Face Masks and Cough Etiquette Reduce the Cough Aerosol Concentration of Pseudomonas aeruginosa in People with Cystic Fibrosis

Am J Respir Crit Care Med. 2018 Feb 1;197(3):348-355. doi: 10.1164/rccm.201707-1457OC.


Rationale: People with cystic fibrosis (CF) generate Pseudomonas aeruginosa in droplet nuclei during coughing. The use of surgical masks has been recommended in healthcare settings to minimize pathogen transmission between patients with CF.

Objectives: To determine if face masks and cough etiquette reduce viable P. aeruginosa aerosolized during coughing.

Methods: Twenty-five adults with CF and chronic P. aeruginosa infection were recruited. Participants performed six talking and coughing maneuvers, with or without face masks (surgical and N95) and hand covering the mouth when coughing (cough etiquette) in an aerosol-sampling device. An Andersen Cascade Impactor was used to sample the aerosol at 2 meters from each participant. Quantitative sputum and aerosol bacterial cultures were performed, and participants rated the mask comfort levels during the cough maneuvers.

Measurements and main results: During uncovered coughing (reference maneuver), 19 of 25 (76%) participants produced aerosols containing P. aeruginosa, with a positive correlation found between sputum P. aeruginosa concentration (measured as cfu/ml) and aerosol P. aeruginosa colony-forming units. There was a reduction in aerosol P. aeruginosa load during coughing with a surgical mask, coughing with an N95 mask, and cough etiquette compared with uncovered coughing (P < 0.001). A similar reduction in total colony-forming units was observed for both masks during coughing; yet, participants rated the surgical masks as more comfortable (P = 0.013). Cough etiquette provided approximately half the reduction of viable aerosols of the mask interventions during voluntary coughing. Talking was a low viable aerosol-producing activity.

Conclusions: Face masks reduce cough-generated P. aeruginosa aerosols, with the surgical mask providing enhanced comfort. Cough etiquette was less effective at reducing viable aerosols.

Keywords: N95 mask; cough etiquette; cystic fibrosis; infection control; surgical mask.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Australia
  • Cohort Studies
  • Cough / microbiology*
  • Cystic Fibrosis / microbiology*
  • Disease Transmission, Infectious / prevention & control
  • Female
  • Humans
  • Inhalation Exposure / prevention & control*
  • Male
  • Masks*
  • Pseudomonas Infections / prevention & control*
  • Pseudomonas Infections / transmission
  • Pseudomonas aeruginosa / isolation & purification*
  • Reference Values