M-20 provides oxygen for how long?

The M-20 oxygen self-rescuer is designed to provide a safe and reliable source of oxygen for miners in the event of a hazardous situation, such as smoke or toxic gas exposure. It is specifically constructed to offer a duration of approximately 10 minutes of breathable oxygen during such emergencies. This timeframe is critical, allowing miners sufficient time to navigate to safety or reach a breathable environment. The design prioritizes the needs of emergency escape, making the 10-minute supply both practical and effective in life-threatening situations. The duration is based on estimates of average human breathing rates and the need to ensure that individuals have a reasonable amount of time to evacuate effectively, thus supporting the chosen answer.