1.   Another approach would require ground crews to add a harmless gas to partially filled fuel tanks prior to departure.

2.   Another would add the harmless gas to fuel tanks while in mid-flight as a way to reduce vapors.

3.   That releases a harmless gas, usually nitrogen or argon, that fills the bag.

4.   The drums were found to contain only a harmless gas, but the police evacuated two square blocks while they investigated it.

5.   The Defense Threat Reduction Agency is monitoring the flow of a harmless gas being released over the Salt Lake valley this month for a weather study.