1.   Airlines also want to use another technology, known as explosive trace detection, to help meet the requirement, Wascom said.

2.   But their ability to pick up explosive traces on people is far more limited.

3.   The San Francisco airport was the first in the nation to test the explosive trace detector, Wilson said.

4.   Then the paper is inserted into a hole in the explosive trace detector.

5.   To investigators the explosive traces were certainly significant, but hardly conclusive.