CWA 17934:2022

Real drive test method for collecting vehicle interior air quality data

Scope

This document provides a test methodology for collecting comparable interior air quality test data for different light duty vehicle makes and models. It covers topics around the technical conducting of tests and reporting results, which includes equipment, calibration, test boundaries and outputs.

The scope has been defined in order to achieve two priorities. First, the data shall be most relevant to the increasingly understood problem of the health effects of poor air quality inside light-duty vehicles, in particular from particle ingress from outside. Second, a methodology has been created that measures a characteristic value of pollution ingress that is independent of how the vehicle is driven and the absolute exterior pollution concentrations. In other words, the rate of ingress for a given vehicle is constant if the boundaries of the test method are met. This constant value can then be compared between vehicles.

The methodology described in this CWA considers not only the particle ingress, but the build-up of carbon dioxide in the cabin on different ventilation system settings. While measurement of nitrogen dioxide is not included at this stage, it, along with other pollutants, may be considered at a later stage.

The scope of this CWA in more detail is:
- to provide the basis for collection of accurate interior air quality test data across different light duty vehicles for the purposes of facilitating comparison;
- to present vehicle interior air quality test data in a transparent, consistent and concise manner;
- to allow the aggregation of vehicle interior air quality test data from multiple sources.

Excluded from the scope initially is measurement of ozone, carbon monoxide, sulphur dioxides and volatile organic compounds. Measurement especially of VOCs had been covered by the UNECE Information Working Group.

The methods described in this CWA are considered to be suitable for measuring interior air quality of vehicles of the following characteristics:
- passenger cars and light commercial vehicles (classes M1 and N1);
- covering primarily urban driving;
- for in-cabin ambient concentrations of particles and CO2.

While the methodology proposed may also be suitable for other vehicle categories (such as M2, M3, N2 and N3), driving conditions and pollutants, this would require further future work in a subsequent workshop.

Outside of scope of this CWA is the use of the outputs to compile comparable ratings.