The OXD-01 enables continuous monitoring of atmospheric oxygen levels. In confined rooms and work areas which have the possibility of reduced oxygen levels this can be of life saving importance. The monitor gives Alarm indication warnings at two levels:  1) An early warning when Oxygen falls below 20% signifies caution. 2) When the oxygen level falls below 19.5 %, a Danger alarm is activated so that appropriate action may be taken.  The alarm conditions are indicated by two LEDs with an additional beeper for the Danger level. The battery backup provided will last for a day in case of power failure.