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

dander, pollen, and smoke from candles or fireplaces. In urban areas, soot from car exhaust or industrial pollution can also play a role.
Cooking fumes and volatile organic compounds (VOCs) from household cleaning products or new furniture can also contribute to the problem. These particles are often too small to be seen with the naked eye but can accumulate over time, especially in areas with limited ventilation.
4. When Dark Carpet Edges Might Indicate Mold Instead
While filtration soiling is a common cause of dark carpet edges, there are instances