Guessing the problem with the air horn is in part due to how directional it is? I understand wanting to avoid firing a gun, an explosive. But my mind recalls

Guessing the problem with the air horn is in part due to how directional it is? I understand wanting to avoid firing a gun, an explosive. But my mind recalls putting dry ice in a 2-liter soda bottle containing already hot water. Lid goes on quickly and tightly.... Legal? Not sure. Definitely gives you shotgun-level decibels though. Not at all directional.