I keep sweeping up fine white powder under my vents and it keeps coming back. What is it?

5. When Old Plaster, Popcorn Ceilings, or Paint Start Shedding Into Your Vents
Old plaster, popcorn ceilings, and degrading paint can also contribute to fine white dust accumulation. As these materials age, they can begin to crumble and flake, particularly when subjected to the vibrations and airflow from an active HVAC system.
Inspect areas around vents for signs of peeling or flaking materials. The presence of tiny, white flakes on surfaces near vents can indicate that these materials are shedding. In some cases, the vibrations from the HVAC system can exacerbate this shedding, leading to increased dust accumulation. Addressing this issue may involve repairing or replacing the affected materials.
6. Harmless House Dust or Something More Serious?
While many cases of fine white dust are harmless, it’s important to consider more serious possibilities. Household dust is a mix of various particles, including skin cells, hair, and fabric fibers, which are generally non-toxic. However, if the dust is accompanied by unusual symptoms such as persistent coughing, respiratory irritation, or allergic reactions, it may warrant further investigation.
Potentially harmful sources of dust can include mold spores, chemical residues from cleaning products, or hazardous materials like asbestos. Conducting air quality tests or consulting with professionals can help determine if the dust in your home poses any health risks.