July 20, 2022

HEPA vs. ULPA Filtration: What’s the Difference?

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HEPA vs. ULPA Filtration: What’s the Difference?

HEPA versus ULPA Filtration: What’s the Difference? 1

It’s difficult to imagine a time when clean air was the exception rather than the standard in places such as factories, hospitals, distilleries, and doctors’ offices. But before commercial air filtration was invented, workers were exposed to all manner of indoor air pollution (IAP). As a result, illnesses such as asthma, blood poisoning, even cancer, were not uncommon occupational hazards. The need for worker protection was great.

It wasn’t until 1942 that the first step toward safeguarding indoor air quality (IAQ) was taken. During WWII, a small band of research and development scientists working on a top-secret nuclear program were tasked with finding a way to control the spread of minuscule particles of radioactive matter in order to protect their fellow government workers. Due to their efforts on that classified post, code-named “The Manhattan Project,” the atomic bomb was developed. So, too, was the first HEPA filter.

But that one effort wasn’t the end of development of air filtration products to improve IAQ for workers.

In any industrial setting, there are multiple sources of IAP, most of which are a complex mix of substances which can vary in their potential health risks. Pollutants can originate from both biological and non-biological sources. (1) Biological contaminants include mold, dust mites, and rodent feces and dander. Non-biological include emissions from VOCs, smoke, and chemical vapors. In businesses such as healthcare, where no manufacturing occurs, the threat of infection is the main exposure risk.

Major IAQ Inventions That Led Up To ULPA filtration:

1823 – “Smoke Helmet”: protected firefighters from harmful coal and soot.

1854 – Gas mask: powdered charcoal was used as the filtering agent.

1908 – Electrostatic precipitator: collected and eliminated fumes and mists in factories and vineyards.

1942 – The HEPA (High-Efficiency Particulate Air) filter: based on the gas masks worn by soldiers which were made from a filter paper containing asbestos and cellulose fibers.

1970s – ULPA (Ultra Low Penetration Air) filter: was born after years of trying to create a higher level of indoor air cleaning, one that blocked even the smallest particles from reentering worker’s breathing space.

Today, both HEPA and ULPA filters are designed to catch airborne particulates and operate in a similar fashion. The filters are made up of minuscule strands of crossed and pleated glass fibers. When air is forced through the fine mesh filter, particles become trapped and are unable to reenter the atmosphere. But their similarities end here.

What researchers learned over the years is that a one-size-fits-all air cleaner isn’t suitable for all applications and that the size of the particles needing to be captured should determine the kind of filtration used. Fine particles need one kind of filtration, coarse particles, usually another.

Submicron Particulate

Fine particles or particulate matter (PM) is the sum of all liquid and solid airborne emissions 2.5 microns or less. Coarse particles fall between 2.5 and 10 microns.

A micron is a unit of measurement; 25,000 microns per inch. In industry, PM can be smoke and fumes from chemicals burning, or dust from metals and wood. In healthcare, smoke and dust are not as much a concern as are fine particles from viruses, bacteria, and mold.

In order to meet the minimum standard as set by the Department of Energy, HEPA filtration must trap at least 99.97% of all particles larger than 0.3 microns. (2) ULPA filters, on the other hand, are required to be 99.999% efficient and able to remove particles smaller than .12 microns in diameter.

To illustrate the size of particles, envision a strand of human hair. The average is somewhere between 50-70 microns. Dust, pollen, and molds are usually less than 10 microns in diameter. And fine particulates, such as viruses, usually measure under 2.5 PM. (3) This generally includes dust like pollen, mites, and pet dander. But airborne chemicals such as VOCs and mists from bacteria and viruses are too small to be caught by HEPA filters and pass right through. ULPA filtration was invented specifically for this purpose.


HEPA filters can remove fine PM as well as some coarser particulates. ULPA filtration traps the finest of PM – the ones that go right through a HEPA filter. But there are other considerations beyond capture capacity to be made before deciding what product to use for your office, lab, or facility.

Efficiency measures the ability of the filter (over the life of the product) to remove airborne particles. Since the ULPA traps more of the smallest particles than does the HEPA, it is considered more efficient.

And, resistance refers to the airflow capacity of matter as it moves through the filter. Since the ULPA filter media is denser, airflow is lower than a comparably sized HEPA filter, resulting in lower air circulation plus higher power use required by the unit blower to move air through the filter. This affects the life and longevity of the filter, making the ULPA less economical.

Industries and Applications

HEPA filters were designed for most industrial, military, and government applications, particularly in types of manufacturing where airborne particulate matter is constant. HEPA popularity has grown and is now common for home use ranging from bedroom air purifiers to vacuum cleaners.

ULPA filtration is used in situations where a more efficient means of capturing the smallest PM and preventing the spread of airborne bacterial and viral pathogens is important. ULPA filters are best suited for more critical applications in fields such as medical and healthcare, pharma research and manufacturing, biomedical labs, airline cabin purifiers, clean rooms, electronics, nuclear and aerospace industry applications.

When deciding between HEPA and ULPA filtration, one should start with safety. If both types of filtration methods can meet your particulate capture needs for a safe and healthy workplace, then take into consideration a unit’s efficiency and resistance.

To reduce the risk to manufacturing and healthcare workers, experts recommend a multi-layered approach to achieving a safe and healthy IAQ. This includes indoor air filtration. (4)

At Air Impurities Removal Systems, Inc., we protect our manufacturing and healthcare customers by providing them with high-quality products and IAQ expertise. Contact us today to speak to a clean air specialist.

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