1.   But their levels are dropping dramatically.

2.   But when a manganese plant south of the city closed, those levels dropped dramatically.

3.   Tests were conducted to ascertain whether pollution levels have dropped.

4.   While its petrol-engined equivalent must have unleaded fuel, the diesel catalyser will only become effective when sulphur levels drop.

5.   These are rapidly restored when prolactin levels drop at the end of lactation or more abruptly if lambs are weaned early and the suckling stimulus removed.

6.   Already, lead levels have dropped all over town.

7.   An early cold snap, which lasted for several weeks, caused storage levels to drop sharply.

8.   And the researchers say cholesterol levels drop with tamoxifen use.

9.   Aquifer levels are dropping at the rate of almost a foot a day, said Tammy Valentine, a spokeswoman for the Edwards Aquifer Authority in San Antonio.

10.   As glucose levels drop to normal, the system would shut off.