A worker's hand was crushed in a hydraulic press. The injured worker has been given first aid and transported by EMS. What should the safety technician do FIRST in the investigation?

Secure the area and keep the press and scene as they were found

Gather all of the witnesses in one room to compare their accounts

Have maintenance repair the press so production can resume

Write the corrective action list for the supervisor to sign

A convenience store chain has had several robberies during late-night shifts, when one clerk works alone and handles cash. Which combination of measures BEST reduces the risk of violence?

Drop safes with low cash on hand, clear windows, and good lighting

Close the store blinds at night so clerks are less visible

Arm each clerk and train them to resist the attacker during a robbery

Post a zero-tolerance policy statement near the register

A technician must train a new crew on the safe use of a chemical transfer pump. Most crew members speak Spanish as their first language, and several have limited reading ability in any language. Which approach is MOST effective?

Demonstrate the task in Spanish, then have each worker show it back

Hand out the English procedure and have workers sign that they read it

Have a bilingual worker translate the written procedure for the crew

Show a narrated English video and then give a written quiz in Spanish

A technician samples a paint-mixing area where acetone, methyl ethyl ketone (MEK), and toluene are present together and act on the same organ systems. Results are acetone 300 ppm (limit 500 ppm), MEK 80 ppm (limit 200 ppm), and toluene 30 ppm (limit 100 ppm). What is the mixture exposure index, and is the mixture limit exceeded?

1.3; the mixture limit is exceeded

410 ppm; not exceeded, as it is under 500 ppm

0.43; the mixture limit is not exceeded

0.60; not exceeded, as no single ratio reaches 1

Employees in a printing plant report recurring headaches and want an independent evaluation of their workplace. They ask the technician what role NIOSH can play. Which answer is correct?

It can do a health hazard evaluation and recommend controls

It can issue citations and penalties for the conditions

It can adopt an enforceable exposure limit for the plant

It can order the employer to shut down the process

Arriving at the scene of a forklift tip-over in a yard, a technician notices rain starting to fall on fluid trails, tire marks, and a puddle near the truck. Which evidence should be documented FIRST?

The tire marks and fluid trails before the rain washes them away

The written statements from the yard workers on the shift

The operator's training records kept in the personnel office

The maintenance logs and repair orders for the forklift

A parking lot at a manufacturing plant is bordered by tall, dense shrubs and has several dark areas, and employees report feeling unsafe walking to their cars after the late shift. Which CPTED measure BEST addresses this?

Trim shrubs and add lighting to improve natural surveillance

Plant taller hedges to block views of the lot from the road

Close the lot at night and have workers park on the street

Post a sign stating that the lot is used at the owner's risk

After a small ammonia release at a plant, neighbors call the site and local reporters arrive. The cause is still under investigation, and no off-site injuries have been reported. How should the site communicate with the community?

Share known facts plainly, note unknowns, and update regularly

Release the full technical incident file without explanation

Decline all comment until the investigation is fully complete

Assure everyone there was no risk before air data are reviewed

OHST – Occupational Health and Safety Technologist

Free OHST Practice Questions

10 sample questions for the OHST – Occupational Health and Safety Technologist, with the correct answer and an explanation for each. No account needed. Try each one before you open the answer.

Sections covered on the exam: Fundamental Math and Science and Business Calculations/Analysis, Safety, Health, and Environmental Programs and Risk Management, Hazard Identification and Control, Emergency Preparedness, Fire Prevention, and Security, Health Hazards and Basic Industrial Hygiene, Organizational Communication and Training/Education, Ethics and Professional Conduct.

