- What a CHO Actually Is
- Why the Role Exists: The Laboratory Standard
- What a CHO Does Day to Day
- Who Hires Chemical Hygiene Officers
- The NRCC Credential Behind the Title
- The 18 Examination Subject Areas
- Exam Format, Fees, and Registration
- Eligibility and Renewal
- Sequencing Your Preparation
- Frequently Asked Questions
- A CHO is the Chemical Hygiene Officer responsible for a laboratory's chemical safety program and its written plan.
- The NRCC examination has 150 multiple-choice questions, three hours, and is delivered by computer with a local proctor.
- The fee structure is a $185 application fee plus a $195 examination fee.
- NRCC lists 18 unweighted subject areas, starting with the OSHA Laboratory Standard and ending with audits and self-evaluations.
What a CHO Actually Is
In laboratory safety, CHO stands for Chemical Hygiene Officer: the person designated to provide technical guidance in developing and implementing a laboratory's chemical hygiene program. If a lab handles hazardous chemicals, someone needs to own the written plan, make sure people follow it, and answer questions when a procedure, a spill, or an inspection raises a concern. That person is the CHO.
This article covers the Chemical Hygiene Officer role and the credential offered through the National Registry of Certified Chemists (NRCC). If you have seen the same three letters attached to unrelated fields, set those aside. Everything here concerns chemical safety in laboratories. For other phrasings of the same question, see our explainers on what CHO stands for and CHO meaning.
Why the Role Exists: The Laboratory Standard
The position traces back to the OSHA Laboratory Standard, which requires employers whose laboratories use hazardous chemicals to maintain a Chemical Hygiene Plan and to designate a Chemical Hygiene Officer. That regulation is the first official subject area on the NRCC examination, and it shapes much of what follows. A candidate who understands why the standard exists, what it requires employers to document, and how it differs from general industrial rules has a head start on the rest of the material.
What a CHO Does Day to Day
The role is practical and varies with the size of the facility, but its core duties map neatly onto the exam's subject areas:
- Maintaining the Chemical Hygiene Plan and the standard operating procedures that sit beneath it.
- Assessing hazards before new chemicals, reactions, or equipment enter the lab.
- Supervising control measures such as fume hoods and other laboratory ventilation, respirator programs, and exposure monitoring.
- Training employees and making hazard information accessible, including GHS labels and safety data sheets.
- Coordinating medical consultation when an exposure or symptom triggers it.
- Preparing for emergencies, including spills and power failures that can compromise ventilation or storage.
- Managing outsiders such as visitors, contractors, and maintenance personnel who enter spaces they do not routinely work in.
- Keeping records and running audits so the program can be shown to work.
Notice how closely this list mirrors the credential's scope. The examination is built around the actual responsibilities of the job rather than an abstract body of theory.
Who Hires Chemical Hygiene Officers
Any organization with laboratories that use hazardous chemicals has a use for this role. Typical settings include:
- Universities and colleges, where teaching and research labs multiply the number of people and procedures to oversee.
- Industrial and manufacturing R&D and quality-control laboratories.
- Pharmaceutical, biotechnology, and chemical companies.
- Hospital, clinical, and testing laboratories.
- Government and environmental laboratories.
In some organizations the CHO is a full-time safety professional; in others it is a duty assigned to a senior chemist or lab manager alongside other work. For a closer look at how the title appears in job postings, see CHO jobs, and for earnings context see the CHO salary guide.
The NRCC Credential Behind the Title
The National Registry of Certified Chemists administers the Chemical Hygiene Officer certification. The credential gives employers and regulators a recognized way to see that a person has demonstrated knowledge across the full scope of laboratory chemical hygiene. It is useful both for people newly assigned to the role and for experienced safety staff who want documented proof of competence. The question of whether it pays off is covered in Is the CHO Certification Worth It?, and a broader overview lives on the CHO certification page.
One honest caveat about sourcing: NRCC publishes its subject scope on its Examination Standards page, but this article does not rely on any official examination outline PDF, and NRCC does not publish percentage weights for the subject areas. Anyone claiming a precise percentage breakdown is guessing, so treat the areas below as an unweighted list of everything you may be asked about.
The 18 Examination Subject Areas
NRCC's Examination Standards list 18 subject areas. They fall naturally into five clusters, which makes them easier to learn. For a deeper treatment of each, read the complete guide to all 18 CHO content areas.
Regulatory and Framework Areas
Domains 1-3: OSHA Laboratory Standard, GHS, and Other Pertinent Regulations
The legal foundation. Expect questions about what the Laboratory Standard requires, how chemicals are classified and labeled under GHS, and how other regulations interact with it.
- Required elements of a Chemical Hygiene Plan
- GHS classification, label elements, and hazard communication
- Where other rules apply alongside the Laboratory Standard
Planning and Practice Areas
Domains 4-8: SOPs, Hazard Assessment, Safe Work Practices, Personal Hygiene, and General Laboratory Practices
The everyday mechanics of working safely. These areas test whether you can translate a hazard into a procedure and a habit.
- Writing and applying standard operating procedures
- Hazard assessment before work begins
- Personal hygiene practices that prevent ingestion and skin exposure
- General housekeeping, storage, and handling practices
High-Hazard Areas
Domains 9-10: Special Procedures by Hazard Class, and Select Carcinogens, Reproductive Toxins, Highly Toxic Substances, and Substances of Unknown Toxicity
Some materials demand more than baseline practice. These areas cover the added precautions for particular hazard classes and for the most dangerous or least understood substances.
