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Propagation of Dental and Respiratory Cells and Organs in Microgravity
Published on: May 25, 2021
Modeling the risk of airborne transmission of respiratory viruses in microgravity
Chayanin Sararat1, Natnicha Jiravejchakul2, Kawin Nawattanapaiboon3
1Biophysics Group, Department of Physics, Faculty of Science, Mahidol University, Bangkok, Thailand.
Abstract:
Airborne transmission is one of the most efficient routes of respiratory viral spread, posing a significant challenge in controlling major infectious diseases such as COVID-19. In microgravity environments, such as the International Space Station (ISS), this mode of transmission requires heightened vigilance and preventive measures due to the prolonged suspension of virus-laden particles, which increases the risk of infection. Using the COVID Airborne Risk Assessment (CARA) tool, we assess the risk of airborne transmission of respiratory viruses, using SARS-CoV-2 as a case study, in microgravity by simulating the emission, dispersion, and inhalation of virus-laden particles. Our simulations show that the unique conditions of microgravity allow these particles to remain airborne for more extended periods compared to Earth, leading to a 286-fold increase in virus concentration in the air and resulting in nearly twice the probability of infection for a susceptible host. We also evaluated the effectiveness of preventive measures. We found that facemasks could reduce the risk by up to 23%, while continuous HEPA filtration at five air changes per hour proves crucial for managing air quality and minimizing infection risks by reducing airborne virus concentration by 99.79%. To explore potential effects of spaceflight-induced immune suppression on transmission risk, we modeled hypothetical scenarios with increased viral shedding based on herpesvirus reactivation data. An 8-fold increase in viral load (as observed for herpesviruses in space) raised infection probability by 12 percentage points above baseline. Sensitivity analysis with 4-fold and 16-fold increases showed infection risk scales proportionally with viral shedding intensity. Although facemasks and air filtration help mitigate the risk, their effectiveness diminishes when viral load is elevated. Enhancing host immunity through vaccination or other interventions is vital, potentially reducing infection probability by up to 14.17% when combined with HEPA filtration.
Insights
Microgravity significantly increases airborne virus concentration and infection risk. HEPA filtration and masks help, but enhanced host immunity is vital for spaceflight safety.
Area of Science:
- Aviation and Space Medicine
- Infectious Disease Epidemiology
- Environmental Health Engineering
Background:
- Airborne transmission is a primary route for respiratory viruses like SARS-CoV-2.
- Microgravity environments, such as the International Space Station (ISS), pose unique challenges for controlling airborne pathogens due to prolonged particle suspension.
- Heightened vigilance and preventive measures are essential in space to mitigate infection risks.
Purpose of the Study:
- To assess the risk of airborne transmission of respiratory viruses in microgravity using SARS-CoV-2 as a case study.
- To evaluate the effectiveness of preventive measures, including facemasks and HEPA filtration, in reducing airborne virus transmission in space.
- To investigate the impact of spaceflight-induced immune suppression on viral transmission risk.
Main Methods:
- Utilized the COVID Airborne Risk Assessment (CARA) tool to simulate virus-laden particle emission, dispersion, and inhalation in microgravity.
- Modeled scenarios with increased viral shedding based on herpesvirus reactivation data to assess the effects of spaceflight-induced immune suppression.
- Performed sensitivity analyses to determine the relationship between viral load and infection probability.
Main Results:
- Microgravity conditions led to a 286-fold increase in airborne virus concentration and nearly doubled infection probability compared to Earth.
- Facemasks reduced infection risk by up to 23%, while HEPA filtration decreased airborne virus concentration by 99.79%.
- An 8-fold increase in viral load, simulating spaceflight-induced immune suppression, raised infection probability by 12 percentage points.
Conclusions:
- Airborne viral transmission poses a significantly elevated risk in microgravity environments.
- HEPA filtration is critical for maintaining air quality and minimizing infection risk in space.
- While masks and filtration offer protection, enhancing host immunity through vaccination or other interventions is crucial for mitigating infection risk, especially under conditions of increased viral shedding.
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