Close-up of a carbon filter for gases and odours

How does the activated carbon filter work?

The activated carbon filter is an air filtration process for the removal of smoke and odours. This filter is used in most air purifiers, as it can adsorb smoke and odours.

In practice, the activated carbon filter is never used alone in air cleaners. It is combined with other air filters to effectively remove airborne particles. Common air purifiers have at least a 3-stage air treatment system consisting of a pre-filter, an activated carbon filter and a HEPA filter. With this combination, you can enjoy fresh, clean air.

What is an activated carbon filter?

The activated carbon filter is available in granular or powder form. Its surface is very porous Activated carbon is made up of millions of absorbent pores. This filter is extremely effective in adsorbing gas molecules, chemicals and volatile organic compounds (VOCs), which is why it is an important criterion in the choosing an air purifier. However, it cannot remove fine particles such as dust, dust mites, animal dander or pollen.

In air cleaners, the activated carbon filter is usually used in conjunction with the HEPA filter to capture other unwanted particles such as dust, mould spores, pet dander and pollen.

You will find in the high quality activated carbon filters of potassium permanganate or potassium iodide to remove chemicals, formaldehyde and cigarette smoke more effectively. This type of charcoal stands out in particular in the products we have listed in our guide "Which air purifier should I choose to remove cigarette smoke?".

Home Air Guides | What is an activated carbon filter? (with French subtitles)

How long does activated carbon last?

The activated carbon filter is an indispensable filter for all air purification systems, but its service life is short. A typical activated carbon filter lasts on average only two to four weeks. After this period, it must be vacuumed or cleaned before being used again. To maintain its filtration capacity, the activated carbon filter should be replaced every two months. This is due to the adsorption process The activated carbon filter stores pollutants, but when it is saturated, the filter is no longer able to absorb unpleasant odours.

The granular activated carbon filter has a longer life than its fibre counterpart. Its grain size is usually no more than 3 mm in diameter. They are also more efficient than fibre filters, which are made up of grains between 10 and 50 µm in size (100 times smaller). They have a faster adsorption capacity, but are less efficient because their density is much lower.

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Can activated carbon be reused?

The answer is yes. Because of its porous nature, this air filter can be recycled a maximum of two to three times. You will then need to replace it to ensure your air purifier is highly effective against smoke, odours and chemicals.

If your activated carbon filter is not specifically labelled as washable, you cannot wash it without damaging it. Otherwise, follow the instructions for your appliance to clean it.

Advantages and disadvantages of the activated carbon filter

Can be reusedRequires additional air filters
The only air filter capable of removing chemicals, gases, odours and smells from pets, cooking, smoke, paints and cleaning productsMust be changed regularly