Modelling shows how mitigation reduces COVID risk for rail passengers

Computer simulations have shown that passengers on the London Underground and similar rail systems were at low risk of being exposed to the virus that causes COVID-19.

High levels of wearing masks reduce the level of viruses people are exposed to (Image: AdobeStock)

The modeling found that risks were reduced if ventilation was good and passengers followed COVID-19 mitigation measures, including wearing a face covering or mask; maintaining a social distance from other travelers; wash or disinfect your hands regularly; and encouraging people with COVID-19 symptoms to stay at home.

Scientists and engineers from Leeds University, the Defense Science and Technology Laboratory (DSTL) and Manchester University developed the model to identify the relative risks of spreading the virus on a public transport system used for short commutes.

In a statement, Leeds University professor Cath Noakes, the study’s lead researcher, said: “All environments where people interact have a risk of virus transmission and public transport is no exception. If the journeys are short and not overcrowded and the carriage well ventilated, the risks are likely to be quite low.

“Wearing a face covering can significantly reduce the risk of spreading the virus, especially since it can be more difficult to maintain social distancing in a subway or subway car at certain times of the day.

“Although there is a small chance of transmission from touching a contaminated surface, it can be managed by regular hand hygiene and avoiding touching your eyes, nose and mouth.

“The results show that adherence to good mitigation measures is likely to be effective in reducing infection.”

The computer model simulated the risks of human exposure to the virus through the main transmission routes: within two meters of an infectious person; touching a contaminated surface – then touching their nose, mouth or eyes; or by breathing airborne viral particles (aerosol inhalation).

Present their findings inindoor airThe scientists said: “…the risk of exposure to the virus was predicted to be low through all transmission routes. The highest modeled doses (of the virus) were for a small proportion of people in close proximity to an infected person.” , which is through a combination of aerosol inhalation and direct droplet deposition.”

The researchers added: “To date there is no evidence that public transport is a major driver of the pandemic, but as a shared enclosed environment where people can be close to each other, transmission is possible and it is important to control the factors. understand that affect the probability of transmission. for introducing and managing effective mitigation strategies.

“This is particularly important because public transport is a necessity for many people and it can be an environment where social distancing is difficult to maintain, especially in dense urban transport systems.”

The computer model was independently developed by researchers as part of the £1.7 million TRACK project, funded by the Department for Transport and the Engineering and Physical Sciences Research Council. TRACK is a multi-part study investigating the COVID-19 risks in public transport – buses, trams and trains – and the ways in which those risks can be reduced.

dr. Simon Parker, a Dstl modeler and co-author, said: “Building a virus transmission model for this environment requires a detailed understanding of the unique characteristics of public transport spaces and how people use them. The results are complex but fascinating and hopefully valuable. They reflect the interactions between disease prevalence, passenger behavior and the environment itself.”

The research team recognizes the limitations of their model in that it does not take into account vaccination rates among the traveling public, and the model was created before the advent of the Delta and Omicron variants. The modeling did not analyze viral spread in highly overcrowded carriages, as seen when large numbers of people return to their offices and workplaces.

Professor Noakes believes that mitigation measures will continue to reduce the risks.

“The Omicron variant is more transmissible and the risks of exposure in different environments, including public transport, are not yet clear,” she said. “However, the mitigations identified in the study will likely still be effective in reducing the risk of exposure to the virus.”

Practical steps to reduce the spread of viruses

The scientists outlined the practical steps passengers and carriers can take to reduce the risk of exposure to the virus:

  • COVID-19 spreads more easily when people are close together, within 1-2 meters of each other. In times when the number of COVID-19 infections in the community is high, measures to reduce crowds on public transport can reduce the infection.
  • The more passengers are contagious, the greater the risks for other travelers. The researchers said public health policies should encourage people who are contagious to stay at home.
  • High levels of wearing masks reduce the level of virus passengers that passengers are exposed to.
  • The modeling also predicted that a small minority of travelers could be exposed to a large dose of the virus by touching contaminated surfaces. Hand sanitizers near high touch points, when people get on and off trains, or near escalators can reduce this risk.

Abhishek Maheswari
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