Use of Medical Metered Dose Inhalers for Functionality Testing of Bioaerosol Detection and Identification Systems.

摘要

Fielded instrumental bioaerosol detection and identification systems must be periodically checked to ensure they are responsive. Variants of pressurized metered dose inhalers, referred to here as bioaerosol metered dose distributors (bioMDDs), are considered for this role. BioMDDs were filled with 1,1,1,2-tetrafluoroethane (HFA134a) propellant and an ethanol suspension of either fluorescently tagged polystyrene microspheres (PSLs) or simulants for pathogenic Bacillus anthracis spores. For PSLs or spore aerosols with geometric mean sizes of approximately 1 micron, the geometric standard deviations of aerosols are approximately 1.22-1.68 microns, but the aerosols are near-monodisperse for larger sizes (3 and 5 micron PSLs). Shot weight from the metering valves and aerosol dose are constant up to approximately 170 actuations, although the dose is much more variable. Devices prepared with PSLs have a useful shelf life of at least 9 months, and those prepared with biological spores have a shelf life of at least 1 year, provided they are refrigerated. BioMDDs were used to check the triggering of two UV bioaerosol detectors, and the results were favorable. The bioMDDs appear to be suitable for functionality testing but are not applicable to general calibration of field-deployed instruments. The devices may, however, be useful for checking particle-sizing devices such as optical particle counters.