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<p>The measurement of elements in PM<span class="inline-formula">₁₀</span> was performed with 1&thinsp;h time resolution at a rural freeway site during summer 2015 in Switzerland using the Xact<span class="note-anchor" id="fna_Ch1.Footn1"><a href="#fn_Ch1.Footn1">¹</a></span> 625 Ambient Metals Monitor. On average the Xact elements (without accounting for oxygen and other associated elements) make up about 20&thinsp;% of the total PM<span class="inline-formula">₁₀</span> mass (14.6&thinsp;<span class="inline-formula">µg m⁻³</span>). We conducted source apportionment by positive matrix factorisation (PMF) of the elemental mass measurable by the Xact (i.e. major elements heavier than Al), defined here as PM<span class="inline-formula">_10el</span>. Eight different sources were identified in PM<span class="inline-formula">_10el</span> (elemental PM<span class="inline-formula">₁₀</span>) mass driven by the sum of 14 elements (notable elements in brackets): Fireworks-I (<span class="inline-formula">K</span>, <span class="inline-formula">S</span>, <span class="inline-formula">Ba</span> and <span class="inline-formula">Cl</span>), Fireworks-II (<span class="inline-formula">K</span>), sea salt (<span class="inline-formula">Cl</span>), secondary sulfate (<span class="inline-formula">S</span>), background dust (<span class="inline-formula">Si</span>, <span class="inline-formula">Ti</span>), road dust (<span class="inline-formula">Ca</span>), non-exhaust traffic-related elements (<span class="inline-formula">Fe</span>) and industrial elements (<span class="inline-formula">Zn</span> and <span class="inline-formula">Pb</span>). The major components were secondary sulfate and non-exhaust traffic-related elements followed by background dust and road dust factors, explaining 21&thinsp;%, 20&thinsp;%, 18&thinsp;% and 16&thinsp;% of the analysed PM<span class="inline-formula">₁₀</span> elemental mass, respectively, with the factor mass not corrected for oxygen content. Further, there were minor contributions (on the order of a few percent) of sea salt and industrial sources. The regionally influenced secondary sulfate factor showed negligible resuspension, and concentrations were similar throughout the day. The significant loads of the non-exhaust 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 implemented via the SourceFinder software (SoFi Pro version 6.2, PSI, Switzerland) 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>