Exam Question

### (a) Gases Usually Found Inside Enclosed Spaces (6 Marks)
An enclosed space is defined as a space with limited openings for entry and exit, inadequate ventilation, and not designed for continuous worker occupancy. The atmosphere within can be hazardous due to the presence or absence of certain gases:
1. **Oxygen (O₂) Deficiency:**
* **Cause:** Normal atmospheric oxygen (~20.9%) can be depleted through processes like oxidation (rusting of steel), microbial action (decomposition of organic matter), combustion, or displacement by other gases (e.g., inert gas from purging).