Browsing by Author "Canha, Nuno"
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- Citizens’ perception on air quality in Portugal: how concern motivates awarenessPublication . Canha, Nuno; Justino, Ana Rita; Gamelas ou Carla A. Gamelas, Carla; Almeida, Susana MartaThis study aimed to understand the knowledge of Portuguese citizens about air quality and the extent to which the concerns about specific environmental problems can motivate their acquaintance of information. Moreover, this study also allowed to understand which information about air quality needs further dissemination to provide the citizens with all the available tools and the correct knowledge. For this, a national online survey about air quality perception was conducted, where 1131 answers were obtained and two different populations were compared: the general population and a sub-population from an urban-industrial area of Lisbon metropolitan area that had experienced frequent air pollution events in the past. Air pollution was considered the environmental topic of higher concern among this sub-population (61.4%), while in the general population it ranked thirdly (27.4%). Generally, the sub-population showed higher knowledge about air quality than the general population, with 61% being able to identify at least one air pollutant. The perception of the local air quality was also very different between populations, with 61% of the sub-population considering it poor or very poor, while only 14% of the general population had the same perception, which highlights the different levels of concern between populations. A weak knowledge about air pollutants (50% of the general population could not identify any air pollutant) and an erroneous perception of the contribution of the different pollution sources to air quality levels were found. More than 50% of the respondents of both populations were considered to not have enough information regarding the air quality in their area of residence, with the national air quality database being unknown to almost everyone. Overall, strong efforts should be made to increase the awareness about the importance of air quality, which may promote a higher acceptance of the implementation of future actions to improve air quality.
- Microplastic contamination of lettuces grown in urban vegetable gardens in Lisbon (Portugal)Publication . Canha, Nuno; Jafarova, Mehriban; Grifoni, Lisa; Gamelas ou Carla A. Gamelas, Carla; Alves, Luís C.; Almeida, Susana Marta; Loppi, StefanoUrban vegetable gardens are very often a feature of cities that want to offer their citizens a more sustainable lifestyle by producing their own food products. However, cities can have significant pollution levels (or pollution hotspots) due to specific sources of pollution, such as traffic. Among the various pollutants, microplastics (MPs) are emerging as a consensual concern due to the awareness of the environmental contamination, their bioaccumulation potential and human intake, and, consequently unknown human health impacts. The present study compared the content of MPs in lettuce plants cultivated in Lisbon urban gardens with those cultivated in a rural area, as well as samples bought in supermarkets. Microplastics were detected in all washed leaves, with mean levels ranging from 6.3 ± 6.2 to 29.4 ± 18.2 MPs/g. Lettuce grown in urban gardens from areas with high traffic density showed higher MPs levels. Weak positive Spearman’s rank correlations were found between MPs content and concentrations of Cu and S (determined by Particle Induced X-Ray Emission, PIXE), suggesting a possible role of traffic contribution to MPs levels, as both elements are considered traffic-source tracers. These results contribute to shed light on the MP contamination of vegetables grown in such urban environments, that may represent a potential MP exposure route through the dietary intake, corresponding to a 70% increase in annual MP intake compared to lettuces bought in supermarkets.
- Oxidative potential of fine aerosols from a Portuguese urban-industrial area: preliminary resultsPublication . Canha, Nuno; Gamelas ou Carla A. Gamelas, Carla; Mendez, Sergio; Almeida, Susana Marta; Guascito, Maria Rachele; Contini, Daniele
- Source apportionment of PM2.5 before and after COVID-19 lockdown in an urban-industrial area of the Lisbon metropolitan area, PortugalPublication . Gamelas ou Carla A. Gamelas, Carla; Canha, Nuno; Vicente, Ana; Silva, Anabela; Borges, Sónia; Alves, Célia; Kertesz, Zsofia; Almeida, Susana MartaThe lockdowns held due to the COVID-19 pandemic conducted to changes in air quality. This study aimed to understand the variability of PM2.5 levels and composition in an urban-industrial area of the Lisbon Metropolitan Area and to identify the contribution of the different sources. The composition of PM2.5 was assessed for 24 elements (by PIXE), secondary inorganic ions and black carbon. The PM2.5 mean concentration for the period (December 2019 to November 2020) was 13 ± 11 μg.m−3. The most abundant species in PM2.5 were BC (19.9%), SO42− (15.4%), NO3− (11.6%) and NH4+ (5.3%). The impact of the restrictions imposed by the COVID-19 pandemic on the PM levels was found by comparison with the previous six years. The concentrations of all the PM2.5 components, except Al, Ba, Ca, Si and SO42−, were significantly higher in the winter/pre-confinement than in post-confinement period. A total of seven sources were identified by Positive Matrix Factorisation (PMF): soil, secondary sulphate, fuel-oil combustion, sea, vehicle non-exhaust, vehicle exhaust, and industry. Sources were greatly influenced by the restrictions imposed by the COVID-19 pandemic, with vehicle exhaust showing the sharpest decrease. Secondary sulphate predominated in summer/post-confinement. PM2.5 levels and composition also varied with the types of air mass trajectories.
