- Which CMR This Guide Covers
- Confirm You Qualify Before You Study
- Exam Format and Delivery
- The Seven Domains Without Invented Weights
- The Prescribed Reference Library
- Scenario Thinking for Each Domain
- A Domain-Ordered Study Sequence
- Fees, Courses and Books
- Reading the Pass-Rate Data Honestly
- After You Pass: Renewal and Career Evidence
- Frequently Asked Questions
- The exam is 100 multiple-choice questions in three hours, closed book, with a 75% passing criterion.
- ACAC publishes seven unweighted domains; do not trust any percentage breakdown claiming to be official.
- Initial US/Canada cost is USD 500; a retake is USD 100.
- The 2025 pass ratio of 31% is 4 passes in 13 examinations, a tiny, mixed cohort.
Which CMR This Guide Covers
Several credentials share the acronym, so let us be precise. This guide covers the Council-certified Microbial Remediator (CMR), administered by the American Council for Accredited Certification (ACAC). Certification decisions are made by ACAC's CMR Certification Board, and Kryterion, Inc. provides the testing. If you are weighing it against a similarly named credential from another organization, read our overview at What Is CMR Certification? before you spend time on the wrong syllabus.
One distinction matters for study planning: the ACAC credential for remediators is separate from the CMRS credential and from NORMI's separately issued remediator credential. Their eligibility rules and exam details are not interchangeable, so avoid borrowing study notes or fee assumptions from them.
Confirm You Qualify Before You Study
Many candidates lose weeks because they study first and discover an application gap later. The pathways are specific:
- Experience route: a high-school diploma or GED plus two years of documented microbial-remediation experience.
- Education route: a qualifying two-year postsecondary degree, or equivalent 15 qualifying science-related credits, plus at least one year of relevant experience.
Accepted education fields include microbiology, engineering, science, architecture, industrial hygiene and related sciences. The application package involves four project sheets, applicable education transcripts, the online application, an electronic affidavit and required email verifications. The handbook also requests employer affidavits. The process ends with the exam and a unanimous certification-board review.
Also note that passing a licensing-only examination does not itself confer the CMR designation. If your state requires an exam for a license, that is a different outcome from certification.
Exam Format and Delivery
| Feature | Detail |
|---|---|
| Questions | 100 multiple choice, at least four answer choices |
| Time | Three hours |
| Resources | Closed book |
| Passing criterion | 75%, set by the certification board using modified Angoff |
| Delivery | Testing center or online video-proctored |
| Question order | Randomized questions and answer order |
| Results | Immediate |
Online candidates need their own computer, an approved webcam, a private location and a continuous 2 Mbps upload and download connection. Run your equipment check well before exam day rather than discovering a bandwidth problem at check-in. For the scoring logic, see CMR Passing Score, and for scheduling mechanics, CMR Exam Dates.
Because the exam is closed book with randomized answer order, you cannot rely on memorizing the position of a correct option or on looking up a table mid-exam. Three hours for 100 questions gives you pacing room, which is better spent on careful reading of scenario stems than on speed.
The Seven Domains Without Invented Weights
ACAC's examination chart, approved February 21, 2024, lists seven domains as official exam objectives. It does not publish percentage weights, and the numbered subdomain columns on the chart are not weights. Any resource that gives you a tidy percentage split should be treated as that provider's own organization of material. A fuller breakdown lives in our CMR exam domains guide; here is the study-relevant summary.
Domain 1: Principles & Equipment
The foundation for everything else. Expect to reason about how contamination behaves and how the tools of remediation work.
- Containment concepts and the pressure relationships that make them work
- Air filtration, negative air and the equipment that supports them
- Why a technique is chosen for a given material and condition
Domain 2: Guidelines, Regulations & Standards
This is where the prescribed references earn their keep. The ACAC Code of Conduct appears within this domain; it does not create an eighth domain.
