1.   A few minutes of rest, and he recovered his oxygen level, although something within felt attenuated.

2.   Besides discussing ducks, the report also will look at reducing erosion, increasing oxygen levels and improving fishing.

3.   The second allegation was that medical staff allowed the oxygen level to remain above the accepted safety level.

4.   Patrick was grey and blue about the mouth and he appeared to have stopped breathing and his oxygen level was low.

5.   As blood levels of carbon dioxide rise and oxygen levels fall, the hapless sleeper struggles to take a breath.

6.   As carbon dioxide levels fell, oxygen levels would rise, until they reached a point at which any terrestrial life other than mangroves might be endangered.

7.   As the attack progresses, oxygen transfer in the lungs is limited and oxygen levels fall.

8.   At the same time, the low oxygen level causes blood pressure to shoot up.

9.   A fifth, his oxygen level.

10.   A pulse oximeter, which is clipped to a finger or toe, measures blood oxygen levels.