Motorists with allergies can breathe easier in a Mercedes-Benz passenger car according to the European Centre for Allergy Research Foundation (ECARF) which has awarded its seal of approval for allergy-friendliness to all the Mercedes-Benz model series, from the A- to the S-Class, following rigorous tests.
A new testing procedure developed by Mercedes-Benz, for which a patent application has been filed, has shown that even the minutest of allergenic particles are trapped by the charcoal fine particle filters in the vehicle. The results were later confirmed by a medical study conducted by ECARF Institute GmbH in a mobile pollen chamber in the grounds of the Charité university hospital in Berlin.
Allergies are now the commonest form of chronic illness in industrialised countries. In Europe, around 30 percent of the population are affected. Not only airborne pollen from spring until autumn, but also emissions given off by materials, or skin contact with them, can lead to a strong immune reaction with symptoms such as swelling of the nasal passages and bronchial tubes or swollen, itching eyes.
Mercedes-Benz’s laboratory testing procedure uses a filtration apparatus with a vacuum suction flask. Small test particles were sucked into a flask through a tube. The minutest particles included fragmented birch pollen, cat hair allergens and moulds. These are up to 1 µm in size, i.e. 50 to 100 times thinner than a human hair. The flask contained a filter medium – an approximately 5cm circular piece from the air conditioner filter. The solution was collected in a test tube at the bottom of the suction flask.
The efficiency of the filter was measured by comparing the concentration of allergens before and after the addition of the filter. In tests with fungus spores, the Mercedes-Benz researchers formed a dilution series and counted the number of spores in a Petri dish. In the case of cat hair epitheliums and fine particles, the concentration of allergens was determined as the average outgoing quality in the ELISA test (Enzyme Linked Immunosorbent Assay). Depending on the concentration of allergens, the colour reaction of a liquid differs in intensity.
The findings were that the fine particle filter in Mercedes-Benz vehicles trapped even the minutest of allergenic particles. The activated charcoal fine particle filter (standard in the S-Class, optionally available in many model series) offered optimal filtering of the outside and inside air; the activated charcoal also kept odours out of the interior. The air quality could be further improved by ionisation.
In relation to asthmatics, a medical study conducted by ECARF Institute GmbH with asthmatics as test subjects also confirmed the anti-allergenic effect of the filters. The tests were carried out using a section of the air conditioner from the current S-Class.
The ECARF mobile pollen chamber ranks as a milestone in allergy research. This is because, in a field study, which involves the patients keeping a daily diary at home, the medical experts cannot be sure whether the test subjects have really been exposed to the allergen. On the other hand, large, fixed exposure chambers do not allow multi-centre studies with different patient types and a cross-section of the population. A modern exposure chamber makes it possible to conduct tests with a multiplicity of different aero-allergens and various patient types.
The mobile pollen chamber is made up of two large standard containers which are joined together and can be easily loaded and off-loaded. The scientists sit in one of the two containers and monitor the tests. The second container is the actual chamber, which has seats for the test subjects. Above each seat is an outlet, through which the pollen particles are released, laser-counted, through an air cone. Inside the chamber, it is possible to individually select for each test subject whether the air stream contains pollen or not. This also allows for placebo testing. Every ten minutes, the test subjects make a note of any complaints on a standardised symptom sheet. In addition, there is intermittent testing of pulmonary and nasal function as well as monitoring of eye reddening.
In December 2015, Mercedes-Benz opened a new 300 cubic metre test chamber for interior emissions at the Mercedes‑Benz Technology Centre in Sindelfingen. A vehicle is placed in this chamber and precisely defined temperature profiles are run over the course of a week. During this time it is tested for several hundred substances. In several cycles, over 100 air samples are taken from the vehicle interior and analysed. In addition to the overall emissions, it is also possible to measure the emissions of individual organic compounds.
Mercedes-Benz’s experts in development and materials technology work on the interior air quality in new models. From the early stages of the development of a vehicle, up to six years before it goes into production, the minimisation of interior emissions is a factor helping to define the materials concept.
Such analyses have been conducted by Mercedes-Benz since 1992. Component assessment involves the testing of numerous parts from each trim variant of a model series – door panels and seats as well as the roof liner and trim. In order to ensure that a realistic impression is gained, the team do not use specially produced sample components, but standard production components made using the tools that will be subsequently used for series production. The testing procedure requires adherence to the VDA 276 standard as laid down by the German Motor Industry Association – the components are stored and measured in a test chamber 1 m3 in size at a defined temperature, humidity level and air circulation rate. Air samples are then extracted and used to measure the quality and quantity of gaseous substances in the air.
The examination of the vehicle as a whole involves an even more complex process. The necessary preparation of the vehicle alone, in other words the installation of the measuring equipment, takes the well-rehearsed team three quarters of an hour, while the measurements themselves last a full week. The test chamber is lined with stainless steel in order to prevent it giving off emissions of its own. Large radiant heaters are used to simulate the sun and heat up the interior of the vehicle, since, for physical reasons, emissions are greater under the influence of heat. The solar irradiance is measured by special devices called pyranometers.
Inside the vehicle, as many as ten sensors are used to record the temperature in various areas, for example on the top of the dashboard. A rotating paddle stirs up the air inside the vehicle to ensure an even mix. Overall emissions within the vehicle are calculated with the help of a rack-mounted flame ionisation detector. The rack projects into the vehicle interior over the opened window on the driver’s side, which has been made airtight and emission-neutral with the aid of aluminium foil.
If taking measurements according to test method FAT AK 26, for example, measuring can begin as soon as a temperature of 65 degrees Celsius has been reached at the level of the driver’s nose. Samples of air are extracted from the interior and the air flow directed into a series of test tubes. The chemical composition of the evaporated substances is then analysed in the laboratory
There are also tests conducted with people suffering from severe asthma, with pulmonary function tests providing information about the impact on the bronchial system.
In addition, all materials that might come in contact with the skin were dermatologically tested. What are known as epicutaneous skin tests were undertaken with test subjects suffering from contact allergies in order to test the tolerance levels for known contact allergens such as chrome-nickel and various pigments. This involved substances from the interior that were deemed to be potential allergens being applied with plasters to the skin for 72 hours and the reaction to them being evaluated after 48 and then 72 hours.
All model series from the A- to the S-Class meet the requirement extensive criteria of the ECARF seal for allergy-friendly car interiors. In addition, the pollen filter is tested for correct functioning in both the new and used condition.
So, the next time you get into a Mercedes-Benz, you can relax without worrying about allergens in your environment. It’s all been tested for and is being filtered out.