Is a HEPA Filter Effective for Hand Dryers?

by:Jiali     2020-08-07
Sanitation in restrooms plays a primary role in anyones restroom experience. Recently more and more noise is being generated about HEPA filters and HEPA-type filters in restroom hand dryers. While we all understand that cleaner air equals less bacteria in the air, it seems that few people have asked if this is a practical application to begin with.
Let's start by looking at where HEPA filters are generally used. Commonly you can find HEPA filters in vacuums, airplanes, medical centers, and even some cars these days. All literature about HEPA filters will point out one important point, however, and that is that the filter is used in closed systems. Airplanes, medical centers, and cars all filter air continuously, so that if any particles are introduced to the system the filter will quickly capture them. The key word is continuously.
When Mitsubishi designed the Mitsubishi Jet Towel they originally considered including a HEPA filter. Ultimately they decided against including one, because the purpose of the Jet Towel is to dry hands and not purify air. For each time a hand dryer would be used for 8-10 seconds, someone would have opened the door to the restroom, introducing unfiltered air into the system. Counting on the Jet Towel to clean the air would be like turning on an air purifier for ten seconds every time someone opened a door and calling the air clean.
Some might argue that the clean air from the nozzles is the important part, and that is HEPA clean. While that is true, the air around the nozzles and the air through which the user walked through to get to the dryer still do not benefit from filtration. After washing, hands will be their cleanest, but filtered air loses its importance if after washing you pull your hands through the 'dirty' air that the HEPA filter would protect against.
But surely anything is better than nothing? Why did Mitsubishi not include a HEPA filter anyways? Because it would add to cost and add no benefit to the actual drying outcome. Japan Food Labs tested a new and a 2-year old Jet Towel and found that with just the large particle filter, there was no significant increase in bacterial growth. The deciding factor was the most obvious: how thoroughly you wash your hands. HEPA filter or no, washing your hands well is still the best way to protect against bacteria in the restroom.
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