Air Purifiers Buying Guide

Published April 28, 2010 | Updated June 24, 2015

Today's homes keep us comfortable with air-tight construction that helps heating and cooling systems work efficiently. However, those closed doors and windows also trap air in the house, making it smell stale and concentrating airborne particles. Air purifiers are electronic air cleaners that capture allergens and contaminants, including dust, pollens, pet dander, and odors. Unlike climate-control appliances of the past, most of today's air purifiers are quiet and energy efficient. Several cleaning methods are available; most air purifiers use filters or electronic precipitators to refresh your home environment. This guide explains the available options, so you can be familiar with what you're looking for.

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  • Filtration Systems

    Filter-based air purifiers are the most popular. In this system, a fan pulls air through a paper or mesh filter. The air filter can be a replaceable model or a permanent, washable model. Washable filters are good for trapping dust, but they don't trap pollen and smaller particulates. Many newer air purifiers incorporate pre-filters that catch larger particles in the air flow to boost the efficiency of the main filter.

  • HEPA Filters

    High-efficiency particulate arresting (HEPA) filters are designed to capture 99.97 percent of airborne particles measuring 0.3 micrometers or larger from the air as they pass through the filter. HEPA filters efficiently remove mold spores, bacteria, and dust from the air, making HEPA air purifiers some of the best on the market for people with asthma, allergies, or increased susceptibility to illness.

  • Activated Carbon

    Filters are not very good at eliminating odors; therefore, many air purifiers include some form of activated carbon in the design to absorb odors and chemicals. If you have pets or young children at home, look for an air purifier with activated carbon to remove odors from the air.

  • Electronic Precipitators

    The second most common type of air purifier, electronic precipitators draw air through an electrical field and use the electric charge to capture and trap particles on charged metal plates or filters. Some electronic precipitators use a fan to circulate more air at a time. These air cleaners release a small amount of ozone into the air, which is an important consideration if you use the unit in a small room.

  • Ionizer Purifiers

    Both filtered cleaners and electronic precipitators can have built-in ionizing circuitry. Ionizers discharge electrons into the air, forming negative ions by attaching themselves to air molecules. The negative ions attract dust and pollen particles to form larger particles that are more easily trapped by filters. An ionizer helps the air purifier work more efficiently. However, the ionized particles may also attach themselves to upholstery, drapes, and carpets, increasing the need for vacuuming.