Journal of Applied Sciences and Clinical Practice

: 2021  |  Volume : 2  |  Issue : 3  |  Page : 63--65

Air travel during COVID-19 pandemic-how safe it is? – A public health perspective

Sudip Bhattacharya 
 Independent Public Health Researcher, Dehradun, Uttarakhand, India

Correspondence Address:
Dr. Sudip Bhattacharya
Independent Public Health Researcher, Jolly Grant, Dehradun, Uttarakhand

How to cite this article:
Bhattacharya S. Air travel during COVID-19 pandemic-how safe it is? – A public health perspective.J Appl Sci Clin Pract 2021;2:63-65

How to cite this URL:
Bhattacharya S. Air travel during COVID-19 pandemic-how safe it is? – A public health perspective. J Appl Sci Clin Pract [serial online] 2021 [cited 2021 Nov 27 ];2:63-65
Available from:

Full Text

“The challenge isn't just on a plane, consider the airport and the whole journey.” - Saskia Popescu - (Infection prevention specialist)


As the COVID restrictions are relaxed and the vaccination process has been rolled out in many countries more people are now flying every day. Simultaneously the dangerous virus variants (mutants) have led to 2nd, 3rd, and 4th waves [1],[2] of the pandemic. Now our moot question is how safe is to travel now? To answer this question, we need to know about the air circulation which takes place in the aeroplanes.

We constantly inhale a mixture of fresh and recirculated air in most of the airplanes (single-aisle) models. In this kind of planes, air is constantly blown down from ceiling ducts to the floor vents. Nearly 50% of the sucked air is released from the aeroplane, remaining air is filtered and eventually sent back into the cabin, the mechanism is very much similar with the modern-day operation theatres/air-conditioned shopping malls.[3]

To understand the virus particulate dynamics in the air cabin, and how the virus may pose life-threatening risks, a group of researchers simulated >2 million air particles in the aeroplane cabin. Air change was done every 2–3 min which is a higher rate than in grocery stores and other indoor spaces. The simulation process in the cabin revealed that, in addition to the safety protocols, that a limited number of super spreader events were documented. This may be due to the high exchange rate of the air which forces the mixing of fresh air uniformly in the air cabin and minimizing pockets of air that could become stale or linger for too long. However, this phenomenon does not mean that flights are completely safe for the prevention of COVID particles. As an example, air blows from the sides, and they combine with air from the opposite row, whenever someone sneezes on board despite wearing a mask/face shield. An interesting fact is that not all sneezing particles are of the same size, and most do not contain infectious viral matter. Problem occurs when the passengers nearby were not wearing masks/face shields during the brief eating/drinking on the aeroplane, the sneezed air increase their chances of inhaling viral particles during that period. The same phenomenon will happen if people sneeze in different segments of the aeroplane, it is contained to a few rows thus preventing air from circulating throughout the cabin. The ventilation system is dependent on the operation of the aeroplane: the powerful engines that propel the plane, constantly sucking in the outside air which is then pressurized, and conditioned to control for temperature. The process of pressurization plays a vital role because high altitude air at cruising is less dense which is ideal for flying fast, but its oxygen content is less, hence it is not great for breathing.[4] After condensed air serpents into the aeroplane, it eventually climbs up to the ceiling ducts which distributes the fresh air into the cabin. Throughout the air journey, the cabin air is regularly sucked within two high-efficiency particulate air (HEPA) filters into a manifold under the floor, and mixing of fresh and recirculated air takes place. Commonly each HEPA filter catches most of the microscopic particles through densely pleated fiberglass mesh consist of 12 panels.[5],[6],[7] In most of modern flying machines, it has similar filtration and recirculation methods. Once mixed air has been dragged out of the cabin, 50% of that is not recirculated and leaves the rear of the plane through a valve which helps to maintain a constant cabin pressure. [3],[8],[9]

A similar particle airflow simulation was conducted using a later version Boeing 737NG. The model assumed that the passengers occupying all the seats in that aeroplane. To simulate the flow of >2.5 million particles a computational fluid dynamics code system known as (Finite Element subsurface FLOW system) FEFLO-a computer program was used. Many small particles were introduced at the cabin inflow ducts, to determine the movement of pathogens that may have escaped through the HEPA filters. The simulation resulted that the contact period of the air which came close to passengers' heads was <50 s, which is sufficient to lodge a virus in our respiratory system. In that simulation, different positions of sneezes were observed using smaller particles to estimate airborne infection spread. In addition, the research team concluded that in the aeroplane face coverings such as face masks/face shields could block larger particles expelled during a sneeze that can otherwise land on surfaces and body parts.[10]

In addition to this, the factors lowering the risk of COVID-19 transmission on board aircraft are [Figure 1]:{Figure 1}

Seats and passengers face forward meaning limited face-to-face interactionsSeat backs act as a solid barrierFrequent airflow exchange rates 2–3/min and direction are less conductive to droplet spread than other indoor environments, or modes of transportHospital-grade HEPA filters can filter microparticles effectively.

