Free CRST Occupational Hygiene Fundamentals 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?

Accepted Answer

Absorption

Answer

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'?

Accepted Answer

Fumes result from condensation of a vaporized solid, whereas dusts are generated by mechanical action.

Answer

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?

Accepted Answer

A recommended airborne concentration to which nearly all workers may be exposed daily without adverse effect.

Answer

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?

Accepted Answer

To capture and remove airborne contaminants at their point of generation.

Answer

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)?

Accepted Answer

85 dBA

Answer

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.

CRST - Canadian Registered Safety Technician Practice Test

CRST - Canadian Registered Safety Technician Practice Test

Free CRST Occupational Hygiene Fundamentals Questions and Answers