Toward Understanding the Risk of Secondary Airborne Infection: Emission of Respirable Pathogens
By M. Nicas, William W. Nazaroff, Alan E. Hubbard. Journal of Occupational and Environmental Hygiene, 2005
905 citations recorded by the source corpus.
Certain respiratory tract infections are transmitted through air. Coughing and sneezing by an infected person can emit pathogen-containing particles with diameters less than 10 μ m that can reach the alveolar region. Based on our analysis of the sparse literature on respiratory aerosols, we estimated that emitted particles quickly decrease in diameter due to water loss to one-half the initial values, and that in one cough the volume in particles with initial diameters less than 20 μ m is 6 × 10− 8 mL. The pathogen emission rate from a source case depends on the frequency of expiratory events, the respirable particle volume, and the pathogen concentration in respiratory fluid. Viable airborne pathogens are removed by exhaust ventilation, particle settling, die-off, and air disinfection methods; each removal mechanism can be assigned a first-order rate constant. The pathogen concentration in well-mixed room air depends on the emission rate, the size distribution of respirable particles carrying pathogens, and the removal rate constants. The particle settling rate and the alveolar deposition fraction depend on particle size. Given these inputs plus a susceptible person's breathing rate and exposure duration to room air, an expected alveolar dose μ is estimated. If the infectious dose is one organism, as appears to be true for tuberculosis, infection risk is estimated by the expression: R = 1 − exp(−μ). Using published tuberculosis data concerning cough frequency, bacilli concentration in respiratory fluid, and die-off rate, we illustrate the model via a plausible scenario for a person visiting the room of a pulmonary tuberculosis case. We suggest that patients termed “superspreaders” or “dangerous disseminators” are those infrequently encountered persons with high values of cough and/or sneeze frequency, elevated pathogen concentration in respiratory fluid, and/or increased respirable aerosol volume per expiratory event such that their pathogen emission rate is much higher than average.
Subfields: Health, Toxicology and Mutagenesis, Pulmonary and Respiratory Medicine
View Paper: https://www.semanticscholar.org/paper/5f68ff03fcf2875fb3f48dd57dd1160839c8c42a
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Health, Toxicology and Mutagenesis
In Pulmonary and Respiratory Medicine
Citations in the corpus
- The role of particle size in aerosolised pathogen transmission: A review (2010, neutral): “also further comments on the role of relative humidity, indicating that it affects both the rate of evaporation and the equilibrium (final) size of the particle.(29) Relative humidity may also play a role in affecting particle trajectory.”
- How far droplets can move in indoor environments--revisiting the Wells evaporation-falling curve. (2007, background): “, 2004; Hamburger and Roberston, 1946; Jennison, 1942; Loudon and Roberts, 1967; Papineni and Rosenthal, 1997) and excellent reviews exist (Morawska, 2005; Nicas et al., 2005).”
- Aerosol transmission of influenza A virus: a review of new studies (2009, background): “…of water in ambient air; the resulting desiccated particles are termed 'droplet nuclei'; for particles with an initial diameter ,20 mm the evaporation occurs in ,1 s (Nicas et al. 2005; Xie et al. 2007) and the diameter shrinks to a little less than half the initial diameter (Nicas et al. 2005).”
- Comparing the Markov Chain Model with the Eulerian and Lagrangian Models for Indoor Transient Particle Transport Simulations (2015, background): “Exhalation activities by an infected person, such as breathing, coughing, and sneezing, can generate particles carrying infectious viruses (Nicas et al. 2005).”
- Transmission of SARS‐CoV‐2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event (2020, neutral): “17,24 The model of infection risk due to airborne transmission is based on the Wells-Riley formulation, 25,26 as amended by Gammaitoni and Nucci.”
- Characterization of expiration air jets and droplet size distributions immediately at the mouth opening (2008, methodology): “Smaller pathogen-laden droplets have higher infectivity (Nicas, Nazaroff, & Hubbard, 2005) compared to the larger ones for diseases that have the lower respiratory tract as the target infection site (e.g., tuberculosis).”
- The coronavirus pandemic and aerosols: Does COVID-19 transmit via expiratory particles? (2020, background): “Neither the aerosol viral load nor the minimum infectious dose for COVID-19 have been definitively established, although it is believed for other viral respiratory illnesses that a single virus can serve to initiate infection (Nicas, Nazaroff, and Hubbard 2005).”