A Risk Assessment of an Airborne Disease inside the Cabin of a Passenger Airplane

Abstract

<div class="section abstract"><div class="htmlview paragraph">Analytical calculations along with computational fluid dynamic (CFD) simulation of a Boeing 737-600 cabin with a single infector (a passenger) has been performed using a passive scalar gas with particle sizes similar to the sizes of influenza virus laden particles which are assumed to be comparable to the sizes of the Coronavirus laden particles. CFD results of the virus transport and concentration were used in conjunction with the Wells-Riley (WR) quanta estimation from two well-documented cases of influenza infection on airplanes (with the assumption that the infections were primarily from the airborne route), to estimate the infectious rate. The risk of infection is estimated by the quanta of viruses inhaled assuming 0.3 CFM of passive scalar gas corresponds to 1267 viruses/minute released. Results indicate that with a 3-hour flight, the risk of infection is nearly 50% for those sitting in the vicinity of the infector which is equal to 2-3 infections for 131 passengers.</div><div class="htmlview paragraph">A comparison to a documented COVID-19 case shows that 4 symptomatic passengers could infect 2 others if the COVID-19 virus infectiousness lays mid-range of the influenza infectious doses.</div><div class="htmlview paragraph">The use of masks could dramatically reduce the risk of airborne infection. When the infector wears a mask the virus concentration is reduced for all other passengers and the mask is more effective at catching the virus droplets before they dry out in the cabin air. A significant reduction in virus transport and the infectious rate was observed with the N95 mask for a 3-hour flight.</div><div class="htmlview paragraph">With 2.9-ft social distancing (vacant middle seat) resulting in 2/3 cabin passenger capacity, the ventilation rate per person is increased by 45% and the risk of infection was dropped by more than 48%.</div></div>

Covid 19 and beyond: a procedure for HVAC systems to address infectious aerosol illness transmission

“…The measured influenza TCID50 ranges between 300 and 3,000 virus copies (Nikitin) and with virion measured in airplanes and other settings (Yang et al, 2018) as calculated by Horstman and Rahai for two cases: q n = 0.645 case I, q n = 0.681 case II). (Horstman and Rahai, 2021).…”

“…Suppose the epidemiology studies show that an equal reproduction number should be the goal for all environments rather than the sum of the experience fractions. Also, suppose they show that the reproduction number should be based on a more infectious disease that lies between the quanta source estimated from airplane data (0.645-0.681 quanta/minute) (Horstman and Rahai, 2021) and less than 1.667 quanta/minute from asymptomatic SARS-CoV-2 subjects performing vocalizations (Buonanno et al, 2020).…”

“…CFD studies and experiments investigating the spread of aerosols, for example, Bennett et al (2013), Horstman and Rahai (2021) and Silcott (2020) (see Figure 1) have shown that ventilation created air currents can spread aerosols quite far in terms of numbers of persons who might be infected by these aerosols in aircraft cabins if they are susceptible. Nevertheless, while aerosols will disperse much further than droplets, Morgenstern pointed out that the concentration of infectious aerosol particles generally falls with distance, even when those infectious particles are carried by aerosols (Morgenstern, 2021).…”

Recent progress on studies of airborne infectious disease transmission, air quality, and thermal comfort in the airliner cabin air environment

“…Khatib et al 59 stated that the use of face masks had significantly reduced onboard transmission. Hostman and Rahai 68 used a COVID‐19 case in which four index patients had infected two others as an example. They found that mask wearing could dramatically reduce the risk of airborne infection.…”

Evaluating vacant middle seats and masks as Coronavirus exposure reduction strategies in aircraft cabins using particle tracer experiments and computational fluid dynamics simulations

“…The MMWR report was not alone in predicting lower exposure without adjacent seating. Horstman and Rahai 20 assayed this scenario using CFD in a single‐aisle, three‐on‐each side seating arrangement and report a 40% infection risk decrease due to increased supply air per occupant and specific flow patterns. Pavlik et al 21 compare various seating distance and masking implementations while illustrating the dependence of pattern optimality on occupancy level and spatial risk model.…”