AMSTERDAM - Airplane passengers sitting more than three rows away from a person infected with coronavirus are not at risk of getting infected. This emerged from a research jointly carried out by the Netherlands Aerospace Center (NLR) and the Dutch public health agency RIVM.
"If this person does sit in the cabin, fellow passengers sitting in seven rows surrounding the infectious passenger are at relatively low risk of COVID-19 on average. [The risk] is lower than in, for example, unventilated rooms of the same size," NLR stated.
To assess the risks of coronavirus infections during flights, NLR teamed up with RIVM to carry out a scientific study on behalf of the Ministry of Infrastructure and Water Management. The experiment was conducted using dummies in an airplane setting.
"In the experiment, dolls were placed in the seats to imitate passengers in a seven-row cabin section in economy class. The dolls were optionally heated, to mimic the heat output of real passengers. A 'contagious passenger' who emitted artificial saliva, without the presence of the actual virus, was placed in the middle," NLR explained.
"During the measurement runs, large quantities of aerosols were injected at the start of each run. Only very low volumes of aerosols were detected in two rows further in front of the seven-row section that was investigated. This suggests that, at least in the rear section of the economy class, recirculation of aerosols from the HEPA-filter-equipped cabin ventilation system does not, or only to a very limited extent, occur," the research said.
The risk of infection increases when the contagious passenger spreads more viral particles than average, the experiment proved. In the case of super extractors, persons who shed an average of 300 times as many virus particles, average risks increased from 1:370 to 1:16. According to the report, these types of biomedical aspects have the greatest influence on the infection risk.
At the same time, the risk of contracting the virus increased with the flight duration. Wearing face masks on board during a flight lowers the risk of getting infected with the SARS-CoV-2 coronavirus, the study proved. Transmission of the virus via direct contact and surfaces was not investigated in the study.
The findings were expected to be similar different variants of concern. "Even though variability among variants may result in differences in transmissibility and infectivity, differences between variants were outside the scope of this study. Given the relative short time between emission and exposure in aircraft, that was typically less than 10 minutes, possible differences in stability of virus variants in aerosol particles was not expected to lead to differences in transmission," the study said.
Based on June 7 figures, the researchers estimated that there could be an infectious passenger onboard every 11 to 33 flights. Among passengers on board, it was estimated that less than 3% were super extractors.