Open doors of passenger ships aggravate the spread of Covid-19

The spread of Covid-19 in passenger ships is exacerbated when a cabin door is left open to let in fresh air, according to new research led by Cranfield University.

High performance simulations were developed to show how infected particles from a person’s mouth were distributed on board small passenger ships. The main finding was that keeping the cabin door closed resulted in shorter particle spread.

The research aims to help with the post-pandemic recovery of the maritime industry – which has seen a 43% reduction in passenger ship operations due to Covid-19. The results will advance onboard protective measures against future viruses – reducing the economic and social impact of pandemics on seafarers, passengers and the shipping industry.

The maritime industry hit hard by the pandemic

Passenger transport around the world has been significantly affected by the Covid-19 pandemic, with the time passengers spend confined together creating a health risk and spreading the virus.

Although research into how the virus spreads in hospitals and other environments such as cars is extensive, equivalent studies of Covid-19 on ships have been limited.

The main conclusions – published in the ocean engineering log – show that the airflow environment on ships is unique due to their forward motion and that the location of a forward facing door can cause a large windflow to diffuse more largely the infected particles.

Researchers – led by Dr Luofeng Huang, senior lecturer in mechanical engineering at Cranfield University – conducted research using a series of computer models to examine the airborne transmission of Covid-19 at the interior of a ship. They looked at what happened when an infected person coughed or spoke when the door was opened, and how the spread of this virus changed when the door was closed.

Closed doors and air conditioning units

Research modeling results showed that the movement of virus particles was limited to a radius of half a meter, less than the width of a seat, when the doors were closed. The passenger seats could then be adjusted accordingly to account for this spread radius.

The researchers also looked at the influence of air conditioning units and found that adjusting the downward airflow direction acted as a measure to limit the spread of the virus.

Dr Luofeng Huang, of Cranfield University, lead author of the paper, said: “We initially started the research focusing on Indonesia, a nation that relies heavily on shipping. But when the pandemic hit there were ships around the world that were either unable to leave port or had to operate at reduced capacity Our research has demonstrated a safe path for ships and will help the shipping industry recover from the effects of the pandemic.

“We were very surprised by the research results as they differ from the general guidance on covid and fresh air. In the case of ships, obviously guarding the front door of a ship closed will mitigate the spread of infection.

“Our next step is to continue research to develop guidelines for fishing vessels, on which the catching process typically requires more than 10 crew members working side-by-side, and the physical demands make it impossible to carry masks. With this concern, hundreds of thousands of fishing vessels are still suspended, adding to the economic toll of the region.”

The UK-Indonesia collaboration was initiated by Professor Giles Thomas of UCL, in partnership with Cranfield University and ITS University in Indonesia, and funded by the British Council. A series of workshops are being held with Indonesian partners to help government departments and industrial operators adopt the COVID-19 guidelines developed under this project.


Journal reference:

Huang, L. et al. (2022) Transmission of COVID-19 inside a small passenger vessel: risks and mitigation. ocean engineering.

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