黒煙

1. Origins, structure, and basic meaning

• Structure: 黒煙 (こくえん) is black smoke often produced by incomplete combustion. It appears as observed subject and simulated hazard.
• Basic usage: Black smoke rises beyond a warehouse roof; a drill assumes black smoke and adopts a low posture.

2. Common pitfalls and similar expressions

• Smoke observed at a scene and smoke assumed in training
  • The first が is an actual phenomenon; を想定して sets a simulation. Do not read the drill as a real fire report.