Professional and home-made face masks reduce exposure to respiratory infections among the general population.
BACKGROUND
Governments are preparing for a potential influenza pandemic. Therefore they need data to assess the possible impact of interventions. Face-masks worn by the general population could be an accessible and affordable intervention, if effective when worn under routine circumstances.


METHODS
We assessed transmission reduction potential provided by personal respirators, surgical masks and home-made masks when worn during a variety of activities by healthy volunteers and a simulated patient.


RESULTS
All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks. Regardless of mask type, children were less well protected. Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by healthy volunteers).


CONCLUSIONS
Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection. Masks worn by patients may not offer as great a degree of protection against aerosol transmission.
van der Sande
Marianne
M
National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands. marianne.van.der.sande@rivm.nl
Teunis
Peter
P
Sabel
Rob
R
D000328:Adult; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D017053:Infection Control; D017757:Infectious Disease Transmission, Professional-to-Patient / Q000517:prevention & control; D007251:Influenza, Human / Q000517:prevention & control* / Q000635:transmission; D019570:Inhalation Exposure / Q000517:prevention & control; D008297:Male; D008397:Masks; D008422:Materials Testing / Q000592:standards; D016273:Occupational Exposure / Q000517:prevention & control; D044382:Population Groups; D012134:Respiratory Protective Devices