Spatial Distribution of Air Pollution, Hotspots and Sources in an Urban-Industrial Area in the Lisbon Metropolitan Area, Portugal—A Biomonitoring Approach

Abstract

This study aimed to understand the influence of industries (including steelworks, lime factories, and industry of metal waste management and treatment) on the air quality of the urban-industrial area of Seixal (Portugal), where the local population has often expressed concerns regarding the air quality. The adopted strategy was based on biomonitoring of air pollution using transplanted lichens distributed over a grid to cover the study area. Moreover, the study was conducted during the first period of national lockdown due to COVID-19, whereas local industries kept their normal working schedule. Using a set of different statistical analysis approaches (such as enrichment and contamination factors, Spearman correlations, and evaluation of spatial patterns) to the chemical content of the exposed transplanted lichens, it was possible to assess hotspots of air pollution and to identify five sources affecting the local air quality: (i) a soil source of natural origin (based on Al, Si, and Ti), (ii) a soil source of natural and anthropogenic origins (based on Fe and Mg), (iii) a source from the local industrial activity, namely steelworks (based on Co, Cr, Mn, Pb, and Zn); (iv) a source from the road traffic (based on Cr, Cu, and Zn), and (v) a source of biomass burning (based on Br and K). The impact of the industries located in the study area on the local air quality was identified (namely, the steelworks), confirming the concerns of the local population. This valuable information is essential to improve future planning and optimize the assessment of particulate matter levels by reference methods, which will allow a quantitative analysis of the issue, based on national and European legislation, and to define the quantitative contribution of pollution sources and to design target mitigation measures to improve local air quality.

Source apportionment of PM2.5 before and after COVID-19 lockdown in an urban-industrial area of the Lisbon metropolitan area, Portugal

“…6 ). In relative terms, this was a consequence of the reduction of “Vehicle exhaust”, but the absolute contribution of the “Industry” factor was also significantly higher in the post-confinement (1960 ± 2400 ng.m −3 ) than in the pre-confinement (991 ± 1439 ng.m −3 , p -value = 0.000), probably due to increased resuspension in the dry season and also corroborating the fact that the industries (namely, steelworks) of the study area did not stop to operate during the confinement period ( Abecasis et al, 2022 ).…”

“…Seixal is one of the most densely populated municipalities in Portugal, with 167,294 inhabitants in 95.5 km 2 ( PORDATA, 2022 ). The sampling site is at 2–3 km from high density traffic highways (A2-IP7 and A33), and is surrounded by small and medium-sized industries, as well as an industrial park (at 1 km) ( Abecasis et al, 2022 ): a steelworks that manufactures galvanised sheet metal; an Electric Arc Furnace steelworks; a lime factory involving the calcination of limestone in a coke kiln; and a metal waste management and treatment factory. Furthermore, the sampling site is at 3.5 km distance from a shipyard and the ferry terminal that connects the two river banks for commuting ( Fig.…”

“…Occasional settled dust events, when houses, cars, plants etc. were covered by dust (coarse particles of a granulometric dimension much higher than PM 10 ) have increased the population's concerns regarding the impacts of the air pollution on their health, leading the local Council of Seixal to promote actions, such as the assessment of the chemical composition of the settled dust to determine its sources ( Justino et al, 2019 ) and an air biomonitoring study using lichens in the area ( Abecasis et al, 2022 ). In both studies, the influence of the steel industries was identified due to the content of Fe, Cr and Mn, along with the traffic influence.…”

Developing human biomonitoring as a 21st century toolbox within the European exposure science strategy 2020–2030

“…3 HBM is also applied to study spatial distribution in the environment, e.g. to compare exposures by distance to an identified source and to determine to what extent such exposure estimates can be associated with observed health effects that may be clustered around a (suspected) hot spot of environmental pollution (Abecasis et al 2022;Odabasi et al 2015;Wilhelm et al 2005). Contaminated sites may be related to industrial activity, sanitary landfill or certain applications of high-risk chemicals, such as pesticides in agricultural settings (Figueiredo et al 2021;Silva et al 2021;Trushna et al 2022).…”

Citizens’ Perception on Air Quality in Portugal—How Concern Motivates Awareness

“…Moreover, considering that some populations may be aware of the impact of local pollution sources in their daily life, this study also aimed to understand to which extension their concerns influence their awareness and knowledge about air quality. To achieve these goals, a national online questionnaire was made available during two months and the overall population was compared with a sub-population from an urban-industrial area of Portugal that is known to be aware of air pollution due to occasional settled dust events in the area [7,8].…”