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. colibacteria 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 isnot 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.
Mats are so important to a green cleaning program that they are now required in order for a facility to even be considered for LEED certification. LEED now requires the installation of at least 10 feet of what they refer to as “entryway systems,” which typically refers to mats but can also refer to grates and grills designed to remove soils and contaminants from shoe bottoms. According to LEED, these systems “capture dirt and particulates entering the building at regularly used exterior entrances…[which help] promote occupants’ comfort, well-being, and productivity by improving indoor air quality.”
Furthermore, the EPA’s Indoor Air Quality Tools for Schools program recommends that mats be installed at all key school entries. Referring to matting as a “cost effective” action to take, the EPA says, “entry matting…can reduce contaminants in schools and help protect the health of children and staff.”
High-Performance Mats
Not all types of mats are as effective at source control. High-performance mats do the best job of capturing contaminants. These mats, which are produced by different manufacturers, are in most cases purchased rather than rented. What qualifies them as high performance are the following factors:
- Pile: They are made using higher quality fibers and have a deeper, thicker pile, allowing them to more effectively capture and trap soils.
- Backing: They are typically made with a higher-grade rubber backing engineered to be longer lasting, resist curling, cracking, and hold up under different climactic conditions.
- Construction: Many are “bi-level,” allowing soils and moisture to be trapped below the surface of the mat so soils/moisture are not transferred from the mat onto shoe bottoms.
- Warranty: Because they are built using higher quality materials, high-performance mats are more durable and have longer warranties, usually one to six years (compared to a rental mat that may only be warrantied for three months).
The length of the matting is also very important. For the matting to be truly effective, at least 15 feet of matting — outside and inside the facility — should be installed. This not only reduces the number of contaminants entering the facility, but it also enhances safety for building users.
1 New shoes were worn for two weeks by 10 study participants. Following the wear trial period, the bottom and inside of the shoes were sampled for total number of bacteria and coliform/E. coli.