What Are HEPA Filters And How Do They Work?

HEPA Filtration Technology & Effectiveness

Air filtration and ventilation systems keep our indoor air clean. Not only is this necessary for the safety and comfort of residential spaces, like apartments and homes, but clean air is a governmental requirement for commercial spaces. 

HEPA filters are just one of the technologies that can be used to clean air as it passes through a ventilation system and into the spaces we work. 

There are several different types of air filters, and each performs a specific function. Here’s everything you need to know about HEPA air filters and why you should consider getting one to improve your indoor air quality. 

Airborne Contaminants HEPA Filters Remove.

What is a HEPA Filter?

The HEPA filter is a fibrosis air filter that stands for high-efficiency particulate air filter, which refers to a standard for air filtering efficiency. 

Basic HEPA filters are typically built using borosilicate glass fibers, plastic fibers (also known as polypropylene), or fiberglass (and if this is the case, then these fibers can get into the air and be harmful to your health) bound together with up to 5% acrylic binder (the compound that binds latex paint to a house). 

There are other types of particulate filters, each of which collects aerosols (but they may do so by mechanical or electrostatic methods):

Other particulate filters include fibrosis, low-efficiency, mechanical, and polarized. Each of these filter types is graded by filter efficiency based on the MERV rating system. So, for example, low-efficiency filters are MERV 12, and HEPA filters are MERV 17. Therefore, organizations can buy higher efficiency (higher MERV ratings) or numerous filters with a range of MERV ratings to optimize their air quality. 

The HEPA Standard

When you buy HEPA filters, you aren’t purchasing the HEPA brand, but you are buying a type of filter that can effectively clean air according to HEPA standards. 

HEPA is an official government and industrial (non-consumer) standard defined by the US Department of Energy (DOE), but there are also European standards (if you see a filter with a rating that looks like H13 or U16, the European standard is being used). 

The DOE’s definition of HEPA was developed in the 1940s during the Manhattan Project because they needed filters that could screen radioactive particles. It’s important to note that the standard does not define how the filter must be made or what it is to be made out of, but it indicates that it can trap certain particle diameters and types.

Unfortunately, any filter using the HEPA name does not have to go through any certification through the DOE. Government contractors must adhere to strict standards when installing HEPA filters in ventilation systems or nuclear facilities. In those cases, they would have to prove that they achieved DOE’s HEPA standard. However, this approval does not apply to commercial products like air purifiers.

HEPA Filter Air Flow.

Particles HEPA Filters Remove

The standards that HEPA falls under requires that any filter which is approved to be HEPA must remove 99.95% to 99.97% of particles in the air that passes through it. This refers to a certain diameter of particles, specifically (for HEPA) ones equal to 0.3 µm (which refers to a micrometer or micron, one-millionth of a meter). 

Common particles that a HEPA filter captures include:

This type of filter is extremely common and usually found in smaller and portable air filters. 

HEPA filters cannot capture gaseous pollutants like chemicals, fumes, gases, and odors, nor do they affect odors or volatile organic compounds (VOCs). If an air purifier says it can remove VOCs and gaseous pollutants, it may be more than just a HEPA filter. They may be a hybrid filter with a carbon or activated carbon filter. 

When it comes to improving air quality, air filtration systems balance the airflow, air pressure, and air filtration to clean as much air as possible. Most air purifier systems look at cleaning a quantity of air measured in cubic feet per minute (CFM; or Q). They also usually promote a Clean Air Delivery Rate (CADR), or the rate that air flows through the filter.

How Do HEPA Filters Work?

There are different types of HEPA filters, but True HEPAs filter by mechanical air filter method. Air is forced through a fine mesh, which can trap particles of 0.3 µm in size

HEPA filters are made by randomly arranging the polypropylene or fiberglass fibers (between 0.5 and 2.0 µm). While sometimes the fibers are arranged in a tangle, the fibers can pass air through and trap some of the particles. The important part is that the fibers create narrow pathways for the air to pass through. Larger particles are trapped because they can’t keep up with the constant movement and maneuver through the fibers. But some smaller particles have very little inertia and can pass through with the air and along with the twists and turns of the fiber mesh.

Critical factors of the HEPA filter are the fiber diameter, filter thickness, and face velocity. The filters capture particles through diffusion, interception, and impaction.

Replacing True HEPA Filter.

Types of HEPA Filters

There are different types of HEPA filters. Ones labeled True HEPA should conform to the DOE standards for HEPA filtration. 

Office Indoor Air Quality Monitor.

The Importance of HEPA Filters for Indoor Air Quality

HEPA filters are great at cleaning particulates from the air and should be used as one air purifier method. Look for True HEPA filters or air purifier systems that can provide some data on the effectiveness of their HEPA filter at removing 0.3 µm.

Sanalife’s air purifier systems, for example, uses five stages to clean the air: 

Whether you are looking to improve your indoor air quality to meet health standards or to reopen following the COVID pandemic, it’s essential to get an air purifier with a HEPA filter in it. See today how an air purifier system with Sanalife can improve your air quality and keep your building occupants safe and healthy.

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