While there are many different models of air purifier on the market, most fall into one of two types. HEPA or HEPA-type air purifiers use a filter to clean the air, while ionic air purifiers electrically charge particles to neutralize them. Choosing the right air purifier can have a considerable effect on the severity of your allergies.
HEPA
HEPA, which stands for High Efficiency Particulate Arrestor, is a certification given to certain types of air filters. To receive this certification, a filter must capture 99.97 percent of all particles greater than 0.3 microns in size that pass through it. This standard ensures that the filter will be extremely effective at trapping most types of airborne contaminants including smoke particles, pollen, dust, spores and other allergens.
Ionic Purifiers
An ionic air purifier works by using airborne particles against each other. Air that passes through an ionic purifier enters an electrical field that charges any particles, such as smoke, pollen or dust. Basic units give all particles that pass through a single charge, usually negative, and these charged particles tend to settle on positively charged surfaces in your home like walls and furniture. More advanced purifiers can give positive and negative charges to airborne particles, causing them to stick together and become heavy enough to fall out of the air.
Clean Air Delivery Rate
When choosing a filter, you should look for the Clean Air Delivery Rate. This is a series of numbers, usually divided into figures for tobacco, pollen and dust, that indicate how efficient the filter is at cleaning the air. The higher the number, the quicker a filter can clean and purify the air in the room. In most cases, filter-based purifiers will have a higher CADR than ionic purifiers. Select a purifier with a CADR rating equal to two-thirds of your room's square footage for the best results.
Ozone
One major drawback of ionic air purifiers is that they can produce ozone as a side effect. Ozone is an unstable molecule that can destroy biological contaminants and odor through oxidation, but it can be a lung irritant in high concentrations. The amount of ozone produced by an ionic purifier is usually very small, but if there is anyone in your home with a respiratory illness or if you have small pets in the house, you should choose a filter-based purifier instead.
Bottom Line
While ionic air purifiers are good at removing odors, it is hard to beat the effectiveness of a HEPA air filter for removing as many different types of allergen as possible. If odors are a major concern, look for a HEPA air purifier that includes an activated charcoal pre-filter. This extra layer of protection will help deodorize the air and you will still get the benefit of superior HEPA filtration.
