2014 the Partner Organisations. We introduce an approach that enables continuous monitoring of airborne nanoparticles by online detection and quantification of the collected species. Our method uniquely combines ultra-high flow rate sampling (up to thousands of liters per minute) with sensitive detection based on localized fluorescent complexation, permitting rapid quantitative measurement of airborne nanoparticle concentration. By coupling these components, we show initial results demonstrating detection of airborne ultrafine Al2O3 nanoparticles at environmental concentrations below 200 g m-3 in air sampled at 200 L min-1. This capability suggests potential for online monitoring, making it possible to establish dynamic exposure profiles not readily obtainable using current-generation personal sampling instruments. The underlying fluorescent complexation interactions are inherently size and composition dependent, offering potential to straightforwardly obtain continuous detailed characterization.