New Cross Centre publication - Analysing the health effects of simultaneous exposure to physical and chemical properties of airborne particles

Analysing the health effects of simultaneous exposure to physical and chemical properties of airborne particles There is a clear policy need for research to determine which components and/or sources of the airborne particle mix are driving the observed health effects. The traditional statistical models allow for one or two particulate components to be compared to health outcomes but do not account for the constantly changing mixture of particulate we are exposed to.

A new paper published by investigators across the Centre takes a novel approach to this problem. Instead of looking at different parts of the particle mix, the study looked for similarities; grouping days according to the mixtures of particles that Londoners were exposure to. Importantly the numbers of respiratory deaths was also included in the grouping process, having controlled for known mortality effects such as temperature. Between 2001 and 2005 three different 'types' of day were found. Days with high concentrations of non-primary particles especially sulphate and nitrate were associated with a 2% increase in respiratory deaths. These days were mainly during the spring and autumn, similar in nature to this month's episode. A particulate mixture view such as this could have an important role in health impact analysis of polices to improve air pollution. Between 2005 and 2012, London’s particulate mix changed as a consequence of decreases in regional non-primary PM (mainly secondary sulphate) and changes to the sulphur content of fuel rather than London specific policies. Using this new approach, and comparing the pollution mixture in 2005 to 2012; a 3.5 % reduction in respiratory mortality was predicted; equivalent to around 270 people. http://www.sciencedirect.com/science/article/pii/S0160412015000379 The author, Monica Pirani was a Centre funded student at Imperial College and King's College London.

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