Respiratory dose of inhaled ultrafine particles in healthy adults

Abstract
Ultrafine particles (less than 0.10 μm in diameter) are ubiquitous in the atmosphere and possess unique physicochemical characteristics that may pose a potential health risk. To help elucidate the potential health risk, we measured respiratory dose of ultrafine particles (0.04, 0.06, 0.08 and 0.10 μm in diameter) in healthy young adults using a novel serial bolus–delivery method. Under normal breathing conditions (i.e. tidal volume of 500 ml and respiratory flow rate of 250 ml s−1), bolus aerosols were delivered sequentially to a lung depth ranging from 50–500 ml in 50 ml increments and deposition was measured for each of ten equal–volume compartments.