Assessment of particulate matter levels and sources in a street canyon at Loures, Portugal – A case study of the REMEDIO project

Abstract

Air quality in urban environments is directly related to structural aspects of streets and traffic variables, justifying the need for local assessments. This information is crucial as input to obtain accurate and reliable statistical modelling of the implementation of different mitigation scenarios aiming to improve the local air quality management. The present study intended to assess temporal trends of particulate matter levels in a street canyon of the urban area of Moscavide (Loures, Portugal) for one-month in autumn of 2016. Moreover, fine and coarse particles were characterised for their carbonaceous and elemental contents in order to identify the main pollution sources affecting the study area.Particle concentration peaks were observed during daytime and were associated with traffic intensity due to commuting. During the studied period, no exceedances of the limit values set by the European legislation were registered. The natural sources sea salt and mineral dust contributed, on average, to 6 and 8% of PM10 levels. The Fe/Cu ratios indicated the contribution of wear emissions from road traffic. Enrichment of anthropogenic elements in PM was found and several traffic markers were identified from specific correlations between elements (good: Cu–Mn, Cu–Pb; moderate: Cu–Zn, Mn–Zn, Pb–Zn), highlighting the contribution of local traffic to PM levels.This information is valuable to understand possible health effects of particulate matter levels on citizens due to their exposure and to establish a reference scenario with which the future implementation of mitigation measures targeting local traffic can be compared to assess improvements in air quality in the studied street canyon.