A system includes a nasal cannula having a flexible tube configured to transmit oxygen gas to a user, an optical fiber coupled to the nasal cannula and configured to transmit light having a frequency spectrum range at least including that of light resulting from combustion of the nasal cannula while transmitting the oxygen gas to the user, a detector operatively coupled to the optical fiber and configured to detect the light transmitted through the optical fiber, and a valve. The valve is configured to be actuated to interrupt the transmission of the oxygen gas to the user through the nasal cannula in response to a signal from the detector.
