|Author, year||Study Design||Level of Evidence||Subjects (n)||Study Groups||Study outcomes||Conclusion||Directness of evidence|
|Tseng, 2014 ||Experimental study||N/A||15||Healthy subjects||Bacterial contamination of atomizer nozzle tip (bacterial cultures).||1. 18 out of 30 samples (60%) were positive for bacterial growth at the atomizer tip.|
2. During the spray process, aerosols were noted traveling backwards through the reversed jet flow and attaching to the nozzle tip, contaminating the tip.