Aerosol extractors might have the potential to shield against the spread of airborne diseases

Service Engineering

Plans are being drawn up to make an aerosol extractor, following the creation of a mathematical model which foretells the spread of airborne diseases.

In addition to discovering a basic distinction between small, intermediate and large droplets, Dr Cathal Cummins, Heriot-Watt School of Mathematical and Computer Sciences and the Institute for Infrastructure and Environment, devised a mathematical model for droplet distribution. In using the formulas, Dr Cummins and his colleagues were able to assess the maximum droplet range and reported their results in the journal of Physics of Fluids.

“Aerosol extractors might have the potential to shield against the spread of airborne diseases.“

While the model prophesied that little and large droplets could spread far; it has been discovered that medium-sized droplets fall incredibly close to the source, which follows the alert from the WHO that COVID-19 aerosol transmission is undervalued.

Dr. Cummins, stated: “The flow physics of someone coughing is complex, involving turbulent jets and droplet evaporation and the rise of COVID-19 has revealed the gaps in our knowledge of the physics of transmission and mitigation strategies. One such gap in the physics is a clear, simple description of where individual droplets go when ejected. We wanted to develop a mathematical model of someone breathing that could be explored analytically to examine the dominant physics at play. A big surprise for us was when we found that both small and large droplets travel far from the source, albeit for very different reasons. But there are medium sized droplets that don’t get far at all. This had been previously observed in experiments with people breathing, but the bimodality was typically attributed to a biological function.”

Co-author and academic surgeon, Edinburgh University, Dr Felicity Mehendale, stated: “We can’t afford to be complacent about these small droplets. PPE is an effective barrier to large droplets, but may be less effective for small droplets. This has important implications for the COVID-19 pandemic. Larger droplets would be easily captured by PPE - such as masks and face shields. But smaller droplets may penetrate some forms of PPE, so an extractor could help reduce the weakness in our current defence against Covid-19 and future pandemics.”

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