Flushing urinals can spew clouds of virus-laden particles: Study

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Flushing urinals can release clouds of virus-carrying aerosols which people may potentially inhale, according to a study which says wearing masks when in washrooms amidst the COVID-19 pandemic “should be mandatorily implemented.”

The research, published in the journal Physics of Fluids, simulated and tracked virus-laden particle movements when urinals are flushed.

Since earlier studies have shown that both feces- and urine-based COVID-19 transmission is possible, the scientists, including those from Yangzhou University in China, cautioned that public restrooms can be dangerous places for potentially becoming infected during the ongoing pandemic.

“To do this, we used a method of computational fluid dynamics to model the particle movement that occurs with the act of flushing,” said study co-author Xiangdong Liu from Yangzhou University.

According to the researchers, flushing a urinal involves an interaction between gas and liquid interfaces, resulting in a large spread of aerosol particles to be released from the urinal.

The simulations performed by the scientists revealed that the trajectory of the tiny particles ejected by flushing a urinal “manifests an external spread type, with more than 57 per cent of the particles travelling away from the urinal.”

They said when men use urinals, these tiny particles can reach their thigh within 5.5 seconds when compared to the toilet flush, which takes 35 seconds to reach slightly higher.

However, according to Liu, particles from urinals “show a more violent climbing tendency. The climbing speed is much faster than toilet flushing.”

Since urinals are used more frequently within densely populated areas, the researchers pointed out that particles will travel faster and farther, posing a serious public health challenge.

The study underscored the importance of wearing a mask within public places, especially in restrooms.

“From our work, it can be inferred that urinal flushing indeed promotes the spread of bacteria and viruses,” Liu said. “Wearing a mask should be mandatory within public restrooms during the pandemic, and anti-diffusion improvements are urgently needed to prevent the spread of COVID-19,” he added.