Question

Dust particles most harmful to human respiratory system are the size of

• A. About 1 micron
• B. About 0.5 micron
• C. About 5 micron
• D. About 0.05 micron

Hint:

Respirable dust particles around 1 micron can lead to long-term health issues like silicosis in miners.

Answer 1

The Correct Option is A

Dust particles most harmful to the human respiratory system are those small enough to be inhaled deeply into the lungs, particularly into the alveoli, where they can cause damage or diseases like pneumoconiosis. Particles around 1 micron in size are considered respirable dust, as they can penetrate deep into the lungs. Particles much smaller (e.g., 0.05 micron, option 4) may not settle in the lungs as effectively, while larger particles (e.g., 5 microns, option 3) are often trapped in the upper respiratory tract. Option 0.5 micron (option 2) is close but not the most commonly cited size for maximum harm. Thus, the correct answer is About 1 micron.