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Projeto de investigação
Air Pollution in an African Megacity: Source Apportionment and Health Implications
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First exploratory study of gaseous pollutants (NO2, SO2, O3, VOCs and carbonyls) in the Luanda metropolitan area by passive monitoring
Publication . Alves, Célia; Feliciano, Manuel; Gama, Carla; Vicente, Estela D.; Furst, Leonardo; Leitão, Anabela
An air quality monitoring campaign for gaseous pollutants using passive sampling techniques was carried out, for the first time, at 25 locations in the metropolitan area of Luanda, Angola, in June 2023. Concentrations of benzene, toluene, ethylbenzene, xylenes, trimethylbenzenes, SO2 and NO2 were generally higher in locations more impacted by traffic. Benzene, SO2 and NO2 levels did not exceed the World Health Organisation guidelines. Ozone concentrations surpassed those documented for other African regions. Higher O3 formation potential values were recorded at heavy-trafficked roads. The top 5 species with potential for ozone formation were m,pxylene, toluene, formaldehyde, propionaldehyde and butyraldehyde. The Mulenvos landfill presented a distinctive behaviour with a very low toluene/benzene ratio (0.47), while values close to 5 were obtained at traffic sites. The maximum levels of α-pinene, D-limonene, formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butyraldehyde, benzaldehyde, valeraldehyde, hexaldehyde and crotonaldehyde were recorded at the landfill. The formaldehyde/acetaldehyde ratio ranged from 0.40 at the Mulenvos landfill to 3.0, averaging 1.8, which is a typical value for urban atmospheres. Acetaldehyde/propionaldehyde ratios around 0.4–0.6 were found in locations heavily impacted by traffic, whereas values between 0.7 and 1.2 were observed in green residential areas and in places with more rural characteristics. All hazard quotient (HQ) values were in the range from 1 to 10, indicating moderate risk of developing non-cancer diseases. The exception was the Mulenvos landfill for which a HQ of 11 was obtained (high risk). The cancer risks exceeded the tolerable level of 1 × 10-4, with special concern for the landfill and sites most impacted by traffic. A mean lifetime cancer risk of 9 × 10-4 was obtained. The cancer risk was mainly due to naphthalene, which accounted, on average, for 94.6% of the total.
Bioethanol fireplaces as indoor pollution sources: The role of burner design and fuel type
Publication . Vicente, Estela D.; Cipoli, Yago; Charres, Isabella; Nunes, Teresa; Cerqueira, Mário; Feliciano, Manuel; Galindo, Nuria; Yubero, Eduardo; Alves, Célia; Ryšavý, Jiří
Bioethanol fireplaces are marketed as clean and decorative heating alternatives. However, their impact on indoor air quality (IAQ) remains poorly characterised. This study investigates the indoor levels of gaseous and particulate pollutants using a bioethanol fireplace operated under realistic conditions. Two types of bioethanol fuels and two burner designs, a single-chambered (SC) and a double-chambered (DC), were tested under minimal ventilation. Concentrations of CO, NO, NO2, CO2, NH3, N2O, C2H6O, total volatile organic compounds (TVOCs), and carbonyl compounds were measured, while particulate matter (PM10) was characterised chemically and toxicologically. Combustion of both fuels led to substantial increases in indoor pollutant concentrations compared to background levels. Indoors, maximum average CO levels reached 5.67 & micro;g m-3, NO 0.33 & micro;g m-3, NO2 0.85 & micro;g m-3 and TVOCs exceeded 1400 & micro;g m-3. Acetaldehyde and formaldehyde were the dominant carbonyls, with the latter frequently surpassing the WHO guideline value along with NO2. Compared with traditional wood combustion, bioethanol combustion produced relatively higher indoor concentrations of nitrogen oxides, acetaldehyde, and formaldehyde. Average PM10 concentrations ranged from 31.5 to 173 & micro;g m-3, with higher indoor concentrations for the DC burner and Fuel 2. PM10 samples were enriched in bromine, ammonium and nitrate during combustion, and exhibited elevated oxidative potential. Differences in indoor pollutant levels and oxidative potential were observed depending on the burner design, fuel type and initial fuel load. These results demonstrate that flueless bioethanol fireplaces can markedly deteriorate IAQ, underscoring the need for performance standards, improved fuel formulations, and adequate ventilation to mitigate exposure risks associated with their use.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de Projetos de I&D em Todos os Domínios Científicos - 2022
Número da atribuição
2022.04240.PTDC