mold in HVAC systems 2

https://getfieldstonecellarmoldworld.moderncairn.com/posts/fieldstone-cellar-mold-understanding-the-risks-and-remediation-strategies-for-historic-homes

Mold in HVAC systems often hides in dark, damp ductwork and around cooling coils, sending spores through vents every time the heat or AC kicks on. This can trigger allergies and foul, musty smells throughout a building.