Background: Secondary inhalation of medical aerosols is a significant occupational hazard in both clinical and homecare settings. Exposure to fugitive emissions generated during aerosol therapy increases the risk of the unnecessary inhalation of medication, as well as toxic side effects. Methods: This study examines fugitively-emitted aerosol emissions when nebulising albuterol sulphate, as a tracer aerosol, using two commercially available nebulisers in combination with an open or valved facemask or using a mouthpiece with and without a filter on the exhalation port. Each combination was connected to a breathing simulator during simulated adult breathing. The inhaled dose and residual mass were quantified using UV spectrophotometry. Time-varying fugitively-emitted aerosol concentrations and size distributions during nebulisation were recorded using aerodynamic particle sizers at two distances relative to the simulated patient. Different aerosol concentrations and size distributions were observed depending on the interface. Results: Within each nebuliser, the facemask combination had the highest time-averaged fugitively-emitted aerosol concentration, and values up to 0.072 ± 0.001 mg m⁻³ were recorded. The placement of a filter on the exhalation port of the mouthpiece yielded the lowest recorded concentrations. The mass median aerodynamic diameter of the fugitively-emitted aerosol was recorded as 0.890 ± 0.044 µm, lower the initially generated medical aerosol in the range of 2–5 µm. Conclusions: The results highlight the potential secondary inhalation of exhaled aerosols from commercially available nebuliser facemask/mouthpiece combinations. The results will aid in developing approaches to inform policy and best practices for risk mitigation from fugitive emissions.

Background: Nebulised medical aerosols are designed to deliver drugs to the lungs to aid in the treatment of respiratory diseases. However, an unintended consequence is the potential for fugitive emissions during patient treatment, which may pose a risk factor in both clinical and homecare settings. Methods: The current study examined the potential for fugitive emissions, using albuterol sulphate as a tracer aerosol during high-flow therapy. A nasal cannula was connected to a head model or alternatively, a interface was connected to a tracheostomy tube in combination with a simulated adult and paediatric breathing profile. Two aerodynamic particle sizers (APS) recorded time-series aerosol concentrations and size distributions at two different distances relative to the simulated patient. Results: The results showed that the quantity and characteristics of the fugitive emissions were influenced by the interface type, patient type and supplemental gas-flow rate. There was a trend in the adult scenarios; as the flow rate increased, the fugitive emissions and the mass median aerodynamic diameter (MMAD) of the aerosol both decreased. The fugitive emissions were comparable when using the adult breathing profiles for the nasal cannula and tracheostomy interfaces; however, there was a noticeable distinction between the two interfaces when compared for the paediatric breathing profiles. The highest recorded aerosol concentration was 0.370 ± 0.046 mg m⁻³ from the tracheostomy interface during simulated paediatric breathing with a gas-flow rate of 20 L/min. The averaged MMAD across all combinations ranged from 1.248 to 1.793 µm by the APS at a distance of 0.8 m away from the patient interface. Conclusions: Overall, the results highlight the potential for secondary inhalation of fugitive emissions released during simulated aerosol treatment with concurrent high-flow therapy. The findings will help in developing policy and best practice for risk mitigation from fugitive emissions.

Background: During mechanical ventilation of a patient requiring ventilatory support bystanders could potentially be exposed to aerosolised drug. Methods: Fugitive drug aerosol emissions during simulated adult mechanical ventilation was assessed on a dual limb circuit. Tidal volume was set at 270 mL and 820 mL. The use of a protective filter on the exhalation port of the mechanical ventilator was assessed. Results: Higher fugitive aerosol mass concentrations in the local environment were associated with larger tidal volume (0.077 (0.073, 0.091) mg m-3 at Vt = 820 ml vs. 0.062 (0.056, 0.065) mg m-3 at Vt = 270 mL) when no protective filter was used. The range of mass median aerodynamic diameters recorded was from 0.93 to 2.96 µm. When a filter was placed on the exhalation port of the mechanical ventilator, no fugitive emissions were recorded. Conclusion: This study confirms that an appropriate filtration protocol mitigates the risk of fugitive emissions being released when patients undergo aerosol therapy during mechanical ventilation. A larger tidal volume resulted in higher fugitive aerosol mass.

Open circuit aerosol therapy is associated with the potential for fugitive emissions of medical aerosol. Various nebulisers and interfaces are used in respiratory treatments, including the recent consideration of filtered interfaces. This study aims to quantify fugitive medical aerosols from various nebuliser types, in conjunction with different filtered and non-filtered interfaces. For both simulated adult and paediatric breathing, four nebuliser types were assessed including; a small volume jet nebuliser (SVN), a breath enhanced jet nebuliser (BEN), a breath actuated jet nebuliser (BAN) and a vibrating mesh nebuliser (VMN). A combination of different interfaces were used including filtered and unfiltered mouthpieces, as well as open, valved and filtered facemasks. Aerosol mass concentrations were measured using an Aerodynamic Particle Sizer at 0.8 m and 2.0 m. Additionally, inhaled dose was assessed. Highest mass concentrations recorded were 214 (177, 262) µg m^-3 at 0.8 m over 45-minute run. The highest and lowest fugitive emissions were observed for the adult SVN facemask combination, and the adult BAN filtered mouthpiece combination respectively. Fugitive emissions decreased when using breath-actuated (BA) mode compared to continuous (CN) mode on the BAN for the adult and paediatric mouthpiece combination. Lower fugitive emissions were observed when a filtered facemask or mouthpiece was used, compared to unfiltered scenarios. For the simulated adult, highest and lowest inhaled dose were 45.1 (42.6, 45.6)% and 11.0 (10.1,11.9)% for the VMN and SVN respectively. For the simulated paediatric, highest and lowest inhaled dose were 44.0 (42.4, 44.8)% and 6.1 (5.9, 7.0)% for the VMN and BAN CN respectively. Potential inhalation exposure of albuterol was calculated to be up to 0.11 µg and 0.12 µg for a bystander and healthcare worker respectively. This work demonstrates the need for filtered interfaces in clinical and homecare settings to minimise fugitive emissions and to reduce the risk of secondary exposure to care givers.