- Knowing which document governs which situation
- Edition awareness for the standards on the reference list
- Professional conduct expectations for certified remediators
Domain 3: Water Damage
Moisture is the root cause behind most remediation jobs, so questions here often connect to other domains.
- Water-source classification and what it means for materials
- Drying principles and the sequence of response
- When a material is restorable versus when it must be removed
Domain 4: Structural and Contents Remediation
The hands-on core: how affected building materials and belongings are assessed, cleaned or removed.
- Choosing cleaning versus removal for porous and nonporous materials
- Handling contents separately from structure
- Controlling spread during demolition and cleaning
Domain 5: HVAC System Remediation
HVAC questions test whether you understand a building system that can distribute contamination.
- How air handling components become contaminated and how to evaluate them
- Isolating and protecting systems during a project
- Cleaning approaches and when components need replacement
Domain 6: Project Documentation & Verification
Remediation is not finished when the work stops; it is finished when it can be shown to be complete.
- Scope-of-work logic and what records a project should generate
- Post-remediation verification concepts and who performs them
- Communication of findings and limitations
Domain 7: Safety
Chemical safety and fall protection appear within this domain; they do not form additional domains.
- Respiratory protection selection logic and its limits
- Chemical hazard handling for cleaning and biocide products
- Fall protection when working at height
The Prescribed Reference Library
The handbook points candidates to specific texts and assumes comprehensive knowledge of them. Its selected study pages are examples, not exhaustive coverage, which means reading only the sample pages is a mistake. The prescribed references include:
- AIHA, Recognition, Evaluation & Control of Indoor Mold, second edition (2020)
- EPA, Mold Remediation in Schools and Commercial Buildings (2001)
- ANSI/IICRC S500-2021
- S520-2015 with R520-2015, or S520-2024
- NIOSH, Respirator Selection Logic (2004)
Edition matters. Notice that the S520 entry allows two paths. Know which edition you are studying from and keep your notes consistent with it. Some OSHA bibliography entries on the shared ACAC page belong to the CMRS list only and are not part of the CMR reference list, so do not spend study hours there on the assumption they are tested.
Scenario Thinking for Each Domain
Closed-book multiple-choice exams in this field tend to reward applied judgment more than isolated recall. Here are original practice scenarios of the kind worth rehearsing. They illustrate reasoning, not actual exam content.
Scenario A: Water and materials (Domains 3 and 4)
A supply line failed in an occupied office and wicked into drywall and carpet cushion before anyone noticed. Ask yourself: what does the source of the water imply about the materials, how long has moisture been present, and which items are realistically restorable? The answer depends on principles from the water-damage standard, not on a single rule of thumb.
Scenario B: A shared air handler (Domains 5 and 1)
Contamination is found in a room served by an air handler that also serves clean spaces. Work through how you would isolate the system, what containment and pressure relationships protect the unaffected areas, and how you would evaluate whether the system itself needs attention.
Scenario C: Finishing the job (Domains 6 and 2)
The crew believes the work is complete. What documentation should exist, what does verification mean in this context, and which guideline determines what "complete" looks like? Here you must connect records to standards.
Scenario D: Protecting the worker (Domain 7)
A task involves chemical products in a confined area with an elevated work surface. Think through respirator selection logic, chemical handling and fall protection together, since real jobs combine them.
For more question practice, use the full-length simulations on our CMR practice test site. Practice questions are a tool for finding gaps, not a substitute for the prescribed texts.
A Domain-Ordered Study Sequence
Methodology advice is generic; sequencing is not. Because the domains build on one another, the order below follows dependency rather than a rigid template. Adjust the length to your experience and test date.
