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Under the microscope: the allergy label ECARF: Emphasis on clean air
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All the new passenger car models from Mercedes-Benz bear the Seal of Quality of the European Centre for Allergy Research Foundation (ECARF). This makes Mercedes-Benz the only vehicle manufacturer to bear this seal. The ECARF Seal of Quality is used by ECARF to designate products that have been scientifically tested and proven to be suitable for allergy sufferers. Alongside comprehensive testing for inhaled and contact allergens, Mercedes-Benz has been testing the interior emissions of all its model series for 23 years now.
The new CLA Shooting Brake is the latest Mercedes-Benz model to have received the ECARF Seal of Quality. The conditions of certification have been met by all model series launched in recent years, from the A-Class to the S-Class. The criteria behind the ECARF Seal are also included in the specifications book for all future Mercedes-Benz passenger car model series.
The emphasis on clean air applies for Mercedes-Benz in three particular areas: along with the avoidance of allergens, the concern is to reduce interior emissions and to keep odours at a consistently pleasant level. "We have been measuring the interior emissions of our vehicles since 1992 and have been able to make steady progress in reducing them", according to Dr Jörg Breuer, Director Certification, Regulatory Affairs & Environment at Daimler AG. "We have a strict internal limit these days, which has to be met by all Mercedes-Benz passenger cars - by our compact vehicles and roadsters but equally by our large estates and SUV models."
There are currently a dozen or more experts working in the development and materials technology area on the interior air quality of new models. This year, the team will also be moving into a new test centre at the Mercedes-Benz Technology Centre in Sindelfingen – a fact which also serves to emphasise the importance given to this topic.
Even in 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. As far back as 1996, Mercedes-Benz's own internal standards set emission levels for materials used for components in the passenger compartment and boot. Today designers and developers can make their choice from a database of around 8000 interior materials that have been approved by the specialist department.
Interior emissions: extensive testing of many components and all cars
Just before a new model goes into series production, its interior emissions are tested in a series of complex procedures. This type of analysis has been conducted by Mercedes-Benz since 1992. Component assessment involves the testing of numerous parts from each equipment 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 produced using the tools that will be subsequently used for series production. The testing procedure prescribes 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.
"We use different sampling techniques for the various categories of substance that we analyse", explains Hartmut Kovacs, Design for Environment, Head of Interior Emissions at Mercedes-Benz. "All in all, we take more than 100 samples from each vehicle." As well as the overall emissions, it is therefore also possible to measure the emissions of individual organic compounds.
The emissions experts also look at a vehicle's propensity to fogging - in other words the creation of a film of condensable substances on a car's windscreen: the measuring rack therefore also includes a cooled sheet of glass upon which these less volatile substances, if present, are deposited.
In addition to this static test, a further series of tests are used to evaluate emission activity in the interior of the vehicle while it is in use. These tests take place with the engine running and the air-conditioning system switched on, with and without air recirculation. A further touch involves the driver's door being opened once during each measurement cycle to simulate the driver getting into the vehicle.
ECARF Seal: extensive allergen testing
"In our estimation, Mercedes-Benz currently represents the benchmark in terms of allergen optimisation for vehicles", according to Professor Dr Torsten Zuberbier, Director of the European Centre for Allergy Research Foundation (ECARF), which is based at the Charité university hospital in Berlin. In industrialised countries these days, allergic conditions are now the most common form of chronic illness. In Germany, for example, around 30 percent of the population are affected. One in ten absences from work as a result of sickness is now attributable to an allergy.
But the pollen count is not the only problem to afflict motorists who suffer from allergies: emissions given off by the materials used in the interior or when contact surfaces are touched can also lead to a strong reaction, with symptoms such as swelling and inflammation of the nasal passage, hay fever or asthma.
But not in a Mercedes-Benz vehicle: numerous model series from the A- to the S-Class meet the criteria of the allergy label. The conditions involved are extensive: numerous components from each equipment variant of a vehicle have to be tested for inhaled allergens, for example. Furthermore, the function of the pollen filter must be tested in both new and used condition.
In addition, tests are undertaken with human "guinea pigs". Driving tests, for example, were conducted with people suffering from severe asthma, with lung 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.
The air-conditioning filters also have to meet the stringent criteria of the ECARF Seal in both new and used condition: amongst other things the tests measure their retention efficiency with regard to dust and pollen.