What do the different air purifier filters do?

by Christina Cini    

What do the different air purifier filters do? - Andatech Distribution

When shopping for air purifiers, you would come across a range of filters including HEPA filters, carbon filters, and titanium oxide filters. You’d think the more filters and air purifier has, the better it is… but the truth is every filter does a different job and when buying an air purifier, you should consider what its filters can do to help you.

Below, we explain what each air purifier filter does and how they work, so that you can make a more informed decision when you shop for an air purifier.



Pre-filters are an economical means of saving time and money replacing a household’s air filters. They are always the first filter that air must go through in an air purifier, and they’re really important because they prevent the larger particles like hair from ever reaching the main filters.

This increases the efficiency and life of the other filters and internal components, and ensures that the  air filtration system is in optimal condition. They can usually be washed, vacuumed, or just replaced.

air purifier hepa filter

HEPA Filters

The gold standard in residential filtration systems; HEPA filters are proven to remove over 99.97% of particles larger than 0.3 microns.

HEPA stands for high efficiency particulate air, and this type of filter is widely considered to be a standard in air purifiers. HEPA filters are highly effective at removing the majority of finer particles commonly found in the air at home.

This includes pet dander, pollen particles, and mite residue. Both homes and apartments (especially in urban areas) will inevitably collect some dust from the outdoors, from cars, polluted outdoor air, or bad indoor air circulation.

Since older air filters are most effective at removing larger particles and irritants, the performance of the HEPA filter is optimal when paired with them (i.e. HEPA filters don’t usually work well alone). As such, it will last longer and be less likely to lose its efficacy in the long run.


air purifier carbon filter

Carbon Filters

Carbon filters are some of the most effective odour filtration devices on the market. Carbon reacts with oxygen in the air, causing a reaction that changes the chemical makeup of the carbon by stretching out the molecules.

This change exponentially increases the absorbency of the filter, essentially creating a surface area averaging 100 acres!  The oxygenated carbon filter is a foolproof way to trap odours and gaseous pollutants, allowing odour-free air to pass through to the next layers of filters in an air purifier, typically the HEPA and Titanium Oxide filters.



air purifier negative ioniser

Ioniser Purifiers / Negative Ionisers

Negative ionisers are not exactly filters but they are now becoming prominent in air purifiers. Negative ionisers use charged electrical surfaces or needles to ionise (or electrically charge) air molecules and convert them into their ionic state.

These ions attach to air pollutants and are then magnetically attracted to the plate surface and can be cleaned later on by wiping away. This is one of the most advanced and effective air purification systems on the market and best of all, it is absolutely maintenance-free!

Read more on negative ions


air purifier titanium oxide filter

Titanium Dioxide (TiO2)

Most air purification systems use absorption technology to cleanse the air of various residual particles and pollutants. Titanium dioxide filters use a radically different technology; converting the chemicals themselves. When combined with calcium carbonate, Titanium dioxide will neutralise any gaseous molecules; this is environmentally friendly decomposition process known as Photocatalysis.


air purifier uv light

Ultraviolet (UV) Germicidal Radiation

UVGI is used to sterilise the air that passes UV lamps via forced air.  The fan forces air past the UV light at such a speed that it breaks down any organic particles or organisms (dead or alive). This is a very effective system to prevent the growth of mold or other biohazardous cultures. It is imperative that the device is placed in close proximity to a filter. This way, the filter is able to absorb the airborne components broken down by the UV lamp.

uv air purifiers

TiO2 + UV light rays

When UV light is combined with a TiO2 coated filter, photocatalysis occurs. This is a process that creates hydroxyl radicals and super-oxide ions, which are highly reactive electrons. These highly reactive electrons then aggressively combine with other elements in the air, such as bacteria and VOCs. Once bound together, the chemical reaction oxidises the pollutants, which breaks the pollutants into harmless carbon dioxide and water molecules.


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Disclaimer: The information provided in this article is for general reference only. Please seek advice from professionals according to your needs.

Christina Cini

Christina is our very skilled Quality Assurance Manager/ Technician. With her background in Mechatronics Engineering, she is able to apply her knowledge in providing a better understanding into our more technical blog posts such as how products work and the best ways to maintain them.