Why is a H.E.P.A. Filter the industry standard?
Basically, a H.E.P.A. (short for "High Efficiency Particulate Air" -or- "Absorbing" -or- "Arrestance") Filter is a screen made of dense fibres that removes particles in the air, trapping them by forcing them through microscopic-sized openings or pores. In general, the performance of a H.E.P.A. Filter depends on the speed of the air being forced through it, the diameter of the pores and the thickness of the screen. H.E.P.A. Filters are ideal for trapping incredibly minute airborne particles including mold, dust and other pollutants – making them amongst the best products on the market available to maintain the cleanest and therefore the safest of environments. They can also reduce or eliminate hazardous aerosols, toxins, radioactive particles and even airborne bacteria and viruses.This makes them ideal for hospitals, pharmaceutical laboratories, nuclear plants and similar facilities where a sterile environment is crucial.
H.E.P.A. Filters function in 3 distinct ways. Particles are either "intercepted" by the fibres (unable to pass through the microscopic-sized openings, so they adhere to them), actually embed themselves in the fibres (called impaction) or collide with even smaller gas molecules (called diffusion) and are therefore impeded. H.E.P.A. Filters do have different ratings for efficiency (usually posted on the actual unit) and need to be replaced regularly. Regardless of exactly how they function, the fact is that H.E.P.A. Filters are often the last line of defence in protecting employees, consumers and patients.
To be designated a real H.E.P.A. Filter (called a "True" or an "Absolute" H.E.P.A. Filter) it must be able to trap at least 99.97% of .3 micron-sized particles from 85 litres of forced air per minute in a test. A serial number and the actual test results should be printed on the unit itself.
So how big is .3 of a micron? A micron is actually one millionth of a metre. To give you an idea how incredibly small that is, the period at the end of this sentence is about 400 microns – or more than 1,200 times larger than our .3 particle size! Pull a single strand hair from your head (hopefully you still have some left!) and realize that it’s likely 40 to 120 microns in diameter. This gives you a clearer picture of just how remarkably efficient H.E.P.A. Filters have to be.
One final point: "H.E.P.A.-Type" or "H.E.P.A.-Like" Filters are also available on the market and may indeed look the same, but in general they capture only 85% – 90% of airborne particles.
