The Effect of Temperature, Humidity, Wind Speed, and UV-Light on the Recovery of Aerosolized Influenza Virus
Methods: Influenza A virus (A/WS/33 H1N1) was aerosolized via nebulizer (droplet nuclei) and airbrush (droplet nuclei/droplet mix). Virus was collected through a mannequin head into a breathing bag of an artificial lung system filled with virus transport media. During emission virus was exposed to varying environmental conditions: (1) indoor (20oC; 40%RH); (2) winter (6oC; 35%RH); and (3) summer (34oC; 77%RH). Within each condition, directed air flow (low: 137ft/sec, high: 154ft/sec) and exposure to UV-C light (low dose: 18W; high dose: 36W) was applied. Quantitative virus detection was performed via plaque assay in MDCK cell cultures.
Results: With indoor set as standard, winter reduced virus recovery by 44% (p=0.01) in droplet nuclei and increased recovery, though not significantly (12%, p=0.58) in droplet nuclei/droplet mix. Summer decreased recovery by 64% in droplet nuclei (p=0.0001) and 11% in droplet nuclei/droplet mix (p=0.67). Within each condition, increased air flow led to a reduction in droplet nuclei (p<0.0001). There was indication that increased air flow may improve recovery across all conditions for droplet nuclei/droplet mix (p=0.09). Application of low dose UV-C resulted in a >98% reduction for droplet nuclei across all conditions (p<0.0001). For droplet nuclei/droplet mix, low dose UV-C had no effect across all conditions (p=0.35), but high dose UV-C decreased droplet nuclei/droplet mix (p=0.0019).
Conclusion: Indoor conditions most effectively supported the potential for airborne Influenza transmission by small particles (droplet nuclei). However, winter shifted virus recovery to large particles making droplet transmission more likely. Summer decreased both, small and large particles. Within each condition, directed airflow reduced small particle collection by dilution, while increasing larger particle recovery by acceleration towards the collection point. UV-C light reduced virus recovery with the smallest impact observed in large particles.
A. Anderson, None
J. Stehle Jr., None