Summary

The design and operation features of two prevalent nebuliser technologies which are in clinical use today were assessed for their emission of exhaled aerosols. Vibrating mesh/jet nebuliser and facemask/mouthpiece are examples of aerosol generators and non-invasive ventilatory support. This study investigated the effect of these in terms of quantities of secondary aerosol mass concentrations emitted at varying distances (0.8 m & 2.2 m).

The characterisation of exhaled aerosol emissions for two combinations of commercially available aerosol generators and non-invasive ventilation interfaces was investigated. Mass & number concentrations, and size distribution of the airborne particles were continuously measured in real time at different distances relative to a simulated patient.

Results: The VMN/filtered mouthpiece was found to emit the lowest mass concentration over time (0.00441 mg m^‑3 at 0.8 m & 0.00436 mg m^-3 at 2.2 m). The JN/open facemask emitted the highest mass concentrations (mg m^-3) at both distances. For 0.8 m the JN/open facemask facilitated a near two fold higher emitted mass concentration (mg m^-3) compared with the VMN/valved facemask (0.048 vs 0.025 mg m^-3), near fivefold higher compared with the JN/filtered mouthpiece (0.048 vs 0.00980 mg m^-3) & tenfold higher compared with the VMN/filtered mouthpiece (0.048 vs 0.00441 mg m^-3).

This study successfully demonstrated the obvious escape of aerosol to the environment and further established the risk to caregivers and other bystanders during the course of a standard nebuliser treatment.