What is HEPA filtration?

The history of the HEPA (High Efficiency Particulate Air) filter is one of the most interesting tales in American history. Many people may be surprised to find out, for example, that the filter was developed under the sponsorship of the Atomic Energy Commission and in connection to the Manhattan Project. Keen on developing the atomic bomb before Nazi Germany did, the US was nevertheless cautious about exposing its scientists and soldiers to the radioactive particles expected to be given off during a nuclear explosion.

To protect those working with this new horrifying technology, an air filter was designed that could intercept 99% of particles (as small as 0.3 microns) from the air; although it did not meet its original intent, the device did work to protect against fine-particle air pollution. Thus was the HEPA filter born.

Although efficient from the beginning, the air filter was bulky and expensive to produce and was, for the most part, reserved (against contamination) for pharmaceutical companies, research labs, hospitals, and military facilities. In time, however, it was designed small and affordable enough to be used in home settings.

Especially useful for people suffering from breathing diseases such as asthma, allergies, and Multiple Chemical Sensitivity (MCS), and for people who wish to avoid developing such problems, HEPA air filtration devices have come a long way in terms of technological advancement. Some HEPA air purifier products, for example, using a combined electrostatic and mechanical filtration process, can trap 99.97% of microscopic particle, odor, and gas pollutant contamination.

In fact, the latest models can intercept such strong allergens and irritants as pet dander, smoke, tobacco, mold, bacteria, viruses, dust, pollen, insecticides, laundry detergent, paint fumes, perfumes, hairstyling spray, and air fresheners without the additional use of UV bulbs and chemicals.
Another way that HEPA air filtration has been made better is with the use of chemical absorption technology. In addition to activated carbon, for example, other chemicals can be used in the filtering process that can help absorb dangerous toxins. Two such purifying chemicals are Zeolite and potassium permanganate.

As for how HEPA purifier filters work, well, contrary to popular opinion, they do not work like membrane filters, allowing only particles that fit through the smallest openings to come through. Instead, HEPA filters, targeting particles at the microscopic level, work by trapping or getting to pollutants to “stick” to the special fibers (which are stacked in layers) in one of three possible ways: diffusion, impaction, and interception. Each of these processes involves complicated microscopic particle motion physics. It should suffice to say that HEPA filters act more like magnets than sieves or colanders.

Although originally trademarked (1940), the term “HEPA” now refers to any efficient air pollution filtering system or device, according to specific filter ratings given by authorized agencies.

HEPA filtration is one of the frontline defenses against airborne diseases, such as tuberculosis, the flu, and respiratory infections. For that reason, it is highly depended upon in healthcare facilities, as well as in medical research labs and in nanotechnology. This fine-particle-filtering technology is also useful in the fight against asthma and airborne allergies. With that in mind, the best vacuum cleaners today use HEPA filtration technology. Naturally, the technology is also invaluable for other devices used in the home to protect inhabitants against breathing disorders; other such devices include air conditioners, heating units, humidifiers, dehumidifiers, etc.
Keeping in mind that indoor air can be much more highly polluted than outside air, some of the advantages of HEPA air filtration devices and systems include:

  • It can remove both fine hard particles and gases.
  • Some HEPA filters are washable.
  • Filters are being made for just about any device that brings or takes air out of a home or a place of work.
  • Devices using HEPA filtration are usually very quiet.
  • HEPA filtration can be used as a stand-alone system or in conjunction with other systems/devices.
  • HEPA filters very effectively reduce indoor air contaminants, thus greatly enhancing indoor air quality.
  • Air filtration devices come in models and sizes to fit all budgets.

Several companies now make HEPA devices, thus increasing the impetus for product improvement; this also helps to keep prices down.

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