The Myth of HEPA Filter Importance in Hand Dryers.
What is a HEPA Filter?
HEPA is an acronym which stands for High Efficiency Particulate Air. A HEPA filter provides a very high level of filtration efficiency for the smallest as well as the largest particle contaminants. As defined by the Institute of Environmental Sciences and Technology, IEST-RP-CC001.3 and MIL-STD-282 Method 102.9.1, a HEPA filter must capture a minimum of 99.97% of contaminants at 0.3 microns in size.
Now all that sounds good and a HEPA filter used in the correct application is undoubtedly a critical component.
Let’s look at the sealed and pressurised cabin of an aircraft.
There may be hundreds of passengers in an aircraft, each one sharing the same air in the cabin. There may be a dozen people with some sort of a disease in that cabin- a cold, flu or some other disease.
It makes perfect sense that when that air gets recirculated through the air conditioning system that it passes through the appropriate HEPA filter to filter out any bacteria before it is “released” in to the cabin for everyone to breathe!
Now let’s look at a washroom environment.
A public washroom is located in a public area. There may or may not be a door in to the washroom; even if there is a door it is not airtight!
You may be in the washroom alone or you may be with many people.
Some of these people may also have colds, flus or other diseases. You are all sharing the same air for several minutes while you attend to your business and even have a chat to someone.
It comes time to wash your hands and now you look for the hand dryer. You sure hope it has a HEPA filter to blow bacteria free air on to your hands!
By the way, you are still breathing the air in the washroom in to your lungs!
You then make your way to the door and pull it open by the handle, hoping the previous user of the washroom washed their hands thoroughly.
Can you see my point?
A HEPA filter is only of any value in a closed, controlled environment, like in a pressurised aircraft or other controlled air tight environment- a Hermetically sealed environment. It makes no difference if the air in a public washroom blowing on to your hands is HEPA filtered or not! You have been contaminated long before you get to dry your hands.
A hand dryer without a HEPA filter is blowing the same air you are breathing in and walking through, on to your hands.
It can’t be less hygienic than a hand dryer with a HEPA filter.
Do we now demand a HEPA filter on a Hair dryer? After all it is blowing air on to your Head and Face!!
In fact I will present a case as to why a HEPA filtered hand dryer MAY in some cases be less hygienic than a non HEPA filtered unit.
A HEPA filter filters out 99.97% of airborne contaminants. They have superfine filtration capabilities.
This means they have to have heavier duty motors to push air through the filters. It also means the HEPA filter will clog up much quicker than a regular filter. When the filter clogs up, the unit becomes less efficient. When the HEPA filter starts to fill up with contaminants, which includes the bacteria and viruses we are so afraid of, the air in the washroom being sucked in to the contaminated HEPA filter, may in fact be cleaner than the air leaving the contaminated HEPA filter.
To avoid this, the HEPA filter, which is very costly to produce, must be changed on a regular basis.
How regularly- who knows- it depends on the use and amount of contaminants in the washroom and the diligence of the cleaners.
Because of the cost of the filters, they will usually be changed less often than they should be.
The only effective HEPA filter for a washroom or everyday living would be for a person to wear a sealed mask with a HEPA filter built in to filter the air before it enters your system.
Is a HEPA filter a waste of money in a hand dryer? You be the judge!