Thomas Falasca, DO FACA FACPM
Infection and Travel
Recently, we all have become highly aware of the infection risks that constantly surround us. Dealing with this has frequently involved restricting travel. But restrictions are difficult to observe long-term, especially when they keep us from friends and family over the holidays. In the upcoming holidays, we will be traveling more than we have in the last few years. Accordingly, here are some tips on maintaining safety from infection during holiday travel.
Riding in a Car
The safest way to travel in a car is to travel alone, as the infection risk of auto travel increases proportionally to the number of occupants in the vehicle. Nevertheless, solo travel is often not practical.
Engineers have examined the case in which a vehicle has two occupants, a driver and a rear passenger seated diagonally from the driver at the greatest possible distance in the vehicle. The engineers did computer simulations of air flow in the vehicle to examine the effect of various open-window configurations.
They examined simulations of a Toyota Prius traveling at less than 30 mph and of more than 30 mph. In all cases, ventilation was best when all windows were open. However, at greater than 30 mph, with less than four open windows, some results were a surprise.
The intuitive best configuration, with both the driver and diagonal rear seat passenger each having their windows open, was a disappointment. Instead, at these speeds, Bernoulli effects promote the inflow of air through an open rear window and the outflow through a diagonally opposed open front window.
The safest configuration for the passenger was to have the driver’s side rear window and the passenger side front window open. The safest configuration for the driver was to have the driver’s side rear window, the passenger side rear window, and the passenger side front window open.1
Observing such window configurations continuously over a long period of time might be impractical in some types of weather. In these cases, opening the windows in these configurations confers some benefit even if done for ten seconds every 5-10 minutes.2, 5
Car Cabin Air Recirculation
So, it seems that if increased ventilation is a good idea, then decreased ventilation, or cabin air recirculation is a bad idea. Certainly, this is true. Indeed, recirculation may be beneficial in protecting from outside dust or dirt and may enhance the effect of heating or air conditioning; but, when infectious agents in the cabin air are concerned, recirculation only concentrates these agents.3
Although car rental agencies may wipe down car surfaces between customers, and, although delayed turn-around time between customers may reduce the viability of infectious agents, it is never a bad idea to use disinfecting wipes on high-touch surfaces of any rental car.4
Of course, hands may become contaminated, often when the person is unaware. This is the rationale for avoiding touching the face thereby transferring infectious agents to the mucous membranes of the eyes, nose, and mouth, where they may more easily enter the body.4
It is also a good idea for each person in the vehicle to load their own luggage.
Also, avoid touching money or receipts. Make as many payments as possible online or with contactless apps or cards.8
Finally, do not let your guard down ... ever. A major risk in car rental devolves from the renter’s interactions with rental employees and other customers.4
In the Airport
Accept only beverages arriving in containers sealed at the factory. Then, do not defeat the purpose by adding ice from a local source.
If possible, minimize the amount of time face mask is down by drinking liquids through a straw passed under the mask.
When possible, consume only the snacks you have brought from home.8
Do not place excessive confidence in the screening afforded by airport temperature checks, as some studies suggest that these have a detection rate for COVID of only about 45%.7
On a Plane
If airplane blankets or pillows do not come to you in a package, they may well have been used previously and not processed.6
Some studies suggest that the safest places on an aircraft are toward the rear and in window seats.7
The High Efficiency Particulate Air (HEPA) Filters in most modern aircraft remove over 99.97% of particles, including those of virus size. Further, at each circulation, 50% of the air exchanges for outside air so that the entire cabin air replaces every 2-3 minutes.
Additionally, the air inlets and outlets line the entire cabin. The inlets are along the top of the cabin, not just at the over-seat air nozzles. The air outlets are along the sides of the floor. You can further increase your safety by adjusting your overhead nozzle to maximum and pointing it directly at your face to maintain air flow going away from you.
All this air flow dynamics means that exposure from fellow passe
ngers diminishes rapidly when other passengers are more than two seats away.7, 10 But it is important not to defeat this safety factor.
Do not congregate around lavatories, sit in high traffic areas, or walk unnecessarily around the cabin. On long flights, make every effort to exercise in place.9
For boarding and disembarking, remain seated until the gate agent calls your boarding group or until disembarking reaches your row. There is obvious excitement about departing or arriving, but, really, you gain nothing by crowding around the entry to the jetway on boarding. Disembarking is even worse, whenever passengers squeeze into narrow aisles and struggle with overhead luggage when disembarking is not imminent.
So, unless we ourselves, those we visit, or those to whom we return are sick or immune compromised, it should not be necessary to spend another holiday at home. And, although it may be difficult to implement all these measures all the time, we can certainly do much to increase infection safety during holiday travel.
Thomas Falasca, DO
1 Mathai, V., Das, A., Bailey, J., & Breuer, K. (2021, January 1). Airflows inside passenger cars and implications for airborne disease ... Retrieved September 13, 2022, from https://www.science.org/doi/10.1126/sciadv.abe0166
2 Office, P. (2021, August 16). How to cut covid risk in the car - researchers reveal Best Methods. Swansea University. Retrieved September 13, 2022, from https://www.swansea.ac.uk/press-office/news-events/news/2021/08/how-to-cut-covid-risk-in-the-car---researchers-reveal-best-methods.php
3 Prior, N. (2021, August 14). Covid study: How to avoid catching virus in a shared car. BBC News. Retrieved September 13, 2022, from https://www.bbc.com/news/uk-wales-58202468
4 Is it safe to rent a Car? MIT Medical. (2021, November 16). Retrieved September 13, 2022, from https://medical.mit.edu/covid-19-updates/2020/06/it-safe-rent-car
5 Freeman, S. (2021, February 24). Carpooling precautions during COVID-19. National Collaborating Centre for Environmental Health. Retrieved September 13, 2022, from https://ncceh.ca/content/blog/carpooling-precautions-during-covid-19.
6 WebMD. (2021, December 17). How to avoid germs when you travel. WebMD. Retrieved September 13, 2022, from https://www.webmd.com/parenting/germs-and-travel
7 Bielecki, M., Patel, D., & Hinkelbein, J. (2020, November 10). Air travel and COVID-19 prevention in the pandemic and peri-pandemic period: A narrative review. Travel Medicine and Infectious Disease. Retrieved September 13, 2022, from www.elsevier.com/locate/tmaid
8 Must read safety & hygiene tips for flight (air) travellers. FabHotels Travel Blog. (2021, September 7). Retrieved September 13, 2022, from https://www.fabhotels.com/blog/air-travel-safety-hygiene-tips/
9 Flight Safety Foundation. (2020, June). New norms in air travel hygiene etiquette - flight safety foundation. Flight Safety Foundation. Retrieved September 13, 2022, from https://flightsafety.org/wp-content/uploads/2020/06/New-Norms-in-Air-Travel.pdf
10 Bundesverband der Deutschen. (2020, July). Luftfahrt aktuell 1|2015 - Bundesverband der Deutschen ... luftfahrt-aktuell%40bdl.aero. Retrieved September 13, 2022, from https://www.bdl.aero/wp-content/uploads/2019/09/BDL-LuftfahrtAktuell-2019-5_en-1.pdf