HEPA Air Filters--A Breath of Fresh Air!

HEPA air filters first emerged in the 1940s during the second World War.  It was then when researchers discovered that this powerful air filter was able to remove radioactive dust from the air. Later, the HEPA filter became to be known as a highly efficient air filter, and has been used in  scientific industries, specifically by  hospitals, aerospace, nuclear power, and pharmaceutical companies.  Today, the HEPA air filter is readily available for personal use, and is instrumental in the well-being of allergy sufferers.  If you're among the 42 million people who suffer from airborne allergies, then you must have this powerful filter in your home!

HEPA, abbreviated for High Efficiency Particle Arrestor, has gained a reputation for its outstanding ability to remove harmful micro-organisms from the air. When a HEPA air cleaner is used, it can trap up to 99.97% of every ten thousand particles floating in the air. These particles include any airborne allergy irritant, including bacteria, viruses, dust mites, pet dander, mold, pollen, and smoke. Its efficiency to remove such harmful substances is the reason why HEPA filters are the most recommended among any air filter. As a matter of fact, the HEPA filter is recognized as the most effective technique that ensures the breathing in of purer air.

Those with allergies aren't the only ones who can benefit from having a HEPA filter. Anyone who wants to breathe in cleaner air will notice improved quality of breathing. Furthermore, those who suffer from asthma can benefit from the HEPA filter as well. In fact, both the American Lung Association (ALA), The Asthma and Allergy Foundation of America recommends the use of HEPA air filters for asthma patients.

Uses

Currently HEPA filter air cleaners are available two forms for home use: via an air purifier and by vacuum cleaners. An air purifier uses a fan to force air through the filter, which removes the particles in the air. Air purifier HEPA filters can also be installed in air conditioning and heating units. Some vacuum cleaners are equipped with HEPA filters to ensure that dust is trapped instead of being redistributed elsewhere. These vacuums also have more powerful motors.

HEPA air filters construction vertically to create pleats that are pressed together. Then, the filter is placed in frames to hold the shape in tact. The filter itself is made up of minute glass fibers tightly woven into a paper-like filter, creating numerous small sieves. It is the sieves that actually do the dirty work, capturing small particles. HEPA filters are so effective because of the pleated design and the thickness of the fibers which doesn't allow contaminants to escape.

Particles get trapped by the filter by way of three mechanisms:

• Interception-- particles the get within one radius of a fiber will stick to the fiber
  
• Impaction-- larger particles are embedded within the fibers when air is pushed through the filter
• Diffusion-- the smallest, most microscopic particles collide with gas molecule in the air. As the particles and gas molecules meet, the force will cause the particles to stick or get embedded in the fibers.

HEPA filters can not remove odor, vapors, and gases. However, they can be used in conjunction with an air ionizer that is able to remove those contaminants.

HEPA air purifiers vs. other air purifiers

One of the reasons that air HEPA filters are so effective is their thickness. A HEPA air filter is usually 11 1/12 inches thick compared to 1-4 inches of conventional disposable filter refills.

Other types of air cleaners, such as electronic and electrostatic, become less efficient the more they are loaded with debris. Even at the highest efficiency, these type of filters are not as effective in trapping particles than HEPA air filters. Furthermore, the filters must be cleaned more frequently to maintain effectiveness.

The cost of HEPA air purifier filters depend on the size and quality of the unit.  If you are looking to buy a HEPA purifying unit you should look for the CADR (clean air delivery) rate.  The CADR measures the volume of air moving through the system as well as the size and percentage of the particles removed.  Generally, the higher the rate, the better.

Another factor determining the cost is the difference between a true HEPA filter and a HEPA type filter.  A true HEPA filter must pass a strict test that proves it is able to trap at least 99.97% of particles of .3 microns.  A HEPA type filter may have similarities to the true filters, but do not have to adhere to the same high standards. A HEPA type filter tends to capture 85-90% of particles of .3 microns, and the percentage may decrease for particles below 1 micron.  A true HEPA filter will be more expensive than a HEPA type filter, and serial number with test results will be printed on the filter.

The prices of true HEPA purifiers for home use can range from a little over $100 to just under $3000.  The larger units with a higher CADR that are able to filter more air per square footage are the most expensive, while the smaller portable units are the least expensive.  Prices for replacement HEPA filters range from $10 to under $200. The frequency in which you have to replace the filter depends on the unit.  The cost for a HEPA filter vacuum for home use ranges from $100-$2500. Replacement filters can range from $2 to $90.