CIH - Certified Industrial Hygienist Air Sampling and Instrumentation Questions and Answers

Question 1

An industrial hygienist is sampling for respirable crystalline silica in a dusty construction environment using a 10-mm nylon cyclone.
To ensure the cyclone correctly separates the respirable fraction according to the ACGIH/ISO/CEN convention, what is the required flow rate and corresponding 50% cut-point?

Accepted Answer

2.5 L/min for a 4.0 µm cut-point

Answer

1.7 L/min for a 5.0 µm cut-point

Answer

2.0 L/min for a 10.0 µm cut-point

Answer

3.0 L/min for a 3.5 µm cut-point

Question 2

A key limitation of using Phase Contrast Microscopy (PCM) via NIOSH Method 7400 for analyzing asbestos samples is its inability to:

Accepted Answer

Differentiate between asbestos and non-asbestos fibers.

Answer

Quantify fibers smaller than 5 µm in length.

Answer

Be used for personal air sampling.

Answer

Achieve a low enough detection limit for clearance sampling.

Question 3

Which of the following direct-reading instruments is most suitable for detecting a broad range of volatile organic compounds (VOCs) at low parts-per-million (ppm) levels and operates by using a high-energy ultraviolet lamp to ionize the target molecules?

Accepted Answer

Photoionization Detector (PID)

Answer

Electrochemical Sensor

Answer

Catalytic Combustion Sensor

Answer

Non-Dispersive Infrared (NDIR) Analyzer

Question 4

An industrial hygienist is setting up a personal sampling pump for an 8-hour TWA sample. According to standard industrial hygiene practice, when must the pump's flow rate be checked with a calibrated flowmeter?

Accepted Answer

At the beginning and end of the shift

Answer

Only at the beginning of the shift

Answer

Only at the end of the shift

Answer

Once per week, if used daily

Question 5

A significant advantage of using passive dosimeters for personal exposure monitoring compared to active sampling methods is that they:

Accepted Answer

Do not require a sampling pump or calibration.

Answer

Provide real-time concentration readings.

Answer

Are suitable for sampling all types of chemical hazards.

Answer

Have higher sampling rates for short-duration tasks.

Question 6

In the context of direct-reading gas monitors, the process of exposing the instrument to a known concentration of a target gas to adjust its response is correctly termed:

Accepted Answer

Calibration (or Span Calibration)

Answer

Zeroing

Answer

Bump Testing

Answer

Field Screening