Question 1 · Fundamental Math and Science and Business Calculations/Analysis
A safety technician reviews a full-shift exposure profile for a parts-washer operator. The operator worked 2 hours at 120 ppm, 3 hours at 60 ppm, and 2 hours at 30 ppm of a solvent vapor, then spent a 1-hour meal break in a clean break room with no exposure. The solvent's 8-hour OEL is 65 ppm. What is the 8-hour TWA, and how does it compare with the OEL?
- A.52.5 ppm, below the OEL
- B.60 ppm, below the OEL
- C.68.6 ppm, above the OEL
- D.70 ppm, above the OEL
Show answer and explanation
Answer: B. 60 ppm, below the OEL
TWA = (120 × 2 + 60 × 3 + 30 × 2 + 0 × 1) / 8 h = 480 ppm-h / 8 h = 60 ppm, which is below 65 ppm. The break hour is counted as zero because there was truly no exposure, so dividing by only the 7 exposed hours (68.6 ppm) overstates the TWA. Simply averaging the three concentrations (70 ppm) ignores how long each one lasted.
Question 2 · Safety, Health, and Environmental Programs and Risk Management
OSHA cites a company's warehouse for blocked exit routes. Three years earlier, a final order cited the same company at another of its warehouses for a substantially similar exit-route violation. Which citation type is MOST likely?
- A.Other-than-serious
- B.Willful
- C.Failure to abate
- D.Repeat
Show answer and explanation
Answer: D. Repeat
A repeat violation is a same or substantially similar violation cited again within 5 years of a prior final order against the same employer, and it can involve a different establishment of that employer. Failure to abate applies when the originally cited condition was never corrected by its abatement date. Willful requires intentional disregard or plain indifference, which the facts do not show.
Question 3 · Hazard Identification and Control
A worker's hand was crushed in a hydraulic press. The injured worker has been given first aid and transported by EMS. What should the safety technician do FIRST in the investigation?
- A.Secure the area and keep the press and scene as they were found
- B.Gather all of the witnesses in one room to compare their accounts
- C.Have maintenance repair the press so production can resume
- D.Write the corrective action list for the supervisor to sign
Show answer and explanation
Answer: A. Secure the area and keep the press and scene as they were found
Once the injured person is cared for, the scene should be secured so physical evidence such as control settings, guard positions, and tool locations is not disturbed. Repairing the press first would destroy the evidence needed to find the cause. Interviewing witnesses together allows accounts to blend, so witnesses should be interviewed separately.
Question 4 · Emergency Preparedness, Fire Prevention, and Security
A convenience store chain has had several robberies during late-night shifts, when one clerk works alone and handles cash. Which combination of measures BEST reduces the risk of violence?
- A.Drop safes with low cash on hand, clear windows, and good lighting
- B.Close the store blinds at night so clerks are less visible
- C.Arm each clerk and train them to resist the attacker during a robbery
- D.Post a zero-tolerance policy statement near the register
Show answer and explanation
Answer: A. Drop safes with low cash on hand, clear windows, and good lighting
Robbery-related violence is reduced by lowering the reward (drop safes, minimal cash), raising visibility and natural surveillance (clear windows, bright lighting), and limiting isolation. Closing the blinds makes the clerk less visible to passersby and police, which increases risk. Resisting a robbery raises the chance of injury.
Question 5 · Organizational Communication and Training/Education
A technician must train a new crew on the safe use of a chemical transfer pump. Most crew members speak Spanish as their first language, and several have limited reading ability in any language. Which approach is MOST effective?
- A.Hand out the English procedure and have workers sign that they read it
- B.Have a bilingual worker translate the written procedure for the crew
- C.Demonstrate the task in Spanish, then have each worker show it back
- D.Show a narrated English video and then give a written quiz in Spanish
Show answer and explanation
Answer: C. Demonstrate the task in Spanish, then have each worker show it back
Training must be delivered in a language and vocabulary workers understand, and for low-literacy workers a hands-on demonstration with a return demonstration verifies understanding without relying on reading. A translated written procedure still depends on reading ability, and a signature confirms only receipt, not comprehension.
Question 6 · Fundamental Math and Science and Business Calculations/Analysis
