1.3 The BGC Blueprint, Subject Areas, and a Calculation-First Study Plan

The BGC Blueprint, Subject Areas, and a Calculation-First Study Plan

Two different official documents describe CIH exam content, and confusing them is a common source of bad study plans. This section separates them, states the weights that actually govern item allocation, and turns them into a preparation sequence.

---

1. The Blueprint: Three Domains, Nine Tasks

The CIH Exam Blueprint is based on the 2021 Job Analysis and has been effective since April 1, 2022. It defines three performance domains — major areas of responsibility — and nine tasks performed within them, together with the knowledge and skills required.

Domain I (50%) runs from anticipation and recognition of hazards, through assessing the exposure–health-effect relationship, designing and implementing a qualitative or quantitative assessment strategy, to forming conclusions and communicating them.

Domain II (35%) runs from selecting a control using the hierarchy of controls, through developing and implementing it, to validating that it works.

Domain III (15%) covers developing and implementing programmes and systems that address health risk, and evaluating and maintaining their effectiveness — including the BGC Code of Ethics, which is named explicitly in the blueprint.

---

2. The Subject Areas (Rubrics): How Items Are Categorised

Separately from the domains, BGC maintains Subject Area Definitions — historically called rubrics — that categorise individual examination questions. BGC states that you should expect questions in all subject areas:

  DOMAIN I (50%)                    DOMAIN II (35%)               DOMAIN III (15%)
  ------------------------------    ---------------------------   -------------------------
  Basic Science                     Engineering Controls /        Work Environments and
  Air Sampling & Instrumentation      Ventilation                   Industrial Processes
  Analytical Chemistry              Noise                         IH / OEHS Program
  Toxicology                        Thermal Stressors               Management
  Biostatistics & Epidemiology      Radiation - Ionizing
  Biohazards                        Radiation - Nonionizing
  Community Exposure                Non-Engineering Controls
  Health Risk Analysis &            Ergonomics
    Hazard Communication

The public BGC list collapses the two radiation entries into one, giving the familiar count of 16 subject areas; the Subject Area Definitions document separates them.

The relationship to remember: domains carry the weights, subject areas carry the content. An item about calculating a hood exhaust volume is a Domain II item categorised under Engineering Controls/Ventilation. An item about the same hood's capture efficiency measurement is a Domain II validation item. An item about deciding whether a worker is overexposed is Domain I.

---

3. How This Guide Maps to the Blueprint

---

4. A Calculation-First Study Plan

Scoring is compensatory across subject areas — there is no per-area minimum — but items are drawn from all areas. The optimal strategy follows directly:

Do not spend 200 hours perfecting ventilation because you enjoy it. Do eliminate every area where you would score at chance.

A defensible allocation for a 150–250 hour plan, proportional to the domain weights:

Layered across all three phases:

1. Build calculation fluency, not formula recall. The BGC Equation Sheets are provided during the exam. What is not provided is the judgement to recognise that a problem is a purge problem, a mixture problem, or a shift-adjustment problem. Practise classifying problems before solving them.
2. Drill unit conversion until it is automatic. ppm to mg/m³, cfm to m³/s, inches of water to pascals, rem to sievert, and non-standard temperature and pressure corrections underlie items across every domain. A unit error turns a correct method into a wrong answer.
3. Learn paired standards, not single numbers. OSHA versus ACGIH for noise; PEL versus TLV versus REL; NIOSH versus OSHA for respirator selection. Items are frequently written on precisely the point where the two frameworks disagree.
4. Time yourself at 100 seconds per item. That is the true pace: 90 items per 150-minute section.
5. Practise on an on-screen calculator. Logarithms, exponentials, and roots on an unfamiliar interface cost real time.