Why was hydrogen a poor choice for blimps in the 1960s

Hydrogen is the earth’s lightest element, and it can be obtained easily and inexpensively, but its flammability makes it unacceptable for manned airship operations.Dozens of hydrogen airships were destroyed by fire, and no American airship has been inflated with hydrogen since the crash of the U.S. Army airship Roma in 1922.  The use of hydrogen as a lifting gas for passenger airships was completely abandoned by the late 1930s.

the andes or andean mountains (spanish: cordillera de los andes) are the longest continental mountain range in the world, forming a continuous highland along the western edge of south america. this range is about 7,000 km (4,300 mi) long, about 200 to 700 km (120 to 430 mi) wide (widest between 18° south and 20° south latitude), and of an average height of about 4,000 m (13,000 ft). the andes extend from north to south through seven south american countries: venezuela, colombia, ecuador, peru, bolivia, chile and argentina.

from wikipedia

hope this !

this question shoud be under spanish category, not