The Incheon Pharmaceutical Association encouraged its members to stay open on Sundays, to receive as many daily shipments as possible, so Ms. Yoo began working seven days a week. Her daily shipment went from 50 to 400 masks, with more on the weekends.

This week, the Centers for Disease Control and Prevention is weighing whether to recommend that everyone — not just health care workers and people infected with the coronavirus — wear masks. If this advice is issued, Americans may finally embrace wearing face masks, something that has long been common in East Asia, not only during disease outbreaks, but also during cold season and whenever air pollution levels rise.

Such guidance could also worsen the already dire shortage of N95 face masks and other personal protective equipment. 3M has promised to make more than a billion N95 masks by the end of the year. But without a vast expansion of complementary manufacturing or imports, supplies will be inadequate.

South Korea and Taiwan responded to their mask crises with significant market interventions. America needs to do the same. The U.S. government, and state and municipal bodies, should immediately enter into large-scale contracts to produce masks that can be sold at an affordable, standard price.

These masks (and other personal protective equipment) should go first to health providers and hospitals, then to essential workers in sanitation, warehouses, transportation, food service, child-care centers, and people in prisons and detention facilities. A distribution plan along the lines of those in East Asia could then get masks to the public, perhaps through pharmacies, corner stores and post offices. Some of those masks should also be allocated, free of charge, to people who are homeless or living below the federal poverty level.

For most of us, an N95 mask is not strictly necessary. Last weekend, I used a free online pattern to sew masks for myself and family members, using old handkerchiefs, shirts and elastic hair ties. I wore my homemade mask, reinforced with a large gauze bandage, to the grocery store and bodega, while trying to stay six feet away from fellow shoppers.

To survive this pandemic, we Americans must stop viewing masks as a sign of disease, and see them instead as a social kindness, a courtesy as common as “please” and “thank you.” As Choi Gwi-ok, a pharmacist in northern Seoul, told me, “Koreans wear masks to protect themselves from infections, but, even more important, to show consideration for others in public.”