- Source apportionment of PM2.5 in the pre-pandemic versus pandemic period in an area near Lisbon: lessons for air quality managementPublication . Gamelas ou Carla A. Gamelas, Carla; Canha, Nuno; Vicente, Ana; Silva, Anabela; Borges, Sónia; Alves, Célia; Kertesz, Z.; Almeida, S. M.
- Spatial distribution of air pollution, hotspots and sources in an urban-industrial area in the Lisbon Metropolitan Area, Portuga: a biomonitoring approachPublication . Abecasis, Leonor; Gamelas ou Carla A. Gamelas, Carla; Justino, Ana Rita; Dionísio, Isabel; Canha, Nuno; Kertesz, Zsofia; Almeida, Susana MartaThis 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.
- Strawberry plant as a biomonitor of trace metal air pollution: a citizen science approach in an urban-industrial area near Lisbon, PortugalPublication . Gamelas ou Carla A. Gamelas, Carla; Canha, Nuno; Justino, Ana R.; Nunes, Alexandre; Nunes, Sandra; Dionísio, Isabel; Kertesz, Zsofia; Almeida, Susana MartaA biomonitoring study of air pollution was developed in an urban-industrial area (Seixal, Portugal) using leaves of strawberry plants (Fragaria × ananassa Duchesne ex Rozier) as biomonitors to identify the main sources and hotspots of air pollution in the study area. The distribution of exposed strawberry plants in the area was based on a citizen science approach, where residents were invited to have the plants exposed outside their homes. Samples were collected from a total of 49 different locations, and their chemical composition was analyzed for 22 chemical elements using X-ray Fluorescence spectrometry. Source apportionment tools, such as enrichment factors and principal component analysis (PCA), were used to identify three different sources, one geogenic and two anthropogenic (steel industry and traffic), besides plant major nutrients. The spatial distribution of elemental concentrations allowed the identification of the main pollution hotspots in the study area. The reliability of using strawberry leaves as biomonitors of air pollution was evaluated by comparing them with the performance of transplanted lichens by regression analysis, and a significant relation was found for Fe, Pb, Ti, and Zn, although with a different accumulation degree for the two biomonitors. Furthermore, by applying PCA to the lichen results, the same pollution sources were identified.
- The impact of COVID-19 confinement measures in the Air Quality in an urban-industrial zone in PortugalPublication . Abecassis, Leonor; Gamelas ou Carla A. Gamelas, Carla; Canha, Nuno; Almeida, Susana MartaThis work aims to evaluate the temporal evolution of the concentrations of pollutants PM10, NO2 and O3, from 2001 to 2020, and to evaluate the impact of the COVID-19 pandemic on the levels of these atmospheric pollutants, in an urban-industrial zone (Paio Pires-Seixal, Portugal). The results showed that a significant improvement in air quality resulted from the large restriction of anthropogenic activities that occurred due to the pandemic, namely the March-May 2020 lockdown. The mean concentrations of PM10, NO2 and O3 in 2020 were compared with the average concentrations measured from 2014 to 2019. The most expressive reduction in NO2 (-43.9%, p=0.000) was found in April 2020, when a very expressive PM10 reduction was also registered (- 40.0%, p=0.000) and significant reductions of both pollutants were found in the months thereafter.
- The impact of COVID-19 confinement measures on the air quality in an urban-industrial area of PortugalPublication . Gamelas ou Carla A. Gamelas, Carla; Abecasis, Leonor; Canha, Nuno; Almeida, Susana MartaThis study evaluated the temporal variability of the concentrations of pollutants (namely, NO2, O3, PM2.5, PM10 and SO2) in an urban-industrial area of mainland Portugal during two decades (from 2001 to 2020), to assess the impact of the COVID-19 pandemic on the levels of these atmospheric pollutants. Mean levels of pollutants in 2020 were compared with those measured in the six previous years (2014–2019). A significant improvement in air quality, namely regarding PM10 and NO2, was found and it can be attributable to the restrictions of anthropogenic activities (such as traffic) promoted during the March–May 2020 national lockdown that occurred due to the pandemic. Significant and expressive reductions of 44.0% and 40.3% were found in April 2020 for NO2 and PM10, respectively, showing the impact of local traffic in the study area. A similar trend of reduction for these pollutants was also found in the following months. However, ozone levels did not show the same trend, with significant increases in several months after the lockdown period, highlighting other contributions to this pollutant. This unique period can be considered as a living lab, where the implementation of strict measures due to COVID-19 confinement promoted the reduction of anthropogenic activities and allowed us to understand more comprehensively their impact on local air quality.