Browsing by Subject "air pollution"
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(2023)Lichens are sensitive organisms widely used for environmental biomonitoring. Urban environments have been under heavy pollution, especially sulphur dioxide and nitrogen oxides, due to human activity which has led to the disappearance of lichens in city centres. Regulations and technological changes have led to cleaner air and less deposition of pollutants, especially sulphur dioxide on the vegetation in both rural and urban areas. This in turn has led to recolonization of lichens in former lichen deserted areas. In this study epiphytic macrolichens on park maples were surveyed using simple tree-based random sampling in three parks in Helsinki, and in one park in Loviisa, Siuntio and Raasepori each. The sampling and surveying methods were selected based on the SFS standard “Ambient air. Biomonitoring with lichens. Assessing epiphytic lichen diversity”. Species identification took place on site and in Botanical museum (Finnish Museum of Natural History). The results from parks in Helsinki were used to estimate if lichens have recolonized the trees. In addition, the results from the other Uusimaa municipalities were used to assess how different is the lichen species assemblage when comparing the relatively more polluted region of Helsinki to the less polluted regions in Uusimaa. The study found that pollution levels in Helsinki have declined enough to enable recolonization, of which there have been signs already in 1990s and 2000. The study used lichen diversity value of defined functional groups as one of the statistical methods which gave new information about how the species tolerance or sensitivity to pollutants shapes the recolonization. Comparison between the study areas in Uusimaa region revealed that concentrations of nitrogen oxides steer lichen species assemblage in Helsinki. Lichen surveys in Helsinki are scarce. This study brings topical information about the lichen situation in Helsinki, and it uses an as yet relatively unknown method to extract information from lichen assemblage. Regular, comparable lichen surveys are needed to further research the pressure that human activities cause on urban nature. Such time series would help to monitor both the urban nature loss and the impact of climate change on the urban nature.
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(2023)Due to population growth, urbanization, and increase in life expectancy, the urban population is growing, and by 2050 68% of the global population is expected to live in urban areas. Even though the air quality in urban settings has greatly improved in recent decades due to increased legislation, restriction, and monitoring, the negative health impacts associated with pollutants have not completely diminished. Air quality varies on a local scale due to urban form and function, that creates differences in experienced exposure among individuals. These exposure differences among socio-economic groups have been studied, but no clear consensus has been found, as the results have been very diverse and even contradictory. Therefore, conducting local level studies is important in order to identify local patterns of exposure and to recognize them in urban planning. However, previous literature on the topic in Finnish context is lacking. This thesis studies interpolated air pollutant exposure among one susceptible socio-economic group – the elderly – and aims to identify possible hotspots of both in Helsinki, Finland. The distribution of the elderly and air quality is assessed through Moran’s I calculations. Global Moran’s I is used to assess for spatial autocorrelation, and local Moran’s I is applied to identify local clusters. To further examine the relationship, correlation coefficients are calculated through Spearman’s rank correlation coefficient. According to the results, there is a weak positive correlation between the elderly and air quality, indicating that generally air quality tends to be worse when the number of elderly people increase. However, the relationship is stronger among younger age groups, although the differences between age groups is very small. The exposure was also assessed through overlapping high value clusters, which indicate that elderly clusters in the city center are located in areas with low air quality, while elderly clusters in Lauttasaari and Vuosaari are located in areas with good air quality. Previous studies regarding the relationship between age and air pollution exposure have been contradicting in different cities, and therefore these results provide important knowledge about the problem specifically in the context of Helsinki. Additionally, the results are be observed in the light of the larger discourse around socio-economic status and air pollution, but further studies on the topic are still needed. Including multiple socio-economic variables and the dimension of negative health outcomes would aid in identifying 1) the most important socio-economic factors in the context of negative health outcomes associated with air pollution, and 2) those areas where multiple important socio-economic factors and low air quality are overlapping and therefore might have higher risk for negative health outcomes.
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