What is a HEPA Filter & How Does It Work?

HEPA filters are vital for air purification, effectively capturing tiny particles and improving indoor air quality. People widely use them in diverse applications, from residential air purifiers to industrial cleanrooms. Here, we’ll delve into HEPA filters, including their types and operation.

What Is a HEPA Filter?

A mechanical air filter known as a HEPA filter successfully removes dust, pollen, pet dander, smoke, mold spores, and even certain germs and viruses by catching 99.97% of particles with a size of 0.3 millimeters or Greater.

Different Types of HEPA Filters

HEPA filters come in several variations, each designed for specific applications. Here are some common types:

True HEPA Filters:

The most prevalent and well-known variety is true HEPA filters. They fulfill the DOE’s stringent criteria, collecting 99.97% of particles 0.3 microns or Bigger. People widely use True HEPA filters in home and office air purifiers.

HEPA-Type Filters:

HEPA-type filters are less efficient than True HEPA filters. They capture particles larger than 1 micron at a rate of approximately 85%. While they offer some air-cleaning benefits, they are not as effective as true HEPA filters.

HEPA-Grade Filters:

HEPA-grade filters, similar to HEPA-type filters, often find use in lower-cost air purifiers. They may capture particles down to 2 microns or larger but do not meet the stringent requirements of true HEPA filters.

ULPA Filters:

Ultra-low Penetration Air (ULPA) filters are even more efficient than HEPA filters, capturing 99.999% of particles at 0.12 microns or larger. ULPA filters typically find use in environments requiring extremely clean air, such as semiconductor manufacturing and pharmaceutical cleanrooms.

How HEPA Filters Work:

Mechanical Filtration:

HEPA filters operate on the principle of mechanical filtration. HEPA filters contain dense fiber webs made of materials like fiberglass, paper, or synthetics. These intricately woven fibers create a Dense mat that captures airborne particles effectively.

Particle Capture:

Particles in the air clash with the fibers as they pass through the filter. The thick filter’s design captures even the tiniest particles, including 0.3-micron-sized particles.

Diffusion and Interception:

HEPA filters capture particles through two primary mechanisms: diffusion and interception.

  • Diffusion: Very Small particles, often less than 0.1 microns in size, tend to move erratically due to their Brownian motion. These tiny particles collide with air molecules and change direction frequently. Eventually, they Collide with and adhere to the HEPA filter fibers through diffusion.
  • Interception: Interception captures somewhat bigger particles, often in the 0.1 to 0.4 micron range. As particles move through the air, they approach the filter fibers. Due to the airflow and the particle’s size, they are intercepted by the Fibers and adhere to them.


Larger particles, those over 0.4 microns, are captured through sieving. They are simply too large to fit through the gaps between the filter fibers and get trapped on the filter’s surface.

Particle Retention:

The filter’s structure retains captured particles once they are collected. This process continues until particles saturate the filter, at which point you need to replace it.

Some of the Applications of HEPA Filters are as follow:

HEPA filters find applications in various fields due to their exceptional particle-capturing capabilities:

Residential Air Purifiers:

Households often use HEPA-equipped air purifiers to enhance indoor air quality and minimize allergies.

HVAC Systems:

HEPA filters may be incorporated into HVAC systems to supply clean air throughout a facility.


Industries such as pharmaceuticals, electronics manufacturing, and biotechnology rely on HEPA and ULPA filters to maintain sterile environments.

Medical Facilities:

HEPA filters are commonly used in hospital operating rooms, isolation units, and laboratories to prevent the spread of airborne pathogens.

Aircraft and Automobiles:

Some aircraft and high-end automobiles use HEPA filters to provide passengers with clean, filtered air during travel.

Climate Grip significantly enhances HEPA filter performance in applications ranging from residential air purifiers to industrial cleanrooms. Leveraging advanced technology and real-time data analysis, Climate Grip offers features like continuous monitoring, data analysis, automation, remote control, alerts, energy efficiency optimization, and seamless integration with Building Management Systems (BMS). These capabilities ensure HEPA filters operate at peak efficiency, capturing particles and allergens effectively. Whether in homes, commercial buildings, or critical environments like cleanrooms and medical facilities, Climate Grip empowers users to maintain clean indoor air, optimize filter performance, and reduce energy consumption for a healthier and more sustainable environment.


High-Efficiency Particulate Air (HEPA) filters are indispensable tools for enhancing indoor air quality by effectively capturing particles and allergens. HEPA filters serve numerous applications, from residential air purifiers to critical environments like cleanrooms and medical facilities. Climate Grip is a valuable tool for maximizing HEPA filter efficiency in various applications. Climate Grip offers real-time monitoring, data analysis, automation, remote control, alerts, energy efficiency optimization, and seamless BMS integration, enabling users to maintain clean indoor air, optimize filter performance, and reduce energy consumption for a healthier and more sustainable environment.

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