air purifier in living room with woman

HEPA, which stands for High-Efficiency Particulate Air, is a standard for the most efficient and effective air purifying filters on the market. Known also as a high-efficiency particulate absorbing filter, this appliance is capable of removing at least 99.97% of particles that are as small as 0.3 μm. 

This means HEPA filters are highly efficient in purifying air, making them one of the most common solutions for people with allergies and everywhere else where bacteria, viruses, and other microscopical pollution are not welcomed. 

At first, HEPA filters were utilized in spaces like laboratories and factories, where the highest quality of air was necessary for various production processes and for conducting research. Now, they are available for individual customers, significantly improving the quality of air in spaces of your choice. 

If you wonder whether investing in a HEPA air purifier is worth the trouble, keep reading. Below we’re explaining how a HEPA filter works and what are its most common applications.

What Is HEPA Air Purifier?

HEPA air purifier is a purifier that utilizes HEPA technology to filter the air. The most common types of filters used in air purifiers are HEPA, antibacterial, charged media, and germicidal. Out of all of these, HEPA filters are the most effective at removing various, even very small particulate matter from the air. For this reason, HEPA air purifiers are considered one of the best purifying appliances available on the market. 

How is this result achieved? HEPA filters must meet the highest standards, filtering out at least 99.97% of particles with a diameter equalling 0.3 micrometers or larger. Filters undergo rigorous testing during the manufacturing process to ensure their effectiveness against such small particulars. 

In fact, they might be more effective at removing smaller impurities, like bacteria and viruses, than larger ones due to the patterns of behavior such microscopical particulars are exhibiting. 

That’s why particles the size of 0.3 micrometers are considered a golden standard for all HEPA filters. But how exactly does a HEPA filter work?

HEPA filter for air purifier

How Does a HEPA Filter Work?

Why are HEPA filters so successful at removing really small particles from the air that is going through them? The secret lies in what the actual filters are made of. 

In the simplest terms, a HEPA filter consists of glass fibers that are interlaced and twisted in such a way that traps the pollution, directs it through the fibers’ “maze,” and takes it out of circulation. 

There are a few ways through which this process takes place. These would be:

  • Direct Impaction – this is when larger contaminants, like dust or mold, travel through the “maze” in a straight line and stick to the fibers.
  • Sieving – a particle gets trapped between two fibers. 
  • Interception – air flow is not strong enough to force particles to stick to the fibers, but contaminants stick to the sides of the fibers. 
  • Diffusion – microscopic particles move in a more unpredictable manner than the larger ones, causing them to hit and stick to the fibers. 

Diffusion is how the particles below 0.3 μm are captured, making this filter highly effective in dealing with the smallest of contaminants. However, there are some types of pollution that will not be filtered out by a HEPA filter – this concerns gasses and odors.


Although there is a high likelihood you’ll be able to filter out most of the viruses, mold, and other really small particles from the air with a HEPA filter, it will not prove to be very effective against cigarette smoke or various odors. To do that, you will need a carbon filter.

High-Efficiency Gas Adsorption filters (HEGA), also known as carbon cloth filters, can often be found in air purifiers next to HEPA filters, providing a sufficient amount of protection against chemical vapors, odors, and fumes. 

American and European HEPA Standards

While American standards require HEPA filters to remove at least 99.97% of particles the size between 0.3 μm and 10 μm, this is not the case for European standards. HEPA filters are certified in Europe when they filter out at least 99.95% of very fine particles. 

The U.S.-certified HEPA filters are held to a higher standard, and because of that, they are often called the “True HEPA.” It’s not an official term used by any accrediting bodies in the U.S. or Europe (its origins can be tracked down to various marketing efforts), but it is often used to differentiate between the two types. 

Where Are HEPA Filters Used?

HEPA air purifiers are used everywhere the highest quality of air is required. Now available to the average consumer, these filters are found in homes, cars, and offices. Here are some of the most common applications for HEPA filters.


Pollen season can be particularly difficult for those with allergies and asthma. As HEPA filters are exceptionally good at removing allergens and mold from the air, they are often utilized in homes and spaces to mitigate the symptoms of allergies. 

Volatile Organic Compounds (VOCs)

VOCs are organic compounds that can easily accumulate in the air at room temperature. These compounds come from cigarette smoke, paint, carpeting, or sealants and, in higher amounts, can be a cause of some health issues. A HEPA filter can minimize the presence of VOCs in the air you breathe. 

Bacteria and Viruses

HEPA filters are also commonly used in all the spaces where we want to avoid contamination with bacteria and viruses. So if you wish to reduce the concentration of germs in your home (something particularly beneficial during flu seasons and global pandemics), investing in a HEPA air purifier is a good idea. 

Find a HEPA Air Purifier For Your Home 

You don’t know which HEPA air purifier to choose? Check out our reviews and comparisons to find the best product for your needs. We specialize in air purifying systems, offering you comprehensive reviews based on our own experiences with those appliances.

Trust the experts and enjoy clean air in your home.