- What the Published Number Actually Says
- Why a Small Annual Sample Cannot Predict Your Result
- What Is (and Isn't) in the Count
- What You Are Actually Tested On
- Exam Mechanics That Shape Your Odds
- Eligibility, Fees, and the Cost of a Miss
- A Domain-Ordered Prep Sequence
- How to Vet Pass-Rate Claims From Training Sellers
- Frequently Asked Questions
- ACAC's 2025 exam pass ratio report is reported as 37 passes from 37 administrations, but that sample is small.
- The reported figure includes retakes and state-licensing-only exams, so it is not a first-attempt probability.
- The CRMR exam is 50 multiple-choice questions in two hours, closed book, with a 70% passing score.
- A miss costs a $100 retake fee; the initial total is $400 ($100 exam plus $300 certification).
What the Published Number Actually Says
If you search for the Council-certified Residential Microbial Remediator (CRMR) pass rate, you will find one figure worth discussing. A prior review of ACAC's 2025 Exam Pass Ratio report attributed 37 passes from 37 exam administrations, or 100%, to the CRMR in 2025. ACAC's current statistics page still links the report, though the PDF could not be re-fetched during our most recent research check on October 5, 2026. Treat the figure as a preserved prior-review statistic, not a newly verified one.
A 100% headline looks like great news, and in a narrow sense it is: nobody in that reported group failed. But a number like this tells you very little about your odds. This article explains why, what the figure includes, and how to use it responsibly while you plan your preparation. For a broader look at difficulty, see our guide on how hard the CRMR exam is.
Why a Small Annual Sample Cannot Predict Your Result
Thirty-seven administrations is a small number. Small samples swing wildly: a handful of additional failures would have moved the percentage noticeably, and a perfect score can occur by chance even when the true pass rate is well below 100%. Statisticians would say the uncertainty around the figure is large. You should not infer that a CRMR candidate has a near-certain chance of passing.
Several other factors limit what the number can tell you:
- Self-selection. The credential requires attestation of current employment in microbial remediation. Candidates are working professionals who often have field exposure to the subject matter, which is different from a general-public test-taker pool.
- One year only. A single year cannot show a trend. We have no verified multi-year series to cite, so we will not invent one.
- No score distribution. A pass/fail tally does not show whether candidates cleared the 70% threshold comfortably or barely.
- No first-attempt breakdown. The figure does not separate first-time candidates from repeat candidates.
For the cut score itself, our CRMR passing score guide covers exactly what 70% means on a 50-question exam.
What Is (and Isn't) in the Count
The preserved reporting notes that the ratio includes retakes and state-licensing-only exams. That matters for interpretation:
| Question | What the reported figure can tell you | What it cannot tell you |
|---|---|---|
| Did candidates pass in 2025? | Reported 37 of 37 administrations passed | Whether future cohorts will match |
| Is it a first-attempt rate? | No: retakes are included | How many first-timers passed on try one |
| Does it isolate the CRMR credential alone? | Partly: it includes state-licensing-only exams | The CRMR-only certification outcome |
| Is it a marketing guarantee? | No | Any individual outcome |
The state-licensing point deserves a note. Some jurisdictions use an examination for licensing purposes, and ACAC is clear that passing an examination solely for state licensing does not itself confer ACAC certification. So the exam count and the number of people who earn the credential are not the same thing. For the certification pathway itself, see CRMR requirements and eligibility.
What You Are Actually Tested On
A pass rate only means something relative to the content. The ACAC candidate handbook publishes five competency statements for the CRMR. These are unweighted issuer competencies. We have not verified official percentage weights for them, and this article will not assign any. Nor should you treat them as a verified exhaustive blueprint of every question. Here are the five areas in the handbook's own terms:
Domain 1: Basic Principles of Microbial Remediation
Understand the basic principles of microbial remediation as described in the listed reference texts.
- This is reference-driven: know what the named texts say, not just general field habits.
- The AIHA mold-control book is a central source for recognition, evaluation, and control concepts.
Domain 2: Equipment, Supplies, Calibration, and Operation
Maintain familiarity with the equipment and supplies necessary to conduct a microbial remediation project, and with the methods for calibration and operation of such equipment.
