Free CRST Occupational Hygiene Fundamentals Questions and Answers — Questions and Answers
Question 1: An employee working with powdered pigments frequently has dust on their hands and forearms but wears a standard dust mask. Which route of entry is MOST likely for a chemical to enter their bloodstream, besides inhalation?
- Ingestion
- Absorption (Correct answer)
- Injection
- Puncture
Correct answer: Absorption
Absorption through the skin is a primary route of entry for many chemicals. While inhalation is often the most common workplace route, direct contact with skin can allow substances to pass into the bloodstream, especially with prolonged contact or if the skin's barrier is compromised.
Question 2: In occupational hygiene, what is the fundamental difference between 'fumes' and 'dusts'?
- Fumes are liquid droplets, whereas dusts are solid particles.
- Fumes are larger than 2.5 micrometers, whereas dusts are smaller.
- Fumes result from condensation of a vaporized solid, whereas dusts are generated by mechanical action. (Correct answer)
- Fumes are always toxic, whereas dusts are considered nuisance particles.
Correct answer: Fumes result from condensation of a vaporized solid, whereas dusts are generated by mechanical action.
Dusts are solid particles created by mechanical processes like grinding, cutting, or crushing. Fumes are extremely fine solid particles formed when a material that is normally a solid (like metal) is vaporized by high heat and then condenses in cool air.
Question 3: A safety technician is reviewing a Safety Data Sheet (SDS) for a new solvent. They see a Threshold Limit Value (TLV) listed. What does the TLV, as established by the ACGIH, represent?
- A mandatory federal exposure limit that cannot be legally exceeded.
- The concentration at which a worker will first begin to feel adverse health effects.
- The maximum legally permissible concentration averaged over a 15-minute period.
- A recommended airborne concentration to which nearly all workers may be exposed daily without adverse effect. (Correct answer)
Correct answer: A recommended airborne concentration to which nearly all workers may be exposed daily without adverse effect.
Threshold Limit Values (TLVs) are guidelines developed by the American Conference of Governmental Industrial Hygienists (ACGIH) as recommendations for airborne concentrations. They represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day over a working lifetime without adverse health effects. They are not legal standards like OSHA's PELs.
Question 4: A local exhaust ventilation (LEV) system is installed to control welding fumes at the source. Which of the following is the primary purpose of this type of ventilation?
- To cool the general work area for thermal comfort.
- To dilute the contaminant concentration throughout the entire facility.
- To capture and remove airborne contaminants at their point of generation. (Correct answer)
- To provide a continuous supply of fresh, breathable air to the entire building.
Correct answer: To capture and remove airborne contaminants at their point of generation.
The primary purpose of a local exhaust ventilation (LEV) system is to capture airborne contaminants at or very near the source before they can disperse into the wider workplace environment and be inhaled by workers.
Question 5: In most Canadian jurisdictions, when noise exposure levels are measured to determine if a hearing conservation program is needed, what is the typical action level for an 8-hour time-weighted average (TWA)?
- 75 dBA
- 90 dBA
- 100 dBA
- 85 dBA (Correct answer)
Correct answer: 85 dBA
Most Canadian occupational health and safety regulations use an 8-hour time-weighted average exposure limit of 85 dBA. Exposure at or above this level typically requires the employer to implement a hearing conservation program, which includes noise measurement, engineering controls, administrative controls, hearing protection, and training.
Question 6: Which of the following is a primary goal of an occupational hygiene program within an organization?
- To respond to workplace injuries after they occur.
- To ensure compliance with building fire codes.
- To anticipate, recognize, evaluate, and control health hazards in the workplace. (Correct answer)
- To manage employee payroll and benefits related to health.
Correct answer: To anticipate, recognize, evaluate, and control health hazards in the workplace.
The core function of occupational hygiene is the systematic process of anticipating potential health hazards, recognizing existing ones, evaluating the extent of exposure, and controlling those hazards to protect worker health.
Free CRST Occupational Hygiene Fundamentals Questions and Answers
An employee working with powdered pigments frequently has dust on their hands and forearms but wears a standard dust mask.
Which route of entry is MOST likely for a chemical to enter their bloodstream, besides inhalation?