If you’re seeing fine white powder under your vents that keeps coming back, it’s usually one of a few common things:
1. Dust mixed with household debris
- Vents circulate air, and tiny dust particles can accumulate as a white, powdery layer.
- This is normal, especially if you have forced-air heating/cooling.
2. Drywall or plaster dust
- If your home is newer or recently renovated, drywall dust can settle in vents and reappear when airflow blows it out.
3. Mold or mildew spores
- Some molds appear white and powdery.
- Check for musty odors or visible growth near vents, which could indicate moisture problems.
4. Pest-related residue
- Certain insects (like powderpost beetles) or rodent droppings can look like fine white powder, though this is less common.
How to check and fix it
- Vacuum and clean vents – Use a HEPA filter vacuum.
- Inspect ductwork – If dust returns quickly, ducts may be dirty.
- Check humidity – High moisture encourages mold.
- Replace filters – Ensure HVAC filters are clean and rated for fine dust.
- Monitor for pests – Look for droppings or other signs of infestation.
⚠️ If you see mold, pests, or a persistent unusual substance, consider a professional inspection—especially for your HVAC system.
If you want, I can give a step-by-step guide to identify exactly what the white powder is and how to stop it from coming back safely.
Do you want me to do that?
