CIH Air Sampling and Instrumentation 2

Question 1

Which sampling method is most appropriate for collecting a time-weighted average (TWA) sample of a volatile organic compound over an 8-hour shift?

Accepted Answer

Passive diffusion badge sampler

Answer

Passive diffusion badge samplers are designed for TWA sampling over full work shifts without requiring a pump.

Question 2

A personal air sampler pump calibrated at 2.0 L/min drifts to 1.85 L/min by end of shift. What is the most appropriate corrective action for future sampling?

Accepted Answer

Recalibrate the pump before and after each sampling period

Answer

NIOSH recommends calibrating pumps before and after sampling to detect drift and ensure data validity.

Question 3

What does the term 'face velocity' refer to in the context of a laboratory fume hood?

Accepted Answer

The inward air velocity measured at the hood sash opening

Answer

Face velocity is the inward air velocity measured at the plane of the open sash, typically 80–120 fpm for adequate containment.

Question 4

Which instrument principle is used in a flame ionization detector (FID) for measuring total hydrocarbons?

Accepted Answer

Ionization of compounds in a hydrogen flame creating a measurable current

Answer

FIDs burn sampled air in a hydrogen flame; organic compounds produce ions that generate a current proportional to carbon concentration.

Question 5

When sampling for respirable crystalline silica using a 10-mm nylon cyclone, the recommended sample flow rate is:

Accepted Answer

1.7 L/min

Answer

The 10-mm nylon cyclone must be operated at 1.7 L/min to achieve the ISO/ACGIH respirable particle size-selective criterion.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Air Sampling and Instrumentation 2