We investigated the effects of long-term air pollution exposure on public health in Scotland, focusing on the 4 major urban areas, Aberdeen, Dundee, Edinburgh, and Glasgow. In particular, the associations between respiratory hospital admissions in 2005 and exposure to both PM10 and NO2 between 2002 and 2004 are estimated using a small-area ecological design. The results showed that long-term exposures (over 3 years) to PM10 and NO2 were significantly associated with respiratory hospital admissions in Edinburgh and Glasgow, whereas the risks for Aberdeen and Dundee were generally positive but non-significant.
This work led to a follow up paper that addressed why the effects of air pollution were different across the four cities. Our modeling approach is based on the premise that these differences are due to differences in exposure levels and population vulnerability across the four cities. We propose a penalised spline model for estimating these spatially-varying health risks, which allows the pollution-health relationship to depend on additional risk factors.