Urban aerosol size distributions: a global perspective

Abstract. Urban aerosol measurements are necessary to establish associations between air pollution and human health outcomes evaluate the efficacy of quality legislation emissions standards. The measurement urban particle size distributions (PSDs) is particular importance as they enable characterization size-dependent processes that govern a particle's transport, transformation, fate in atmosphere. PSDs also improve our ability link effects through evaluation deposition respiratory system inhalation toxicity. To inform future observations, this paper reviews critically analyzes current state knowledge on PSD by synthesizing 737 observations made 1998 2017 114 cities 43 countries around globe. Significant variations shape magnitude number mass were identified among different geographical regions. In general, Europe (EU) North America, Australia, New Zealand (NAAN) dominated nucleation- Aitken-mode particles. Central, South, Southeast Asia (CSSA) East (EA) shifted larger sizes, with meaningful contribution from accumulation mode. typically bimodal, presenting dominant mode secondary coarse Most published literature short-term, only 14 % providing data for longer than 6 months. There paucity measured Africa (AF), CSSA, Latin America (LA), West (WA), demonstrating need long-term across wide ranges many Geographical effective densities reviewed. Size-resolved density functions 3 10 000 nm established regions intra-city sampling locations order accurately translate PSDs, significant observed near-road background sites. results study demonstrate global initiatives urgently needed develop infrastructure routine monitoring spanning nucleation Doing so will advance understanding spatiotemporal trends throughout world provide foundation more reliably elucidate impact aerosols atmospheric processes, health, climate.