Abstract
Background: The effectiveness of recommended measures, such as “cover your mouth when coughing”, in
disrupting the chain of transmission of infectious respiratory diseases (IRD) has been questioned. The objective
of the current study was to determine the effectiveness of simple primary respiratory hygiene/cough etiquette
maneuvers in blocking droplets expelled as aerosol during coughing.
Method: In this study, 31 healthy non-smokers performed cough etiquette maneuvers in an effort to cover their
voluntarily elicited best effort coughs in an open bench format. A laser diffraction system was used to obtain
accurate, non-invasive, quantitative, real time measurements of the size and number of droplets emitted during the
assessed cough etiquette maneuvers.
Results: Recommended cough etiquette maneuvers did not block the release and dispersion of a variety of
different diameter droplets to the surrounding environment. Droplets smaller than one-micron size dominate the
total number of droplets leaked when practicing assessed maneuvers.
Conclusions: All the assessed cough etiquette maneuvers, performed as recommended, do not block droplets
expelled as aerosol when coughing. This aerosol can penetrate profound levels of the respiratory system. Practicing
these assessed primary respiratory hygiene/cough etiquette maneuvers would still permit direct, indirect, and/or
airborne transmission and spread of IRD, such as influenza and Tuberculosis. All the assessed cough etiquette
maneuvers, as recommended, do not fully interrupt the chain of transmission of IRD. This knowledge urges us all to
critically review recommended CE and to search for new evidence-based procedures that effectively disrupt the
transmission of respiratory pathogens. Interrupting the chain of transmission of IRD will optimize the protection of
first responders, paramedics, nurses, and doctors working in triage sites, emergency rooms, intensive care units, and
the general public against cough-droplet-spread diseases.