CHST Noise Exposure and Hearing Conservation Programs

Question 1

Under OSHA 29 CFR 1926.52, what is the permissible exposure limit (PEL) for occupational noise averaged over an 8-hour workday?

Accepted Answer

90 dBA TWA

Answer

OSHA's construction noise PEL is 90 dBA as an 8-hour time-weighted average (TWA). The action level triggering a hearing conservation program is 85 dBA TWA. Exposures above 90 dBA require engineering/administrative controls and/or hearing protection.

Question 2

A concrete saw operates at 105 dBA. Using OSHA's 5 dB exchange rate, what is the maximum daily exposure duration allowed at this level?

Accepted Answer

1 hour

Answer

OSHA's 5 dB time-intensity exchange rate means permissible time halves for every 5 dB increase above 90 dBA. At 90 dBA = 8 hrs; 95 dBA = 4 hrs; 100 dBA = 2 hrs; 105 dBA = 1 hr. Workers on this saw are limited to 1 hour per shift without additional controls.

Question 3

Which instrument is used to measure a worker's personal noise dose over the course of a full work shift?

Accepted Answer

Noise dosimeter

Answer

A noise dosimeter is worn by the worker and integrates variable noise exposures over the entire shift to calculate a percent dose or TWA. A sound level meter gives instantaneous readings at a fixed point. An octave band analyzer characterizes frequency content for engineering control design. A vibration meter measures vibration, not sound.

Question 4

An audiometric baseline test reveals that a worker has a 10 dB Standard Threshold Shift (STS) in the 2000–4000 Hz range after 6 months on-site. What is the safety technician's FIRST required action?

Accepted Answer

Notify the worker in writing within 21 days and refit hearing protection to achieve greater attenuation

Answer

OSHA 29 CFR 1910.95 (applied to construction via OSHA guidance) requires that workers be notified in writing within 21 days of an STS determination, and that hearing protection be refitted or upgraded. Removal from noise is not mandated. The STS may or may not be recordable depending on whether it is work-related and permanent.

Question 5

What is the primary purpose of the 'noise reduction rating' (NRR) labeled on hearing protection devices?

Accepted Answer

To allow employers to estimate the degree of noise attenuation in the field

Answer

The NRR is an EPA-standardized laboratory rating used to estimate field attenuation. OSHA instructs employers to derate the NRR by 50% (for earmuffs) or up to 70% (for formable earplugs) to account for real-world fit variability, giving a realistic estimate of protected exposure.

CHST - Construction Health and Safety Technician Practice Test

CHST - Construction Health and Safety Technician Practice Test

CHST Noise Exposure and Hearing Conservation Programs