A Low Airflow Aerosol Generator for the Delivery of Respirable Aerosols

Abstract

ABSTRACT

A low airflow aerosol generator, the Pitt #4, was designed and constructed at the University of Pittsburgh for the delivery of respirable aerosols. This generator operates at an airflow rate of 1.5 - 2.0 L/min while still producing a concentrated aerosol. Characterization of the Pitt #4 was performed with polyethylene glycol-200, NaCl solutions and a radioactively labeled compound, platelet activating factor (PAF). A syringe pump operating at 0.6 mL/hr to 3 mL/hr was used to feed the liquid to the aerosol generator. Aerosol concentrations of polyethylene glycol-200 (270 to 1400 mg/m³) in a 200 mL chamber operated with an airflow of 2 L/min were obtained. The aerodynamic mass median diameter (AMMD) was 2.6 um with a geometric standard deviation (GSD) of 2.8. When fed with NaCl solutions resulting in concentrations from 10 to 267 mg/m³, an AMMD of 1.0 and 1.2 um with a GSD of 2.0 and 2.1 at the lowest and highest concentrations respectively, was produced. Solutions of C¹⁴-PAF resulting in airborne concentrations from 2 to 50 mg/m³ has an AMMD of 1.3 um with a GSD of 2.6. For an eight hour time course study with polyethylene glycol-200, the concentration remained stable with a deviation of less than +/− 10%. Since this generator is capable of producing aerosols using low airflow rates with good stability, it is ideal for use in toxicological or pharmacological studies where the material can be very expensive or available in small quantities or is highly toxic.