Testing for Aerosolization Caused By Indoor Pressure Washing
One question has come up regarding the spray and vac process in hospitals: Does the indoor pressure washer aerosolize bacteria, exposing workers to potentially harmful disease, as well as propagating the spread of infectious disease to building occupants? To answer this question, Kaivac conducted a test that analyzed 17 data points in a small restroom (12' x 5.5'). In the end, all of the 17 test points showed zero (0) colony forming units (CFUs).
First, we created a fecal-urine solution to simulate the bioload typically found in a restroom. Prior to starting, we tested the solution to make sure it was active, and found a CFU count that was 'too numerous to count' (TNTC).
Second, using a mechanical sprayer to insure consistency, we applied one ounce of the fecal-urine solution in a four-square-foot area beneath the toilet as well as the urinal, and a third ounce on the seat, plus a fourth on the urinal rim.
Third, we placed 3M Aerobic Bacteria Plates around the restroom in 17 locations. The plates ranged in height from 28 inches (about waist high) to 71 inches (head level) as measured from the floor. The labeled CFU plates were placed horizontally, securing the protective layer in an open position, so as to leave the plates exposed and facing upwards.
Fourth, we employed a Kaivac KV 2150 to clean the restroom, using a typical spray and vac cleaning procedure. The pressure washer was set at 500 psi. We used KaiSan II, a concentrated no-rinse hospital use disinfectant cleaner with a neutral pH, diluted to 2 oz. per gallon.
Fifth, we waited 30 minutes, to allow potentially aerosolized particles to settle on the plates. We then removed them and placed the protective layer in the closed position.
Sixth, we incubated the plates for 48 hours, before removing them and documenting our findings.
There was not a single CFU found on any of the 17 plates, indicating that no live bacteria were aerosolized. Several of the plates did show indications that some fluid had settled on them, but no CFU were present. This indicates that if any bacteria were aerosolized in the process, they were killed by the Kaisan II.
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