What should be done if cabin air quality is compromised during a flight?

When cabin air quality is compromised during a flight, preparing to use oxygen masks and informing passengers is crucial for ensuring safety. This action is a direct response to potential decreases in oxygen levels or the presence of harmful fumes. Using oxygen masks allows both crew and passengers to maintain adequate oxygen supply, which is vital for consciousness and overall health during adverse conditions.

Informing passengers helps them stay calm and prepared for an emergency situation. Communication is key to ensuring that everyone is aware of what actions need to be taken, which can significantly reduce panic and confusion.

Other options, while they may seem relevant, do not directly address the immediate need for ensuring the safety and health of those onboard. For instance, patching the air supply system may not be feasible during a flight and could take considerable time, during which passengers would still be at risk. Adjusting cabin pressure is also an advanced procedure that may not be directly related to air quality and could lead to its own complications. Closing off sections of the cabin might isolate affected individuals but does not provide a necessary solution for ensuring everyone can breathe safely. Thus, preparing for the use of oxygen masks and communicating effectively is the safest and most immediate response to compromised cabin air quality.