Air Quality Modelling for Informing Air Pollution Policy

Managing air quality through emissions control entails significant societal benefits in Canada and around the world. As the public health impacts of emissions depend on the atmospheric conditions conducive to pollutant transport and transformation, sophisticated atmospheric models are necessary to link public health impacts with sources of emissions directly. This thesis develops a novel method to integrate health benefit assessment and formal sensitivity analysis tools. It employs a reverse sensitivity analysis technique, infused with epidemiological and economic data, to attribute air pollution health effects to emissions sources. This linkage creates a streamlined approach for assessing the damages incurred by anthropogenic emissions, and the benefits of their control, on a source-by-source basis. The findings presented in this thesis indicate that the public health benefits of emission controls vary considerably from source-to-source and by emitted species. A main feature of emission control benefits is their dependency on the composition of the atmosphere and hence on emission quantities. As the atmosphere becomes cleaner with progressive emission reduction policies, the benefits-per-ton of emissions control are likely to change, particularly for pollutants that undergo nonlinear transformations in the atmosphere. Further, the shape of the concentration-response function (CRF) between pollutant exposure and mortality plays a determining role in estimating these benefits. This thesis investigates how both atmospheric chemistry and assumptions about the CRF influence the health benefits of emission control. For secondary pollutants such as ozone, the benefits-per-ton of NOx control are found to increase substantially as the atmosphere becomes less polluted. For primary pollutants such as NO2, compounding benefits of NOx control exist due entirely to a supralinear CRF. The findings of this thesis indicate unforeseen and long-term benefits of emissions control, suggesting that current emission controls make future abatement efforts more worthwhile. Assessment of recent emission trends in North America indicates that we are currently at an important point on the abatement trajectory, where the benefits of emission controls have increased in the past and will do so considerably in the near future. Regard for the compounding nature of emission control benefits can cast abatement policies in a self-propagating, self-rewarding light in the long-term.