A person works in a silicone manufacturing industry for thee past 20 years. Since a few years he has stated feeling quite breathless and has cough all the time . His doctor says that this is because of his occupation as he is exposed constantly to silica dust . What must have been the size of the particles to cause such an issue ?

Options

A. PM 3.5
B. PM 2.75
C. PM 5
D. PM 2.5

Answer

To solve the question regarding the size of particles that can cause respiratory issues due to exposure to silica dust in a silicone manufacturing industry, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The individual has been working in a silicone manufacturing industry for 20 years and is experiencing breathlessness and a persistent cough. The doctor attributes these symptoms to exposure to silica dust.

2. **Identifying the Cause**:
- Silica dust is known to be harmful when inhaled, leading to respiratory problems. The size of the particles plays a crucial role in their ability to penetrate the respiratory system.

3. **Researching Particle Sizes**:
- According to health and environmental guidelines, particularly from organizations like the Central Pollution Control Board, particulate matter (PM) is categorized based on size.
- Particles smaller than a certain size can enter the lungs and cause health issues.

4. **Evaluating the Options**:
- The options given are PM 3.5, 2.75, 5, or 2.5 micrometers.
- It is known that particles less than 2.5 micrometers (PM2.5) can be inhaled deeply into the lungs and are not filtered by the body's natural defenses.

5. **Conclusion**:
- Since the question asks for the size of particles that can cause respiratory issues due to inhalation, the correct answer is **2.5 micrometers or less**. This size is significant because it can penetrate the lung tissue and lead to chronic respiratory problems.

### Final Answer:
The size of the particles that can cause such respiratory issues is **2.5 micrometers or less** (Option D).

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