Invisible combustion gas that can cause serious injury or death.
Immediate principle
Do not continue ordinary DIY troubleshooting when this hazard is plausible. Move to the relevant emergency, utility or qualified-professional path.
Document from safety
Only record what can be observed without approaching, opening or energizing the hazardous area.
After the hazard is controlled
The original building symptom still needs a source investigation and verification plan.
Observe→Distinguish→Control source→Verify
Living dossierPublished knowledge is connected and improved as new cases, images and outcomes are added. Updated 2026-07-20.
