New directions : 1 Airborne ultrafine particle dust from building activities – a source in need of 2 quantification 3

Urban infrastructure, such as bridges, roads and buildings, is constructed from a complex 16 mixture of construction materials including concrete, metals, ceramics and plastics. The 17 creation and operation of this infrastructure requires building activities (referring here to 18 construction, refurbishment, demolition and recycling) over the life cycle of individual assets. 19 Such building–related activities are recognised as important but poorly quantified sources of 20 coarse particles (i.e. ≤10 μm, PM10). However, far less attention has been paid to associated 21 emissions of fine (i.e. ≤2.5 μm, PM2.5) and ultrafine particles (UFP; <100 nm in diameter). In 22 fact, it remains largely unknown whether these activities also cause the unintended release of 23 UFPs. As a consequence the focus of this article is limited to the UFP fraction arising from 24 building activities both due to length constraints and the lack of published information 25 compared with larger size fractions. This should not distract from the fact that investigation 26 of the release and exposure to both the coarse and fine fractions of particles from building 27 activities are important and worthy of investigation. In seeking to address this under explored 28 topic preliminary evidence of UFP dust release during the processing of concrete materials is 29 presented and the importance of such emissions and associated exposure discussed. The need 30 for risk assessment and management strategies is also examined and some of the research 31 gaps highlighted. The term „UFP dust‟ is used throughout this article to refer to the UFP 32 produced from the building activities to make them distinct from those arising from 33 combustion or other engineered processes (Kumar et al., 2010). 34