Why square pod hospital masks aren't available outside

There is a shortage of masks. All the masks in the hospital have been taken to the fever clinic to prepare for the war. According to incomplete statistics, now every day the square cabin hospital needs more than 10,000 pieces of protective clothing, N95 masks more than 22,000, medical surgical masks more than 40,000, in addition to the need for a number of CT machines, cardiac monitors and so on.