Consumer fireworks, small arms cartridges, and distress flares classified under Division 1.4 are characterized primarily by which hazard profile during transport?

1. They present no significant blast hazard, and explosive effects are largely confined to the package
2. They detonate instantaneously with intense shockwaves capable of collapsing adjacent bridge structures
3. They release dense clouds of highly toxic systemic blood poisons upon combustion
4. They spontaneously ignite upon contact with ambient humidity at room temperature