Hepa Air Purifiers - The King Of The Crop?
Let's start by saying that Hepa, is NOT a brand! How many thought it was? I certainly did until I did some investigation. HEPA stands for High Efficiency Particulate Arrestor, which is really talking about an air filter to remove particles and allergens from the atmosphere, rather than some scientific process. Also, a Hepa process should be considered as air cleaning rather than purifying. So whilst during the course of this and following discussions we might refer to Hepa air purifiers, we are really talking about air cleaners .....
At the time of writing, HEPA air filters were 99.97% efficient at removing particles down to 0.3 microns in size from the air, which is pretty good going. Certainly these encompass things such as dust, pollens and smoke, which account for a high percentage of the air bound allergens in the home. In industry, when asbestos needs to be removed from a site or from a demolition, HEPA air filters are the standard issue to do the job.
In terms of general efficiency, a HEPA air purifier will be able to clean up a room during the course of a relatively short period of time, say an hour. They will not be able to clean a whole house from a single position. Please note that these are very approximate, because a lot depends on outside factors as well, so what we are discussing is very general.
Cleaning air with Hepa filtration requires that air is passed over the filter as many times as possible in an hour. A normal domestic cleaner may be able to pass air over the filter two or three times an hour. In larger than average rooms therefore, a domestic Hepa filter will pass the air fewer times an hour, and as a result, the air quality will not improve so much. Some machines also contain charcoal which help in reducing odours and such like. Without carbon filtration, don't expect your Hepa cleaner to be as effective dealing with bad smells as machines that possess carbon.
So, the bottom line is that you have to obtain a cleaner that will be able to clean the room for which it is intended.
For those wishing to look at alternative air purifiers, could consider using light as an air purifier.
