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Physical Agents: Noise and Radiation Flashcards

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  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?

    Answer: 75%

    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%.

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

    Answer: Foam earplugs

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

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

    Answer: Destruction of hair cells in the organ of Corti

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

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

    Answer: 85 dBA TWA

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

  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?

    Answer: 5 mSv

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

  6. Which ionizing radiation type has the greatest penetrating power in tissue?

    Answer: Gamma rays

    Gamma rays are high-energy electromagnetic radiation that can penetrate deeply through the body and require dense shielding materials like lead or concrete.

  7. The NIOSH recommended exposure limit (REL) for noise uses an exchange rate of 3 dB, whereas OSHA uses 5 dB. What does this mean practically?

    Answer: NIOSH halves allowable exposure time for every 3 dB increase in level

    With a 3 dB exchange rate, NIOSH halves the allowable duration for every 3 dB increase in level, which is more protective than OSHA's 5 dB exchange rate.