- Expect to reason about what tool suits what task, and how instruments are calibrated and operated correctly.
- Field experience helps, but the exam frames it through the reference texts.
Domain 3: Safety Hazards and Protection
Appreciate the safety hazards presented by microbial remediation projects, and follow the procedures necessary to protect building occupants and remediation workers from such hazards.
- The handbook specifies regulatory awareness, safe work practices, and appropriate PPE.
- Think about both worker protection and occupant protection.
Domain 4: Regulated Substances
Recognize that microbial remediation may bring the remediator into contact with regulated substances such as lead and asbestos.
- The competency is about recognition and awareness, so know when a job crosses into regulated territory.
Domain 5: Water Damage in the Indoor Environment
Properly address water damage in the indoor environment.
- Water is the driver behind most microbial growth, so expect moisture-source thinking and drying-practice concepts.
- The IICRC S500 water-damage standard is the key reference here.
For a deeper walk-through, read our complete guide to all five CRMR content areas.
The three reference headings in the study guide
ACAC's CRMR study guide also organizes preparation by three references: AIHA, Recognition, Evaluation and Control of Indoor Mold; IICRC, S500-2021; and IICRC, S520. These are unweighted preparation categories, not additional official exam domains, and they do not guarantee exhaustive coverage. The required reference list is:
- The ACAC Code of Conduct
- AIHA, Recognition, Evaluation & Control of Indoor Mold, second edition (2020)
- ANSI/IICRC S500-2021, fifth edition
- S520-2015 with R520-2015, third editions, or S520-2024, fourth edition
The study guide highlights S500 sections A, B, and 1 through 8, plus glossary pages 99-118. ACAC expects study of the full references, not only the highlighted reading locations. A candidate who studies only the highlights is gambling. Note too that these reference editions do not establish a numbered "2026 exam version," so be wary of any seller who claims one. We have only retrieved the public handbook and reference list, not the paid books, so use ACAC's current instructions to decide which S520 edition to buy. Our CRMR study guide shows how to work through this reading list.
Exam Mechanics That Shape Your Odds
The format details below come from the CRMR-specific handbook. ACAC's general examinations page mentions a 75-120-question range, but that does not reflect this credential, so use the CRMR numbers here.
| Feature | CRMR specifics |
|---|---|
| Questions | 50 multiple choice |
| Time | Two hours (written exam duration, not a course length) |
| References | Closed book |
| Answer choices | At least four per question |
| Passing score | 70% |
| Question/answer order | Randomized |
| Results | Electronic, available immediately and confirmed by email |
| Testing provider | Kryterion, Inc.: authorized testing centers or secure online video proctoring; instructor-proctored vocational option by arrangement |
Two hours for 50 questions is generous on pacing, which means time pressure is rarely the main risk. The real challenge is recall under closed-book conditions. Because questions and answers are randomized, memorizing answer positions or a fixed question order is useless. You need the underlying concepts. And since the exam is closed book, being able to look something up in the S500 on the job does not help you on test day.
On the 70% threshold: with 50 questions, that works out to 35 correct answers. See our passing-score article for how to think about margin of safety. For timing and scheduling details, see CRMR exam dates and scheduling.
Eligibility, Fees, and the Cost of a Miss
Pass-rate conversations should always include what failing costs you. Here are the fees from ACAC, in USD:
| Item | Amount |
|---|---|
| Examination | $100 |
| Certification | $300 |
| Initial total | $400 |
| Retake | $100 |
| Renewal | $300 |
A retake at $100 is not ruinous, but it does add up in time and scheduling. Prep providers may quote their own course and practice-exam prices, which are separate from ACAC's fees. For the full picture, see our CRMR certification cost breakdown.
Who can sit for it
Eligibility requires attestation of current employment in microbial remediation, application and identity verification, a successful examination, and certification-board approval. ACAC does not specify a minimum duration of experience, project sheets, or a mandatory preparatory course for the CRMR. This is a vocational, non-CESB-accredited designation. Completing a course does not itself confer ACAC certification; the board must approve your application and exam result.
