Ohio Industrial Hygienist Exam Practice

Ohio Industrial Hygienist Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2025|2026 Q&A | Instant Download Pdf

• What is the permissible exposure limit (PEL) for benzene according to

OSHA?

• 0.5 ppm
• 1 ppm
• 1 ppm (8-hour TWA)
• 5 ppm

Rationale: OSHA's PEL for benzene is 1 ppm averaged over an 8-hour work

shift.

• Which instrument is commonly used to measure airborne particulate

concentrations?

• Colorimeter
• Gravimetric sampler 1 / 4

• Gas detector tube
• Sound level meter

Rationale: Gravimetric samplers collect airborne particles on a filter, which

is weighed to determine concentration.

• What is the main route of entry for asbestos fibers in occupational

settings?

• Ingestion
• Inhalation
• Skin absorption
• Injection

Rationale: Asbestos fibers primarily enter the body through inhalation,

leading to lung diseases.

• Which of the following noise levels requires the use of hearing

protection according to OSHA?

• 75 dBA
• 80 dBA
• 85 dBA
• 85 dBA (8-hour TWA)

Rationale: OSHA requires hearing protection for workers exposed to noise

levels at or above 85 dBA over an 8-hour TWA.

5. The threshold limit value (TLV) represents:

• Maximum legal exposure limit 2 / 4

• A recommended airborne concentration not likely to cause harm
• Immediate danger to life limit
• None of the above

Rationale: TLVs are guidelines published by ACGIH indicating safe exposure

levels.

• Which of the following is an example of a chemical asphyxiant?
• Carbon dioxide
• Carbon monoxide
• Ammonia
• Sulfur dioxide

Rationale: Carbon monoxide binds to hemoglobin, reducing oxygen

transport, making it a chemical asphyxiant.

• In a confined space, the presence of which gas is most immediately

life-threatening?

• Methane
• Carbon dioxide
• Carbon monoxide
• Nitrogen

Rationale: Carbon monoxide can quickly cause hypoxia by binding to

hemoglobin.

• What is the most common unit used to express airborne

concentrations of gases? 3 / 4

• mg/mL
• ppm
• ppmv
• ppb

Rationale: Parts per million (ppm) is commonly used for measuring gas

concentrations in air.

• Which of the following best describes a synergistic effect?
• Two chemicals cancel each other
• One chemical reduces the effect of another
• Combined effect greater than the sum of individual effects
• Effects are independent

Rationale: A synergistic effect occurs when two substances produce a

greater effect together than individually.

10. The main purpose of a respirator fit test is to:

• Train employees
• Filter air
• Ensure a proper seal for protection
• Measure air quality

Rationale: Fit testing ensures that the respirator seals correctly and

provides adequate protection.

• Which type of ventilation is most effective at removing airborne

contaminants at the source?

• / 4