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

How ACAC Structures the Council-certified Residential Indoor Environmentalist Exam

The Council-certified Residential Indoor Environmentalist (CRIE) credential is issued by the American Council for Accredited Certification (ACAC), and certification decisions rest with its CRIE Certification Board. The exam is delivered through Kryterion, Inc., either at a testing center or by online video proctoring. This guide walks through the five published examination topics, what each one asks of you, and how to turn that structure into a study plan.

Before domains, the format. The exam consists of 50 multiple-choice questions, each with at least four answer choices. You have two hours, the exam is closed book, and the passing criterion is 70%, set by the certification board using a modified Angoff method. Question and answer order is randomized, and results are immediate. If you want the arithmetic and context behind the cut score, see our CRIE passing score guide.

The five topics come directly from ACAC's CRIE Candidate Handbook, in the exam study guide section titled Examination Topics. They are not a reverse-engineered list from a third-party course. That distinction matters, because several training vendors publish their own chapter structures, practice-bank sizes and mock-exam timers, and those are course measures, not official exam specifications.

The Published Question Allocations

ACAC publishes how many questions each topic receives. It does not publish percentage weights, and you should be skeptical of any site that presents percentages as official. Here is what is actually stated:

Those allocations add up to 50, matching the exam length. The practical read: the four contaminant domains are tied for the largest allocation, so no single contaminant domain can be treated as a "minor" area. The Code of Conduct is small, but two questions out of 50 is 4 points of margin you can't afford to waste when the cut score is 70%. Missing both ethics items makes the other 48 questions harder to carry.

A note on conflicting information: the generic ACAC examinations page cites a 75-120-question range, but the exact CRIE handbook specifies 50. Use 50. If you are mapping effort across domains, our CRIE study guide shows how to translate these counts into study hours.

Domain 1: Identifying IAQ Contaminants

The identification domain is where the EPA reference list becomes your syllabus. The handbook's reference set covers asbestos, biological pollutants, carbon monoxide, formaldehyde, lead, nitrogen dioxide, pesticides, radon, respirable particles, environmental tobacco smoke, combustion products and volatile organic compounds. Notably, the two asbestos entries link to different EPA resources, and formaldehyde and lead each include an additional EPA resource beyond the primary page. Reading only one page per contaminant leaves gaps.

Typical identification questions describe a property and ask which contaminant fits. Think about what makes each one unique: radon is a radioactive gas that arises from the ground, carbon monoxide is a colorless, odorless combustion gas, and biological pollutants are living or once-living agents such as mold, dust mite allergens and pet dander. Learn the "signature" of each so a scenario stem can be matched quickly.

Domain 2: Sources of IAQ Contaminants in the Home

Source questions reward a spatial habit: for every room or system in a typical home, ask what it might emit. A gas stove, an unvented space heater, a fireplace and a poorly maintained furnace connect to the combustion gases. New cabinetry, composite wood and carpeting connect to formaldehyde and VOCs. A damp basement connects to biological pollutants, and also to radon entry through the same foundation. Pre-1978 housing raises lead paint, while older insulation, flooring and pipe wrap raise asbestos.

This domain pairs naturally with fieldwork. Candidates must be employed in indoor environmental investigation, so you may already encounter these sources on the job. Our CRIE requirements guide covers the eligibility route in detail.

Domain 3: Health Effects of IAQ Contaminants

Health-effects questions are where memorizing a single sentence per contaminant pays off. Carbon monoxide interferes with oxygen delivery and is associated with headache, dizziness and, at higher exposures, far worse. Radon is associated with lung cancer risk over long-term exposure. Lead is associated with developmental and neurological harm, especially in young children. Asbestos is associated with serious lung disease after long latency. Biological pollutants are associated with allergic and asthma-type responses. Formaldehyde and VOCs are associated with irritation and, depending on the compound and level, more serious effects.

