Evaluating Repeatability and Reproducibility of CEN Workshop Real Driving Cabin Air Quality Testing Method

Emissions from motor vehicles are generally recognized to pollute the outside air, with negative effects on human health and the environment. Little is known about the extent to which these pollutants enter the interior of the vehicles through their ventilation systems. The cabin air quality inside vehicles is very lightly regulated around the world, and there is no recognized standard method for measuring pollution ingress. This article tests the effectiveness of a method originally proposed in an SAE paper in 2019 for characterizing the degree of particle ingress. This cabin air quality index is hypothesized to give a repeatable, characteristic value for the vehicle to reduce in-cabin pollutant concentration compared to outside pollutant concentration, which may be suitable for inter -vehicle comparison. To test the method, a series of real-world on-road tests were conducted in Germany with three different types of measurement equipment, two different drivers, and two different routes, with a view to quantifying the repeatability and reproducibility of measurements. The methodology used was based on a draft test protocol being developed by the standardization organization, the Comite Europeen de Normalisation (CEN), and its Workshop 103. The results showed strong levels of repeatability and reproducibility regardless of the route and the driver. The cabin air quality indices were different between different particle metrics, reflecting size-dependent filtration efficiency and different mode diameter for different metrics for the same particle size distribution, but there was high consistency within measurements from the device measuring the same metric. The conclusion is that the method proposed in 2019 is a suitable method for deriving charac-teristic cabin air quality values for vehicles, which could then be used for comparison or regulation.