In-Car Cabin Filters

In-Car Cabin Filters2024-02-13T13:03:36+00:00

In-Car Cabin Filters

On average, people spend up to 90% of their time indoors, and indoor air can be two and a half times as polluted as outdoor air. This figure does not only include time spent in homes and workplaces, but also in enclosed vehicles.

In industrialised countries, people spend on average over an hour a day in vehicles, and this can make a substantial contribution to a person’s daily exposure to particulate air pollution. Exposure to allergens in vehicles includes traffic-related pollutants and pollen from roadside trees and grasses.

Indoor Air Quality is of particular concern for those affected by asthma and allergies, but healthier air is of broader benefit to all.

The asthma & allergy friendly® Certification Program seeks to assist people to identify products which will make a genuine difference to their indoor environment. It develops certification standards for relevant categories of products, and all certified products undergo testing to those standards. In this way, the consumer can then make an informed choice about materials like paint, flooring products, etc. that they bring into their home.

In the case of in-cabin air filters, pollen and dust particles are an issue in the in-cabin environment. Filters can lose efficiency when they are loaded. And some filters can shed fibres which, because of their size, can enter the breathable zone and cause irritation. Our standard tests for these factors.

Our in-cabin air filter standard is one of over 50 standards in the asthma & allergy friendly® Certification Program, covering appliances, bedding products, air filters, building products, and services that can have an impact on the indoor air environment. You can explore the in-cabin air filter standard in more detail using the menu on the left, or use the links above to explore other standards.

Standard Abstract : Cabin Air Filters

Automotive cabin air filters that are Certified asthma & allergy friendly® are tested to the ASP:08-02/101 automotive cabin air filters Certification Standard. The Certification Standard utilizes an algorithm of proprietary and recognized scientific techniques to assess cabin filters for their ability to reduce allergenic and irritant materials. Submitted filters that pass certification testing are granted a certificate stating that the particular filter meets the requirements for the asthma & allergy friendly® ASP:08-02/101 Certification Standard.

Allergy Standards Ltd (ASL) subjects the automotive cabin air filters to allergen measure based performance testing for their ability to remove allergen from the air flow. Assessment for certification requires that the filter be evaluated in terms of allergen levels that are representative of those found in car cabin interior spaces. The asthma & allergy friendly® Certification mark is awarded to those automotive cabin air filters that have been scientifically demonstrated to contribute to the goals of allergen reduction.

Part 1: Evaluation of Allergen Capture and Filter Efficiency

The ability of the automotive cabin air filter to reduce total allergen burden by removal of pollen from the air is of primary importance in the Certification process. As such, the filter is challenged with dust containing Timothy Grass Pollen, Birch Tree Pollen and Ragweed Pollen.

Filter performance is measured as loading progresses. As the filter becomes loaded with particulate allergen, air flow may decrease. This may lead to increased energy consumption, pressure differential across the filter, and decreased performance.



During filter loading with allergen containing test dust, all three of the introduced pollen allergens must be demonstrably removed from the airflow by the Cabin Air Filter

>90% capture of three pollens (Phl p5, Bet v1, Amb a1)

The initial and final efficiencies of the filter are assessed

≥85% capture of particles >3.0 μm

The average differential pressure across the Cabin Air Filter after loading with allergen containing test dust is assessed.

Must not increase by ≥20% of the average value obtained immediately prior to loading with allergen containing test dust.

Certified filters must be replaced with a new Certified filter at service intervals specified by the manufacturer’s recommendations.

All certified asthma & allergy friendly® Automotive cabin air filters are associated with a unique Certification code.

Why and how we certify in-car cabin air filters – a Q&A

There is ever-increasing awareness of the chemicals and allergens we come into contact with every day, particularly if you or a member of your family has asthma or allergies. We created the asthma & allergy friendly® Certification Program to help you improve your indoor environment by identifying products and services that can help to reduce allergens and create a healthier home environment.

But what is it that makes some in-car cabin air filters better for the indoor environment than others, and where do we draw the line to decide to certify a in-car cabin air filter as   asthma & allergy friendly® ? We hope that the questions below will clarify this. Let us know if you have more questions!

Car-Cabin-Indoor-Air-Allergy-StandardsWhy do we certify car cabin filters?