- Hazard-class-specific handling requirements
- Extra controls for select carcinogens, reproductive toxins, and highly toxic materials
- The principle of treating unknown-toxicity substances conservatively
Controls, Information, and People Areas
Domains 11-14: Information Sources, Control Measures, Training, and Medical Consultation
How you find answers, engineer risk down, and take care of people.
- Locating reliable hazard information
- Respirators, laboratory ventilation, and exposure monitoring
- Employee training and information requirements
- When medical consultation and examination are triggered
Response and Program Management Areas
Domains 15-18: Emergencies, Visitors and Contractors, Record Keeping, and Audits
What happens when things go wrong and how the program proves itself.
- Emergency planning, including power failure and spills
- Controlling access and exposure for visitors, contractors, and maintenance personnel
- Record keeping and documentation
- Audits, inspections, and self-evaluations
Exam Format, Fees, and Registration
The examination consists of 150 multiple-choice questions and runs three hours. It is a computer-based, internet-delivered test taken with a local proctor acceptable to NRCC, so you arrange a qualified proctor rather than traveling to a fixed testing center. Confirm proctor requirements with NRCC before you schedule.
| Item | Detail |
|---|---|
| Question count | 150 multiple-choice questions |
| Time allowed | Three hours |
| Delivery | Computer-based, internet examination with a local proctor acceptable to NRCC |
| Application fee | $185 |
| Examination fee | $195 |
| Combined initial cost | $380 ($185 + $195) |
Fees are listed on NRCC's fee page and can change, so verify them at the source before paying. A fuller breakdown, including renewal, is in the CHO certification cost guide. The numeric passing threshold is not stated in the sources used for this article, so we do not quote one; see CHO passing score for what is and is not known. Timing and scheduling questions are addressed in CHO exam dates.
What the Questions Tend to Reward
With 150 questions spread across 18 areas, the exam samples broadly. A single question rarely depends on memorizing one obscure figure; it usually asks you to apply a principle. Expect scenarios such as which control is appropriate for a given exposure situation, what a plan must document, when a training or medical-consultation obligation arises, or how to respond to a spill. Candidates who understand the reasoning behind the Laboratory Standard handle these better than those who memorize isolated facts. To gauge how demanding that is, read How Hard Is the CHO Exam? and the discussion of the CHO pass rate.
Eligibility and Renewal
Eligibility
NRCC sets a combined education and experience bar. Applicants need a minimum of 16 semester or 24 quarter hours of science coursework, plus professional experience that scales with academic degree level:
| Education Level | Experience Required |
|---|---|
| No degree | Three years |
| Associate degree | Two years |
| Bachelor, master, or doctoral degree | One year |
The experience must fall within six years of your application. One practical warning: NRCC's current application materials and its Examination Standards page contain differences in timing and approval wording. Rather than assuming one unified rule, read both documents, and contact NRCC directly if they appear to conflict for your situation. Our CHO requirements guide walks through qualifying in more detail.
Renewal
Keeping the credential current costs $100 for a one-year renewal or $275 for a three-year renewal. The three-year option costs less per year than renewing annually, which matters if you expect to hold the credential long term.
Key Takeaway
Check your eligibility before you pay anything. Confirm your science hours, your degree level, and that your qualifying experience falls within six years of application. A rejected application on a technicality wastes both time and money.
Sequencing Your Preparation
Because NRCC publishes no weights, treat all 18 areas as fair game, but order your study so that foundational material comes first. This is a suggested sequence tied to the clusters above, not an official schedule:
Regulatory foundation
- OSHA Laboratory Standard, GHS, and other pertinent regulations (Domains 1-3)
- Learn what a Chemical Hygiene Plan must contain; later areas depend on it
Daily practice and planning
- SOPs, hazard assessment, safe work practices, hygiene, and general lab practices (Domains 4-8)
High-hazard material and controls
- Hazard-class procedures and select carcinogens, reproductive toxins, highly toxic and unknown-toxicity substances (Domains 9-10)
- Respirators, ventilation, and exposure monitoring (Domain 12)
People, response, and verification
- Information sources, training, medical consultation, emergencies, visitors and contractors, records, and audits (Domains 11, 13-18)
- Finish with timed mixed practice
For a complete preparation plan, use the CHO study guide, keep the CHO cheat sheet handy for final review, and pressure-test yourself on the CHO Exam Prep practice tests. Timed, mixed-domain practice at the main practice site also helps you manage the three-hour clock across 150 questions.
Frequently Asked Questions
CHO stands for Chemical Hygiene Officer, the person designated to guide a laboratory's chemical hygiene program under the OSHA Laboratory Standard. The related credential is administered by the National Registry of Certified Chemists. See what CHO means for more.
The exam has 150 multiple-choice questions and a three-hour time limit. It is delivered by computer over the internet with a local proctor acceptable to NRCC.
Initial costs are a $185 application fee and a $195 examination fee, for $380 combined. Renewal is $100 for one year or $275 for three years. Confirm current figures on NRCC's fee page.
No. NRCC lists 18 official subject areas but does not publish percentage weights for them, so you should prepare for all of them rather than betting on a few.
Yes, in principle. NRCC requires a minimum of 16 semester or 24 quarter science hours, and applicants without a degree need three years of experience, compared with two years for an associate degree and one year for a bachelor, master, or doctoral degree. The experience must be within six years of application. Review what CHO certification involves and the requirements page, and verify details with NRCC.
A Chemical Hygiene Officer is, at heart, the person who keeps a laboratory's chemical safety promises. The NRCC credential tests whether you can do that across all 18 areas of the job, from the OSHA Laboratory Standard to audits and self-evaluations. Understand the framework, learn the hazard-specific controls, and practice applying both under timed conditions.