Short of Breath

They are a simple symbol of the pandemic that has overwhelmed the world. Face masks, unavoidable from supermarkets to subways, have become everyday essentials. But they remain controversial to some, and as regulations tighten and relax in different countries, their importance will continue to be questioned. Improved understanding of their effectiveness helps individuals and governments to make decisions, so a new study used computer simulations with updated parameters to realistically estimate the distance water droplets capable of carrying virus particles travel during normal human breathing without (start of the video) and with (end of video) a mask. The simulations suggest that without a mask, saliva droplets travel up to 2.2 metres in 90 seconds, compared to just 0.72 metres in 2 minutes from a masked person. The study also assessed the complex vortex rings and aerodynamics behind the breath-powered propulsion, helping further unmask the mystery of mask effectiveness.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Videos by Ali Khosronejad and colleagues
• Department of Civil Engineering, Stony Brook University, Stony Brook, NY, USA
• Video copyrights held by the original authors
• Published in Physics of Fluids, June 2021