To put a finer point on it — while reusing an old mask might prevent you from getting Covid19, it might also expose you to a bacteria or fungus that could _also

To put a finer point on it — while reusing an old mask might prevent you from getting Covid19, it might also expose you to a bacteria or fungus that could _also_ lead to a pneumonia or other such lung diseases. You really don't want to be needing a ventilator for any reason in the next few weeks/months.