Our goal in the asthma & allergy friendly® Certification Program is to create a healthier indoor environment for you and your family, as well as to reduce allergens in the home. So we look at all elements of the indoor air environment.

It is easy to forget that the time you spend in your car counts as being indoors. In industrialised countries, people spend an average of one hour per day in a vehicle, and during this time you can be exposed to traffic-related pollutants as well as pollen from roadside trees and grasses. Certified cabin filters can help improve the air quality in the confined space of a vehicle cabin.

How do we test in-car cabin filters?

We use a standardised test duct to test these filters. This is a controlled duct where the filter can be inserted at the centre, and air can be forced through it. We can introduce dust containing allergens in the ‘upstream’ part of the duct. This air is then pressed through the filter, and we can test the ‘downstream’ area past the filter to see how much allergen and dust has passed through the filter.

1. Removal of Allergen and Dust

We introduce a specific amount of test dust that contains three common types of pollen, and a blower forces the dusty air through the filter. When the air passes through the filter, we test it on the other side to see how much of the dust and the allergen passed through. We require that at least 90% of each type of pollen is captured by the filter, and we also make sure that the filter has 85% efficiency in capturing all particles of greater than 3 micrometers.

2. Loaded Performance

It isn’t enough to only test a brand-new filter and check if it can remove allergens and small particles. Over time, dust can build up on a filter, which is why you need to change it every so often. This may lead to increased energy consumption, a differential in pressure across the filter, and decreased performance. It is therefore important that even when it is loaded with dust the filter can still perform well.

In order for the filter to maintain its performance even when loaded, we require that the difference in pressure across the Cabin Air Filter after loading with allergen containing test dust must not increase by ≥20% of the average value obtained immediately prior to loading with allergen containing test dust.

Why do we test with different pollens?

We use three common pollen types in our testing – timothy grass, birch tree, and ragweed. These pollens vary in terms of size, with ragweed being the smallest on average, and timothy grass being the largest. They are also prevalent at different times of the year, although pollen season does vary by region. But generally in the US, tree pollens (including birch) peak in Spring, grass pollens (including Timothy) peak in Summer/early Fall, and weed pollen (including ragweed) peaks in Fall.

Car-Cabin-Indoor-Air-Allergy-Standards2How often should you change your in-cabin filter?

You should always follow the manufacturer’s instructions for changing the filter. When a filter is certified asthma & allergy friendly®, we will have tested it when the filter is loaded with dust to make sure it retains most of its efficiency. But as more and more dust settled on the filter, the performance will inevitably start to drop.

What else do we certify?

We have over 50 different asthma & allergy friendly® certification standards for products and services, addressing all areas of the indoor air environment. Some of these relate to products which remove allergens and dust from the indoor environment, like vacuum cleaners, air cleaners, dehumidifiers, and washing machines. Some of them relate to products where it is important not to provide an easy home for allergens and that it is possible to remove allergen from them – like bedding, toys, and flooring. And some of them relate to household products that should make as little an impact on the indoor environment as possible – like flooring and paint.

You can find out which products are certified asthma & allergy friendly® and read more here:


Fuel for Thought

Car-Cabin-Indoor-Air-Allergy-Standards2I have to admit, its not something I have ever spent much time thinking about. In fact, it’s true to say that I take it completely for granted. But without it, about 2 hours of every day of my life would be really uncomfortable and probably even dangerous.

I’m talking about my car cabin air filter and believe it or not it is crucial to my everyday life and if you drive a car, to yours too.

This is what happens without an effective filter:

