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- Olstrup, Henrik, 1978-
(författare)
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Air pollution and health – Indicators, trends and impacts
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on some of the limitations and difficulties that exist when it comes to quantifying the human health effects that arise as a result of air pollution exposure. The following four issues are particularly analysed and discussed: 1) The measurement techniques used for carbonaceous particles and their lack of consistency; 2) Do the health risks associated with exposure to PM10 depend on the content of elemental carbon in the aerosol?; 3) Trends in air pollutants and the health effects that arise as a result of changed exposure to the measured pollutants; 4) The associations between the measured concentrations of different air pollutants in Stockholm and the daily number deaths; 5) Air quality indicators and health outcomes as basis for an air quality health index (AQHI).The method that has been used is largely based on empirical data analysis, where further statistical processing has been used in order to clarify the scientific issues. The overall conclusions are the following: 1) The health impact assessments associated with exposure to carbonaceous particles would benefit from the introduction of a more uniform measurement technique in order to get more consistent and reliable results; 2) The health risks associated with exposure to PM10 are dependent on the content of elemental carbon; 3) The life expectancy increase associated with decreasing NOx trends during 1990–2015 in Stockholm, Gothenburg and Malmo make up as much as about 20 % of the total gain in life expectancy during this period, which clearly shows the beneficial effects related to decreased exposure; 4) The associations between daily mortality and the concentrations of O3 and PM2.5-10 in Stockholm are statistically significant, which does not apply to the exhaust-related pollutants, possibly reflecting behavioural factors affecting the degree of exposure; 5) In comparison with the currently used air quality index (AQI), the air quality health index (AQHI) is a more useful tool in order to address the short-term health effects associated with multi-pollutant exposure to NOx, O3, PM10 and birch pollen.We hope that these findings will be useful from a policy point of view. Introducing a more consistent measurement technique for soot particles would be beneficial in assessing the health effects related to exposure to these particles. The increase in life expectancy associated with decreasing NOx trends shows the benefits from a public health perspective when it comes to introducing emission-reducing measures from traffic. The AQHI would be beneficial to implement in legislation, as it is based on several pollutants, which means that the cumulative health effects associated exposure to several different air pollutants are accounted for.
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| 2. |
- Reyes Forsberg, Diana Carolina, 1984-
(författare)
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Experimental study of alkalinisation of cellulose in industrial relevant conditions
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mercerisation of cellulose pulp with a solution of NaOH is the first step of manufacturing cellulose-based value-added products, e.g. viscose fibres and cellulose ethers. During this process, cellulose transforms into a swollen crystalline structure, alkali cellulose (Na-Cell). This increases the reactivity of the cellulose and makes it more accessible for reagents to penetrate and react with the hydroxyl groups. The mercerisation conditions are known to affect the degree of alkalinisation of cellulose as well as the final products. The main objective of this thesis is to investigate how the alkalinisation of softwood sulphite dissolving cellulose pulp is influenced by the co-variation of process variables in the mercerisation in industrial relevant conditions, for both viscose and cellulose ether production. This objective was achieved by quantitative analysis of the effect of simultaneous variation of a set of key parameters on the degree of alkalinisation (i.e. degree of activation, DoA) of the chosen dissolving pulp. Quantitative measurements were performed using Raman spectroscopy data, evaluated by partial least squares (PLS) regression. For mercerisation at viscose production conditions, the effect of studied variables on mass yield was also considered. In the case of mercerisation at ether processing conditions, formation of alkali cellulose at a fixed temperature was included. The knowledge obtained on mercerisation under ether processing conditions was then applied for preparation of the ionic cellulose ether carboxymethylcellulose (CMC). The overall results show that temperature has a strong effect on DoA and mass yield for mercerised samples under steeping conditions. Measured DoA decreases as the temperature increases from 20 to 70 °C. Mass yield correlates positively with the temperature up to 45-50 °C in the PLS model, after which the relation is negative. The [NaOH] and reaction time show a complex dependence of other variables. At mercerisation conditions for cellulose ether production, the NaOH/AGU stoichiometric ratio, denoted as (r), shows to be very important for DoA, with a positive correlation. At these mercerisation conditions, temperature shows no effect on DoA. The influence of the [NaOH] (which also refers to the concentration of water) shows a complex dependence on (r). As (r) increases and [NaOH] decreases, the measured DoA increases. Prolonged mercerisation time shows no significance in the modelled DoA. However, a gradual increase of the DoA over time was seen when mercerisation was performed with 30% and 40% [NaOH] at (r) = 0.8, suggesting a slow diffusion of NaOH and Na-Cell formation. 