What Is CIH? The Certified Industrial Hygienist Credential
CIH is widely regarded as the global standard credential for industrial hygiene practice — the profession focused on protecting worker and public health from chemical, physical, ergonomic, and biological hazards. Here's what it actually certifies, who administers it, and how it stacks up against CRSP and CRST.
CIH stands for Certified Industrial Hygienist, administered by BGC (Board for Global EHS Credentialing, formerly ABIH). It certifies competency across 16 industrial hygiene knowledge domains — from toxicology and radiation to noise and ventilation — and requires a specific science/IH coursework background plus 4 years of professional-level IH experience before you can even sit the exam.
What Does CIH Actually Certify?
Industrial hygiene, at its core, follows a recognition-evaluation-control loop: anticipate a hazard before it causes harm, recognize it in the workplace, evaluate how severe the exposure actually is, and control it down to an acceptable level. CIH certifies that a practitioner can do this competently across chemical, physical, ergonomic, and biological hazard categories — not just one narrow specialty.
CIH holders aren't restricted to one career lane. Some practice broad-scope, generalist industrial hygiene; others specialize narrowly (radiation safety, industrial ventilation design, toxicology consulting) and their focus often shifts multiple times across a career. The credential itself doesn't restrict which direction you take it.
The 16 CIH Knowledge Domains
To earn CIH, you have to demonstrate minimum competency across all of the following, per BGC's published requirements:
A few of these already have dedicated references on this site — Radiation Units, Ventilation (HVAC Air Cycle), and Toxicology — with more being added as the study journal works through each chapter.
Who Administers CIH?
BGC (Board for Global EHS Credentialing) administers the CIH credential. BGC was previously known as ABIH (American Board of Industrial Hygiene) — if you see older material referencing ABIH, it's the same organization and the same credential. The exam itself is delivered through Pearson VUE test centres.
How Do You Become a CIH?
BGC requires all of the following before you can sit the exam:
- 60 semester hours of science, math, engineering, or science-based technology from a bachelor's or higher degree (at least 15 of those hours at junior/senior/graduate level).
- 180 academic hours (or 240 continuing education hours) of industrial hygiene coursework, at least half covering Fundamentals of IH/OEHS, Toxicology, Measurements, and Controls.
- At least 2 contact hours of ethics coursework.
- Active practice within 12 months of applying.
- 48 months (4 years) of professional-level industrial hygiene experience, supported by 2+ professional references (at least one from a current CIH).
- Pass the CIH comprehensive exam.
- Agree to the BGC Code of Ethics and Ethics Case Procedures.
- Pay the applicable fees.
For the full breakdown of every requirement — including the exact STEM/IH hour thresholds and reference options — see the complete CIH Exam Eligibility checklist.
CIH vs. CRSP vs. CRST
All three are Canadian- or North-American-recognized OHS credentials, but they certify different things at different levels:
| CIH | CRSP | CRST | |
|---|---|---|---|
| Administered by | BGC (formerly ABIH) | BCRSP | BCRSP |
| Focus | Technical/scientific industrial hygiene specialist | OHS management & leadership generalist | OHS technical/tactical practitioner |
| Degree requirement | Bachelor's+ with specific STEM & IH coursework | Bachelor's in any discipline | 1-year certificate or 2-year diploma |
| Experience required | 48 months professional-level IH | 48 months OHS | Lower entry threshold |
| Knowledge domains | 16 (chemistry, toxicology, radiation, noise, etc.) | 6 (management systems, hazard ID/control, ethics, etc.) | 5 (technical fundamentals, hazard ID/control, etc.) |
In short: CIH goes deep on the science behind hazard measurement and control; CRSP goes broad on managing an entire safety program; CRST sits at the technical/tactical level under either. See the full CRSP vs. CRST comparison for detail on those two specifically.
Why Practitioners Pursue It
Recognition, Not Just a Line on a Resume
CIH holders consistently describe it less as a credential and more as a professional identity — a signal, to both peers and clients, that someone has met a rigorous, independently-verified bar in a field where the consequences of getting it wrong are measured in worker health outcomes. It's frequently described as the ceiling credential in the profession: the one people work toward for years, not the first one they get.
Following My Own CIH Prep?
I haven't sat the CIH exam yet — I'm documenting the process in real time as I study, chapter by chapter, plus building free reference guides and the Equation Master along the way.
Explore the CIH Exam Prep Hub →Or jump straight to the live study journal
What Is CIH — Frequently asked questions
What does CIH stand for?
Certified Industrial Hygienist. It is the global standard credential for protecting worker and public health by anticipating, recognizing, evaluating, and controlling chemical, physical, ergonomic, and biological workplace hazards.
Who administers the CIH credential?
BGC (Board for Global EHS Credentialing), previously known as ABIH (American Board of Industrial Hygiene). The exam itself is delivered through Pearson VUE test centres.
What topics does the CIH exam cover?
16 knowledge domains: Air Sampling & Instrumentation, Analytical Chemistry, Basic Science, Biohazards, Biostatistics & Epidemiology, Community Exposure, Engineering Controls/Ventilation, Ergonomics, Health Risk Analysis & Hazard Communication, IH/OEHS Program Management, Noise, Non-Engineering Controls, Radiation (ionizing and non-ionizing), Thermal Stressors, Toxicology, and Work Environments & Industrial Processes.
Is CIH harder to qualify for than CRSP or CRST?
CIH's academic bar is higher in a specific way: it requires 60 semester hours of science, math, engineering, or science-based technology from a bachelor's or higher degree, plus 180 academic hours (or 240 continuing education hours) specifically in industrial hygiene coursework. CRSP requires a bachelor's degree in any discipline plus 48 months of OHS experience — no specific STEM or IH coursework requirement. CRST has the lowest entry bar of the three.
Do I need a science degree to become a CIH?
You need 60 semester hours of science, math, engineering, or science-based technology coursework (with at least 15 of those hours at the junior, senior, or graduate level) from an accredited bachelor's or higher degree program, plus dedicated industrial hygiene coursework on top of that. The degree itself doesn't have to be titled "Industrial Hygiene" as long as the coursework requirements are met.
