Emission factors from road dust resuspension in a Mediterranean freeway

Particulate matter emissions from paved roads are currently one of the main challenges for a sustainable transport in Europe. Emissions are scarcely estimated due to the lack of knowledge about the resuspension process severely hampering a reliable simulation of PM and heavy metals concentrations in large cities and evaluation of population exposure. In this study the Emission Factors from road dust resuspension on a Mediterranean freeway were estimated per single vehicle category and PM component (OC, EC, mineral dust and metals) by means of the deployment of vertical profiles of passive samplers and terminal concentration estimate. The estimated PM10 emission factors varied from 12 to 47 mg VKT−1 (VKT: Vehicle Kilometer Traveled) with an average value of 22.7 ± 14.2 mg VKT−1. Emission Factors for heavy and light duty vehicles, passenger cars and motorbikes were estimated, based on average fleet composition and EPA ratios, in 187–733 mg VKT−1, 33–131 VKT−1, 9.4–36.9 VKT−1 and 0.8–3.3 VKT−1, respectively. These range of values are lower than previous estimates in Mediterranean urban roads, probably due to the lower dust reservoir on freeways. PM emitted material was dominated by mineral dust (9–10 mg VKT−1), but also OC and EC were found to be major components and approximately 14–25% and 2–9% of average PM exhaust emissions from diesel passenger cars on highways respectively.