Purchasing an air purifier can be confusing, and you do get an awful lot of information thrown at you when you visit the different manufacturing websites, don't you? How can you tell what's what, and why do we need air filters anyway? And how do air purifiers work? Is the air really that bad? Haven't we been breathing the same air for thousands of years?
Yes and no. First of all, we've been breathing the same air for thousands of years, but we live in a symbiotic relationship with the plants around us - that is, we rely on each other to survive. We breathe oxygen to live, and give off carbon dioxide. Plants exchange carbon dioxide for oxygen, effectively "exchanging" the air in a healthy relationship with us. This makes plants the first primitive air purifiers on earth, and explains why scientists are so concerned about the ecological balance on earth and the need for the survival of rain forests and plants - they ensure our own survival as well by preserving oxygen in our atmosphere.
Nature cleans the air in other ways as well - ozone (positively charged oxygen molecules) is generated by waterfalls and thunderstorms. Ozone also cleans impurities and particulates from the air naturally.
The Industrial Revolution and Air Quality
The industrial revolution made great strides in everything but air quality. In fact, pollution such as emissions from automobiles, smog and pollution from everyday chemicals like cleaning fluids, carpeting and paints enter the air every day. In industrial settings, air purifiers clean the air before it is released into the atmosphere in order to meet government requirements.
Today's homes are also more energy efficient and cost effective, but to get there they have become much more "closed in." When they are this sealed up, indoor pollutants are shut in so that today's Homes are actually two to five times more polluted than outdoor levels! Obviously, air purifiers are essential to improving indoor air quality to combat the effects of this stale, recirculated air.
Beginning in the 1980's, medical practitioners began to take note of the direct link between poor air indoor air quality and the increased incidence of conditions such as asthma, allergies and recurring colds and upper respiratory infections. The development of a variety of improved, scaled-down air filtration systems for in-Home use soon emerged.
How the Main Types of Air Purifiers Work
One of the most commonly used type of air purifier is also one of the first developed, and is used in most hospitals and clean rooms. This is the HEPA filter.
HEPA Filters
During the Manhattan Project in the 1940's, the Arthur D. Little firm developed the first HEPA filters in order to filter out very small particles that had become contaminated by nuclear radiation in atomic bomb testing areas. It was during this initial development that the HEPA standards were set at 0.3 microns, which could effectively capture condensed radioactive iodine.
The filters at that time were called "absolute filters," and not called HEPA (High Efficiency Particulate Air) until the filters were marketed in the 1950's. Today these filters are used by hospitals, surgical wards, biopharmaceutical research labs, micro circuitry labs, and the aerospace industry for their exceptional ability to control dust and particulates.
HEPAs remove 99.97% of particles of 0.3 microns or larger. For even more intense filtration, there is an ULPA, or Ultra-HEPA filter, which filters out 99.99% of contaminants pass through the filter.
Obviously, something has to draw the air through the filter, and with HEPA filters this is a motorized fan. This can make them noisy, which makes them an annoyance to some people. A HEPA filter will need to be replaced every 12-18 months, depending upon how it is used and the interior environment of your Home. For instance, if you have pets, especially cats or dogs that shed a lot, you may need to change it m
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