71.   Some believe it boosts oxygen levels in the blood.

72.   Some scientists also wonder about rising water temperatures and low oxygen levels in the water.

73.   Space stations, like aircraft, are pressurized to maintain proper oxygen levels for the crew.

74.   That was followed by the Cambrian explosion of animal life, which could have been aided by the rising oxygen levels.

75.   The mixing equipment brought the oxygen levels closer together, but in some sections of the South Bethany canal, oxygen levels were still very low.

76.   The reports follow warnings from fisheries officials on the dangers of eating shellfish contaminated by red tide, which depletes oxygen levels in the water.

77.   The suit was not transmitting data on its condition to Mission Control, which normally would allow controllers to monitor oxygen levels and other safety factors.

78.   The study said, however, the so-called reformulated gasoline with the additive has characteristics other than higher oxygen levels that lower pollution from automobiles and light trucks.

79.   The treatment is to increase oxygen levels in his bloodstream and so help repair tissue and nerve damage from frostbite, particularly in feet which are numb and swollen.

80.   The work was ordered because submerged, decaying trees could reduce oxygen levels in the reservoir and promote the growth of harmful algae.