Since the Covid-19 pandemic began last year, face masks and other personal protective equipment have become essential for health care workers. Disposable N95 masks have been in especially high demand to help prevent the spread of SARS-CoV-2, the virus that causes Covid-19. All of those masks carry both financial and environmental costs. The Covid-19 pandemic is estimated to generate up to 7,200 tons of medical waste every day, much of which is disposable masks. And even as the pandemic slows down in some parts of the world, health care workers…