How car cabin filters work

What you need to know:

While cars are not entirely airtight, the cabin air filter works diligently to filter the air entering your vehicle from the outside.

Just like the filter in your home, your car’s cabin filter also requires attention. It is an essential piece of your car’s heating and air conditioning system and helps remove allergens and other contaminants from the air you breathe. A clean and well-maintained cabin air filter will make your vehicle a healthier place for you and your passengers.

According to, cabin air filters are typically located behind the vehicle’s glove box. They are usually rectangular and have a pleated filter made of paper-based multi-fibre cotton. As air travels through the vehicle’s HVAC system, the pleated filter catches dust, pollen and other pollutants before the air reaches the cabin.

Joel Kibirige, a car service attendant at Total Petrol Station in Bombo Town in Luweero District, says cabin air filters are essential for maintaining a comfortable and healthy driving environment, the reason car owners must ensure they are properly maintained.


There are basically three main types of cabin air filters and these serve several benefits. Cabin air filters are typically made from various filter materials designed to effectively capture and filter out airborne particles and contaminants such as paper, synthetic fibers and charcoal, among others. Types include:

Particle cabin filter

These are the most common types of cabin air filters found in modern cars. They have a filtration medium that is designed to capture and filter out particles such as dust, pollen, mold spores and other airborne contaminants. Particle cabin filters can be made from various materials such as paper, synthetic fibers, or HEPA (Basic HEPA filters are typically built using borosilicate glass fibers, plastic fibers (also known as polypropylene), or fiberglass).

Activated carbon cabin filters

According to, these filters include an additional layer of activated carbon or charcoal. Activated carbon is effective at absorbing odours, gases and volatile organic compounds. They are excellent at eliminating smoke and unpleasant smells from the cabin and are often used in filters designed for odour control.

For instance, if you have elderly persons or children in the vehicle, their respiratory system is more prone to the dangers of harmful gases and this type of filter minimises the risk.

Electrostatic cabin filters

Electrostatic cabin filters use an electrostatic charge to attract and trap particles. They are efficient at capturing various types of contaminants such as ultra-fine particles such as cigarette smoke, ozone, and diesel carbon. They are unique as are often washable and reusable.

When choosing a cabin air filter, Kibirige says, it is essential to understand the conditions of the area you stay in and reasons why you are buying that particular cabin air filter.

“Despite the high price, car owners who often drive in urban areas with slow moving traffic need to have a carbon air filter while those in rural areas can have either the carbon or particle cabin air filter or both,” he adds.

How they work

Cabin filters work by intercepting and capturing airborne contaminants as incoming/external air passes through them, resulting in improved air quality inside the car.

When the car’s climate control system pulls fresh air from a vent under the dashboard, the air enters through the inlet and is directed to the heater box, which contains components such as the blower motor, cabin air filter and flaps. The components are essential for selecting fresh or recycled air and all the heating and cooling elements in general. Kibirige says cabin air filters then filter the air that enters the vehicle’s interior through the HVAC system.

“They capture and remove physical particles such as dust, pollen, mold spores, and other particulate matter. If an activated charcoal section is equipped, it absorbs chemicals and other contaminants, thus preventing them from entering the cabin,” he says.

Why you need to clean them

A clean cabin filter helps the HVAC system work more efficiently as it allows for better airflow and prevents debris from clogging or damaging the system’s components.

In addition to improving air quality, cabin filters can also offer some protection against external pollutants, such as exhaust fumes and other harmful particles, from entering the cabin.

A clean cabin filter also allows the HVAC system to work optimally, helping to defog or defrost your windows more quickly in adverse weather conditions. This improves visibility and safety.

When the HVAC system has to work harder due to a clogged cabin filter, it can consume more energy and negatively impact fuel efficiency. Keeping the filter clean can help maintain optimal fuel economy.


Cabin filters are typically designed to be replaced periodically as part of regular vehicle maintenance to ensure they continue to perform effectively. The replacement interval carys, depending on the manufacturer’s recommendations and driving conditions.

“Cabin air filters tend to last around 15,000 miles or a little over one year. However, you can encounter conditions that cause it to expire early,” Kibirige says.

When replacing a cabin filter, it is essential to use one that matches your vehicle’s specifications and your specific needs.


Carefully remove the cabin filter behind the dashboard at the co-driver side and examine it for dirt, debris, and contamination. For a washable, use water and a mild detergent to clean it. Gently rinse the filter from the clean side to the dirty side to prevent pushing contaminants deeper into the filter.

“Do not use high-pressure water or compressed air since can damage the filter. After cleaning, allow the filter to thoroughly air dry before reinstallation,” Kibirige advises.

For those that are not washable but need cleaning, during service, use a brush with smooth bristles to gently remove particles. Then, use an air compressor with mild air energy to flush out the remaining particles starting from the clean side to the dirty side. Dispose of any cleaning materials and waste water responsibly.

Future of cabin air filtration

Automakers are increasingly aware of the importance of air quality inside the vehicle and as such, there are continuous innovations in cabin air filtration. For instance, some manufacturers are exploring the use of nanotechnology in filters to trap even smaller particles and allergens. Similarly, other companies are investing in research to develop air purification technologies that can effectively eliminate harmful viruses and bacteria.

The future may also see more widespread use of advanced technologies such as ionisation and HEPA filtration in mainstream models, not just in luxury or electric cars. For instance, some companies are already developing «smart» cabin air filters that can adjust their operation based on the air quality inside and outside the vehicle.

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