Breathe easy with DENSO’s Cabin Air Filter programme

The air we breathe, both inside and outside our cars, can become contaminated. There are many sources of this pollution, from the cars we drive to industry, tobacco and other household fuels.

According to the World Health Organisation (WHO –*

  • In the WHO European Region alone, exposure to particulate matter (PM) decreases the life expectancy of every person by an average of almost one year, mostly due to increased risk of cardiovascular and respiratory diseases and lung cancer
  • Some 40 million people in the 115 largest cities in the European Union (EU) are exposed to air exceeding WHO air quality guideline values for at least one pollutant. Children living near roads with heavy-duty vehicle traffic have twice the risk of respiratory problems as those living near less congested streets.
  • Indoor air pollution from biological agents in indoor air related to damp and mould increases the risk of respiratory disease in children and adults by 50%.

Figures like these clearly demonstrate that we all have a responsibility to communicate the important message of cabin filter replacement, for the benefit of everyone. No-one knows this better than DENSO, the world’s leading developer of OE automotive HVAC systems.

Berry Luigjes, Product Manager at DENSO Europe B.V.’s Business Unit After Market, provides answers to the most common cabin air filter (CAF) questions.

Q) Why do we need to replace cabin air filters?
Dirty or clogged CAFs reduce the air quality inside the vehicle. They can harbour mildews and bacteria, causing allergies and discomfort.

Q) What is the purpose of the cabin filter?
The cabin air filter is a filtration medium that is attached to the outside air intake of your vehicle's ventilation system. The CAF helps to improve air quality and filter out pollution from the air that circulates inside the vehicle.

There are two different types of cabin air filter technology:

Particle (pollen) filters:

Particle cabin air filters trap and hold fine pollutants such as dust, bacteria, pollen, soot and exhaust fumes, preventing them from entering the car’s cabin.

Combination (carbon) filters:

Carbon filters offer the same benefits as pollen filters but with the added benefits of preventing odours and harmful gases from entering the cabin such as exhaust gasses, cigarette smoke and fuel vapours. This is achieved by adding a layer of activated carbon to the filter medium, creating an effective ‘adsorption’ process that condenses the gas on the surface.

Q) Why is a cabin air filter important?
As dust and dirt builds up, a clogged CAF is less efficient. It will also make window defogging more difficult as more particles remain airborne and there is less air flow from the fan outlets.

Q) How much air goes through the CAF in a typical year’s driving?
Given an average mileage of 15,000km, at a speed of 60 km/h, this brings the total operation hours to 250h. With an average flow rate of 300 m3/h this means 75,000 m3. Average air volumes in a family house 180-400 m3. If we take 250 as average, your car must refresh your entire house 300 times in a year. Imagine how much dust your house accumulates in one year!

Q) What’s the smallest size particles filtered by a DENSO CAF?
Typically, a human hair is in the range of 40-120 μm (micron). DENSO filters will filter particles that are 1,000 times smaller than that!

Q) Does a cabin air filter prevent leaves & debris from entering the air conditioning system / engine?
DENSO CAFs work to keep tiny particles out of your cabin and ventilation channels, so leaves and debris aren’t a problem.

What motorists need to know

DENSO encourages its aftermarket customers to tell motorists about the importance of regular filter replacement. To ensure optimum filtration performance, hygiene and HVAC efficiency, every cabin air filter should be replaced at least once a year, every 10,000–15,000 km or as specified by the vehicle manufacturer – whichever comes first.

  • Fact: Replacing their cabin air filter regularly can help to reduce the risk of costly damage to a car’s HVAC system.
  • Fact: Without a cabin air filter, the air in the car’s cabin could be up to eight times dirtier than the outside air
  • Fact: On average it takes less than 15 minutes to replace a DENSO cabin air filter.

As we all know, cabin air filters can look and appear the same, but the reality of what’s inside is very different and quality often varies. Unlike DENSO's cabin air filters, some filters can also compromise the car's HVAC system by increasing the pressure drop, which may result in costly damage. DENSO's replacement cabin air filter programme means there is a match to almost every original cabin air filter reference of any brand. Each filter is manufactured to the same exacting OE specification that DENSO supplies to vehicle manufacturers.

DENSO Cabin Air Filter programme
DENSO’s OE quality, all-makes Cabin Air Filter (CAF) programme encompasses both particle and combination filters. There are 309 part numbers and more than 1,200 applications covering 80% of the European car parc. DENSO’s cabin air filter filtration fleece material contains up to five individual layers, which trap almost 100% of harmful pollutants and particles.

Find out more
As well as the printed catalogue, details of DENSO’s continually expanding Cabin Air Filters programme are available online at, in TecDoc or from DENSO Europe B.V.’s Business Unit After Market on +31 (0) 294 493 493.