The next level, called air-dry, occurs at 1000 bar suction.

The lowest levels occur in infancy and old age.

However such high levels of sodium rarely occur without severe coexisting medical conditions.

Higher levels of CO occur in areas with heavy traffic congestion.

"In the 1990's, it's amazing that this level of fraud can occur," he said.

The highest levels occur during sleep and shortly after you wake up.

High levels can occur briefly after a long-distance run or as the result of an inflamed prostate.

Evidence was presented indicating that such a level of purity could not occur by accidental means.

Typically, this level of impairment occurs in people who are already hospitalized with heart failure.

Their three distinct levels of development usually occur in varying habitats.