DoD Study Suggests Low Risk of COVID-19 Exposure While Flying
The risk of spreading CoVid while flying is probably low, but you can still spread it before and after. If you need to fly, you have one less reason to worry. If you don’t need to travel, you shouldn’t.
A new study by the Department of Defense suggests that the risk of transmitting COVID-19 while in-flight is extremely low. This study simulated the spread of virus particles from one sick, mask-wearing passenger on a Boeing 767-300 and 777-200.
A Primer on Airborne Spread of CoVid
To catch COVID-19 , you need to be exposed to a specific amount of the virus. The exact viral load needed to become sick is still unknown, with studies ranging from 300 to thousands of particles. COVID-19 spreads through the air via droplets in the air (i.e. aerosols) that are created when you breathe, cough, and sneeze. The equation for exposure to the virus is simple:
Total exposure = concentration of the virus in the air * time you are breathing / amount of air you breathe
For example, let’s assume you need 1,000 virus particles in your system to get sick. If you are sitting in a room where there are 100 virus particles per liter of air, you would need to breath 10L (liters) of it to get sick. The average adult breathes in 7.5L per minute . To breathe in 10L of air, you would need to be in that room for 1 - 2 minutes.
To reduce the risk of exposure, you need to reduce the concentration of the virus in air, or the amount of time you breathe it. Wearing masks reduces the concentration of the virus by filtering particles everyone breathes out. Improving ventilation reduces the amount of time infected air stays in the room.
The DoD study simulated the spread of a virus from one sick, mask wearing passenger on a Boeing 767-300 and 777-200. It tested the spread of the virus around the plane by placing sensors in every seat of the plane, and measuring how many “virus” particles were detected at each seat over time. If any seat was exposed to 1,000 particles, that passenger would be considered “sick.”
The results showed you would need to be sitting directly next to a sick patient for 54 hours to be exposed to enough virus to get sick. If you’re sitting anywhere else on a 767 , it would take over 100 hours.
The main reason for this low transmission is ventilation - it takes ~5 minutes for all of the air inside of a plane to be recirculated. This, combined with HEPA-3 air filters, makes the inside of a plane less risky for covid transmission than most suburban homes.
Safe to fly, but still risky to travel
Assuming all passengers are wearing masks, the risk of transmitting or catching COVID-19 while on a flight is extremely low (even if you’re in a middle seat). But your time on a plane is just one of many public health risks associated with travel.
Roughly 1 of 6 reported COVID-19 cases are asymptomatic. It can take anywhere from 1 to 14 days to show symptoms of COVID-19 once you are infected. If you have COVID-19 before you fly, or catch COVID-19 at your destination, you will very likely not know until you complete your trip. While you may not catch or transmit the virus on the plane, you may end up doing so in the terminal, at a restaurant, in a meeting, or at home.
Our takeaway - If you absolutely need to get on a plane, this study should give you one less thing to worry about. If you don’t need to travel, you still shouldn’t.