There are several factors to consider when choosing a filtration system, starting with sensitivity to allergens. The more sensitive a person is to allergens, the greater the need for a high-efficiency filtration system.
The efficiency of the air filter should be a top consideration. Efficiency is based on the size of the particles captured by an air filter. The higher the efficiency, the more effective it will be. Look for the filter's MERV (Minimum Efficiency Reporting Value) number, the industry standard for rating filters based on their performance. Residential filters typically have an MERV range of one to eight. Higher ratings ranging from 10 to 16 indicate more efficient filters. High-efficiency particulate air (HEPA) systems use hospital-grade filtration technology with a performance that's equivalent to a MERV 17 filtration efficiency or higher.
Higher filter efficiency not only helps clear the air, but it also improves airflow. Generally, the more efficient a filter is, the less airflow reduction there will be.
Cost is another major factor—both in terms of the initial purchase price and expense of maintenance and upgrades. Purchasing a filter of reasonably high quality can save you money over the long term. Inexpensive filters may not provide the level of filtration you need and may also require frequent filter replacement.
Among the many filtration products available are pleated filters, which are constructed of fiberglass or synthetic fibers woven into a more dense material. The pleats are arranged in V-shaped forms to increase the area of the filter material without increasing the face area. This increases the particle-holding capability.
Electronic air cleaners (EACs) take recirculated air and pass it through a prefilter that traps large pollutants. Then, ionizing wires give a positive electrical charge to remaining particles. A negatively charged collecting section captures the particles. High-efficiency particulate air (HEPA) filters are also very effective at small-particle removal. An optional carbon canister can help control odors and chemicals.