What Works Better: Ionic Air Purifiers or HEPA Air Purifiers?
While both are designed to improve indoor air quality, ionic
and HEPA air purifiers are very different in how they approach the problem.
Below we break down the differences between the two types of air purifiers and
explain why HEPA-based models are ideal for consumers in almost every instance.
Ionic Air Purifiers
There are actually two types of ionic air purifiers –
electrostatic precipitators and air ionizers. In both cases these are
“filter-less” air cleaners and can be quite appealing since there is no filter
Electrostatic precipitators use positive and negatively
charged plates to collect particulates as they pass through. Rather than having to replace the filter, the
user must wash or clean the plates. While it is beneficial from a cost
standpoint, you give up a lot in performance compared to a HEPA filter.
An electrostatic precipitators' performance is best when the
plates are clean. However, even at that point, it performs much worse when
compared to a HEPA filter. To make matters worse, when the plates become dirty,
the performance degrades further.
It is common for ozone to be produced as a by-product of the
charged plates. For someone with a sensitive system such as COPD, emphysema or
asthma, ozone can be a huge problem.
Recently, room air cleaners have to be tested to meet the minimum ozone
requirements in California and as a result there are way less of this type of
ionic air purifier on the market. In our
opinion, the last thing you want an air purifier to do is introduce a pollutant
into your home.
The other type of ionic air cleaner is an air ionizer. These
units don’t actually have a filter but rather send out a charge that attaches
to the airborne particulates that then attach to something else and therefore are
removed from the air. A problem with this that it attaches to something - could
be the carpeting, walls, your clothes and worst case - your lungs.
While inexpensive, an air ionizer is not generally
recommended for relief from allergies, asthma, or any other respiratory
HEPA Air Purifiers
HEPA filters were developed by the US military during World
War II as a way to create an effective gas mask. The technology has not changed
significantly since then. In terms of
air cleaning performance, HEPA air filters are the best technology available.
In addition, HEPA filters become more efficient over time, removing a higher
percentage of particulates as they become dirty.
While HEPA air filters require replacement at some point, it
is for the sake of ensuring you are getting a high level of air cleaning. As the filters collect particulates, the airflow
resistance will increase and that will result in less airflow through the
filter and lower air cleaning performance.
A way to think about this is the paradox with replacing home
air filters. It is common for people to put off replacing the air filters in
their HVAC system. If you understand the big picture, you can see this is a
Your HVAC system is typically the largest energy user in
your home and by “saving” some money in not replacing your air filter, you are
causing your HVAC system to work much harder and operate longer. This reduces
the life of your heating and cooling system and at the same time increases your
energy bill more than if you just replaced the filters. So, you are unknowingly spending dollars to
Finally, on the topic of Ionic vs HEPA air purifiers, it is
interesting to look at the product trends.
If we go back 10-15 years, more than half the air purifiers sold were
ionic based and that was largely due to a strong marketing message. “Clean air without filters.” Since then, it
has become more widely known that HEPA is the best for truly clean air and
there has been a huge shift to HEPA air purifiers in recent years.