The role of particle size in aerosolised pathogen transmission: a review.

Understanding respiratory pathogen transmission is essential for public health measures aimed at reducing pathogen spread. Particle generation and size are key determinants for pathogen carriage, aerosolisation, and transmission. Production of infectious respiratory particles is dependent on the type and frequency of respiratory activity, type and site of infection and pathogen load. Further, relative humidity, particle aggregation and mucus properties influence expelled particle size and subsequent transmission. Review of 26 studies reporting particle sizes generated from breathing, coughing, sneezing and talking showed healthy individuals generate particles between 0.01 and 500 ìm, and individuals with infections produce particles between 0.05 and 500 ìm. This indicates that expelled particles carrying pathogens do not exclusively disperse by airborne or droplet transmissions but avail of both methods simultaneously and current dichotomous infection control precautions should be updated to include measures to contain both modes of aerosolised transmission. Journal of Infection. 2011;62(1):1-13. Epub 2010 Nov 19.