13C CP-MAS NMR measurements of samples produced at room temperature show that formation of the Na-Cell allomorph is mainly determined by the [NaOH]. However, in the transition area between Na-Cell I and Na-Cell II, (r) also seems to be of importance. An increase of DS in the produced CMC samples also shows to be consistent at such conditions with the increase in the measured DoA and with increased (r) and decreased [NaOH]. However, these conditions also favour the formation of by-products. In the synthesised CMC samples, a DS of up to 0.7 was achieved. Measured solubility was lower than expected for any given DS. This, along with the non-statistical distribution of monomer units in the polymer chains, indicates high heterogeneity in the synthesised samples. The distribution of substituents within the AGU shows attachment to hydroxyl oxygens in the order O3 < O2 ≈ O6. The relative importance of the substitution at O3 indicates an increase at this position when [NaOH] increases.The models presented in this thesis will hopefully serve as a basis for predicting the effects of the studied variables on the DoA, as well as on the mass yield of cellulose pulp when mercerisation conditions are adjusted. Moreover, it is believed that the presented studies can give a better understanding of mercerisation at cellulose ether conditions, hence enabling further development of this process step.
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| 3. |
- Tornevi, Andreas, 1975-
(författare)
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Precipitation, Raw Water Quality, Drinking Water Treatment and Gastrointestinal Illness
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background On numerous occasions, outbreaks of acute gastrointestinal illnesses (AGI) have been linked to municipal drinking water in the industrialised world. Many of the reported outbreaks were observed after heavy rainfall events, which suggests that such events could result in a deterioration in the quality of drinking water. The observed drinking water-related outbreaks are, however, probably just the tip of the iceberg, and the extent to which public drinking water also influences the endemic level of gastroenteritis during non-outbreak periods is largely unknown. With climate change projected to increase the frequency of extreme weather events, data for preventive actions are needed now, to ensure safe drinking water today and in the future. The primary aim of this thesis is to increase the knowledge of the extent to which rainfall can still be a risk for insufficient drinking water quality, even with modern drinking water production methods. We aim to study if the incidence of gastroenteritis during normal endemic levels can be associated with water quality and the efficacy of pathogen elimination in different treatment processes. The thesis focuses first on AGI in the Gothenburg population and how precipitation affects its main fresh water supply (papers I-III); this is followed by a broader comparison of AGI in 20 cities across Sweden (Paper IV).Methods Observational time series data was used for all papers to construct generalized additive regression models, using smooth functions to adjust for long-term trends. Delayed effects on the outcome were evaluated using distributed lag non-linear models. In Paper I, the raw water-quality data for the river Göta älv were analysed – this water is used to produce drinking water for the population living in the north part of City of Gothenburg. The short-term variation of daily mean turbidity measurements and samples of three different types of indicator bacteria were modelled with daily precipitation using seven years of data. In papers II and III, the analyses aimed to determine whether the daily incidence of AGI in the population which households received drinking water produced from the river water could be associated with precipitation. As a measure of AGI, we used four years of data on the daily number of phone calls to the nurse advice line about vomiting, diarrhoea or abdominal pain (Paper II), and six years of data of the daily number of visits to health care clinics, when individuals were diagnosed with gastrointestinal infections (Paper III). Paper III also evaluates the similarities and differences between the frequency of nurse advice calls and primary health care visits. Paper IV analyses and compares the occurrence and seasonal patterns of nurse advice calls in twenty cities in Sweden, using seven years of data. The water treatment technique used by the public drinking water plants was obtained, and the processes theoretical efficacy of pathogen elimination was determined. The extent of AGI calls in relation to the pathogen elimination efficacy was analysed using a binomial regression design, adjusting for population size, age distribution and geographical area.Results We observed a strong relation between precipitation and the water quality in the Göta älv. A heavy rainfall event was related to increased concentrations of E. coli bacteria for several days, with the peak increase two days after the event. Precipitation was found to affect raw water quality parameters across all seasons. Heavy precipitation was also associated with a significant increase in the daily number of nurse advice calls due to AGI symptoms, with the number of calls peaking five days