Everything You Need to Know about Cabin Air Filters

A cabin air filter is a crucial component of your vehicle's heating and cooling system, protecting passengers from airborne contaminants. Your car's ventilation system can cycle through up to 500,000 liters of air, bringing in pollutants like particulate matter, pollen, and urban nitrogen oxide. Consequently, the air inside the car can become up to five times more polluted than the air outside.

The cabin air filter cleans the air that enters the vehicle's interior through the heating, ventilation, and air-conditioning (HVAC) system. It captures dust, pollen, and other airborne particles, improving the ride quality, particularly for those with allergies or respiratory issues. Various types of cabin air filters provide different levels of filtration efficiency and capacity, with some even eliminating odors, bacteria, fungal spores, and other airborne microorganisms.

Particulate filters are the most common type, made of paper-like material that effectively catches fine dust, debris, and allergens. They typically remove between 90% and 99% of airborne particles ranging from 5 to 100 microns.

Activated charcoal filters have an additional layer that captures toxic pollutants like nitrogen oxides, sulfur dioxide, and ozone, as well as unpleasant odors. Many European car models come with these filters as standard. For cars with particulate filters, it’s often possible to upgrade to activated charcoal filters at a reasonable cost. This is especially recommended for those with respiratory conditions.

Electrostatic filters, often sold as HEPA or "Premium" filters, feature a specialized media with an electrostatically charged layer that attracts and captures ultra-fine particles, such as cigarette smoke, ozone, brake dust, and diesel carbon. These particles can be particularly dangerous for the human organism: Due to their small size, they are able to transport toxic substances to the most vulnerable regions of the body.

Though because these filters consist of several layers, while they are more effective than traditional filters. they have significantly lower air permeability than conventional filter media. In order to achieve the necessary air flow, the media surface of the filter must be increased up to five times, which is why a HEPA filter often cannot replace a conventional filter.

Replacing the cabin air filter can vary in complexity depending on your vehicle’s make and model. While some vehicles make it a straightforward task, others might require more effort. It’s best to consult service manuals or reliable online resources for accurate guidance, as the user manual may not provide enough detail.

In many vehicles, the cabin air filter is located behind the glove box, and you can access it by removing the glove box from its fasteners. Your service manual should offer specific instructions for this procedure. However, in some cases, the filter may be positioned under the dashboard or hood, making it more difficult to reach.

OEM filters can be expensive, so opting for a replacement from an auto parts store and installing it yourself can save you money. You don’t always need to use an OEM filter, as many aftermarket filters from reputable manufacturers perform just as well. Car makers often outsource filter production to these very same manufacturers. Trusted brands include Mann, ACDelco, Mahle, Sogefi, Hengst, Fram, Bosch, Valeo, Freudenberg, Alco, and Febi.

When selecting a new cabin air filter, it’s generally a simple process. Filters with activated carbon or electrostatic properties from any reputable brand should work effectively. Just ensure the filter is compatible with your vehicle’s make and model before purchasing.