Facts about True HEPA Filtration

With so many brands claiming that their products have HEPA filtration and/or are “HEPA certified”, you may be wondering what all the fuss is about. In this post, we discuss all things HEPA-filtration – read on to learn the ins-and-outs of HEPA filtration.

Why Choose HEPA Filtration?

According to the Centers for Disease Control and Prevention (CDC) Guidelines for Environmental Infection Control in Healthcare Facilities, HEPA filtration is required for the capture of microbial spores and other contaminants that can potentially cause fungal infections and Aspergillosis. Here at Alberta Fire & Flood, we use a variety of HEPA filtration products – including the PREDATOR^® Portable Air Scrubber.

All PREDATOR^® Portable Air Scrubbers are equipped with high-efficiency, HEPA filters that are tested and certified to remove at least 99.97% (9,997 out of 10,000) of particles 0.3 microns (0.000012-inch) in size. To put this in perspective, fungal spores are typically five to 25 microns in size.

Predator Air Scrubber

Testing and Certification by Independent National Laboratories

Abatement HEPA filters meet Institute of Environmental Sciences and Technology standard for Type A 99.97% efficiency HEPA filters. To meet this standard, each and every completed Abatement HEPA filter must be tested for leakage and resistance, to detect any leaks in the media or between the media and the frame or other problems that can compromise the integrity of the completed filter. Test results must be shown on a label on the filter frame. Abatement filter frames are metal or plastic. The CDC Guidelines state that: “Wood can compromise the air quality if it becomes and remain wet, allowing the growth of fungi and bacteria.” Abatement filters also meet UL900 flammability requirements.

How often do Abatement HEPA filters need to be changed?

The size and concentration of airborne contaminants, temperature, humidity conditions and duration of use determine how often filters need replacement. As the filters become loaded with particulate matter, the airflow capacity of the unit decreases and the static pressure differential across the filter increases.

Abatement PREDATOR Portable Air Scrubbers are equipped with easy-to-read filter change indicator lamps that illuminate when filters should be replaced. Unlike gauges, these lamps do not require operator interpretation or calculations. Average filter life (with continuous operation):

• Primary filter: 1 day
• Secondary filters: 3-7 days
• HEPA filter: 500 to 1,000 hours

What does the term HEPA mean?

HEPA is an acronym for “High Efficiency Particulate Air” or “High Efficiency Particulate Arrestance.”

Definition: What is Arrestance? Arrestance is the measure of the ability of an air filtration device to remove a synthetic dust from the air.

This acronym refers to a filter that is manufactured, tested and certified to meet Institute of Environmental Sciences and Technology (IEST) construction, performance and certification standards as currently published in IEST RP-CC001.4.

What is it that makes HEPA filters so efficient?

The ultra-fine, glass-fiber medium captures microscopic particles that can easily pass through other filters by a combination of diffusion, interception and inertial impaction. To qualify as a Type A HEPA filter, the filter must capture at least 99.97% (9,997 out of 10,000) of particles 0.3 microns in size–about 300 times smaller than the diameter of a human hair, and 25 to 50 times smaller than we can see. To a HEPA filter, catching a one-micron particle (1/1,000,000 of a meter) is like stopping a cotton ball with a door screen.

Are all filters made with HEPA filter media HEPA filters?

No. Manufacturing a filter with HEPA filter media does not mean that the filter itself meets true HEPA efficiency requirements. Serious filter leakage can go undetected if filters are not individually tested and certified at the end of the manufacturing process. Even the tiniest pinhole leaks in the media or breach of the seal between the media pack and the filter frame can cause the filter to fail IEST requirements. The testing requires very specific procedures using a thermally generated mono-dispersed aerosol and a laser particle counter. Some regulations also require field-testing by the user prior to going into service and periodically thereafter.

Why is the testing done with a 0.3-micron particle size test aerosol?

Filter efficiency studies have shown that 0.3-microns is predominately the “Most Penetrating Particle Size (MPPS)” for HEPA filter media. Efficiency is typically greater than 99.97% against larger or smaller particle sizes. Particles larger than 0.3 microns are typically more easily trapped, or intercepted, by the media. Smaller particles often lack sufficient mass to penetrate the media.

Is a “HEPA-Type” filter the same as a HEPA Filter?

No. In fact, the differences are huge. According to the American Lung Association, filters classified as “HEPA-type” filters may capture as little as 55% of 0.3-micron particles (5,500 out of 10,000). By this definition, the true HEPA filter could be more than 1,800 times as efficient as the “HEPA-type” filter.

Does HEPA filter efficiency decrease as the filter gets dirty?

No. Filter media with an electrostatic charge and other air purification technologies can experience substantial loss of efficiency as they become dirty. Exactly the opposite typically happens with HEPA filters. The dirtier it gets, the more efficient it can become.

HEPA filtration is discussed throughout many of the seminars at the Restoration Academy. Whether the seminar is on mould, fire and smoke, bed bugs, Hantaviruses, etc., learners are made aware of the HEPA Sandwich technique that Alberta Fire and Flood uses to ensure that their clients are moving back into a healthy and safe home and business environment.

Your HEPA sandwich machine