Permissible workplace noise exposure (8-hour shift) In a chemical plant, the commonly accepted maximum continuous noise level for an 8-hour workday is roughly how many decibels?

Introduction / Context:
Occupational noise exposure limits protect workers from hearing loss. Regulatory agencies and standards bodies specify time-weighted average limits tied to exposure duration. Plants must maintain engineering controls and hearing conservation programs to comply.

Given Data / Assumptions:

• Continuous, broadband industrial noise exposure during an 8-hour shift.
• A-weighted decibels are used for human hearing relevance.
• Representative of general regulatory practice.

Concept / Approach:
Many guidelines adopt about 90 dB(A) as the permissible exposure limit for an 8-hour TWA (with exchange rates determining adjustments for other durations). Some standards are stricter (e.g., 85 dB(A) action levels), but 90 dB(A) remains a widely recognised benchmark in exam problems and legacy codes.

Step-by-Step Solution:

Verification / Alternative check:
Hearing conservation guidance commonly triggers protective measures at 85 dB(A) and sets 90 dB(A) as a legal limit in many jurisdictions.

Why Other Options Are Wrong:

Common Pitfalls:
Ignoring the exchange rate (e.g., 3 dB or 5 dB) that changes allowable time with level; ensure dose accounting when noise varies.

Final Answer:
90