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HEPA Filters: What They Are & How They’re Certified In The US

When researching air cleaners for your healthcare setting, office, school, or home, you’ve likely come across terms like “True HEPA” or “HEPA Like.” But what does HEPA mean? How do you know which air cleaner offers the best results? To help you select the right product for your situation, we’ve highlighted what HEPA filters are, how they’re certified, and what makes them a top choice for your air cleaner system.
HEPA filter

Understanding HEPA Filters & Their Uses

As defined by the U.S. Department of Energy, HEPA stands for High Efficiency Particulate Air.
HEPA filters were first used in the 1940s to prevent the spread of airborne radioactive contaminants during the Manhattan Project. Since then, they have been used commercially to remove dust, pollen, mold, and other airborne particles from indoor settings.

A HEPA filter is a special type of mechanical filter that’s made out of hundreds of thousands of intertwined fiberglass or plastic fibers. This creates a web that traps various airborne particles. In the U.S., all HEPA filters must capture at least 99.97% of fine airborne particles with a size of .3 microns, which is the particles size that most easily penetrates filter media. Any particles that are larger or smaller than .3 microns are trapped with even higher efficiency.

Today HEPA filters are used in a number of devices, including air cleaners, HVAC units, vacuum cleaners, and more.

Are There Different Types of HEPA Filters?

As mentioned above, a filter can only be certified as HEPA if it can trap at least 99.97% of fine airborne particles with a size of .3 microns. A filter is either HEPA or not HEPA; however, there are different grades of HEPA. On the MERV (Minimum Efficiency Reporting Value) Rating Chart, HEPA filters rank between 17-20 MERV, the highest levels of efficiency. A MERV 17 HEPA filter is the standard, and anything above is even more efficient at capturing airborne particles.

If you’re unsure of which one is best for your situation, we recommend asking an expert, such as our team at Air Quality Engineering.

How Do I Know If My Filter Is HEPA Certified?

Manufacturers test each HEPA filter according to the methodologies provided by the Institute of Environmental Sciences and Technologies and the International Organization for Standardization. This test challenges filters with particles or aerosols of a specific size and measures the output. If a filter passes the test, then it is certified as HEPA, and the data is included on a label that states test airflow, resistance to airflow, and penetration (the inverse of efficiency).

It’s also important to note that a HEPA filter may require additional testing after installation. A HEPA manufacturer cannot be responsible for transportation, handling, or installation of a HEPA filter, so to ensure its integrity, you can conduct “in situ certification.” This test uses cold atomized poly-dispersed DOP or poly alpha olefin to scan for leaks in the HEPA filter, frame, or housing gaskets/seals.

HEPA air cleaners are essential for hospital air filtration, office buildings, schools, patient waiting rooms, and even the home, as they are efficient at removing airborne particulate and recommend by the CDC as an additional level of increasing air quality. Are you ready to improve the air quality in your indoor space? Contact us today to find the right product for the job!