CIH Physical Agents: Noise and Radiation 2

Question 1

A worker is exposed to 95 dBA for 4 hours and 85 dBA for 4 hours in an 8-hour shift. What is the noise dose using OSHA's permissible exposure limits?

Accepted Answer

75%

Answer

At 95 dBA the PEL is 4 hours (C1/T1 = 4/4 = 1.0) and at 85 dBA the PEL is 16 hours (C2/T2 = 4/16 = 0.25), giving a total dose of 75%.

Question 2

Which type of hearing protection device typically provides the highest noise reduction when properly fitted?

Accepted Answer

Foam earplugs

Answer

Properly fitted foam earplugs generally achieve the highest noise reduction ratings (NRR), often 29–33 dB, because they expand to fill the ear canal.

Question 3

What is the primary biological mechanism by which excessive noise causes permanent hearing loss?

Accepted Answer

Destruction of hair cells in the organ of Corti

Answer

Excessive noise destroys the outer hair cells in the organ of Corti, which cannot regenerate, causing permanent sensorineural hearing loss.

Question 4

Under OSHA 29 CFR 1910.95, at what action level must employers implement a Hearing Conservation Program?

Accepted Answer

85 dBA TWA

Answer

OSHA requires a Hearing Conservation Program when worker TWA exposures equal or exceed 85 dBA (the action level).

Question 5

A radiation worker receives 2 mSv from external gamma exposure and 3 mSv from internal deposition of a radionuclide in one year. What is the total effective dose equivalent?

Accepted Answer

5 mSv

Answer

Total effective dose equivalent is the sum of external and internal dose components: 2 + 3 = 5 mSv.

CIH - Certified Industrial Hygienist Exam Practice Test

CIH - Certified Industrial Hygienist Exam Practice Test

CIH Physical Agents: Noise and Radiation 2