A technician samples a paint-mixing area where acetone, methyl ethyl ketone (MEK), and toluene are present together and act on the same organ systems. Results are acetone 300 ppm (limit 500 ppm), MEK 80 ppm (limit 200 ppm), and toluene 30 ppm (limit 100 ppm). What is the mixture exposure index, and is the mixture limit exceeded?
- A.410 ppm; not exceeded, as it is under 500 ppm
- B.1.3; the mixture limit is exceeded
- C.0.43; the mixture limit is not exceeded
- D.0.60; not exceeded, as no single ratio reaches 1
Show answer and explanation
Answer: B. 1.3; the mixture limit is exceeded
For additive effects, the index = 300/500 + 80/200 + 30/100 = 0.6 + 0.4 + 0.3 = 1.3, and a sum above 1 means the mixture limit is exceeded. Averaging the three ratios (0.43) or looking only at the largest single ratio (0.60) ignores the combined effect. Adding the concentrations (410 ppm) and comparing them with one chemical's limit is not a valid method.
Question 7 · Safety, Health, and Environmental Programs and Risk Management
Employees in a printing plant report recurring headaches and want an independent evaluation of their workplace. They ask the technician what role NIOSH can play. Which answer is correct?
- A.It can do a health hazard evaluation and recommend controls
- B.It can issue citations and penalties for the conditions
- C.It can adopt an enforceable exposure limit for the plant
- D.It can order the employer to shut down the process
Show answer and explanation
Answer: A. It can do a health hazard evaluation and recommend controls
NIOSH is a research agency that, on request from employees or employers, can conduct health hazard evaluations and recommend controls. It has no enforcement authority, so it cannot cite, penalize, or shut down a process. NIOSH RELs are recommendations, while enforceable PELs come from OSHA.
Question 8 · Hazard Identification and Control
Arriving at the scene of a forklift tip-over in a yard, a technician notices rain starting to fall on fluid trails, tire marks, and a puddle near the truck. Which evidence should be documented FIRST?
- A.The written statements from the yard workers on the shift
- B.The operator's training records kept in the personnel office
- C.The tire marks and fluid trails before the rain washes them away
- D.The maintenance logs and repair orders for the forklift
Show answer and explanation
Answer: C. The tire marks and fluid trails before the rain washes them away
Perishable physical and position evidence such as tire marks, spill patterns, and gauge readings should be photographed and measured first because it can disappear quickly. Paper evidence such as training records and maintenance logs will still be available later. Witnesses should be interviewed soon, but the rain makes the physical evidence the most urgent.
Question 9 · Emergency Preparedness, Fire Prevention, and Security
A parking lot at a manufacturing plant is bordered by tall, dense shrubs and has several dark areas, and employees report feeling unsafe walking to their cars after the late shift. Which CPTED measure BEST addresses this?
- A.Trim shrubs and add lighting to improve natural surveillance
- B.Plant taller hedges to block views of the lot from the road
- C.Close the lot at night and have workers park on the street
- D.Post a sign stating that the lot is used at the owner's risk
Show answer and explanation
Answer: A. Trim shrubs and add lighting to improve natural surveillance
Crime Prevention Through Environmental Design uses natural surveillance, access control, territorial reinforcement, and maintenance. Trimming shrubs and improving lighting removes hiding places and lets people see and be seen. Taller hedges create more concealment, and street parking moves the risk rather than reducing it.
Question 10 · Organizational Communication and Training/Education
After a small ammonia release at a plant, neighbors call the site and local reporters arrive. The cause is still under investigation, and no off-site injuries have been reported. How should the site communicate with the community?
- A.Release the full technical incident file without explanation
- B.Decline all comment until the investigation is fully complete
- C.Share known facts plainly, note unknowns, and update regularly
- D.Assure everyone there was no risk before air data are reviewed
Show answer and explanation
Answer: C. Share known facts plainly, note unknowns, and update regularly
Credible communication with external stakeholders is timely, factual, in plain language, honest about what is not yet known, and followed by regular updates. Saying "no comment" invites rumor, and declaring no risk before the data are reviewed can destroy trust if the data show otherwise.

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