HEPA Air Purifiers – Do They Work?


Many Australian households are now using air purifiers. These devices purify indoor air by filtering harmful contaminants and pollutants. As such, they are regarded as the ultimate solution for improving a household’s indoor air quality.

Like most air purifiers, HEPA air purifiers are designed to eliminate the smallest airborne particles and clean the air inside the house. However, this type of air purifier is equipped with additional features that other similar devices don’t have.

Despite the hundreds of literature published outlining the benefits of these HEPA air filters, many household owners are still questioning if these devices really work. So, to provide a constructive answer to this classic question, here’s a brief discussion of the essential aspects of HEPA air filters you should know.

What Are HEPA Air Purifiers?

A HEPA air purifier is considered one of the best air purifiers sold in the market today. It is equipped with high-efficiency particulate air (HEPA) filters that effectively remove about 99.97% of airborne pollutants as small as 0.3 microns.

Due to its impressive filtering performance, a HEPA air purifier is regarded as a better option than conventional purifiers. Also, it is a top choice for use in various applications, especially in the following.

  • Laboratories
  • Hospitals
  • Planes
  • Aircrafts
  • Automobiles

Almost all medical facilities prefer to use HEPA air purifiers. In most cases, they are used along with UV light that kills live bacteria and viruses to ensure the safety of the patients inside the facility.

How Do HEPA Air Purifiers Work?

HEPA air purifiers work just like conventional air purifiers. These products have internal fans that suck air from the surrounding environment into the device. The air is then passed into the HEPA filters that are responsible for trapping some common household pollutants, such as dust, mould spores, smoke, and bacteria.

The good thing about HEPA air purifiers is that their filters are very effective in trapping various particles of up to 0.3 microns in size, such as pollen, dust, bacteria, mould and other airborne particles. The purified air then flows out of the other side of the device. With the continuous cycle of absorption, filtration and release of purified air, the indoor air quality of the room or house is eventually improved.

What Makes HEPA Air Purifiers Different?

Technically, HEPA air purifiers function similarly to the other purifiers. They only differ with the use of HEPA filters, which give them their highly effective filtering mechanism. These filters come with a multi-layered netting configuration and are made from fine fibreglass threads with varying gaps. The filters’ strands are thinner than the human hair. HEPA filters are also composed of dense sheets of fibres that are sealed and pleated in a plastic or metal frame.

When sucked by the purifier’s internal fan, the pollutants’ large particles are captured due to impaction or when they crash into the fibre. The medium-sized particles are captured via interception, a process where it touches the filter’s fibre and eventually gets caught. Finally, the HEPA filter captures the ultra-fine particles by diffusion, a condition where the particle hits and sticks into the thread while zig-zagging.

How to Check if a HEPA Air Purifier Is Working?

The popularity of using HEPA air purifiers continues to grow. But despite this, many household owners still doubt the purifier’s role in improving the indoor air quality of a house or room. Luckily, there are a number of tests conducted to determine if the HEPA air purifiers are working well. The most commonly used of these are the following.

1. Airflow Test

The airflow test is a physical test used to determine if a HEPA air purifier is working and capable of improving the room’s indoor air quality. This is done by checking if the purifier’s fan is drawing in polluted air from the inside, forcing this to pass through the filters and eventually blowing out purified air back into the room. When the purifier does all these, it simply means that the device is working.

2. Filter Test

The HEPA air purifier’s filters play a crucial role in allowing the device to clean the air it sucks in. However, these filters are also among the most common reasons why the devices are not working well or will not work at all. Thus, it is best to have the purifier’s filters checked regularly. Although many purifiers have filter service indicators, doing a manual check to determine if the filter needs immediate replacement is strongly advised.

3. Air Quality Test

Air quality test provides the most realistic data about the indoor air quality of a home. This is also an excellent way to ensure that the HEPA air purifiers are doing well in cleaning the air circulating around the house.

Air quality test is usually conducted using an air quality monitor, and the following steps:

  • Turn the purifier off and get a baseline air quality reading using an air quality monitor.
  • Turn the purifier on and close all the doors and windows.
  • Allow the device to work for at least 30 minutes, then place the air quality monitor near the purifier’s vent.
  • Get the actual reading and compare it with the baseline reading. A significant improvement in the second reading means that the purifier is working well, while a minor difference means otherwise.

Aside from using the air quality monitor, household owners can also use various chemical test kits to determine if their air purifiers are working. This involves an almost similar set of procedures. The only difference is that this technique uses a chemical test kit instead of a monitor. Also, the collection of the second reading is conducted 24 hours after the baseline reading is obtained.


The use of HEPA air purifiers has provided household owners with an effective option to improve the indoor air quality of their homes. However, it is recommended to be more critical in selecting which purifier to use. Consider testing the available devices to ensure that they are working and obtain the best outcomes.