Cabin air filter in the car - air quality

The pollen count is at its peak every spring and spending time both outside and inside vehicles is particularly problematic for allergy sufferers. Cabin air filters, which are generally standard, are designed to filter exhaust gases and other air pollutants. If the cabin air filter can no longer fulfill its function, more air pollutants such as dust, soot, nitrogen oxides, benzene, ozone or pollen can enter the interior of the car, for example via the air conditioning system.

Cabin air filters reduce air pollutants

The purpose of the cabin air filter in the vehicle is to reduce pollutants and odors from the air and remove them as far as possible. In this way, only the purified air should be fed into the vehicle cabin.

When the cabin system in the vehicle is in operation, such as via the air conditioning system or the fresh air supply, several thousand liters of outside air enter the vehicle every hour. If the filter is already too clogged with dirt, it can no longer provide the necessary purified air. As a result, the concentration of pollutants in the cabin of the vehicle can rise sharply and thus be significantly higher than in the outside air.

International ISO standard 11155 for filters

The filters available in Germany must comply with the international ISO standard 11155. This standard regulates in particular the pollutant content that cabin air filters must remove and clean from the air. Particularly high-performance filters belong to standard classes F7 and F8, which can filter particles larger than 10 micrometers.

Advantages of perfectly functioning cabin air filters in vehicles

They ensure better air quality, as the filter filters out as much pollen as possible in addition to dust and pollutants.
The thorough filtering of particles prevents the proliferation of bacteria, mold spores and unpleasant odors as far as possible.
less moisture accumulates in the car. The windows no longer mist up so quickly.
the air conditioning and heating can work more efficiently. This means they consume less energy.
the air conditioning and heating systems can work effectively and thus extend the service life of the systems.

Regular replacement of the cabin filter

In the inair inside the car can be up to five times more exhaust gases, allergens and pollutants than in the outside air and thus have a harmful effect on health . If the cabin air filter becomes blocked, more and more pollutants and dirt particles are deposited on it. This filter cake, the visible layer of particles, then causes the ventilation pressure to drop, so that less air can flow into the vehicle interior. In this way, the fleece layer of the filter can filter out fewer particles. The result is that the concentration of pollutants inside the vehicle increases.

The right time to change the cabin air filter depends on various conditions. In general, experts and manufacturers recommend this replacement from around 15,000 – 20,000 kilometers or once a year, especially for infrequent drivers.

The time before the start of the pollen count in spring is particularly suitable for changing the filter, as the filter was exposed to a high level of air pollution during the cold and damp season. This also allows more moisture to accumulate and, in the worst case, bacteria and mold to spread.

Cabin filters – distinction between particle and combination filters

There are two systems of cabin air filters for vehicles. The particle filters and combination filters work according to the same basic principle. However, there are differences as with the filter performance.

Particle filter

Particle filters are also known as dust or pollen filters.

This filter is designed to remove particulate impurities by solid or liquid substances. When the air conditioning or ventilation is switched on, an effective particulate filter retains even the smallest particles from the air before the fresh air enters the interior. In addition to dust and soot, it also filters particles caused by abrasion from brakes, clutches and tires, as well as pollen. In this way, they should not be able to enter the vehicle cabin.

The particle filter works on the principle of sieve filtration. Nowadays, these are generally made of multi-layer high-performance fleece. High-quality particle filters can filter out almost all soot and dust particles as well as pollen using this process. They clean more effectively than filters used in the past, which were largely made of paper. The closer the fleece layer is to the clean air side of the filter, the denser and finer the fibers. The multi-layer high-performance fleece consists of a pre-filter, a microfiber fleece and a carrier layer. The pre-filter can be used to catch coarser particles such as insects or sand. The electrostatically charged microfleece enables the filtering of very small materials up to five micrometers in size. The electrostatic charge means that the smallest particles such as dust reliably stick to the filter. The backing layer fulfils the function of stabilizing the other fleece layers.

The filter medium of particle filters isfolded in a zigzag shape . It usually consists of synthetic high-performance fleece based on polyester and polystyrene. The special pleating increases the contact surface and thus improves the effectiveness of filter cleaning.

Combi filter

Combi filters have the advantage of removing a broader spectrum of pollutants from the air. Thanks to their special structure, they also filter gases and therefore odors from the air. In addition, the combi filter, which is also known as an activated carbon filter, also fulfills the functions of a particle filter.

While the classic cabin air filter has two layers, a pre-filter for coarse particles and another fine fleece, the activated charcoal filter has a third layer. This is the activated carbon layer. With this additional layer in the filter, harmful gases such as nitrogen oxides, sulphur dioxide, ozone, odors and even bacteria are captured and filtered out of the outside air. Nowadays, most vehicle models are fitted with activated carbon combi filters as standard.

The activated carbon in the filter layer consists of more than 90 percent carbon. The activated carbon layer has a fine-grained structure with a large open-pored surface. With this special surface, gas molecules are absorbed like a sponge and stored in the branched channels of this structure.

Advantages of using combined filters in vehicles

As combifilters fulfill additional air purification functions beyond the possibilities of a particle filter, such as the filtering of gases, they are considered more suitable for clean, purified air in vehicles. The use of combination filters is recommended, for example, for people who are frequently exposed to high levels of air pollution, such as in large cities or when frequently driving on the highway. Sensitive people and those suffering from allergies and asthma are also better protected by a higher filter performance with combination filters in the vehicle.

Without a cabin air filter, the level of pollutants inside the car can be significantly higher than in the ambient air. It is therefore important to use a properly functioning cabin air filter to prevent air pollutants from damaging your health.

Regular filter changes are important

A regular filter change is also important for a combination filter, as the activated carbon loses its adsorption capacity, i.e. the adsorption of gases or liquids on surfaces, if it becomes further saturated with pollutants. Residues often accumulate on the filter and thus inhibit the efficient filtering of the incoming air. Heavily outdated filters can even release previously collected pollutants back into the fresh air supply. It is therefore advisable to change the filters regularly, especially before the pollen season.

Sources:

www.adac.de/rund-ums-fahrzeug/ausstattung-technik-zubehoer/zubehoer/innenraumfilter/

www.autobild.de/artikel/pollenfilter-die-produkte-der-hersteller-4194831.html

www.autodoc.de/info/innenraumfilter-aktivkohle-oder-standard-was-ist-besser

www.autorevue.at/ratgeber/pollenfilter-austausch

www.auto-werkstatt.de/magazin/innenraumfilter-20206535#partikelfilter-vs-aktivkohle

www.autozeitung.de/innenraumfilter-203044.html

www.bussgeldkatalog.org/innenraumfilter/#wozu_dient_der_innenraumfilter_im_auto