Modern breathing apparatus generally falls into two categories based on how they handle your exhaled breath:
The history of firefighting BA highlights some strange early attempts: breathing apparatus
Breathing apparatus (BA) technology has evolved from crude 19th-century mining tubes to sophisticated life-support systems used by firefighters, divers, and rescue teams. Whether it’s an (Self-Contained Breathing Apparatus) used in fires or SCUBA for the ocean, these devices allow humans to operate in "IDLH" (Immediately Dangerous to Life or Health) environments. 1. The Core Systems: Open vs. Closed breathing apparatus
