PM₁₀ Resuspension of Road Dust in Different Types of Parking Lots: Emissions, Chemical Characterisation and Ecotoxicity

The thoracic fraction of road dust (PM₁₀) was measured for the first time in Portugal in parking areas, both outdoors and indoors, with the aim of completing existing studies carried out in active lanes of various roads. An in situ resuspension chamber was used to collect a total of 23 samples in three parking areas of Aveiro, whilst the laboratory procedures included determination of carbonaceous content (OC and EC) by a thermo-optical technique, elemental composition by ICP-MS and ICP-OES after acid digestion, and the <i>Aliivribrio fisherii</i> bioluminescent bacteria ecotoxicity bioassay. Dust loadings (DL10) obtained were 18.5 ± 9.8 mg PM₁₀ m⁻², in outdoor parking, and 1.8–23.7 mg PM₁₀ m⁻² for indoor parking, corresponding to emission factors of 476 and 75–589 mg veh⁻¹ km⁻¹, respectively. OC represented 9–30 % of PM₁₀ for the indoor parking areas. However, for the outdoor samples, the high iron oxide content jeopardised the OC-EC separation. In those samples, carbonates accounted for 10.0 ± 3.3% of the PM₁₀ mass. The analysis of elemental components focused on major elements (Al, Ca, Fe, K, and Mg) as well as minor elements. The total mass fraction of element oxides accounted for 27.1% (outdoor) and 23.6–34.3% (indoor). Σ_PAH calculated for all parking areas accounted for 8.38–36.9 μg g⁻¹ PM₁₀. The ecotoxicological bioassay showed that all aqueous solutions were toxic to bioluminescent bacteria, whereas no clear correlations could be made with specific component groups, with the exception of Σ_PAH and EC₅₀.