All air purifiers have HEPA filters (High-Efficiency Particulate Air filters). Some of them have a “better” HEPA filter than others. But what do these “better” HEPA filters even mean, and how can you check if you have a good HEPA filter?
Example: A lot of times, you will see True HEPA filters. Are these better ones? Not necessarily. “True” HEPA did start as a US DOE standard but is now used primarily as a marketing term.
The way you can tell how good any HEPA filter actually is, you have to check the HEPA filter classification. 5 key HEPA filter classes include H10, H11, H12, H13, and H14 HEPA filters.
Medical-grade HEPA filter, for example, has to capture at least 99.99% of air particulates with 0.3 microns diameter or larger. That means that only H14 HEPA filters are considered medical-grade (they capture 99.995% of air particulates). Even H13 HEPA (99.95%) doesn’t meet the medical-grade HEPA standard.
Let’s have a look at H10, H11, H12, H13, and H14 HEPA filters by looking at HEPA filtration standards and classifications (we combined all the specs in a neat table), and then proceed with the pros and cons of good vs bad HEPA filters:
HEPA Filter Classes (H10-H14)
| HEPA Class | Efficiency (% Captured) | Applications | Air Purifier Example |
| H10 | 85% | Industrial Pre-Filters | N/A |
| H11 | 95% | Large Commercial Air Handlers | N/A |
| H12 | 99.5% | Limited Cleanrooms, “Cheap” Air Purifiers | Levoit LV-H132 |
| H13 | 99.95% | Air Purifiers, High-Efficiency HVAC Filtrations | Alen BreatheSmart FLEX |
| H14 | 99.995% | Medical-Grade Air Purifiers, Critical Cleanrooms, Laboratories | Medify MA-112 (Medical-Grade) |
We can see major differences between these HEPA filter classes. Here are the key efficiency (at 0.3 micron or large particle size) differences:
- H10 HEPA filters capture only 85% of these small air particulates. That means that 15% or 150,000 out of a million particles are not filtered.
- H11 HEPA filters are a bit better; they capture 95% of air particulates. 5% or 50,000 out of a million particles still get through the filter.
- H12 HEPA filters have a significantly higher efficiency than H10 and H11; they capture 99.5% of air particles. 0.5% or 5,000 out of a million particles still get through.
- H13 HEPA filters are superb; they can filter out 99.95% of small air particulates. That means that only 0.05% or 500 out of a million air particulates escape the filter on the other side. These are considered good HEPA filters for air purifiers.
- H14 HEPA filters are the best-in-the-industry filters with a minimum of 99.995% efficiency. That means they leave through only 0.005% or merely 50 out of a million air particulates. These are the best HEPA filters for air purifiers as well as for clinics, hospital settings, and advanced laboratories. H14 HEPA is commonly referred to as medical-grade filters because of their use in the medical sector.
In short, H11 is better than H10, H12 is better than H11, H13 is way better than H10-H12, and H14 is better than H13 and all the rest.
Now, everybody who is buying an air purifier with HEPA filters, wants the cleanest air (hence H14 HEPA filters). If you need an idea of which is the best unit with H14 HEPA filters, here’s the best example:
This is the Medify MA-112 air purifier, one of the first ones with H14 HEPA filters, and arguably the best H14 HEPA filter air purifier on the market. It costs about $500, you can check the current price and get it here.
Let’s have a look at a comparison between “bad” and “good” HEPA filters:
Bad Vs Good HEPA Filters: Pros And Cons
Needless to say, the most important spec about any HEPA filter is its effectiveness. This means what percentage of 0.3-micron or bigger air particulates a HEPA filter can capture. H14, for example, is the best in this category.
However, it is very important to note the cons of good HEPA filters as well (maybe just to see the challenges engineers designing air purifiers have to overcome). All drawbacks of good HEPA filters come from their finer arranged fibers:
- Airflow Restrictions. H13 and H14 are more airflow-restrictive than H10, H11, and H12. An air purifier has to create a bigger pre-filter pressure to push through the same CFMs as with bad HEPA filters. This is why, for example, we can’t use HEPA filters for air conditioners, heat pumps, or furnaces (too restrictive).
- Energy Consumption. To create that extra pressure, the H13 and H14 HEPA air purifiers have to use more electricity.
- Lifetime. Good H13 and H14 HEPA filters catch more air particulates than bad HEPA filters. They also have smaller holes in the arranged fiber mat. That means the better the HEPA filters, the quicker they will become packed (saturated with captured air particulates), reducing how long they will last.
- Potential Air Leakages. With bad HEPA filters, air leakages due to non-tight seals in the air purifier will not affect their capacity as substantially as with good HEPA filters. H10, for example, already leaves through 15% of particles; 1% extra losses due to air leakage is non-significant. H14, on the other hand, only leaves through 0.005% of particles; 1% air leaking loss here is much more significant.
- Price. Needless to say, good H13 and H14 HEPA filters are much more expensive than simple H10, H11, or H12 filters. Many of the cheap $100 air purifiers use these cheap and less effective H12 filters; that’s why they can cost only $100 but you do get what you pay for.
Should all these disadvantages of good HEPA filters concern you?
Not really. Air purifier design engineers have to overcome these shortcomings when designing H14 air purifiers. Stronger fan motors, higher CFMs, noise level reduction, good pre-filters to protect the all-important and precious HEPA filters are methods they use to offset them.
The result is that you get incredibly clean air with H14 HEPA filters, but air purifiers that contain them can cost over $500. With air purifiers, the price does generally reflect the quality of air you will breathe.
Needless to say, the pros of good HEPA filters (H13, H14) heavily outweigh their shortcomings when it comes to how well they can clean the air we breathe indoors.
About HEPA Filter Classification
Now, you might wonder why you don’t see these H10, H11, H12, H13, or H14 HEPA classes when you are buying air purifiers in the US.
That’s because the US Department of Energy (DOE) – a government agency responsible for HEPA filtration regulations – doesn’t rely on this classification. The H HEPA classes actually come from the European standard. Here are the 2 HEPA standards the whole world follows:
- European Standard (EN 1822). This is the industry-leading standard, based on MERV (Minimum Efficiency Reporting Value). For HEPA filters, they look at efficiency at 0.3-micron air particulate sizes from which the H10, H11, H12, H13, and H14 classification is derived. You can check the EN 1822 document here.
- DOE Technical Standard (DOE-STD-3020-2015). This US standard simply classifies HEPA filters as “filters capable of capturing at least 99.97% of airborne particles at 0.3 microns” (commonly referred to as True HEPA). You can check the DOE HEPA filter standard document here.
With air purifiers sold in the US, you will see that all of them have HEPA filters. However, referring to DOE HEPA filter definitions, most of these filters do not reach the requirements for HEPA filter classification. Only H14 HEPA filters (in accordance with European Standard) can actually be called HEPA filters in the US.
We hope that this overview of HEPA filter classification gives you the insight you need. If you have any additional questions, our comments are always open. Send us a comment and we can help you out.