Estimation of inhaled ultrafine particle surface area dose in urban environments

The UPTECH (Ultrafine Particles from Traffic Emissions and Children’s Health) project aims to link air quality indicators to child respiratory health outcomes across 25 primary schools in the Brisbane Metropolitan Area. The study involves collection of a diverse set of data at each school, including characterisation of ambient gaseous and particulate matter, microbiological agents, chemical speciation of pollutants, as well as a range of health diagnostics, personal 24 hour ultrafine particle exposure using Philips Aerasense Nanotracer, daily activity diary and a health history and demographics questionnaire from participating school children aged 8-111 years old. Data collection was performed continuously for two weeks at each school, and at one school at a time. Here we present a set of Bayesian statistical models developed to estimate the inhaled particle surface area dose from the collected personal exposure within UPTECH. Analysis of the exposures and daily activity diaries identified eight distinct microenvironments were conducted with the Philips Aerasense Nanotracer for the measured 24 hour time series of particle number concentration and mean particle diameter for each of 89 participating students. The particle size distributions of inhaled particles were estimated based on the methodologies presented in previous studies and a dose model developed which accounts for the uncertainty in the estimated particle size distributions. Comparisons of total inhaled dose between and within schools were made with Bayesian hierarchical linear models.