then use the handbook for reference lists and context.
Reference Books the Exam Assumes You Know
The candidate handbook lists the references that underpin the exam. Several offer edition alternatives:
- ACGIH, Bioaerosols: Assessment and Control, first edition (1999) or second edition (2024)
- AIHA, Field Guide for the Determination of Biological Contaminants, second edition (2005)
- ANSI/IICRC S500-2021, fifth edition
- ANSI/IICRC S520-2015 and R520-2015, third editions, or S520-2024, fourth edition
- OSHA, Small Entity Compliance Guide for the Respiratory Protection Standard (2011)
- NIOSH, Respirator Selection Logic (2004)
Two cautions. First, the listed alternatives do not establish an exam revision date, so do not assume a newer edition means a changed exam. Second, the handbook explicitly states that its selected study-guide sections and page references are examples, not an exhaustive prep plan. The exam assumes comprehensive knowledge of the references. Reading only the highlighted pages is a common way to under-prepare. Our CMC study guide shows how to work through the material systematically, and the CMC cheat sheet is useful for a final review once you have done the reading.
Reading the Pass-Rate Data Correctly
ACAC's 2025 Exam Pass Ratio reports a 94% pass rate, based on 16 passes from 17 attempts. Two caveats are important. The attempts include retakes and state-licensing-only candidates, so this is not first-attempt-only data. And with a sample this small, one candidate changes the percentage noticeably. No 2026 rate has been verified.
Some third-party sites claim ACAC does not publish CMC pass rates; the 2025 report shows otherwise. Do not confuse the 94% pass rate with the 75% passing score. One describes outcomes across candidates; the other is the score you need on your own exam. We unpack this further in our pass rate analysis.
ACAC's accredited certification activity as of December 31, 2025 lists 17 applicants, 99 recertifications and 288 current CMC certifications. That tells you the credential is a small, specialized community, not a mass-market certificate.
Cost, Validity and Renewal
| Item | Fee (USD) |
|---|---|
| Examination | $100 |
| Certification (includes $100 nonrefundable processing) | $400 |
| Initial two-year term total | $500 |
| Retake | $100 |
| Renewal | $400 |
No separate member and non-member fee schedule is published. See our full CMC certification cost breakdown for budgeting around these numbers.
Staying certified
Certification is valid for two years. ACAC's current recertification procedures specify 40 recertification credits (RCs) per term: 10 for continued field activity and 30 for professional development. You attest to your activity and retain evidence in case of audit, and a current photo is requested. Other ACAC documents describe the requirement slightly differently (the handbook uses general 40-RC wording, and a program page mentions 20 professional-development hours per year), so follow the current procedures page and keep thorough records.
Who Uses the Credential and What About Salary
The credential is relevant to professionals who plan and interpret microbial investigations in buildings: independent consultants, consulting firms, and practitioners working alongside restoration, industrial hygiene and building science teams. It signals to clients, attorneys and insurers that your sampling methods and interpretation have been peer-reviewed. For a sense of the roles it supports, see our overview of CMC jobs.
On compensation, be skeptical. No reliable salary survey specific to ACAC CMC holders has been verified, and no causal earnings premium has been established. Salary aggregates for unrelated credentials with the same acronym are not applicable. Evaluate the credential on credibility, access to engagements and professional standing rather than a promised pay bump. Our salary guide and ROI analysis take that cautious approach.
Sequencing Your Preparation Around the Domains
With no published domain weights and a reference list the handbook says to learn comprehensively, sequencing matters more than speed. One sensible order follows how the work itself flows:
Foundations: Domains 1 and 2
- Biological agents, growth requirements and exposure concepts
- Read the ACGIH bioaerosols text alongside the AIHA field guide
Core consulting skills: Domains 3 and 4
- Investigation logic first, then sampling design, controls and interpretation
- Rework your own project sheets as practice cases
Action and protection: Domains 5 and 6
- IICRC S500 and S520 for remediation concepts
- OSHA respiratory protection guide and NIOSH respirator selection logic
Integration
- Timed mixed sets under three-hour conditions
- Review weak domains rather than re-reading strong ones
Domain 4 deserves the most hands-on repetition because sampling design and interpretation questions tend to test judgment, not recall. Domain 6 is easy to neglect because the handbook outline omits it, yet the formal chart includes it. When you are ready for timed practice, try the questions on our main practice test site, and use our domain-organized practice sets to find weak areas. Our CMC training overview covers whether a prep course is worth adding; none is mandatory.
Frequently Asked Questions
It stands for Council-certified Microbial Consultant, a credential issued by the American Council for Accredited Certification (ACAC). It is unrelated to other credentials that share the abbreviation.
No. You must qualify through one of three education-and-experience pathways, submit four project sheets, transcripts where applicable and experience verification, and receive unanimous board approval before certification.
The exam has 120 multiple-choice questions, a three-hour limit, closed-book rules and a 75% passing score. The split between scored and unscored questions is not published.
The initial two-year term totals $500: a $100 examination fee and a $400 certification fee. A retake costs $100, and renewal costs $400. No separate member or non-member schedule is published.
Renew every two years with 40 recertification credits: 10 for field activity and 30 for professional development, per ACAC's current procedures. Keep evidence in case of audit and confirm details with ACAC.
For a broader introduction to the designation, you can also read our general CMC certification overview and the related what is a CMC explainer.