CIH Hazards & Exposures 2

Question 1

A worker is exposed to benzene at 0.4 ppm TWA over an 8-hour shift. The OSHA PEL for benzene is 1 ppm. Which statement best describes this situation?

Accepted Answer

The exposure is in compliance but the OSHA Action Level of 0.5 ppm has not been exceeded

Answer

The OSHA benzene PEL is 1 ppm TWA and the Action Level is 0.5 ppm; at 0.4 ppm the worker is below both thresholds, so compliance is maintained.

Question 2

Which biological monitoring specimen is MOST appropriate for assessing recent lead exposure in a worker?

Accepted Answer

Blood lead level (BLL)

Answer

Blood lead level is the primary OSHA-mandated biomarker for recent lead exposure because it reflects current absorbed dose.

Question 3

A confined space contains 16% oxygen. How should this atmosphere be classified?

Accepted Answer

Oxygen-deficient; requires supplied-air respirator or SCBA

Answer

OSHA defines an oxygen-deficient atmosphere as less than 19.5% O₂, requiring supplied-air or SCBA before entry.

Question 4

A noise dosimeter shows a worker received a dose of 150% over an 8-hour shift. What is the calculated TWA noise level?

Accepted Answer

Approximately 93.5 dBA

Answer

Using the formula TWA = 16.61 × log(D/100) + 90, a dose of 150% yields approximately 93.5 dBA TWA.

Question 5

Which type of non-ionizing radiation is most associated with photokeratitis ('welder's flash')?

Accepted Answer

Ultraviolet-C (UV-C)

Answer

UV-C (100–280 nm) is most energetic in the ultraviolet range and causes photokeratitis, the painful corneal inflammation known as welder's flash.

CIH - Certified Industrial Hygienist Exam Practice Test