The limited supply of ventilators is one of the chief concerns facing hospitals as they prepare for more COVID-19 cases. In Italy, where hospitals have been overwhelmed with patients in respiratory failure, doctors have had to make difficult life-or-death decisions about who gets a ventilator and who does not.

In the U.S., emergency plans developed by states for a shortage of ventilators include using positive airway pressure machines — like those used to treat sleep apnea — to help hospitalized people with less severe breathing issues.

While that measure could stretch the supply of ventilators and save lives, it has a major drawback. Officials and scientists have known for years that when used with a face mask, such alternative devices can possibly increase the spread of infectious disease by aerosolizing the virus, whether used in the hospital or at home.

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