When you think of air pollution, the last place you expect to face it is in your own home. However, according to the U.S. Environmental Protection Agency, indoor air pollution could be two to five times higher - and sometimes more than a hundred times higher - than outside levels. That means below par indoor air quality is one of the top 5 risks to better health. Since most of us spend 90% of our time inside our homes and offices, that could be a crisis.

HEPA (High Efficiency Particulate Arresting) filters are one strategy for better indoor air quality. HEPA filters have been used since the 1950s when the US Atomic Energy Commission believed it was important enough to dispose of tiny radioactive particulates from the air.

HEPA filters work like this: think about one sheet of HEPA paper (actually it's made of a paper-like fiber or polymer) with very tiny holes that filter out pollutants and contaminants. Seeing that the surface area is restricted, only very limited amounts of air are able to go through. If the size of the sheet was doubled, it would be possible to get two times the airflow and 2 times the filter life.

A larger surface area would result in a more productive filter. So rather than increasing the total measurements of the sheet itself, the surface area is increased by being folded back and forth many times. Some filters have as much as 40 sq ft of filter material. HEPA material is actually a rather remarkably thin bond of fibers.

Air is forced to make its way through this formidable network of fibers and in the process, the particles hit the fibers and stick. HEPA filters naturally filter out the larger particles like dust, however they also work effectively against mold spores, viruses and bacteria.

Many kinds of air purifiers assert that they clean 99.97% of the air that goes through the HEPA filter - but what they don't indicate is that some air doesn't flow through the filter. If the air doesn't go through the HEPA filter then certainly it isn't filtered. That makes the issue of 99.97% efficiency rather doubtful.

The best quality HEPA filters don't have a problem with respect to this because their designs include fans that actually push air through the filter - the more air that flows through the filters, the cleaner the air becomes.

The size of the room is a key consideration when determining the size the air purifier ought to be. Evidently the larger the room is, the larger the filter needs to be. Another possible idea is to have 2 smaller filters. They can divide the work - and allow twice the amount air to make it through the filter.

Note that HEPA filters do not filter out gasses, chemicals and odors. That's because these molecules are too small compared to HEPA's 0.3 micron holes. In order to filter out these destructive molecules, some type of substance is important to absorb them - activated carbon is routinely used.

Don't be afraid to ask questions prior to making a decision about which air filter to get for your family's health. Knowledgeable business owners know about their brands and can best suggest which size of filter is necessary to guard your home and ensure it's as clean and healthy as it can be.

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