What are the following diseases and what are they due to ?
(i) Asphyxiation (i) Pneumoconiosis (iii) Black foot (iv) Methemoglobinemia

Explanation

To answer the question regarding the diseases and their causes, we will discuss each disease one by one.

### Step-by-Step Solution:

1. **Asphyxiation**:
- **Definition**: Asphyxiation is a condition that occurs when there is a lack of oxygen in the blood, leading to suffocation.
- **Cause**: It is primarily caused by oxygen starvation, which can occur when a person is in an environment with a high concentration of carbon dioxide (CO2) or carbon monoxide (CO). Specifically, asphyxiation can happen when the concentration of CO2 exceeds 75 parts per million (ppm) or CO exceeds 750 ppm.

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