How does CACS manage cabin oxygen levels?

CACS, or Cabin Atmosphere Control System, manages cabin oxygen levels primarily through ensuring adequate pressurization and airflow. At cruising altitudes, the outside atmospheric pressure is significantly lower than at sea level, which affects the amount of oxygen available in the cabin.

To combat this, CACS regulates the cabin pressure to simulate a lower altitude environment where oxygen levels are sufficient for passenger and crew comfort and safety. By maintaining this pressurized environment and ensuring proper airflow, the system mixes fresh air with recirculated air to keep oxygen concentrations at safe levels. This approach is essential for preventing hypoxia (a deficiency in the amount of oxygen reaching the tissues) that can occur if oxygen levels drop too low.

Other options, such as maintaining a consistent cabin temperature, restricting air circulation, or relying solely on specialized oxygen masks, do not directly address the overall management of oxygen levels in the cabin. While temperature and air circulation can contribute to overall comfort and air quality, the critical factor for oxygen management is maintaining adequate pressurization and airflow.