When purchasing air purifiers, HVAC units, and even vacuum cleaners, you’ll often see the word HEPA. So let’s take a look. What exactly is HEPA? Are there different types? What are the differences? And what’s the most powerful?
What is HEPA?
HEPA stands for High Efficiency Particulate Air. It is a standard defined and developed by the U.S. Department of Energy during the 1940s as part of their efforts to contain the spread of particles and contamination resulting from nuclear testing. This standard has since moved into the consumer market and has become commonplace for air purifiers.
To meet the HEPA standard, the filter must remove 99.97% or more of all particles which are 0.3 microns (micrometers) in diameter. In other words, for every 10,000 particles that are 0.3 microns in diameter, only three of them pass through.
The HEPA standard traps very small particles, many of which are invisible to the human eye and harmful to your health. To provide perspective for size, human hair is approximately 80-100 microns in diameter.
CAUTION: HEPA Type and HEPA Like
Unlike True HEPA, “HEPA Type” and “HEPA Like” filters fail the standard. These terms are essentially meaningless and are used in order to confuse consumers into purchasing lower quality filters and air purifiers. While it is variable what percentage of particles these filters do remove, it is certain that they do not remove 99.97% of particles 0.3 microns in diameter. These filters are less dense and thus unable to trap the smallest and most harmful particles.
So, to answer one of the first questions: No – there are not different types of HEPA. There is either HEPA or NOT HEPA.
Most Powerful: Medical Grade HEPA
Although there are not different types of HEPA – as filters either meet or fail the HEPA standard – there are different levels of HEPA efficiency. This is in addition to the above standard and is used to further compare and categorize HEPA filters amongst each other.
True HEPA generally ranges from H10-H12. This is the “grade” of HEPA or the level of efficiency. The higher the grade, the better the filter.
HEPA H13-H14 are within the highest tier of HEPA and are considered medical grade quality. Whereas H10-H12 filters only trap 85-99.5% of all particles that are 0.1 microns in diameter, HEPA H13 and H14 trap 99.95% and 99.995% of such particles, respectively.
Medical grade HEPA filters are commonly used in pharmaceutical manufacturing and electronic control rooms because they have a greater particulate retention rate. This means medical grade HEPA filters are more efficient in removing harmful toxins from the environment. The web of fibers that make up these filters is even more dense than True HEPA and thus traps the smallest particles at a higher rate.
When comparing different air purifiers online or in-stores, it is essential to note whether they use True HEPA filters. HEPA should be the minimum standard you use within your home. For the cleanest air, a higher density filter is necessary: medical grade HEPA.