Tuesday, December 2, 2008

Types of Filtration for Homes - Part II

In the San Francisco Bay Area, we are blessed with some of the cleanest air in the country and probably the world. However, indoor air quality related problem such as allergy or asthma can still be a common household problem. Most people don’t realize that with proper residential air filtration that can be alleviated. Before we go into the solutions we will discuss the irritants. There are three main classes of irritants. The first and most common are small airborne particles such as dust, pollen, allergens. The second class is bio-aerosols such as mold. The third class is odors such as ones from pet or household chemicals.

MERV (Minimum Efficiency Reporting Value) is the standard in which airborne particle filtering is being measured. MERV is measured in a scale of 1 to 16 with the higher number being more efficient. Details of the scale and its relative efficiency can be found from the link below.

Most of the 1” pleated filter in the market ranges in MERV 1 to 4. They are okay for general filtration of larger particles (3-10 micron) but not effective against particles smaller then 3 micron. High efficiency whole house Media Cleaner offers the effectiveness of up to MERV 16 with the right type of filters. However, the filter medium needs to be replaced periodically for it to maintain its efficiency. Electronic Air Cleaner offers a high level of particle filtration. It has a higher first cost but a lower running cost since most can be cleaned out by the homeowner. So the decision to go with one or another depends on budget and desire for convenience. Recently there are studies that bring to question the generation of ozone, an irritant to some people, as a byproduct of some electronic air cleaner. So homeowner should select models that meet the ozone level guideline if they decide to go with electronic air cleaner.
Next time we will continue with the filtration discussion on the other types of irritants and how to combat them.

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