INTRODUCTION: Nebulizer treatments can create aerosolized spread of highly-contagious airborne viruses (eg, COVID-19). With increased risk of aerosolized spread within confined ambulance compartments, this study specifically evaluated a specially-designed nebulizer mask modified with expiratory-port filters and a sealing faceplate to minimize fugitive bio-aerosol emissions (FBAE). METHODS: As FBAE carrying contagious viruses typically range from 0.5 to 1.5 micron (μ), a 6-port (0.3-10μ) Kanomax 3889 particle measurement (PM) counter was placed 78 cm from each of 15 rotating adult volunteers (non-patients;beardless;7 women, 8 men;ages 18-59 yrs) sitting upright in one of 3 rotating fleet ambulances using the EMS agency's usual jet-nebulizers on day 1 with either a conventional mask (CM) or an aerosol-controlling mask (ACM). Each person returned on another day using the other mask as indicated. Ambient ambulance PMs (PMamb) were sampled before subjects entered. After re-closing the door and waiting 5 mins, a pre-nebulization PM (preNeb-PM) was made. Jet-nebulizers (using H2O solutions) were then applied (either by CM or ACM) for 5 min followed by post-neb PMs (Post1) and 2 successive PMs (Post2/Post 3), all 5 mins apart, with masks remaining in place. RESULTS: After “treatment”, mean 1μ CM PMs (Post1CM) were 152.2-fold larger (p=0.001) than mean 1μ ACM PMs (Post1ACM), remaining 49.6-fold (p=0.005) and 7.2-fold (p=0.006) larger at Post2 and Post3 readings. PMamb and preNeb-PM were all similar (NSD) for both ACM and CM across all PM sizes (0.5, 1.0, 3.0 μ) including 1μ ACM preNeb-PMs of 6,977/cf vs. 5.683/cf for CM preNeb-PMs (NSD). While mean 1μ Post1ACM readings decreased (-31.7%) from ACM pre-Neb-PM (6,977 to 4,662/cf;p=0.002), the 1μ Post1CM readings rose 14,500.1% (5,683 to 700,549.93/cf;p=0.002) with corresponding elevations for 0.5μ (p=0.001) and 3μ (p=0.002) particles using CM. Of additional note, ACMs were uniformly well-tolerated over the 15 mins being worn. CONCLUSION: Compared to conventional methods, a modified mask system designed specifically to limit aerosolization of inhaled solutions did provide profound control of fugitive aerosolized particle emissions during nebulizer applications. The findings indicate a much safer approach to treating COVID-19 patients and all others requiring nebulization.
Controlling potentially infectious fugitive bioaerosol emissions during nebulizer treatments