Comparison: Ionic Air Purifiers Vs HEPA Air Purifiers

Ionic and HEPA air purifiers are designed to improve indoor air quality. They are different in their effectiveness. And it's not close.

Below we give some history and break down the differences between the two types of air purifiers. We explain why air purifiers without ionizers are ideal for you in almost every instance. Especially if you want clean, fresh air. We will also share some secrets of the air purifier industry related to air ionizers.

Which Air Purifier Is Most Popular?

In the 1990's, ionic air purifiers were popular. In particular, the Sharper Image Ionic Breeze. There is a similar model, the Ionic Pro air cleaner.

In the early 2000's the Ionic Breeze air cleaner received unfavorable reviews. This was from a result of improved air cleaner testing. 

Since then, air purifiers with high efficiency air filters have become much more popular. Today, HEPA is the most common type of air purifier purchased.

How Ionic Air Purifiers Work

There are actually two types of ionic air purifiers. Electrostatic precipitators and air ionizers. In both cases these are "filter-less " air cleaners. They are also known as an electronic air cleaner.

Electrostatic precipitators have positive and negative charged plates. Particulates collect on the plates as they pass through the air purifier. Rather than having to replace the filter, you must wash or clean the plates. While it is beneficial from a cost standpoint, you give up a lot in performance compared to a high efficiency air filter.

The filter-less air purifiers simply do not remove the particulates effectively. They do not do a good job removing the smallest, most dangerous particles. These are the particles that float in the air for hours or days and can be breathed deep into your lungs.

An electrostatic precipitators' performance is best when the plates are clean. Yet, even at that point, it performs much worse when compared to a high efficiency air 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. Ozone is considered indoor air pollution. We see this often with car air purifiers and it's not what you would expect from an air purification system.

For someone with a sensitive system such as COPD, emphysema or asthma, ozone can be a huge problem. Room air purifiers are now tested to meet ozone requirements. As a result there has been a large shift away from ionic air purifiers to high efficiency air filter purifiers. It's somewhat difficult to even find an ozone generating purifier now and with good reason. In our opinion, the last thing you want an air purifier to do is introduce a pollutant into your home. Your expectation is your home will have clean air rather than ending up with high levels of ozone.

While we are harsh on ozone generators there is one area where they work well. This is in cigarette smoke removal from a room. Commercial ozone generators like this are used in hotel rooms to remove difficult tobacco smoke smells.

Ozone air purification is sold only as a commercial air purifier since the State of California does not allow them to be sold to consumers. Since California is such a powerful state, it's had the effect of limiting the sales nationwide.

Source: Wikipedia

The other type of ionic air cleaner is an air ionizer. These air purifiers don’t actually have a filter. In some cases not even a motor. This is referred to as a negative ion generator. Because they emit a negative ion charge that is meant to attach to the airborne particulates. The idea is that once the airborne particles take on the electrical charge they will be more likely to stick to surfaces.

A problem with this approach is it the particles don't discriminate in what they attach to. It could be the carpeting, walls, your clothes and worst case - your lungs. For mold spores, you really don't want them floating and then sticking to the walls. You want to catch them in the room air purifier.

Air ionizers are not recommended for relief from allergies or any other respiratory condition.

HEPA Filter Based Media 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 much since then.

For air cleaning performance, HEPA filter based media is the best technology. They remove the most airborne contaminants as well as the most dangerous particulates. 

High efficiency air filters need replacement at some point. This is for the sake of ensuring you are getting a high level of air cleaning. As the filters collect particles the airflow resistance will increase. This results in less airflow through the filter and lower air cleaning performance. If the filter is clogged it will have a difficult time in moving the air to clean your room.

To learn more about dust removal see our best air purifiers for dust. If your issue is related to mold growth, see the best air purifiers for mold for additional information and recommendations.

Purifiers that only use filters and a strong motor only use mechanical filtration, which is the safest air cleaning option. They do not generate any unwanted air pollutants such as ozone. 

HEPA Filter Based Media Air Purifiers With Negative Ionizers

In many cases when you buy a HEPA filter based media air purifier it will also have a negative ionizer. This is done to give a boost to the air cleaning performance. If you do not want a negative ionizer your choices among brands are limited. The

The air purifiers that we make do not have an ionizer. And no unwanted ozone.

As mentioned earlier, the concern with an ionizer is that it will generate ozone. The state of California requires all air purifiers to be lab tested.

Negative Ionizers are small devices that create a negative charge. This charge allows the filter to capture more particles. Ion generators come in different shapes and are small in size similar to a dental floss container.

An Inside Look Into The Ozone Testing

In the spirit of full disclosure we will show you how the ozone testing is done and what the results look like. To date, we have not seen anyone else share this type of information.

The ozone testing is done at a certified test lab in the US such as Intertek. This is an extensive test with measurements taken in many places on the air purifier. As you can see in the picture below. The negative ions can travel in different directions. So, many measurements.

The testing is performed for 8 hours with many measurements taken. To pass an air purifier must be less than 0.05 ppm.

Here are the results of the ozone test for the Finn air purifier. Results far below the 0.05ppm standard (about 99% less).

Here are the Max ozone test results. Again, far below the standard for what is considered safe. Actually, this test did not show any ozone.

Secrets Air Purifiers Companies Don't Want You To Know

There is no doubt that ozone is a dangerous gas and harmful to your lungs.

The FDA has established an ozone standard of 0.05 ppm for air purifiers. This means an air purifier must produce less than 0.05 ppm.

Some companies claim zero. Or zero ozone.

The motor can produce even a small amount. So, this is not an accurate claim.

But that's not what you should be concerned about.

The testing for ozone is done in a controlled test lab. The problem is that we do not live in test labs.

We live in homes. Homes that have other things in them like cleaning supplies and nail polish that give off fumes. These fumes when in contact with technologies like PCO or ionizers can produce ozone.

These situations are not replicated in the ozone test lab. You can see why claiming zero ozone is a lie or at least misleading.

What To Look For In An Air Purifier