When we think of green cleaning, our focus is typically on the chemicals, equipment and procedures used to clean facilities. However, an effective green cleaning program starts long before we even consider chemicals, equipment or procedures. In fact, it starts before building users even walk in the door. This is because an effective way to keep buildings clean, healthy and green is with a source control strategy, and the key to this plan is the use of walk-off mats.

However, not all mats are effective. There is a difference between what are called “high-performance mats,” which are typically purchased, and “placement mats,” which are most often rented.

Building users may be walking on sidewalks, through parking lots, in streets, over landscaped areas, in public restrooms and on other surfaces that are heavily trafficked; thus, their shoes can be heavily soiled. Mats stop dust, soils, moisture, pesticides and contaminants that collect on building users’ shoe bottoms from entering the facility.

A study conducted in 2008 by Charles Gerba, PhD, a microbiologist at the University of Arizona, evaluated what types of soils may build up on shoes. According to his investigation, some of the following soils and contaminants are found on shoes:

• Coliforms, a broad class of bacteria, were detected on the outside of 96 percent of the shoes tested.
• E. coli was detected on 27 percent of the shoes tested.
• The transfer of bacteria from the shoe bottoms to uncontaminated tiles inside a facility ranged from 90 percent to 99 percent.

“The common occurrence (96 percent) of coliform and E. coli bacteria on the outside of the shoes indicates frequent contact with fecal material, which most likely originates from floors in public restrooms or contact with animal fecal material outdoors,” adds Gerba. “Our study also indicated that bacteria can be tracked by shoes over a long distance into [a] home or [office] space after the shoes were contaminated with bacteria.”¹

When an effective matting system is installed, the International Sanitary Supply Association (ISSA) estimates that as much as 70 percent to 80 percent of these contaminants can be captured and stopped from entering a facility. They also found that 1,000 people walking into a facility over a 20-day period can track up to 24 pounds of soils into a location if an effective matting system is not in place.

When fewer contaminants and soils enter a facility, it stays healthier and typically requires less cleaning; when less cleaning is needed, fewer chemicals and cleaning tools are used, which means we have reduced the impact of cleaning on the environment, the ultimate goal of green cleaning.