When oxygen levels are high, some individuals may be found in deep water.

"What was the oxygen level like in your room this afternoon?"

All patients had low oxygen levels and improved with treatment.

The person's oxygen level can be read on the display.

Remember, the oxygen level here at the axis is still very low.

How low a person's oxygen level in their blood drops during those times.

Farther east the oxygen levels were higher, though still low.

Oxygen levels are falling because there isn't enough plant life left.

The air's rich oxygen level made it seem as if you could keep going well past the horizon.

The obese men also had lower oxygen levels in their blood.