CIH Air Sampling and Instrumentation 5

Question 1

A hygienist samples noise using a personal noise dosimeter. The dosimeter reading after an 8-hour shift is 87%. What is this worker's 8-hour TWA equivalent sound level?

Accepted Answer

Less than 85 dBA

Answer

A dose of 100% equals an 8-hour TWA of 90 dBA (OSHA criterion); 87% dose corresponds to a TWA slightly below 90 dBA, calculated as TWA = 16.61 × log10(D/100) + 90.

Question 2

Which type of air sampling pump is required when sampling in a potentially explosive atmosphere (e.g., solvent vapor above 10% LEL)?

Accepted Answer

Intrinsically safe (IS) certified personal sampling pump

Answer

Intrinsically safe pumps are designed to prevent ignition of flammable atmospheres by limiting electrical energy to levels that cannot cause ignition.

Question 3

The limit of detection (LOD) for an analytical method is defined as the analyte concentration producing a signal equal to:

Accepted Answer

Three times the standard deviation of the blank signal

Answer

LOD is conventionally set at three times the standard deviation of blank measurements (3σ), representing the smallest detectable signal above noise.

Question 4

A hygienist wants to determine area airborne concentrations of a contaminant without disturbing workers. Which sampling approach is most appropriate?

Accepted Answer

Open-face filter cassette placed at a fixed location in the work area

Answer

Open-face cassettes are used for area/general air monitoring to characterize the airborne environment without being placed in a worker's breathing zone.

Question 5

When preparing a sampling train for hydrogen sulfide using NIOSH Method 6013, the collection medium is:

Accepted Answer

Cadmium sulfate-impregnated filter followed by a sulfuric acid impinger

Answer

NIOSH 6013 uses a cadmium sulfate-treated filter to collect H2S as cadmium sulfide for subsequent colorimetric or ion chromatographic analysis.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Air Sampling and Instrumentation 5