Face masks reduce the distance a virus can travel by more than half

The first case of Covid-19 was reported in December 2019 and a pandemic was declared by the World Health Organization in January 2020. Since the beginning of the outbreak, face masks, sanitizers and gloves have been widely used as preventative measures to limit the spread of Covid-19. 

The efficiency of face masks in curbing the spread of Covid-19 has been a heavily disputed topic. However, a recent study by experts at the University of Central Florida provides compelling evidence that masks are effective in slowing the spread of viruses and other pathogens.

The results of the study show that face masks minimize the distance airborne pathogens can travel by more than half. The research is significant because airborne viral infections like SARS-CoV-2 can be encapsulated and transmitted via liquid droplets and aerosols generated during human respiratory activities such as speaking and coughing.

Methods to shorten the distance that pathogens travel can aid in the management of pandemics like Covid-19, which has led to global infection, healthcare system overload, and economic devastation.

“The research provides clear evidence and guidelines that 3 feet of distancing with face coverings is better than 6 feet of distancing without face coverings,” said study co-author Kareem Ahmed, an associate professor in UCF’s Department of Mechanical and Aerospace Engineering.

According to the study authors, the findings can be used to inform social distancing guidelines by helping to determine the minimum social distance for people wearing masks. 

The researchers employed diagnostic instruments that are routinely used to study how fluids travel through the air. They measured the distance that droplets and aerosols traveled in all directions from people speaking and coughing.

The study examined three scenarios: individuals without a face-covering, with a cloth face covering, and with a three-layered disposable surgical mask. The participants read a phrase and simulated a cough for five minutes under each scenario.

Meanwhile, particle velocity was measured using planar particle imaging. Droplet size, velocity, and volume flow were measured using a phase doppler interferometer at sites within a spray plume. Airborne particle behavior was determined using an aerodynamic particle sizer.

As the airborne particles went forth from the participants’ mouths, the devices recorded their properties, behaviors, and direction. The researchers discovered that wearing a cloth face mask reduced emissions in all directions to roughly two feet, compared to four feet when coughing or speaking without one.

When wearing a surgical mask, the distance coughing and speaking emissions traveled was reduced to less than half a foot. 

The inspiration for the study came from the researchers’ previous work on jet propulsion. “The principles are the same. Our cough and speech are exhausted propulsion plumes.”said Ahmed.

The study is published in The Journal of Infectious Diseases.

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By Ashikha Raoof, Earth.com Staff Writer