What is HEPA Filter？

We often see the word "HEPA filter", which appears in purifiers and vacuum cleaners. So what is a HEPA filter? What does it do? Why is it so beneficial? In this article, let us take a closer look at！

What is HEPA filter? 

HEPA stands for High-Efficiency Particulate Air, and a HEPA filter is a type of air filter designed to remove very small particles from the air.

HEPA filters are made from dense layers of fine mesh that trap tiny particles as air flows through them. To qualify as a HEPA filter, the filter must remove at least 99.97% of particles that are 0.3 microns or larger.

These filters are commonly knowed as HEPA filters air purifiers, HEPA filters vacuums, and HVAC systems to improve indoor air quality and remove allergens, dust, and other pollutants from the air. They are particularly useful for people with allergies or respiratory issues, as they can help reduce symptoms and improve overall air quality.

Although the standard for HEPA filters for home is to be able to filter out more than 99.95% of particles with a diameter of 0.3 microns, they can actually filter out particles of almost any size. HEPA filter captures dust, smoke, pet allergens, PM2.5 (dangerous particles 2.5 microns or smaller).

How do HEPA filters work?

HEPA filter is designed to handle particles of different sizes through a combination of three different mechanisms: interception, impaction, and diffusion.

Interception occurs when larger particles are captured by the filter fibers as they pass through the filter. These particles are too large to pass through the gaps between the fibers, so they become trapped on the surface of the filter.

Impaction occurs when smaller particles are unable to follow the air streamlines and collide with the fibers. The particles are then trapped and removed from the air.

Diffusion occurs when very small particles move erratically due to their thermal motion, which causes them to collide with the filter fibers and become trapped.

Together, these three mechanisms allow HEPA filters to capture particles of different sizes, ranging from large dust and pollen particles to smaller particles like mold spores and bacteria.

Why should we choose HEPA filters?

Some of the most common indoor pollutants and their size include:

Dust and dust mites: Dust can be composed of a variety of materials, including skin cells, pollen, pet dander, and soil. Dust particles can range in size from about 0.5 to 100 microns, with most particles falling between 2.5 and 10 microns. Dust mites, which are a common allergen, are between 100 and 300 microns in size.

Pollen: Pollen is a common allergen that can enter indoor spaces through open windows and doors. Pollen particles range in size from about 10 to 100 microns.

Pet dander: Pet dander is made up of tiny flakes of skin shed by pets. These particles can range in size from about 5 to 10 microns.

Mold spores: Mold spores are a common allergen that can be found in damp indoor environments. Mold spores can range in size from about 1 to 20 microns.

Bacteria and viruses: Bacteria and viruses can be present in indoor air, particularly in spaces where there are many people in close proximity. These particles can range in size from about 0.02 to 10 microns.

Volatile organic compounds (VOCs): VOCs are chemicals that can be emitted by products and materials in the home, such as cleaning products, paints, and building materials. The size of VOC particles can vary depending on the type of chemical, but they are generally very small, ranging from about 0.001 to 0.1 microns.

Tobacco smoke: Tobacco smoke contains many harmful chemicals, including particles that can be inhaled by non-smokers. The particles in tobacco smoke can range in size from about 0.01 to 1 micron.

Overall, indoor pollutants can vary in size, but many can be effectively removed from indoor air using air purifiers or filters with a high efficiency particulate air (HEPA) filter.

As you can see, these are pretty much within range of what a HEPA filter can catch. So looking for a HEPA filter vacuum cleaner or a HEPA filter air purifier can do a lot to keep your home tidy and clean.