Noticed these dark grey bands forming along the edges of the carpet in every room near the baseboards. We don’t wear shoes inside, but the perimeter keeps turning black no matter how much I vacuum. Is

staircases where airflow is restricted. The particles are usually very small, often less than 0.1 microns, which is much smaller than what a standard vacuum cleaner can capture, making these lines particularly difficult to clean.

Filtration soiling occurs when air is forced through gaps or seams in a building’s structure, such as those around doors and baseboards. As air moves through these gaps, it carries with it tiny particles that are deposited onto carpet fibers.

The process is similar to