ABSTRACT
Sewers are dangerous because they are confined spaces containing biologically active material.
In this book, the term “confined space” is used for an enclosed area or restricted space that
1. Is not designed for people to work in continuously 2. Has limited or restricted means of entry or exit 3. May be hazardous to any person entering it due to a. Its design, construction, or location b. Its atmosphere c. The materials or substances in it d. Any other conditions relating to it
Confined spaces are notorious for causing fatalities through oxygen deficiency, explosive gases such as methane, or toxic gases such as hydrogen sulfide.
