The oft-quoted claim that "80% of the dirt entering a building comes in on people's feet" is a long-standing industry rule of thumb, not a figure stated in the British Standard for entrance flooring (BS 7953) itself. The standard sets out how to select, install and size entrance matting to reduce soil and moisture ingress, without quantifying an exact percentage — so treat the 80% figure as directional industry consensus, not a lab-tested number for your building.
Where the '80%' figure actually comes from
The figure is widely repeated across the entrance-matting and cleaning industry as a rule of thumb that the large majority of dirt and moisture entering a building arrives via footfall rather than any other route. We could not trace it to a single, citable primary study, or to BS 7953 itself — different industry sources quote figures ranging from roughly 70% up to 85% or more. Treat it as a directional industry consensus rather than a precise, measured statistic for any one building.
What BS 7953 actually says
BS 7953:1999, Entrance flooring systems — Selection, installation and maintenance, is the genuine British Standard covering this area. It gives recommendations on selecting, planning, installing and maintaining entrance flooring systems specifically to reduce the ingress of soil and surface moisture to buildings, and its transfer between adjacent internal areas, to the lowest practical level — that is, it addresses the objective and the method, not a headline percentage.
Why matting length still matters, regardless of the exact number
The practical design guidance widely used alongside BS 7953 is that a visitor needs several footfalls on matting for it to work — commonly cited as at least three steps — which means matting needs a proper run length in the direction of travel, not a single small mat at the door. A two-zone approach (an aggressive scraper zone outside to remove coarse dirt and grit, and a moisture/fine-dirt wiper zone inside) captures more between the two zones than either does alone.
What this means for your cleaning contract
Regardless of the exact percentage, well-specified entrance matting measurably reduces the soil load your cleaning team has to lift from hard floors and carpet further inside the building — which is why we look at matting provision as part of a site's cleaning specification, not as a separate afterthought.