Abstract

Measurements of particulate matter (PM10 and PM2.5) in ambient air are performed by several air monitoring networks in Europe. These PM measurements are carried out using filters in a monitoring device with ambient air passing through it. Every filter is exposed to ambient air for 24 hours. The laboratories of the air monitoring networks determine the concentration of PM by using the weight of the filters before and after exposure.

In order to investigate whether this weighing procedure - when applied by different laboratories - leads to similar results, a comparison between the laboratories is carried out every two to four years. In general, the weighing results for 2025 were comparable to each other. This means there is a strong basis for comparing and exchanging PM measurements across the participating laboratories.

Nine laboratories in Europe participated in this round's study. A total of 208 filters were compared. The results show relatively small differences between the participating laboratories, and these are well within the limit values for PM measurements. The filters have to be weighed exactly as described in a European standard (EN 12341). For example, the temperature and relative humidity in the weighing rooms must fall within specified value ranges. All participating laboratories matched the temperature requirements, and all but two complied with the relative humidity requirements. The deviating humidity conditions did not have a noticeable impact on the weighing results.

As a member of the European Network of National Air Quality Reference Laboratories, RIVM is responsible for the quality assurance of ambient air pollutant measurements in the Netherlands and performs the measurements together with several air monitoring networks throughout the European Union.