The World Health Organization (WHO) has published a global technical consultation report introducing updated terminology for “pathogens that transmit through the air”.
- The pathogens covered include those that cause respiratory infections, e.g. COVID-19, influenza, measles, Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), and tuberculosis, among others.
- The phrase “transmission through the air” can be used to describe when infectious respiratory particles become airborne and spread, and the subcategories of “airborne transmission” and “direct deposition” can both fall under this blanket phrase.
Infectious respiratory particles
- Individuals infected with a respiratory pathogen can generate and expel infectious particles containing the pathogen, through their mouth or nose by breathing, talking, singing, spitting, coughing or sneezing. These particles should be described with the term ‘infectious respiratory particles’ or IRPs.
- IRPs exist on a continuous spectrum of sizes, and no single cut off points should be applied to distinguish smaller from larger particles.
Airborne transmission or inhalation
- “Airborne transmission or inhalation” sub-category is for cases when IRPs are expelled into the air and inhaled by another person.
Direct deposition
- Direct deposition sub-category is for cases when IRPs are expelled into the air from an infectious person, and are then directly deposited on the exposed mouth, nose or eyes of another person nearby, then entering the human respiratory system and potentially causing infection.