later. Consecutive wet weather periods were associated with both an increased number of AGI calls, as well as visits to clinics that led to diagnoses of AGI. Finally, we observed in Paper IV that cities with a higher pathogen elimination efficacy in their drinking water utility had a lower amount of AGI calls. The relations applied both to surface water and groundwater utilities, although the protective effect of a more advanced drinking water treatment on AGI was observed to be most significant in cities with surface water plants during the winter season.Conclusions The results suggest it is possible to reduce the occurrence of endemic gastroenteritis with a more advanced treatment process for drinking water. The delay between a heavy rainfall event (and the resulting decrease in raw water quality) and the increased number of nurse advice calls suggests viruses are the main cause, as the timing is consistent with viral incubation times. A viral transmission was also proposed when comparing different cities, as a more advanced water treatment process seems to be most beneficial during seasons where viruses are acknowledged as the main cause of AGI. Our research suggests that upgrades to drinking water treatment techniques, especially those aiming to better eliminate viruses, are warranted
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| 4. |
- Åström, Christofer, 1983-
(författare)
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Health effects of heatwaves : short and long term predictions
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Climate change is defined by the Intergovernmental Panel on Climate Change as changes in the state of the climate associated with changes in the mean and/or the variability of its properties. Climate change will affect temperatures both as an increase in mean temperature as well as changes in the frequency of temperature extremes. Health effects associated with extreme heat, both mortality and morbidity, have been observed all over the globe. Groups that are often found to be more vulnerable are the elderly and people diagnosed with certain diseases and/or on taking some specific types of medication. The health effects from climate change in the future depend on a number of underlying sociodemographic and other factors. It is difficult to predict how the underlying societal factors that are likely to alter the health effects from high temperatures will change. The aim of this thesis is to investigate the influence of the underlying assumptions and factors that are key components when predicting and projecting heat-related illness, both in the short and long term. This work aims to identify and to some extent quantify different sources of uncertainty that will have effects on the outcome of health impact assessments.Methods: We wanted to evaluate if different statistical models would alter the ability to identify days with elevated heat-related risk. We used observations of temperatures and daily mortality for Greater Stockholm to model different exposure-response relationships (Paper I). Along the observed data, we collected temperature forecasts for the Stockholm area. We defined what constitutes a risk day and compared the model’s ability to identify these days using both observed and forecasted temperatures to evaluate the predictive performance of models based on the different statistical approaches. To estimate how climate change will alter the heat-related health impacts we used climate change projections from a range of climate change scenarios to be able to get stable estimates as well as a measure of the uncertainty in the climate projections (Paper II-III). We estimated the change in respiratory hospital admissions (Paper II) and the future need for adaptation to keep heat-related mortality at current levels (Paper III) in Europe. We also estimated the change in heat-related mortality due to changes in climate, demographics and health status of the population in Stockholm (Paper IV).Results: The models using a highly complex exposure-response relationship showed lower predictive performance, especially when looking at a longer time-scale. The more complex models did also estimate a lower mortality increase compared to the less complex ones. There was however high agreement of which days to be considered risk days. The estimated increase in heat-related illness from the three health impact assessment studies showed impacts on a similar order of magnitude when looking at changes in climate only. Respiratory hospital admissions were estimated to more than double in Europe and heat-related mortality in Stockholm was estimated to increase to around 257% of current levels. Therefore, adaptation needs to lower the vulnerability to heat by around 50% in the European countries. In study III and IV we take changes in demographics into account and find that the future health burden from heat will increase due to the growing elderly population.Conclusion: To be able to make predictions of future health burdens from heat, both in the long and short term, we need to consider the properties of the epidemiological models and how the choice of model might limit its use within a health impact assessment. Climate change seems to be the main driver of the future health burden from extreme temperatures, but our results suggests that changing demographics will add to the burden considerably unless relevant adaptation measures are implemented. Adding this on top of the challenges posed by climate change, we find that need for adaptation will increase substantially in the future.
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