Units for reporting noise pollution levels in a plant Noise levels in chemical and process plants are typically expressed in which unit?

Introduction / Context:
Quantifying noise is essential for compliance with occupational health standards and for designing controls. The unit used must reflect how humans perceive sound intensity across frequencies and levels.

Given Data / Assumptions:

• Industrial environment with machine noise, compressors, fans, and pumps.
• Standard human-centric metric is required.

Concept / Approach:
The decibel (dB), often A-weighted as dB(A), is a logarithmic unit that relates sound pressure level to a reference pressure and approximates human hearing sensitivity. By contrast, hertz (Hz) measures frequency, not level, and roentgen is a radiation exposure unit, unrelated to acoustics.

Step-by-Step Solution:

Verification / Alternative check:
Standards for permissible exposure and environmental noise ordinances uniformly specify limits in dB or dB(A).

Why Other Options Are Wrong:

Common Pitfalls:
Reporting levels without weighting (A, C, or Z). For human hearing impacts, dB(A) is typically required.

Final Answer:
decibel