<p><strong>Abstract.</strong> Trace element measurements in PM<sub>10</sub> were performed with 1&#8201;h time resolution at a rural freeway site during summer 2015 in Switzerland using the Xact multi-metals monitor. On average the Xact 625 elements (without accounting for oxygen and other associated elements) make up about 20&#8201;% of the total PM<sub>10</sub> mass (14.6&#8201;&#181;g&#8201;m<sup>&#8722;3</sup>). Subsequently, a source apportionment by positive matrix factorization (PMF) implemented via the Source Finder software (SoFi Pro) was applied. Eight different sources were identified (notable elements in brackets) for PM<sub>10</sub>: fireworks-I (K, S, Ba, Cl), fireworks-II (K), sea salt (Cl), secondary sulfate (S), background dust (Si, Ti), road dust (Ca), traffic-related (Fe) and industrial (Zn, Pb). The major components were secondary sulfate and traffic-related followed by background dust and road dust factors, explaining 21&#8201;%, 20&#8201;%, 18&#8201;% and 16&#8201;% of the analysed PM<sub>10</sub> elemental mass, respectively, with the factor mass not corrected for oxygen content. Further, there are minor contributions (on the order of a few percent) of sea salt and industrial sources. The regionally influenced secondary sulfate factor experiences negligible resuspension, and concentrations are similar throughout the day. The significant loads of the traffic-related and road dust factors with strong diurnal variations highlight the continuing importance of vehicle-related air pollutants at this site. Enhanced control of PMF using SoFi Pro allowed for a successful apportionment of transient sources such as the two firework factors and sea salt, which remained mixed when analysed by unconstrained PMF.</p>