Characterisation of non-exhaust emissions from road traffic in Lisbon

Non-exhaust emissions from road transport include particles from brake and tyre wear, road surface abrasion and dust resuspension. Road dust loads and their chemical properties are heterogeneous and their knowledge is still scarce. This study aimed to characterise, for the first time in Lisbon, the thoracic fraction of road dust (PM10) by collecting samples directly from road pavements by an in situ resuspension chamber. The highest PM10 load (15.6 ± 8.75 mg m−2) was obtained on a cobblestone pavement, while for asphalt roads the mean PM10 load was 4.40 ± 0.16 mg m−2. Emission factors for asphalt pavements ranged from 83.5 to 274 mg veh−1 km−1. On average, 65.7% of the PM10 mass was reconstructed, taking into account the carbonaceous content and the sum of the elements in their oxidized form. Cu and Zn, associated with brake and tyre wear, were the most enriched elements in relation to the soil composition (EnF = 440 and 184, respectively). The highest potential ecological risk factor of individual metals (Eri) was also observed for Cu (EriCu = 393). In 90% of the sampled streets, the total carcinogenic risk was higher than 1E-4 for As, suggesting that exposure to this hazardous element may contribute to the development of cancer over a lifetime. The results showed the high contribution of certain dangerous chemical compounds associated with resuspension particles and their potential effects on human health.

Inês Lopes and Ismael Casotti Rienda acknowledge their PhD fellowships (SFRH/BD/147074/2019 and SFRH/BD/144550/2019, respectively) from the Portuguese Foundation for Science and Technology (FCT). The sampling campaign and analytical work were supported by the project “SOPRO: Chemical and toxicological SOurce PROfiling of particulate matter in urban air”, POCI-01-0145-FEDER-029574, funded by FEDER, through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI), and by national funds (OE), through FCT/MCTES. Thanks are also due to RADIATE (H2020, #824096). We are grateful for the support to CESAM (UIDB/50017/2020 & UIDP/50017/2020), to FCT/MCTES through national funds, and co-funding by FEDER, within the PT2020 Partnership Agreement and Compete 2020. Authors also gratefully acknowledge the FCT support through the UIDB/04349/2020 project. An acknowledgment is also given to António Almeida from EMEL, Pedro Ladeira from the Lisbon City Council and the Municipal Police of Lisbon, for all the logistic support.

Peer reviewed