2.3. Integration of models and validation
Four data sources are used to predict personal exposure to BC: individual whereabouts from FEATHERS, hourly LUR models, an in-traffic personal exposure model, and an indoor air model (Fig. 1). Minute-to-minute personal exposure is then modeled as a combination of two interacting geographies: the lifeline of an individual and a constantly changing air quality. When agents are traveling, the in-traffic exposure model is applied taking into account transport mode, timing, location and duration of the trip. For touring activities, the in-traffic exposure model for active modes is used (these are activities where people are in transport but without a specific destination and with the same start and end point). The activity-based model is not specifically built for air pollution exposure assessment: for example there is no formal distinction between indoor and outdoor activities and trips by public transport are grouped in one category (although concentrations inside buses are a factor 2-3 higher than exposure in trains). As a simplification, all activities are assumed to be indoors except for travel.
Dynamic exposure is calculated making full use of the AB2C model, i.e. by including population mobility. The FEATHERS model simulates one diary for every agent in the population, for every day of the week, and the AB2C model can calculate exposures from these data.