- The Short Answer: What CMC Means Here
- Why the Acronym Causes Confusion
- Who Issues the Credential and What Backs It
- What a Microbial Consultant Actually Does
- The Six Official Exam Domains
- Exam Format and Logistics
- Who Qualifies to Sit for It
- Cost, Term and Renewal
- Sequencing Your Preparation by Domain
- Frequently Asked Questions
- CMC here means Council-certified Microbial Consultant, issued by ACAC's CMC Certification Board, not any other credential sharing the acronym.
- The exam is 120 multiple-choice questions in three hours, closed book, with a 75% passing score.
- Six official domains are published, but ACAC publishes no percentage weights for them.
- Initial certification totals $500 for a two-year term; renewal is $400 and requires 40 recertification credits.
The Short Answer: What CMC Means Here
On this site, CMC stands for Council-certified Microbial Consultant. It is a professional credential for people who design, conduct and interpret microbial sampling regimens, typically in indoor environments such as buildings affected by moisture, mold or other biological contamination. The certification is granted by the American Council for Accredited Certification (ACAC) through its CMC Certification Board.
If you landed here searching for the meaning of the acronym, the rest of this article explains what the credential represents, what the exam covers, and what it takes to earn it. For a related overview, see our pages on what CMC certification is and what CMC stands for.
Why the Acronym Causes Confusion
"CMC" is shared by several unrelated credentials and terms across business, healthcare and other fields. A search for the acronym can return management consulting, nursing case management, or pharmaceutical manufacturing material that has nothing to do with microbial work. The practical consequence for candidates is simple: verify the issuer before you study anything.
This matters because exam logistics, fees, prerequisites and content differ completely between credentials. Importing facts from the wrong one leads to wasted study time and bad decisions about cost and eligibility.
Who Issues the Credential and What Backs It
The Council-certified Microbial Consultant credential is issued by ACAC. The certification program is accredited by the Council for Engineering and Scientific Specialty Boards (CESB), which gives the credential an external accreditation layer beyond the issuing body itself. The examination is delivered through Kryterion, Inc., either at a testing center or by online video proctoring scheduled through ACAC.
Scale is worth understanding honestly. ACAC's accredited certification activity as of December 31, 2025 lists 17 applicants, 99 recertifications and 288 current CMC certifications. This is a small, specialized professional community, not a mass-market credential. That affects everything from the availability of study materials to how employers and clients treat the designation.
What a Microbial Consultant Actually Does
The certification requires candidates to demonstrate that they can design, conduct and interpret sampling regimens. In practice, that means a CMC holder is expected to move through the whole investigative chain rather than perform a single task in isolation:
- Evaluate a building or environment and decide what questions sampling needs to answer.
- Select and justify sampling methods and equipment, including attention to calibration and data limitations.
- Interpret results in context, acknowledging what the data can and cannot support.
- Understand health risk concepts well enough to communicate exposure concerns responsibly.
- Document remediation expectations and evaluate post-remediation verification.
- Work safely, including respiratory protection considerations.
ACAC's handbook indicates that qualifying experience should come from Building Sciences, Microbiology and Microbial Risk Analysis. Employers and clients in this space tend to include indoor environmental consulting firms, industrial hygiene practices, building and facility professionals, and restoration-related businesses that need defensible sampling and interpretation. For a closer look at the career side, see CMC jobs and the CMC salary guide; note that no reliable salary survey specific to ACAC CMC holders has been verified, so be skeptical of any precise earnings figure.
The Six Official Exam Domains
ACAC's current linked formal domain chart, approved February 21, 2024, defines six domains. These are the official exam objectives, not a training provider's curriculum. ACAC does not publish percentage weights, so no domain can be declared the most heavily tested. Be wary of any resource that claims to know the weighting. For the full breakdown, read our complete guide to all six CMC content areas.
Domain 1: Scientific knowledge of biological agents
The foundation: what organisms and biological contaminants are relevant indoors and how they behave.
- Characteristics and growth requirements of biological agents
- How moisture and building conditions relate to biological growth
- The distinctions that later drive sampling choices
Domain 2: Potential health effects and risks associated with exposure
Connecting biological agents to people, without overstating certainty.
- Exposure pathways and potential health effects
- Risk concepts and the limits of what sampling data can say about health
- Communicating risk responsibly
Domain 3: Principles of Microbial Investigation
How a consultant structures an investigation from first walkthrough to conclusions.
- Building and environmental assessment logic
- Forming and testing hypotheses about contamination sources
- Documenting findings in a defensible way
Domain 4: Principles of Microbial Sampling
The technical core, and the area the credential's name most directly implies.
- Designing sampling regimens and selecting methods
- Equipment use, calibration and quality considerations
- Interpreting data and recognizing its limitations
Domain 5: Principles of Microbial Remediation
What remediation involves and how a consultant evaluates it.
- Remediation approaches and documentation
- Post-remediation verification concepts
- Industry standards such as the ANSI/IICRC S520 family of documents
Domain 6: Health & Safety
Protecting the consultant and others on site.
