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- Carlsen, Hanne Krage, 1981-
(author)
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Health effects of air pollution in Iceland : respiratory health in volcanic environments
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Air pollution has adverse effects on human health. The respiratory system is the most exposed and short-term changes in air pollution levels have been associated with worsening of asthma symptoms and increased rates of heart attacks and stroke. Air pollution in cities due to traffic is the major concern, as many people are exposed. However, natural sources of air pollution such as natural dust storms and ash from volcanic eruptions can also compromise human health. Exposure to volcanic eruptions and other natural hazards can also threaten mental health. Air pollution has not been extensively studied in Iceland, in spite of the presence of several natural pollution sources and a sizeable car fleet in the capital area.The aim of this thesis was to determine if there was a measurable effect on health which could be attributed to air pollution in Iceland. This aim was pursued along two paths; time series studies using register data aimed to determine the short-term association between daily variation in air pollution and on one hand daily dispensing of anti-asthma medication or the daily number of emergency room visits and emergency admissions for cardiopulmonary causes and stroke. The other method was to investigate if exposure to the Eyjafjallajökull volcanic eruption was associated with adverse health outcomes, either at the end of the eruption, or 6 months later.In paper I time series regression was used to investigate the association between the daily number of individuals who were dispensed anti-asthma medication and levels of the air pollutants particle matter with an aerodynamic diameter less than 10 μm (PM10), nitrogen dioxide (NO2), ozone (O3), and hydrogen sulfide (H2S) during the preceding days. For the study period 2006-9, there were significant associations between the daily mean of PM10 and H2S and the sales of anti-asthma medication 3 to 5 days later. Giving the exposure as the highest daily one-hour mean gave more significant results. Air pollution negatively affected the respiratory health of asthma medication users, prompting them to refill their prescriptions before they had originally intended to.In paper II the main outcome was the number of individuals seeking help at Landspitali University Hospital emergency room for cardiopulmonary disease or stroke. Time series regression was used to identify the lag that gave the best predictive power, and models were run for data for 2003-9 pollutants PM10, NO2, and O3. O3 was significantly associated with the number of emergency hospital visits the same day and two days later in all models, and both for men, women and the elderly. Only emergency hospital visits of the elderly were associated with NO2, and there were no associations with PM10.In paper III the aim was to investigate if the health effects of PM10 were affected by the addition of volcanic ash from the 2010 eruption of Eyjafjallajökull and 2011 eruption of Grímsvötn to PM10 in the capital area. Time series regression of emergency hospital visits and PM10 before and after the Eyjafjallajökull eruption showed that the effect tended to be higher after the eruption, but the results were not significant. Analysis with a binary indicator for high levels of PM10 from volcanic ash and other sources showed that volcanic ash was associated with increased emergency hospital visits. There were no associations with high levels of PM10 from other sources.In paper IV, the health of the population exposed to the ongoing eruption of Eyjafjallajökull in 2010 was investigated thoroughly. Lung function in adults was better than in a reference group from the capital area, though many reported sensory organ irritation symptoms and symptoms of stress and mental unhealth, especially those with underlying diseases.Paper V report the results from a questionnaire study which was carried out six months after the Eyjafjallajökull eruption. The study population comprised a cohort of south Icelanders exposed to the eruption to varying degrees and a reference group from north Iceland. Respiratory and eye symptoms were much more common in south Icelanders than in the reference group, after adjusting for demographic characteristics. Mental unhealth rates had declined considerably.In the studies, we found that urban air pollution and natural particles have short-term effects on anti-asthma medication dispensing and emergency room visits and hospital admissions. Exposure to natural particles in the form of volcanic dust was associated with increased respiratory symptoms in a very exposed population. There were indications that volcanic ash particles were associated with increased emergency hospital visits in the following days.
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| 2. |
- Andersson, John, 1979-
(author)
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Air pollution and dementia in a low exposure setting : the role of noise, olfaction, and theapoe gene
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Previous research indicates an association between air pollution exposure, and risk of dementia. Still, a number of factors that may play a role in this association remain to be explored. In addition, while most studies on air pollution and brain health have taken place in highly exposed large urban areas, the studies included in this thesis are conducted in an area with relatively low levels of air pollution and road traffic noise.The overall aim of this thesis is to investigate possible mechanisms - more specifically the role of noise, olfaction and the APOE-ε4 allele - in the association between air pollution and dementia, in a low exposure area. Because olfactory deficits have been linked to air pollution, and can be an early sign of dementia, an additional aim is to examine associations between exposure to air pollution and olfactory function.Methods: Participants were drawn from the Betula project – a prospective cohort study – in Umeå, Sweden. Modelled data on concentrations of nitrogenoxides (NOx), fine particle matter (PM2.5) and levels of road traffic noise, were matched with participants residential address at baseline. PM2.5 levels at the day of testing were obtained from a measuring station in the vicinity of the test location. Data on dementia diagnoses, APOE status, olfactory functions, and covariates, were drawn from the Betula project. Dementia assessment was primarily based on medical records, and conducted by a geropsychiatrist. Odor identification was assessed using the Scandinavian Odor Identification Test, and odor detection threshold by “sniffin’ sticks”. APOE genotype was determined by DNA analyses of blood samples.Study I. Where there is pollution, there is also often noise. In addition, exposure to noise can increase the risk of dementia. The aim of study I was to investigate the individual and combined effect of noise and air pollution on risk of dementia. The results showed an association between NOx and dementia. However, noise from road traffic did not contribute to this association.Study II. Olfactory deficits can be an early sign of dementia and might also becaused by air pollution. Olfactory receptor cells in the nasal cavity are exposed to inhaled air, and the olfactory bulb is one of the areas of the brain most affectedby air pollution. The APOE-ε4 allele is important to consider, as it is a risk factor for both dementia and declining olfactory functions. The aim of study II was to investigate the role of olfaction and the APOE-ε4 allele in the association between air pollution and dementia. Stratified analyses showed that associations between PM2.5 and dementia persisted only among APOE-ε4 carriers, and those with poor odor identification ability.Study III. The olfactory system may be vulnerable to air pollution, and olfactory dysfunction is an early sign of dementia. In addition, the moderating effect of odor identification ability found in study II, could be explained by air pollution increasing the risk of olfactory functions and dementia independent of each other. Thus, the aim of study III was to investigate the associations between PM2.5 (both long term exposure, and concentrations on the day of testing), and odor identification and detection. A positive association was observed between longterm air pollution exposure and odor identification ability. No association was found between long term air pollution exposure and odor detection, or between short term exposure and either olfactory outcome.Conclusion: Low levels of long-term exposure to air pollution increases the risk of dementia. APOE-ε4 carriers, and those with poor odor identification ability, seem particularly vulnerable. No residual confounding from road traffic noisewas found, suggesting that air pollution is the main component in the association between traffic related exposures and dementia in low-exposure areas. The positive association between air pollution and odor identification might be explained by socioeconomic status, and the links between olfaction and semantic memory.
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| 3. |
- Nyberg, Lars, 1966-, et al.
(author)
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Biological and environmental predictors of heterogeneity in neurocognitive ageing : Evidence from Betula and other longitudinal studies
- 2020
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In: Ageing Research Reviews. - : Elsevier. - 1568-1637 .- 1872-9649. ; 64
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Research review (peer-reviewed)abstract
- Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in aging by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive aging. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive aging.
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