Very simply, cleaning equipment that produces less noise reduces worker fatigue and frustration, which results in healthier, more productive workers. It's actually surprisingand unfortunatethat we have not realized this until just recently.
Imagine a hospital housekeeper working with a loud vacuum cleaner for hours at a time. Over time, this can affect worker productivity, efficiency, and may be as harmful to their health, just as inhaling the fumes of powerful cleaning chemicals.