One practical caution on timing: the current online application gives six months to complete the process, while the handbook retains 90-day and notarized-paper wording. Follow the current application instructions and confirm the operative authorization deadline with ACAC instead of assuming either number. This matters for pass-rate planning because rushing an exam to beat a deadline raises your risk of a miss.
After you pass
Certification lasts two years. Current renewal procedures require 40 recertification credits: 10 for continued field activity plus 30 hours of professional development. Keep evidence for audit and submit the required current photo. Renewal costs $300. Read more in our guides to whether the certification is worth it and CRMR salary context. On pay, note the distinction between occupation-level earnings and any pay premium actually caused by holding the credential, which has not been established.
A Domain-Ordered Prep Sequence
Because the exam is closed book and reference-driven, sequence your study around the source texts. This sample ordering ties each week to specific content and a reason. Adjust it to your schedule and your field background.
Foundations first (Domain 1)
- Read the AIHA mold-control text for recognition, evaluation, and control principles.
- Why first: it supplies vocabulary the other domains assume.
Water damage (Domain 5)
- Work through the full S500-2021, not only sections A, B, 1-8 and the glossary.
- Why here: moisture control underpins most remediation decisions.
Equipment and safety (Domains 2 and 3)
- Review calibration and operation concepts, PPE, safe work practices, and regulatory awareness.
- Why here: these are easier to retain once you understand the project flow.
Regulated substances and S520 (Domain 4)
- Study your chosen S520 edition and the lead and asbestos recognition points.
Timed closed-book practice
- Take 50-question sets in two-hour blocks without notes; review every miss against the source text.
Scenario-based questions are your best rehearsal, since the exam rewards applying reference content rather than reciting it. You can try original practice items on our CRMR practice test site. For a one-page recap near test day, our CRMR cheat sheet may help.
How to Vet Pass-Rate Claims From Training Sellers
Many providers advertise pass-rate or "success" numbers. Use these checks before you rely on any of them:
- Ask what counts as a pass. Is it first attempt, any attempt, or course completion? ACAC states that completing a course does not itself confer certification.
- Ask for the sample size and year. A percentage without a denominator is not informative.
- Check which credential it refers to. The acronym is shared by several unrelated credentials, and some providers pool practice material across the CRMR and related ACAC designations. A pooled bank is not the same as a CRMR-specific one. Confirm the content maps to the five CRMR competencies and the named references.
- Treat provider copy as marketing. Quoted fees and claims can conflict with current ACAC instructions. Verify certification facts on ACAC's own pages.
- Reject guarantees. No honest source can guarantee an individual pass.
Several training providers publish CRMR-relevant material, including Indoor Sciences, Zack Academy, and the IAQ Training Institute. This is a comparator list, not a ranking or endorsement. ACAC also publishes a policy on independent preparation courses; read it before paying for training. Our overview of CRMR training options goes further.
Key Takeaway
Use the reported 37-for-37 result as a reassurance that the exam is passable for prepared working professionals, then ignore it for planning. Plan around the 70% cut score, the full reference list, and closed-book recall. If you are still orienting yourself, start with what CRMR certification is and then the certification overview.
Frequently Asked Questions
A prior review attributed 37 passes from 37 exam administrations (100%) in 2025 to ACAC's 2025 Exam Pass Ratio report. That figure is small-sample, includes retakes and state-licensing-only exams, and could not be re-fetched in our latest check. It is not a first-attempt probability or a guarantee.
No. A small annual sample from a self-selected pool of employed remediation professionals cannot show difficulty. The exam is closed book with 50 questions and a 70% passing score, and it draws on named reference texts, so preparation still matters.
The retake fee is $100. Initial costs are $100 for the exam plus $300 for certification, totaling $400. Confirm your authorization window with ACAC, since the current online application gives six months while older handbook wording references 90 days.
The CRMR handbook specifies 50 multiple-choice questions in two hours, closed book, with at least four answer choices each. The passing score is 70%. Questions and answers are randomized, and results are available immediately and confirmed by email.
ACAC requires attestation of current employment in microbial remediation but does not specify a minimum duration of experience, project sheets, or a mandatory preparatory course for the CRMR. Completing a course alone does not confer certification; board approval is required.