published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

A most important aspect of effects of air pollutants on air quality is their impact upon visibility. As far as can be determined this is the first visibility study performed in the UK in which the influence of individual pollutants, the local microclimate and the long range transport of air pollutants have been simultaneously examined over the whole visibility range. Techniques were developed to analyse the influence of the relative humidity on the light scattering efficiency of hygroscopic particles, and to examine their nature and size distributions. A regression model that specifically included the influence of hygroscopic particles and the relative humidity accounted for over 80% of the total variance in visibility, and showed that over 50% of the visibility degradation was due solely to the presence of sulphate particles. The constant of the regression implied a background visibility of over 60km for Teesside, whereas a mean of 12km was recorded. Original results were obtained by examining the relationship of atmospheric stability and thermal structure to visibility and pollutant behaviour using an acoustic sounder. This was used to investigate the conditions created by the local sea breeze which was associated with a substantial proportion of the summertime hazes. Wind rose analysis of the role played by emissions from Teesside industries together with comparisons of visibility levels at nearby locations showed that 20-40% of the light extinction was due to local factors. An airstream categorisation scheme was developed to study the role of long range transport of air pollutants and other influences on visibility. The study was extended across the British Isles to produce convincing evidence of large scale visibility degradation, due principally to sulphates derived from sulphur dioxide emissions, from sources as distant as 1500km. At Teesside the elimination of local air pollutant emissions would result in a significant but limited visibility improvement. A most effective means of controlling visibility degradation would be the reduction of sulphur dioxide emission to the atmosphere on an international scale. The resulting improvement in the visibility levels experienced at Teesside and in the UK in general would be in the order of 100% or more.

The effects of air pollutants CO, NO₂, O₃, PM₁₀ and SO₂ on congenital heart anomalies are represented by the odds ratio of each disease per unit increase in the concentration of each pollutant. In this study, the effects of air pollutants are summarized using multivariate GLS approach with correlation between outcomes being taken into account, where the correlations are sampled from uniform [-1,1]. Meta-analysis conducted here found no statistically significant increase in odds ratio of any disease. This result is different from what Vrijheid et al. 2011 suggested when correlation is not considered using the same set of data. The difference in conclusions from the two meta-analysis indicate that correlation between outcomes may play an important role when synthesizing effect sizes. Thus, before conduct meta-analysis, a thorough consideration about whether to incorporate the correlation in synthesizing should be given. / text

The past twenty years of research that has associated air pollution with health outcomes has brought remarkable advance in statistical techniques that effectively tease out the intricacies of the relationship. However, while statistical techniques progressed, an assumption based on seminal work in the field persisted: that concentrations of particulate matter (PM) air pollution are spatially homogeneous within urban areas, and consequently, that personal exposures could be based on central monitoring site data alone. Although this assumption went unaddressed for years, it has now come to researchers' attention that it may be flawed and that the assumption may induce exposure misclassification error under certain conditions. This thesis explores intraurban spatial variability in PM through a systematic review of the literature, experimental field testing, modelling, and new methodological approaches. The key outcomes of the thesis are as follows: (i) the publication of the first systematic review of the intraurban particulate literature, challenging the widely-held assumption that PM concentrations are spatially uniform; (ii) an experimental test was conducted in Christchurch, New Zealand, revealing that the homogenous assumption was false for a city with high wintertime particulate matter concentrations; (iii) an integrated meteorological-emission model was evaluated for the first time at the intraurban level for PM and a new study design was suggested; and (iv) the spatial modification effect of social and ecological confounders was analysed with respect to respiratory hospital admissions and PM. Collectively, these outcomes provide a new body of knowledge informing researchers focused on assessing the relationship between air pollution and health in applications ranging from small-area exposure assessment to the wider field of environmental epidemiology.