Stay at the level of the EPA guidance. The exam is not a toxicology test, and you do not need dose-response curves. You do need to separate fast-acting effects (carbon monoxide symptoms) from long-latency ones (asbestos, radon), because that contrast is a favorite way to build distractors. For a sense of how candidates experience this material, see how hard the CRIE exam is.

Domain 4: Reducing Exposure to IAQ Contaminants

The conceptual hierarchy matters here: eliminate or reduce the source first, ventilate second, and treat air cleaning as a supplement rather than a cure-all. Many wrong answers on mitigation questions are plausible-sounding actions that rank lower in that hierarchy, or that could make a problem worse. For example, sanding or scraping suspect lead paint or disturbing suspect asbestos materials is the opposite of exposure reduction.

Be careful with numerical claims about ventilation rates or filter ratings that circulate in third-party study documents. Some user-shared files assert precise figures that need checking against primary sources. If a number is not in the EPA reference pages you are studying, do not memorize it as exam fact.

Domain 5: ACAC Code of Conduct

Read the actual Code of Conduct on the ACAC site rather than relying on a summary. One nuance worth knowing: the Code strongly discourages combining assessment and contracting on a single project, but it does not impose a blanket prohibition. A question that treats this as an absolute ban, or as completely unrestricted, is oversimplifying. The correct framing is strong discouragement with the conflict-of-interest concern behind it.

Because only two questions come from this domain, a candidate can be tempted to skip it. Resist that. It is the cheapest domain to master, since the reference is a single document, and it also underpins the ethical attestations in the application. For application-side details, review the eligibility and application walkthrough.

Building a Contaminant Matrix

ACAC recommends studying each contaminant's identity, household sources, health effects and exposure-reduction measures. That is exactly a four-column grid, and the four contaminant domains map onto those four columns. Build the grid yourself from the EPA pages; the act of filling it in is the study.

The rows above are a starting skeleton. Extend the grid to biological pollutants, nitrogen dioxide, pesticides, respirable particles, environmental tobacco smoke, combustion products and VOCs, following the EPA pages for each. Our CRIE cheat sheet offers a compact review format once your own matrix is complete.

Sequencing Your Domains Across a Study Plan

Generic scheduling advice matters less than ordering, so here is a CRIE-specific sequence. The logic: identity first, because you can't source or mitigate what you can't recognize; ethics last, because it's short and benefits from fresh recall.

If your practice runs on the CRIE practice test platform, match the issuer's own conditions: 50 questions, two hours, no notes. Third-party mock timers, such as a 60-minute setting on some sites, or question banks of other sizes, are convenience features and not official specifications.

Which Sources Define the Exam, and Which Don't

Search for CRIE prep and you will meet several training and practice sites. A few observations help you filter them:

• The issuer defines the domains. The five topics and the question allocations come from the ACAC CRIE Candidate Handbook. A site that lists different "domains" or percentages is describing its own course or a different credential.
• Watch for credential mix-ups. Several credentials share the CRIE acronym, and some marketplace listings use incorrect expansions. Only Council-certified Residential Indoor Environmentalist material applies here.
• Course statistics are not exam statistics. Chapter counts, video hours and continuing-education hours describe a vendor's product, not the exam's structure or duration.
• Experience documentation differs by source. Some providers describe project sheets, but the issuer's current CRIE application expressly exempts CRIE from project sheets. Follow the issuer.
• Practice questions can be duplicated. Some sites display identical practice items, so don't assume two banks give you independent coverage.

For the money side in brief: the initial US/Canada fee is USD 400, made up of USD 100 for the examination and USD 300 for vocational certification covering the first two-year term, and the current application quotes USD 425 outside the US/Canada. A retake is USD 100. Renewal at two years costs USD 300 and requires 40 renewal credits, with current procedures allocating 10 for continued field activity and 30 for professional-development hours. A prep course is optional. Timing details live in the exam dates guide, and the payoff question is explored in whether the certification is worth it.

Frequently Asked Questions

For related background on the credential itself, see what CRIE certification is, and for the career side, the CRIE jobs overview. When you are ready to test yourself against all five domains, start with the CRIE practice exam.