Identification and Verification of Ultrafine Particle Affinity Zones in Urban Neighbourhoods / A Proof of Concept Proposal

Recent research has revealed that inhalation of particulate pollution in the atmosphere of British cities can cause or worsen a number of respiratory and cardiovascular conditions, even leading to an increase in the number of deaths amongst vulnerable persons on especially polluted days. Particulate pollution consists of a wide range of substances present in the air as suspended particles of a wide range of sizes. There is some evidence that the smallest particles, known as ultrafine particles (or UFP), are the most toxic, possibly irrespective of their chemical composition. It is believed that road vehicle emissions are the major source of UFP (although this is yet to be verified in the UK), although many cooking activities can also generate high concentrations. However, not everyone is affected in the same way and this will partly be due to the way that the concentration of UFP in the air is not uniform across a city, but varies enormously - not only between districts, but between local neighbourhoods and even from one street to another. Thus, the dose of UFP to the lungs of any one individual can be considerably different to any other individual depending upon not only exactly where they live, but also where they work or study and how they travel. In order to judge whether or not inhalation of UFP is genuinely causing ill health amongst the population it is necessary to find a way of assessing how much UFP different citizens (and especially vulnerable sub-groups) are exposed to. It is not practical to place UFP monitors in every home and workplace across a city. On the other hand, placing a single monitor in a fixed location within a conurbation so that it represents the exposure of everyone within that conurbation (as is done for some gaseous pollutants, such as sulphur dioxide) is not appropriate for UFP due to the high degree of variability in concentrations across an urban area. A third method / dispersion modelling / is not a viable option for UFP at present as it requires very detailed information on emission sources that we do not yet have. These shortcomings in our knowledge are preventing us from correctly quantifying the threat UFP poses public health and from developing and assessing any strategies to reduce this threat. Recent developments in measurement technology now present an opportunity to overcome this impasse. This proposal combines the expertise of three teams within the University of Manchester linking atmospheric measurements with Geographical Information Science (GISc) and environmental health researchers. Together, we have devised a programme of research in which we start to look at spatial variability in outdoor concentrations on a small scale (between adjacent streets) in residential neighbourhoods of Manchester. Measurements are made and spatial patterns in concentrations are related to variability in sources (such as traffic density) and to patterns describing the exposed population within that neighbourhood (such as the daytime population density). From this analysis we can define zones (at the neighbourhood scale) within which concentrations vary little. The remainder of the project is focussed upon experimentally comparing concentrations between these zones and gradually building up a picture of how and most importantly, why UFP concentrations vary across a large segment of the city of Manchester. Once complete, the project will have provided a foundation for subsequent research by allowing researchers to quantify the exposure of urban citizens with much more confidence than at present, and to site more sophisticated monitoring instrumentation at a small number of fixed locations, or a single one, with a much clearer understanding of how measurements at this one location can relate to exposure of citizens across a wide urban area.