Why is it dangerous to sleep in a closed room with a coal fire burning?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Environment**: When you sleep in a closed room, the air supply is limited. This means that the oxygen available for breathing is reduced.

*Hint: Think about how air circulation works in a closed space.*

2. **Coal Fire Burning**: When coal burns, it produces carbon monoxide (CO) gas as a byproduct. This gas is colorless and odorless, making it difficult to detect.

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