EXPOSURE OF CHILDREN TO ULTRAFINE PARTICLES AROUND AN URBAN INTERSECTION S Kaur, M J Nieuwenhuijsen & R Colvile Environmental Processes & Systems Research Group, Department of Environmental Science & Technology (South Kensington Campus), Faculty of Life Sciences, Imperial College London, UK Further information: surbjit.kaur1@imperial.ac.uk, www.dapple.org.uk BACKGROUND Advances in recent research have highlighted ultrafine particles to have a high potential to cause adverse health effects. This has important implications on the exposure of children, especially those with asthmatic symptoms and other predisposed susceptibilities (Pekkanen et al, 1997). Few studies have investigated the exposure of individuals around urban environments to ultrafine particles in the UK, particularly that of children. This poster presents the initial results for the ultrafine particle count measurements made during the 2003 DAPPLE* field campaign in Central London, and their application to children’s exposure assessment. RESULTS The typical trends observed in the ultrafine particle count (time-series) data for different modes of transport and routes are shown in Fig. 3. The analysis of the time series data is ongoing – assisted by the exposure visualisation technique (Fig. 4) developed by the Health & Safety Laboratory (Walsh et al, 2000) and detailed transcripts. Figure 4 General data analysis (Table 1) indicates the mean ultrafine particle count exposure to vary through the day. The mean ultrafine particle count exposure was higher on the Marylebone Road circuit in comparison to the back-street circuit irrespective of timing and mode of transport. Examination of the mean exposures for only the different modes of transport revealed the mean ultrafine particle count exposure to be the lowest when walking, slightly higher in the car and taxi, and highest in the bus. STUDY DESCRIPTION As a part of the DAPPLE* field campaign in Spring 2003, centred around the intersection of Marylebone Road and Gloucester Place in Central London (Fig. 1), groups of four volunteers collected data on the exposure to ultrafine particle counts (particle size range: 0.02 to > 1m) at 1-second resolution using P-Traks (TSI) (Fig. 2) to obtain a better understanding of children’s exposure to ultrafine particles around a street canyon intersection. Although the volunteers were adults, the equipment was held at Table 1 average children’s heights for 5 years and under. Measurements were made at three times of day, on four modes of transport and on two routes (Fig. 1). Figure 2 Peak exposures up to 500000 pt/cc experienced by children crossing major roads in London Conflict between local journeys made on foot by children and car users driving through local areas is a significant children’s health issue in many parts of large cities Buses used by children in large numbers to travel to and from school Peak exposures to ultrafine particles occur when the bus stops for passengers to alight and embark, or when it stops in congested traffic CONCLUSION The results indicate a variation in children’s exposure within and between transport modes, timings and routes. Future analysis of the complete DAPPLE measurements, including meteorological and traffic measurements, using empirical and deterministic modelling, will identify the determinants and cause of children’s exposure to ultrafine particles in city centre transport and roadside microenvironments. Figure 3 ACKNOWLEDGEMENTS *DAPPLE is a 4-year UK Engineering and Physical Science Research Council funded project that brings together a multidisciplinary research group, from six universities (Bristol, Cambridge, Imperial College London, Leeds, Reading & Surrey), whose aim is to enhance understanding of events from emission to exposure for air pollution in the urban environment. REFERENCES Pekkanen J, Timonen K L, Ruuskanen J, Reponen A & Mirme A (1997) Effects of Ultrafine and Fine Particles in Urban Air on Peak Expiratory Flow among Children with Asthmatic Symptoms. Env. Res. 74: (1) 24-33 Walsh P, Clark R, Flaherty S, Gentry S (2000) Computer-aided Video Exposure Monitoring. Appl. Occup. Environ. Hyg. 15: (1) 48-56.