EXPOSURE ASSESSMENT PAG MEETING, 14/07/2003 SURREY UNIVERSITY

Determinants of exposure - apply to determinants of temporal variability in exposure averaged over a population, as well as variation of time-averaged exposure across population

Exposure Volunteers!

Typical Timings

Exposure Routes Route 1 : Marylebone Road, heavily trafficked Route 2 : back streets with crossings of Marylebone Road Digital Data © Geoinformation Group (2002)

Equipment CO T15 Langan - Measures carbon monoxide every 10 seconds Casella Ultraflow Pump + Filter - average PM 2.5 conc. TSI P-Trak - Measures ultrafine particles every second

Modes of Transport: People Power - Walking & Cycling

Mechanical Transport – Car, Bus & Taxi

Walking & Cycling Routes 1 & 2, 06/05/03 a.m. (40-minute journeys) Peaks crossing Marylebone Rd, otherwise in general 25% less pollution in backstreets People walking along Marylebone Rd experience peak particulate pollution approx 50% less than those cycling

Measurements to understand determinants of exposure in more detail Speciated measurements (PM 2.5 and VOCs) Spatial variability over a common averaging time, including indoor/outdoor ratios Time-series at a fixed point Measurement of sensitivity to parameters that can be controlled Visualisation of relationship between exposure and activity

Elemental carbon Each PM 2.5 filter, in addition to weighing for total mass, has reflectance measured Paired samples for reflectance and laboratory analysis exposed at variety of representative fixed locations, with Quartz filters sent for laboratory analysis for elemental carbon Awaiting results from lab, but quality check has discovered correction factor to apply to mass on PTFE filters Elemental carbon shows more spatial variability than total mass

Indoor (WCC) / Outdoor Variations in indoor and outdoor particulates and VOCs between: WCC rooms on different levels; and with different aspects 2 MSc projects

Summary of preliminary VOC measurements (BRE) Outdoor spatial variability greater than limited measurement of temporal variability Different speciation indoors to outdoors, especially in one room obviously strongly dominated by indoor sources Is indoor temporal variability greater than street canyon temporal variability? What are the implications of this for using outdoor background measurements as a surrogate for exposure?

Stationary Exp – Waiting at Crossing 22 May 03 Adults waiting on the pavement are exposed to over 50% less particulate matter than if waiting in the central reservation – cyclical nature with traffic lights. Children would be receiving a higher dose due to their proximity to the pollution source.

Visualisation Health & Safety Lab, Sheffield Video camera deployed with PTraks which can be incorporated via newvizcd visualisation software