Detection of particles within the nasal airways during respiration

This study introduces a new experimental set-up for particle detection with in the nasal airways and describes intranasal deposition of particles at va rious regions of the nasal cavity and the nasopharynx. During respiration o f an aerosol of starch particles the nondeposited particles in the air were detected in 11 volunteers by a transnasally placed suction probe at numero us sites of the nasal cavity and nasopharynx. Another, identical suction pr obe measured the initial number of inhaled particles at the nostril. The tw o suction probes were connected to two identical laser particle counters an d allowed calculation of particle deposition. Particles 1-3 mum in size wer e deposited to about 60% within the entire nasal cavity, whereas most of th e particles 4-30 mum in size were deposited within the entire nasal cavity. Between 80% and 90% of the particles retained in the nasal cavity were dep osited at the anterior nasal segment. Studies on deposition of various drug s within the nasal cavity using this experimental set-up are conceivable.