Free CRST Industrial Hygiene and Occupational Health Questions and Answers — Questions and Answers
Question 1: What is the primary purpose of a Local Exhaust Ventilation (LEV) system in an industrial setting?
- To provide general comfort cooling for the work area.
- To capture and remove contaminants at their source. (Correct answer)
- To increase the air pressure within a room to keep contaminants out.
- To dilute contaminants by mixing them with fresh air throughout the facility.
Correct answer: To capture and remove contaminants at their source.
LEV systems are designed to capture airborne contaminants at or near their point of generation, preventing them from entering a worker's breathing zone. This is a highly effective engineering control because it removes the hazard before it can spread throughout the workplace. General ventilation, by contrast, only dilutes the contaminant.
Question 2: Which of the following is the best example of an administrative control for reducing noise exposure?
- Providing workers with high-rated hearing protection devices.
- Building a soundproof enclosure around a noisy generator.
- Rotating workers through high-noise and low-noise areas during a shift. (Correct answer)
- Replacing a loud pneumatic tool with a quieter battery-powered model.
Correct answer: Rotating workers through high-noise and low-noise areas during a shift.
Administrative controls involve changing work practices or procedures to limit exposure. Job rotation moves workers out of high-noise areas after a set period, limiting their total daily dose of noise. Providing earplugs is PPE, enclosing machinery is an engineering control, and replacing equipment is substitution.
Question 3: The term 'Threshold Limit Value' (TLV) refers to which of the following?
- A legally enforceable exposure limit set directly by the Canadian federal government.
- The concentration of a substance that is immediately dangerous to life or health (IDLH).
- A guideline published by the ACGIH for recommended occupational exposure levels. (Correct answer)
- The maximum concentration a worker can be exposed to for any length of time without protection.
Correct answer: A guideline published by the ACGIH for recommended occupational exposure levels.
TLVs are guidelines established by the American Conference of Governmental Industrial Hygienists (ACGIH) for airborne substance exposure. While many Canadian jurisdictions adopt or refer to TLVs in their regulations, making them legally enforceable, the term itself originates from the ACGIH as a recommended guideline, not a law.
Question 4: What are the three primary routes of entry for chemical contaminants into the human body in a workplace?
- Inhalation, injection, and radiation.
- Inhalation, skin absorption, and ingestion. (Correct answer)
- Absorption, contact, and exposure.
- Ingestion, injection, and contact.
Correct answer: Inhalation, skin absorption, and ingestion.
The three main pathways for industrial chemicals to enter the body are inhalation (breathing), absorption (through skin or eyes), and ingestion (swallowing). While injection is a possible route, it is far less common in most occupational settings compared to the other three.
Question 5: A direct-reading instrument is most suitable for which of the following sampling applications?
- Collecting a sample on a filter cassette for laboratory analysis.
- Determining a worker's full-shift time-weighted average (TWA) exposure.
- Obtaining an instantaneous measurement of a gas concentration in a specific area. (Correct answer)
- Identifying the precise chemical composition of an unknown substance.
Correct answer: Obtaining an instantaneous measurement of a gas concentration in a specific area.
Direct-reading instruments provide immediate, real-time measurements of a contaminant's concentration. This is ideal for tasks like checking for gas leaks, assessing conditions before entering a confined space, or identifying peak exposure tasks. They are generally not used for collecting samples for later analysis or calculating official 8-hour TWA exposures.
Question 6: Which form of ionizing radiation has the lowest penetrating power and can be stopped by a sheet of paper?
- Alpha particles (Correct answer)
- Beta particles
- Gamma rays
- X-rays
Correct answer: Alpha particles
Alpha particles are relatively large and heavy (two protons and two neutrons) and carry a positive charge. This causes them to interact readily with matter, losing their energy quickly and giving them very low penetrating power. They can be stopped by a simple barrier like paper or the outer layer of human skin.
Free CRST Industrial Hygiene and Occupational Health Questions and Answers
What is the primary purpose of a Local Exhaust Ventilation (LEV) system in an industrial setting?