These are: HEPA air purifiers, ionic air cleaners, carbon-filter air cleaners, ozone purifiers and UV (or ultraviolet) light purifiers.

HEPA's ones are the most common type and are well suited for trapping allergens. The designation HEPA, is defined as a filter that is able to contain particles as small as 0.3 microns and will catch at least 99.97% of pollutants as small as that.

HEPA purification systems are commonly seen in hospital settings. They have filters which must be replaced regularly, normally about twice per year, although some filters can go several years between replacements.

Their brands are not effective for the removal of cigarette smoke, fumes, gases or odors, and for this reason sometimes a carbon filter is also combined in their purifiers.

Ionic air purification devices can remove the smallest of particles from the air and are effective even in large enclosed spaces. Ionic purifiers are also known as electronic air cleaners.

These electronic purifiers charge the air with a blast of positive energy which also charges the particles positively. The particles then get drawn into the device, attracted by the negatively charged collection plates. This process allows for a virtually silent operation, as a fan is not required.

Ionic air cleaners are also well suited to remove particulates in the air, but they use no filters. Instead, the charged particles adhere to the collection blades, which can then be easily wiped down to clean them of the captured contaminates.

Activated carbon purifiers are most effective for removing odors, smoke, gases and chemical residue from the air. These brand of filters have tiny pores that are able to absorb and chemically react with the pollutants as they are carried through the filter.

This process causes the contaminants to bond with the carbon in this chemical reaction, trapping them and eliminating them from the atmosphere. Because carbon room air purifiers can't trap allergens and bacteria, they are commonly combined with the HEPA's brand.

An ozone air purifier is able to eliminate odors, smoke and gases, but does not trap the particulates and allergens in the air. Ozone purifiers are capable of eliminating deep, problematic odors, such as pet urine from carpeting, and the ozone can destroy mold and kill bacteria.

Ozone is somewhat controversial for home use and some experts recommend that those with asthma should use caution around ozone. Some of them on the market combine the ozone purification with the ionic air purification. The combination of these two methods results in a high-tech way to eliminate odors, smoke, gases and also airborne particulate matter.

Ultraviolet light air purifier systems are able to destroy bacteria, but they are not capable of removing allergens, fumes, smoke or odors form the air.

UV air purifier units treat the air with an ultraviolet light as it moves through the purifier, killing germs, viruses and bacteria as soon as they are exposed to the UV light.

This purification method is also often combined with HEPA filters in the same unit to trap the particulate material in the air as well.

The ionic air purifying units might be the most heard about nowadays, but the best one for you and your family will be dependent on the specifics of your home environment and family concerns.

So far, no single purification approach can solve all the air quality needs for a home. Choose the machine that best addresses the areas that are troublesome to your family and take time to research your different options.