  • Debris, such as leaves, cement, ash and soot clog up your cabin air filter. The car air conditioning system is put under strain as it has to push the cool air through the clogged filter and so, the air conditioning becomes much less effective. In turn, the engine has to work harder to power the poorly working air conditioner and unfortunately up goes your fuel consumption. The impact on your wallet is soon apparent, not to mention on the environment.
  • Pollen and dust, among other allergens, enter your car cabin. For a lot of us this one is pretty serious. For us allergy and asthma people, a confined space filled with allergens becomes a serious matter of health and safety. My children spend a lot of time in the car. Ballet, soccer, dancing, tennis, squash, piano, art, hockey – we climb into the car for every one of those runs. Pollen season is no longer a defined few weeks, or even months, but rather stretches out for a good chunk of the year. To be surrounded by allergens entering the car cabin on every journey we take and then to be dragging these allergens back into our home on our clothes and hair means to be at the mercy of these triggers for the entire day. A good car cabin filter is an absolute necessity for good indoor air quality and preferably one that has been approved to be effective against allergens of all types and particle sizes.
  • Exhaust fumes and pollutants enter your car cabin. This is particularly problematic in urban areas or anywhere that engines may be idling. It’s one of my bugbears to see how even rural car parks are turned into toxic environments because so many parents sit in cars with idling engines when dropping and collecting kids. The pollutants being spewed out are so harmful to our children’s lungs and the car cabin air filter is a must to reduce them.
  • VOCs, odours, viruses and bacteria enter your car cabin. This is an interesting one. That new car smell? The one we associate with success, pleasure, money, satisfaction and that some people even try to replicate by putting an air freshener in their car? Its produced by up to 60 volatile organic compounds, including toluene (you are familiar with this one from nail polish removers), styrene and ethylbenzene (in petrol and paint) and is actually a nasty and very unhealthy odour to be enveloped in within an enclosed space. These VOCs are present in the fabrics, carpets, glues and other interior materials that go into making our beautiful new cars. They are responsible for triggering asthma and allergies. They are harmful when inhaled and cause headaches, dizziness, sore throat and nausea. Prolonged exposure may lead to birth defects, disabilities and cancer. Researchers have said that if an office building had the same level of chemicals in their indoor air, then it would be declared a sick building and the workers would be sent home until the building was cured.


Thankfully these chemicals that produce the new car smell do disappear over time (about 20% per week) but not completely, and on a hot day with rising temperatures in the car, the materials off gas again and levels once again rise.

Car manufacturers have recently been taking steps to reduce that new car smell and indeed in the future we may be reminiscing about it to our kids. Natural, renewable materials such as soy are being considered instead of the traditional synthetic fabrics and some progressive companies have introduced more effective filters. Experts advise that the easiest way of reducing our exposure to the VOCs is to roll down the window and let the smell out, but this is a no no on high pollen days, as really, its just facilitating the replacement of one toxic allergy and asthma trigger with another. Anyway, it’s not too comfortable an experience to be hurtling down the highway with the windows open. An effective car cabin filter is the only practical answer. The filter should be replaced regularly but also be capable of withstanding loading with allergen without its performance being affected. An ordinary filter alone cannot capture viruses, exhaust fumes, or other harmful gases. To effectively filter out those harmful pollutants activated charcoal can be used. The activated charcoal acts like a magnet to prevent toxins from entering the inside of the car.

There are a few other simple steps to take (or as I like to do – chores to give the kids) to allergy proof your car. Vacuum regularly to remove pollen and dust. Obviously a vacuum cleaner with an effective HEPA filter is a necessity. Wipe down the console, dashboard and steering wheel regularly. Don’t ignore those spills, whether they be your morning coffee or a kids juice box.. moisture allows mould to grow. Make sure that your windows and doors seal properly to protect from both moisture and pollen.

So next time you sit into your car and breathe in that nice fresh air, free of toxins, allergens and nasty odours, give a moment’s thought to the hard working car cabin filter that is all too easily taken for granted.


Medical & Lifestyle Author Dr Anna O'Donovan

Medical & Lifestyle Author Dr Anna O’Donovan

About Dr. Anna O’Donovan – Medical & Lifestyle Author 

Anna is a mum of three children, one with allergies, and she suffers from allergies and asthma herself. She is a qualified doctor and worked as a General Practitioner and as a dentist for a number of years. She is also an award-winning author.

Key Words

Car cabin filter, indoor air quality, asthma and allergies, allergens, pollen, VOCs, new car smell

References and further reading

Breathe Easy With a New Cabin Air Filter, Champion AutoParts, Click here

Is new-car smell bad for your health? BBC, Click here

Is ‘new car smell’ toxic?, How stuff works, Click here

What causes ‘new car smell’?, How stuff works, Click here

Is That ‘New Car Smell’ Toxic?, WebMD, Click here

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