We've known for a very long time that air pollution is not good for us. But in 2003, a team of Southern California scientists at UCLA and USC discovered that microscopic airborne particles can easily bypass the body's defense mechanisms and travel beyond the lungs to penetrate cell walls. When the particles come in contact with the cells, they trigger a reaction that causes inflammation, which may help explain how particulates affects asthma.

When the particulate pollutant accumulates, damage to that cell is known to lead to a variety of diseases. Worldwide studies have linked particulate pollution to school and work absences, hospitalizations, compromised lung function, heart disease and cancer. Current environmental regulations limit particles that are 10 microns in diameter, but this study shows that particles that caused the most damage are one-tenth of a micron.

Also at issue for indoor air quality are all the chemical contaminants that are found in our newly built or newly furnished indoor environments. Many people now suffer from chemical sensitivities where their home environment contributes to their suffering.

Electrostatic purifiers are a fairly simple technology that filters the air using static electricity charge on the filter causing airborne particles to stick to the filter. They are generally for small areas such as individual rooms of a couple hundred square feet. Their effectiveness is limited as the removal of particles is reduced by the design's increased air flow. They can effectively remove dust and pet dander but are not as effective on chemicals, smoke, molds and pollens.

Air purifiers and air cleaners are designed to reduce airborne particles and pollutants within the indoor environment. Most are designed just to reduce dust and particulates. Some are of great benefit in improving indoor air quality, by both reducing particulate pollution and chemical pollution. They are especially beneficial to people suffering from asthma, allergies and chemical sensitivities — or those wanting to prevent becoming sensitized. Customized air filters can be made for specific pollutants in an environment, such as a hair salon, nail parlor or a car painting and body shop.

HEPA air purifiers are High Efficiency Particulate Air filters. The best are designed to remove 99.97% of all airborne pollutants that are 0.3 microns or larger from the air that passes through the filter. That includes fiber particles from carpets, drapes, bedding and upholstery; tobacco smoke; household dust and pollens. Some models, such as those we have on GreenSage.com, are designed to significantly reduce chemicals as well. HEPA air purifiers are sized for their square footage handling capacities which can range from 700 sq. ft. to 1500 sq. ft. or more. Desktop and car sizes are also available.

The air purifiers offered by GreenSage.com are the ones we consider to be the best: Austin Air .