ASP - Associate Safety Professional Industrial Hygiene and Health Questions and Answers 1 — Questions and Answers
Question 1: An industrial hygienist is evaluating a chemical exposure in a manufacturing facility. The OSHA Permissible Exposure Limit (PEL) for the substance is 20 ppm as an 8-hour TWA. The ACGIH Threshold Limit Value (TLV) is 10 ppm as an 8-hour TWA. Which of the following statements is the most accurate characterization of these exposure limits?
- The PEL is a legally enforceable limit, while the TLV is a recommended guideline that represents a more protective level. (Correct answer)
- The TLV is the legal limit that must be met, while the PEL is a less stringent, outdated guideline.
- Both the PEL and TLV are legally enforceable standards, but the more stringent of the two must always be followed.
- The PEL is based purely on health factors, whereas the TLV takes into account economic and technical feasibility.
Correct answer: The PEL is a legally enforceable limit, while the TLV is a recommended guideline that represents a more protective level.
OSHA's Permissible Exposure Limits (PELs) are legal limits for employee exposure to chemical substances. In contrast, the American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) are recommendations and guidelines, not legal standards. TLVs are often more stringent and updated more frequently than PELs, reflecting more current scientific data, and are considered a recognized standard of care.
Question 2: A safety professional is implementing a local exhaust ventilation (LEV) system to control airborne contaminants from a welding operation. Which of the following are the five essential components of a typical LEV system?
- A filter, a pump, tubing, a collection bag, and an alarm
- An intake valve, a pre-filter, a fan, a silencer, and a discharge pipe
- A hood, ducts, an air cleaner, a fan, and an exhaust stack (Correct answer)
- A sensor, a control panel, a damper, a motor, and a chimney
Correct answer: A hood, ducts, an air cleaner, a fan, and an exhaust stack
A standard local exhaust ventilation (LEV) system consists of five basic elements: a hood to capture the contaminant at the source; ducts to transport the air; an air cleaning device to remove the contaminant; a fan to move the air through the system; and an exhaust stack to discharge the cleaned air.
Question 3: According to the hierarchy of controls, which of the following is considered the MOST effective method for controlling a workplace hazard?
- Implementing a job rotation schedule
- Requiring the use of personal protective equipment (PPE)
- Physically removing the hazard from the workplace (Correct answer)
- Installing a ventilation system
Correct answer: Physically removing the hazard from the workplace
The hierarchy of controls ranks hazard control methods from most effective to least effective. The order is: Elimination (physically removing the hazard), Substitution, Engineering Controls, Administrative Controls, and finally Personal Protective Equipment (PPE). Elimination is the most effective because it removes the hazard entirely.
Question 4: An employee's 8-hour time-weighted average (TWA) noise exposure is measured at 87 dBA. According to OSHA's occupational noise exposure standard (29 CFR 1910.95), what is the employer's primary obligation?
- Immediately implement engineering controls to reduce the noise level.
- Mandate the use of hearing protection for the exposed employee.
- Provide a baseline audiogram and annual training as part of a Hearing Conservation Program. (Correct answer)
- No action is required because the exposure is below the Permissible Exposure Limit (PEL) of 90 dBA.
Correct answer: Provide a baseline audiogram and annual training as part of a Hearing Conservation Program.
OSHA's noise standard requires employers to implement a Hearing Conservation Program (HCP) when employee noise exposures equal or exceed an 8-hour TWA of 85 dBA, which is the Action Level. Key elements of the HCP include noise monitoring, audiometric testing (baseline and annual), providing hearing protection, training, and recordkeeping. While the exposure is below the 90 dBA PEL, it exceeds the 85 dBA Action Level, triggering the requirement for an HCP.
Question 5: To assess a worker's risk of heat stress, an industrial hygienist uses a Wet Bulb Globe Temperature (WBGT) meter. This instrument is designed to provide a composite temperature reading by directly measuring or calculating which three environmental factors?
- Air temperature, barometric pressure, and wind speed
- Radiant heat, humidity, and air temperature (Correct answer)
- Solar load, air velocity, and ambient temperature
- Heat index, dew point, and air movement
Correct answer: Radiant heat, humidity, and air temperature
The Wet Bulb Globe Temperature (WBGT) index is a measure of heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). The WBGT is composed of measurements from a dry bulb thermometer (air temperature), a wet bulb thermometer (humidity/evaporative cooling), and a black globe thermometer (radiant heat). It is the most widely used index for assessing heat stress in occupational settings.
Question 6: In a free field, away from any reflecting surfaces, what is the theoretical reduction in sound pressure level every time the distance from a point source of noise is doubled?
- 3 dB
- 10 dB
- 12 dB
- 6 dB (Correct answer)
Correct answer: 6 dB
This question refers to the inverse-square law as it applies to acoustics. In a free field (an environment with no reflective surfaces), the sound pressure level from a point source decreases by 6 decibels (dB) for each doubling of the distance from that source.
ASP - Associate Safety Professional Industrial Hygiene and Health Questions and Answers 1
An industrial hygienist is evaluating a chemical exposure in a manufacturing facility.
The OSHA Permissible Exposure Limit (PEL) for the substance is 20 ppm as an 8-hour TWA.
The ACGIH Threshold Limit Value (TLV) is 10 ppm as an 8-hour TWA.
Which of the following statements is the most accurate characterization of these exposure limits?