Analysis of the relationship between urban background air pollution concentrations and the personal exposure of office workers in Dublin, Ireland, using baseline separation techniques

Real–time concentrations of PM10 were monitored over a 24 hour period for a number of different subjects as part of an investigation to examine the influence of daily activities and locations on the personal exposure of city centre office workers to air pollution. The resulting data comprised time series plots consisting of a series of peaks and troughs as a result of exposure to the differing sources of particulate matter subjects were encountering as well as the underlying background concentration. In order to separate the background concentration component from the data a number of baseflow separation techniques were employed, commonly used in stream–flow hydrology. Filter separation and frequency analysis techniques were examined comparing their predictions of background concentration with urban background concentration measurements for reference. The results of this investigation highlight a number of different approaches to separating background concentration from real–time personal exposure data. These methods will enable further investigation of purely activity and location based personal exposures as well as improvements in the numerical modelling of air pollution exposure in future. The results of this investigation also demonstrate a novel synergy in methods of analysis between the fields of air pollution and hydrology.