What are these marks around the edge of your upstairs rooms?! Many customers assume it’s where they haven’t vacuumed the edge of the carpets well enough. Actually these marks are where air filters from the floor boards below and out through the edge of the carpet. The carpet literally acts as a filter leaving oily deposits from the polluted air on the carpet pile. They are only usually seen in upstairs rooms because downstairs floors are typically less prone to draught and often made of concrete - draught free. The same greasy air filtration marks are typically seen at the bottom of airing cupboard doors. The air floors through the gap at the bottom of the door using the carpet as a filter. These can be very tricky to remove but it is possible with the right techniques. The first photos show examples of these marks. The second photo shows successful removal of the marks.