University of Washington - ICM Spray-and-Vac Water Only Test
If there is any upside to managing a custodial department during a downside economy, it may be the way it forces innovation in the form of increasingly creative solutions to solve severe budgetary problems. More and more custodial managers have discovered already the successful strategy of reducing cleaning chemical inventories to an absolute minimum. This can cut costs while still contributing positively to one's sustainability efforts. As an additional benefit, it may also allow for maintaining or improving cleanliness levels through simplification and standardization.
But what about taking the next, seemingly unthinkable step, of removing chemicals from the cleaning equation? This would obviously reduce the number and amount of cleaning chemicals introduced into the environment. But would effective cleaning still occur?
A recent comparative beta test conducted at the University of Washington suggests that, at least for certain applications, cleaning without chemicals may be as good if not better than cleaning with them.
First, an experienced worker cleaned and wiped off faucets, sinks, and counters with traditional tools. She did not take time to replace paper products or empty the trash. She disinfected toilets with a correctly diluted EPA-registered product, and mopped floors with a correctly diluted EPA-registered product and a microfiber wet mop. Performing at a normal pace, she cleaned two restrooms, one men's room and one women's room located on the second and third floors of the Health Sciences Building.
In contrast, a manufacturer's representative used a 12 gal. spray-and-vac machine filled with water but no chemicals to clean an identical men's and women's room on the same two floors as the first subject. He pressure-washed vertical and horizontal surfaces, wiped down fixtures, squeegeed counter tops, and squeegeed-vacuumed the floor. He did not replace paper products, or empty trash.
Both subjects started at the same time, with carts or machines already stocked or plugged in and located at the front of the restrooms being cleaned. This seemed practical because custodians are encouraged to set up carts and machinery at the end of a shift in preparation for work to be performed the following day. The time required to prepare carts or machines varies; most Custodial Managers reported carts required 5 minutes for preparation, a restroom machine 5 to 10 minutes.
Before and after cleaning, the tester sampled the same spaces in the comparable restrooms of each subject. He took 4' by 4' swab samples of sink counter tops and floor tile in the main walkway a yard from the room entrance, and floor tile two feet in front of the toilet in the first stall from the room entrance. The tester ran the swab approximately 4-6 seconds each time before placing the swab in an ATP measuring device.
How It Works
ATP is a chemical produced only in living cells and is found in both living and once-living cells. ATP measured from restroom surfaces may contain skin as well as other human cells and residue besides microbial cells. Since ATP is found in organic material, generally large amounts of ATP detected strongly suggests an unclean surface.
ATP is measured in a luminometer (light meter) after the sample is mixed with an enzyme reagent, to provide a light reading. The larger the reading (or light created), the greater amount of ATP in the sample, and the greater amount of organic material on the surface tested. Low readings are desired.
Spraying, agitating, and vacuuming restroom surfaces produced on average an 89% reduction in ATP in two restrooms tested, while the 'microfiber-traditional' method produced a 56% reduction. This means that in the rooms tested, machine cleaning produced 58% better results than microfiber-traditional cleaning. In both cases where the machine was utilized, the ATP reading decreased to below 30, which is considered sanitary. In fact, in two test sites the count dropped to zero.
In addition, the restroom machine reduced cleaning time on the average by 92 seconds (7:25 vs 8:57 minutes). But this difference is negligible if set up times are considered, since some custodial managers reported experiencing up to 5 minutes more being required to set up a restroom-cleaning machine as opposed to preparing a custodial cart.
Explaining the Results
At first glance, plain water does not seem like a likely candidate for achieving particularly clean surfaces. But plain water may still act as a reasonable solvent for some types of soil. In fact, we know from high school biology courses that water is referred to as the universal solvent because it can dissolve both acids and bases of many types. This is why it is so important to the chemical reactions of life. However, agitation presents a special advantage in the cleaning process. Pressurized plain water agitates soil, as does the motion of a squeegee. Both steps seem to be more effective in cleaning than initially realized--at least in loosening and suspending soil. But immediate vacuuming of soil on the surfaces sampled in this study may represent the essential step in achieving favorable cleaning results. Dissolved soil held in solution cannot resettle on surfaces if it is vacuumed immediately after agitation.
While the benefits of EPA-registered disinfectants and other proven modalities such as microfiber cannot be dismissed, this test suggests the viability of a unique non-chemical intervention for reducing organic deposits that foster microbial growth. It appears that following one easy-to learn, step-by-step process, even with an exclusion of chemicals, presents a potentially effective way to clean restroom surfaces.
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