Industrial Pollution Control: Gravity settling chambers are used in industries to remove which pollutants from gas streams? Focus on primary particulate removal by gravitational settling (pre-cleaner). Choose the correct option.

What is being asked?
The pollutant type removed by gravity settling chambers used on industrial exhausts.

Given data

• Device: Gravity (gravitational) settling chamber
• Application: Air pollution control

Concept/Approach
Gravity settling chambers slow the gas velocity and provide large cross-sectional area so heavier particles (typically > 50–100 µm) settle out under gravity; they are ineffective for gaseous pollutants.

Step-by-step reasoning
1) Mechanism relies on particle mass → affects dust/ash only.2) Gaseous pollutants (SO₂, NOₓ, CO) require absorption, adsorption, catalytic reduction, or oxidation, not settling.

Common pitfalls
Choosing gaseous pollutants instead of particulates.

Final Answer
Suspended particulate matter (dust/ash)