Principles & Equipment, then Guidelines, Regulations & Standards
- Read the AIHA text's foundational chapters and build a glossary
- Skim all prescribed references so you know which document answers which question
- Note edition numbers on every reference
Water Damage, then Structural and Contents Remediation
- Work through ANSI/IICRC S500-2021 for water-damage reasoning
- Pair each material type with its likely treatment decision
- Do scenario drills that combine moisture cause with remediation choice
HVAC System Remediation and Project Documentation & Verification
- Study the S520 edition you chose, with R520 where applicable
- Review the EPA remediation guidance for documentation and clearance logic
- Write out what a complete project record should contain
Safety, then integrated review
- Study NIOSH Respirator Selection Logic until you can apply it to cases
- Review chemical safety and fall protection as part of Safety
- Take timed practice sets and revisit weak domains from the prescribed texts
If you tend to forget material, space your reviews so each domain returns at least once before exam day. Our CMR cheat sheet can serve as a final-week skim, and How Hard Is the CMR Exam? helps you judge how much preparation time suits your background.
Fees, Courses and Books
Separate issuer fees from optional preparation spending so your budget is clear.
| Item | Amount / Status |
|---|---|
| Initial US/Canada fee | USD 500 (USD 100 examination + USD 400 certification for the first two-year term) |
| Outside US/Canada | Current official application quotes USD 525 |
| Retake | USD 100 |
| Processing component | USD 100, non-refundable, within the certification fee |
| Prep course | Optional; cost varies by provider |
| Reference books | Separate purchase; prices not covered here |
A prep course is optional. Providers that advertise CMR or CMR/CMRS preparation include Indoor Sciences, IAQ Training Institute and IAQ School; Zack Academy distributes another provider's refresher, so it is not an independent course business. Listed features are provider claims rather than tested outcomes. Some provider schedules appear stale, so confirm that a class is actually open before you plan around it. Third-party question banks may also publish exam details that conflict with ACAC, so rely on the issuer's pages for timing, scoring and fees. The complete picture is in our CMR certification cost breakdown.
Reading the Pass-Rate Data Honestly
ACAC's 2025 exam pass ratio is 31%, which works out to 4 passes in 13 examinations. Three cautions apply:
- The cohort is very small, so a single result swings the percentage substantially.
- The report includes retakes and state-licensing-only examinations, so it is not a clean measure of first-attempt CMR certification.
- It is a dated snapshot and says nothing about your individual chances.
Key Takeaway
Do not let the 31% figure either frighten or reassure you. It mixes populations and is too small to predict anything about a prepared candidate. Judge your readiness by how consistently you reason through scenarios across all seven domains. More context is in CMR Pass Rate: What the Data Shows.
After You Pass: Renewal and Career Evidence
Certification lasts two years, and renewal costs USD 400. Under current procedures, renewal requires 40 renewal credits (RCs): 10 allocated to continued field activity and 30 professional-development hours. Keep supporting documentation, because it is requested on audit. Note that ACAC's issuer overview page still mentions 20 professional-development hours per year, which differs from the current procedures, so follow the procedures page and confirm with ACAC when planning.
On the career side, evaluate the credential against identified remediation roles and employer requirements rather than assuming a pay premium. Look at the job postings you actually want and note whether employers name ACAC certification. Our salary guide, ROI analysis and CMR jobs overview approach this without attributing pay differences to the certificate itself.
Frequently Asked Questions
The exam has 100 multiple-choice questions over three hours, closed book. The passing criterion is 75%, set by the certification board using modified Angoff.
ACAC publishes the seven domains as an unweighted chart. No official percentage weights exist, and the numbered subdomain columns are not weights, so be skeptical of any resource claiming otherwise.
No. A prep course is optional. You must, however, know the prescribed references well, since the handbook assumes comprehensive knowledge of them.
A retake costs USD 100. Review the domains where your scenario reasoning was weakest, return to the prescribed texts and confirm current retake procedures with ACAC.
Yes, delivery is available at a testing center or online with video proctoring. Online candidates need a computer, an approved webcam, a private location and a continuous 2 Mbps upload and download connection.
Preparation for this credential rewards depth in the prescribed references and steady scenario practice across all seven domains. Build your plan around those, confirm your eligibility early, and verify every fee and procedure against current ACAC pages. For a broader orientation, see our complete study guide hub and then test yourself on the CMR practice exam platform.