- Respiratory protection and respirator selection
- Regulatory guidance such as OSHA's respiratory protection standard materials
- Safe work practices during investigation and sampling
Exam Format and Logistics
| Element | Verified Detail |
|---|---|
| Question count | 120 multiple-choice questions, each with at least four answer options |
| Time | Three hours, computer-delivered |
| Open or closed book | Closed book |
| Passing score | 75%, set using Modified Angoff |
| Practical component | No separate practical assessment described |
| Delivery | Testing center or online video proctoring, scheduled through ACAC |
| Scoring feedback | Immediate electronic score; results emailed |
The scored versus unscored question split is not published, and adaptive testing is not described. The handbook indicates the same question set is used with randomized question and answer order. Calculator permission is unverified, so confirm it with ACAC before test day rather than assuming.
Practical requirements: Testing-center candidates need two government-issued IDs, including one photo ID. Online candidates need their own computer, an approved webcam and a private location, with at least 2 Mbps upload and download; phones and tablets are excluded. Arrival guidance is a point of conflict: the current Examinations page specifies 15 minutes early, while the handbook says 30. Plan for the longer window.
For deeper treatment, see our pages on the passing score, exam dates and scheduling, and how hard the exam is.
Reading the 94% Pass Figure Correctly
ACAC's 2025 Exam Pass Ratio reports 94%, based on 16 passes from 17 attempts. Treat that carefully. The sample is tiny, the attempts include retakes and state-licensing-only candidates, and it is not first-attempt-only data. No 2026 rate has been verified. It is also a different thing from the 75% passing score, which is the score a candidate must earn on the exam. Our CMC pass rate analysis goes further into the caveats.
Who Qualifies to Sit for It
Eligibility is built around documented microbial sampling experience combined with education, with three published routes:
- A related four-year postsecondary degree, or 30 qualifying college credits, plus four years of documented microbial sampling.
- A related two-year degree, or 15 qualifying credits, plus six years of documented microbial sampling.
- A high school diploma or GED plus eight years of consulting experience in microbial sampling.
Qualifying fields include microbiology, engineering, science, architecture and industrial hygiene. ACAC's FAQ defines qualifying college coursework and excludes social sciences. Candidates must also submit four project sheets, applicable transcripts and experience verification. No mandatory preparation course or minimum training-hour requirement is published, which means training is a choice, not a gate. A licensing-only exam result does not itself confer CMC certification.
Cost, Term and Renewal
| Item | Amount (USD) |
|---|---|
| Examination fee | $100 |
| Certification fee (includes $100 nonrefundable processing) | $400 |
| Total for initial two-year term | $500 |
| Retake | $100 |
| Renewal | $400 |
No separate member versus non-member fee schedule is published. Certification is valid for two years. Current recertification procedures specify 40 recertification credits (RCs): 10 for continued field activity and 30 for professional development during the term, with attestation and retained evidence for possible audit. A current photo is requested. Be aware that this differs from the handbook's general 40-RC wording and from the program page's reference to 20 professional-development hours per year, so follow the current Recertification Procedures page. See the full cost breakdown and the ROI analysis for a budgeting view.
Sequencing Your Preparation by Domain
The exam assumes comprehensive knowledge of ACAC's listed references, and the handbook explicitly warns that its selected study-guide sections and page references are examples, not exhaustive preparation. Those references include ACGIH Bioaerosols: Assessment and Control (first edition 1999 or second edition 2024), the AIHA Field Guide for the Determination of Biological Contaminants (second edition, 2005), ANSI/IICRC S500-2021, the S520 documents (S520-2015 and R520-2015, or S520-2024), OSHA's Small Entity Compliance Guide for the Respiratory Protection Standard (2011) and NIOSH Respirator Selection Logic (2004). The listed alternatives do not establish an exam revision date.
Because no domain weights are published, a sensible schedule follows the logical dependency between domains instead of a guessed priority. A six-week outline:
Domains 1 and 2
- Build biological agent and exposure-risk vocabulary first, since later domains assume it
- Note where the health-effects literature is cautious about causation
Domains 3 and 4
- Work through investigation logic, then sampling design, equipment, calibration and data limitations
- Spend extra time here using the AIHA field guide and the ACGIH bioaerosols text
Domain 5
- Study remediation principles against the S500 and S520 documents
- Practice reasoning about post-remediation verification
Domain 6
- Cover respirator selection logic and the OSHA respiratory protection guide
- Do not skip this because the handbook's shorter outline omits it
Integration
- Take timed sets of 120 questions in three hours to build pacing
- Review misses by domain, not just by score
When you practice, remember that third-party mock tests have their own formats. A resource advertising a 50-question, 60-minute mock with a 70% pass mark describes that publisher's product, not the official 120-question, three-hour, 75% exam. Use the CMC practice test to rehearse the real timing, and pair it with the CMC study guide and the cheat sheet for quick review.
Frequently Asked Questions
It means Council-certified Microbial Consultant, a credential issued by the American Council for Accredited Certification's CMC Certification Board. It is distinct from other credentials that happen to share the same three letters.
The exam has 120 multiple-choice questions, each with at least four answer options, delivered by computer over three hours. It is closed book, and a 75% score is required to pass.
No. ACAC publishes no mandatory preparation course and no minimum training-hour requirement. Courses are optional, and a provider's own mold-inspector exam is not a replacement for the ACAC CMC exam.
The initial total is $500 for a two-year term, made up of a $100 examination fee and a $400 certification fee that includes $100 in nonrefundable processing. A retake costs $100 and renewal costs $400.
That cannot be established. ACAC publishes six domains but no percentage weights, so any resource claiming specific domain percentages is using its own categories rather than official figures.
For a broader orientation, continue with what CMC is and the CMC certification overview, then return to the practice test hub when you are ready to test yourself against the real format.