What is the maximum permissible limit of daily exposure to noise level without causing damage to hearing?
**Core Concept**
The maximum permissible limit of daily exposure to noise level without causing damage to hearing is a critical concept in occupational health and safety. The National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) have established guidelines to prevent noise-induced hearing loss. The permissible exposure limit (PEL) for noise is a measure of the maximum sound level that an employee can be exposed to without suffering hearing damage.
**Why the Correct Answer is Right**
The correct answer is based on the concept of decibels (dB) and the effects of noise exposure on hearing. Prolonged exposure to sound levels above 85 dB can cause permanent hearing loss. The threshold limit value (TLV) for noise is 90 dB for an 8-hour time-weighted average (TWA) exposure. To calculate the maximum permissible limit, we use the following formula: Time (in hours) x 90 dB / 8 hours = 90 dB. This means that an employee can be exposed to 90 dB for 8 hours without suffering hearing damage.
**Why Each Wrong Option is Incorrect**
**Option A:** 40 dB is too low to cause hearing damage, as it is below the threshold for hearing loss.
**Option B:** 110 dB is above the permissible exposure limit and can cause hearing damage in a short period.
**Option C:** 60 dB is not a valid answer, as it is not a commonly used threshold for hearing damage.
**Clinical Pearl / High-Yield Fact**
To remember the maximum permissible limit, use the mnemonic "90 dB for 8 hours." This will help you recall the correct answer in a high-stress exam situation.
**Correct Answer: C. 90 dB.**