CRER Exam Domains 2026: Complete Guide to All 5 Content Areas

What the Five Domains Actually Are

The Council-certified Residential Environmental Remediator (CRER) credential is issued by the American Council for Accredited Certification (ACAC), with certification decisions made by its CRER Certification Board. If you are still orienting yourself, start with our explainers on what CRER is and what CRER stands for, because several other credentials share the same acronym and nothing about them transfers to this exam.

The five "domains" in this guide come from the ACAC CRER Candidate Handbook section titled "The Required Skills." Each line begins with the same competency phrase, "Understand and execute successful remediation of...", followed by an indoor-environment hazard class:

1. Asbestos in the indoor environment
2. Lead in the indoor environment
3. Hazardous materials in the indoor environment
4. Microbial contaminants and allergens in the indoor environment
5. Chemicals in the indoor environment

How the Exam Is Built Around Them

Knowing the format helps you decide how deeply to study each area. The handbook for CRER specifies 50 multiple-choice questions with at least four answer choices each, two hours, closed book. (ACAC's generic examinations page cites a broader 75-120 question range for its exams overall, but the exact CRER handbook says 50, which is the number to plan around.) The passing criterion is 70%, set by the certification board using a modified Angoff method; our CRER passing score breakdown goes deeper on what that means in practice.

Delivery is through Kryterion, Inc., either at a testing center or by online video proctoring, with randomized question and answer order and immediate results. Online candidates need their own computer, an approved webcam, a private location, and a continuous 2 Mbps upload and download connection. The current form also offers instructor-proctored vocational examinations through ACAC arrangements, which is a separate path from the Kryterion options.

With only 50 questions spread across five hazard classes, you should expect roughly ten questions per area if coverage is even, but that is an assumption, not a published figure. The safer reading is that no domain is skippable, and a gap in any one of them can cost you real points against a 70% bar. For difficulty context, see how hard the CRER exam is.

Domain 1: Asbestos

How to read the asbestos sources

Do not try to memorize the regulations line by line. Instead, read each one asking three questions: Who is covered? What triggers the requirement? What control or practice does it mandate? Exam items in this domain are more likely to test whether you can match a scenario to the right control or regulatory idea than to recite a citation number. Pay special attention to how the EPA-side rules (40 CFR 763 and Subpart M) differ in focus from the OSHA worker-protection standard in 29 CFR 1926.1101.

Domain 2: Lead

Lead study approach

A useful way to study lead is to contrast it with asbestos. Both are particulate hazards governed by an EPA-side rule and an OSHA-side rule, but the mechanisms of exposure and the cleanup priorities differ. Building a short side-by-side comparison of what each regulation covers helps prevent the most common confusion: applying the right idea to the wrong hazard.

Domain 3: Hazardous Materials

Mercury and methamphetamine as study cases

Mercury and methamphetamine laboratory cleanup are the two named, concrete scenarios in this domain's reference list, so treat them as likely sources of scenario questions. For mercury, focus on the response and removal logic rather than the document's page numbers. For methamphetamine cleanup, note that the current EPA PDF is titled Voluntary Guidelines for Methamphetamine and Fentanyl Laboratory Cleanup (revised August 2021), while ACAC still names the methamphetamine title without an edition. The expanded EPA title does not mean ACAC has added fentanyl to the exam scope, so do not over-study fentanyl-specific content on that basis.

Respirator selection as a reading skill

The NIOSH Respirator Selection Logic is a decision framework. Study it as a flowchart: identify the hazard, determine exposure conditions, then narrow to appropriate respirator types. This logic applies across asbestos, lead, hazardous materials, and chemicals, so mastering it pays off in several domains at once.

Domain 4: Microbial Contaminants and Allergens

Why moisture comes first

A recurring principle in remediation guidance is that removing growth without fixing the water source is incomplete work. When you read the NYC guidance, track how it links the extent of contamination to the level of containment and protection required. Candidates who understand that scaling logic usually handle scenario questions better than those who memorize isolated rules.

Domain 5: Chemicals

Four Themes That Run Through Every Domain

The handbook's expectation that each skill group addresses engineering controls, cleaning and removal, worker protection, and applicable regulatory references gives you a reusable study grid. Build a simple table with the five domains as rows and these four themes as columns, then fill it in as you read.

Reference Conflicts to Study Around

ACAC's own materials contain inconsistencies that can trip up careful candidates. The most important one for content study is the mercury reference. The body-of-knowledge list names the EPA Region 5 Mercury Response Guidebook, Section 5: Removal, while the detailed study guide names the National Elemental Mercury Response Guidebook, Section 9.4. EPA's March 2019 National Elemental Mercury Response Guidebook does confirm a Section 9.4, but that does not resolve why ACAC's other list cites a differently titled Region 5 document. The legacy Region 5 link could not be retrieved at the time of our research.

There are also application-process inconsistencies, such as the generic handbook mentioning notarized applications, project sheets, and diploma or transcript requirements while the current application page expressly exempts CRER from project sheets. Our CRER requirements guide works through the eligibility route, and the CRER certification cost breakdown separates ACAC charges from optional prep spending. For reference, the issuer lists an initial US/Canada fee of USD 400, made up of a USD 100 examination fee plus a USD 300 vocational certification fee for the first two-year term, with a USD 100 retake fee.

Sequencing the Domains in Your Plan

Because ACAC publishes no weights, order your study by overlap and difficulty rather than by an assumed blueprint. One reasonable CRER-specific sequence follows, and it is the only generic scheduling advice you need: tie each week to a hazard class and its source documents.

Placing hazardous materials and chemicals together in Week 3 reflects their conceptual overlap and shared respirator logic. Leaving microbial content for Week 4 gives you a lighter reading load before the review stage, and the full-domain practice at the end exposes any weak areas. For a fuller plan, see our CRER study guide, and keep the CRER cheat sheet handy for last-minute fact review.

A final note on expectations: ACAC's 2025 pass ratio is reported as 0% based on 0 passes from 2 examinations. That cohort is far too small to say anything about typical difficulty, and the report includes retakes and state-licensing-only examinations. Read what the CRER pass-rate data shows before drawing conclusions, and use our practice questions to measure your own readiness rather than relying on that figure.

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