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 silica dust particles that can cause respiratory issues, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
- A person 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 at the workplace.

2. **Identifying the Cause**:
- Silica dust is known to cause respiratory problems, particularly when inhaled over long periods.
- The symptoms mentioned (breathlessness and cough) are common indicators of respiratory issues caused by inhaling fine particulate matter.

3. **Researching Particle Sizes**:
- Particulate matter (PM) is categorized based on size. Common classifications include PM10, PM2.5, and PM1.
- PM10 refers to particles with a diameter of 10 micrometers or less, while PM2.5 refers to particles with a diameter of 2.5 micrometers or less.

4. **Consulting Health Guidelines**:
- According to the Central Pollution Control Board (CPCB), particulate matter that is 2.5 micrometers or smaller (PM2.5) is particularly harmful to human health.
- These fine particles can penetrate deep into the lungs and even enter the bloodstream, leading to significant health issues.

5. **Conclusion**:
- Based on the information from health guidelines and the nature of the symptoms, the size of the silica dust particles that could cause such respiratory problems is PM2.5 or smaller.

### Final Answer:
The size of the particles that must have caused the respiratory issues is **PM2.5 or less**.

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