 The COVID Risk Beyond Flights

As per the infectious-disease experts, only safety in the cabin is not the only part of the safety equation, we must consider other aspects of air journey such as contacting infections when people are sitting or roaming in the air terminal, eating, or drinking in the airport restaurants and bars, going through the security check or beyond the airports (i.e., the journey from home to the airports) In addition, maintaining physical distancing a greater challenge as more people fly. The Harvard researchers opined that the chance of infections depends on the airport size, passenger volume, destination, configurations, and on-location businesses. Even increase the chances of exposure depending on the delay or cancellation of flights, where the passengers spend more time. As, face masks are routinely removed and kept off during eating and drinking in-terminal restaurants, can become risky. The Harvard researchers even documented that many airports were not designed to prevent/mitigate the airborne spread of respiratory pathogens. Although after the COVID-19 pandemic few airports have strengthened their air filtration systems by installing new/additional filtration systems, along with strictly maintaining physical distancing measures, vigilance, other safety precautions-COVID appropriate behaviors.[10],[11]

 The Preventive Measures

Generally, Centre for Disease Control and Prevention (CDC) recommends delaying travel for the unvaccinated individuals unless it is extremely urgent, this is because air travel increases the chance of getting infected and spreading COVID-19.

Till date, CDC has recommended two guidelines for vaccinated as well as unvaccinated people in the U.S. This guidance is applied to travel within the United States, and U.S territories who are fully vaccinated with the Food and Drug Administration (FDA) authorized vaccine. During travel, the guideline recommended to strictly adhere COVID-19 appropriate protocols, i. e., covering nose and mouth with mask, maintaining physical distancing of 6 feet or 2 meters, and wash/sanitize the hands with at least 60% of alcohol.[11]

After the travel, the guideline recommends self-monitoring for common COVID-19 symptoms such as fever, sore throat, and mild respiratory problems; they must isolate and get tested for reverse transcription-polymerase chain reaction. In addition, the passengers should follow all state and local health authority recommendations or requirements. The guidelines mentioned that the passenger should still follow all other travel recommendations if he/she is fully vaccinated or have recovered from COVID-19 in the past 3 months. For the travelling of unvaccinated people, they must get tested with a viral test 1–3 days before their trip. During travel, the same above-mentioned protocol (physical distancing, face covering, and hand hygiene) should be maintained. The person should get tested with a viral test 3–5 days after the travel and stay home and self-quarantine for a full 7 days after travel, even if he/she tests negative. If the person becomes positive, the person should isolate himself/herself to protect others from getting infected with COVID-19. If the person is not able to get tested, he/she should stay home and self-quarantine for 10 days after travel. In addition, he/she should avoid being around high-risk people such as people having diabetes, cancer, or taking immunosupressive drugs for at least 14 days. If he/she develops any symptoms, he should get tested and follow state and local health department guidelines. In addition, checking the travel restrictions is most important now. As we are struggling with this pandemic and the knowledge regarding COVID-19 is still in evolving phase, we must keep ourself up-to-date with information and travel guidance, we should regularly check the state or territorial and local health department guidelines where we are, along our route, and where we are going.[10],[11] We should prepare to be flexible during our trip as restrictions and policies may change during our travel. After considering the pros and cons, we conclude that we must restrict our air travel unless this is extremely urgent.


The author would like to thank all the authors of those books, articles, and journals that were referred in preparing this manuscript.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


1Fang FC, Benson CA, Del Rio C, et al. COVID-19-Lessons Learned and Questions Remaining. Clin Infect Dis. 2021;72:2225-40.00
2Grech V, Grech P, Fabri S. A risk balancing act-Tourism competition using health leverage in the COVID-19 era. Int J Risk Saf Med 2020;31:121-30.
3de Wit AJ, Coates B, Cheesman MJ, Hanlon GR, House TG, Fisk B. Airflow characteristics in aeromedical aircraft: Considerations during COVID-19. Air Med J 2021;40:54-9.
4Löhner R, Antil H. High fidelity modeling of aerosol pathogen propagation in built environments with moving pedestrians. Int J Numer Method Biomed Eng 2021;37:e3428.
5COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation. Available from: [Last accessed on 2021 Apr 19].
6Popovich KJ, Calfee DP, Patel PK, Lassiter S, Rolle AJ, Hung L, et al. The Centers for Disease Control and Prevention STRIVE Initiative: Construction of a National Program to Reduce Health Care – Associated Infections at the Local Level. Ann Intern Med 2019;171:S2-6.
7Bell MR, Kuhar DT. An introduction to STRIVE. Ann Intern Med 2019;171:S1.
8Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1,NEJM. Available from: [Last accessed 2020 Oct 01].
9Aeromedical Evacuation of Patients with Contagious Infections. Available from: [Last accessed on 2021 Apr 19].
10How Safe Are You From Covid When You Fly?-The New York Times. Available from: [Last accessed on 2021 Apr 19].
11CDC. COVID-19 and Your Health. Centers for Disease Control and Prevention; 2020. Available from: [Last accessed on 2021 Apr 19].