You should read the whole article:
Things You Should Never Microwave
- Clothing and other large fabric items
The problem with microwaves is that they are not heating any item put inside them homogeneously but create "hot spots" instead. The image shows a simulation of the electric field inside a microwave oven (taken from wikipedia).
Therefore, microwave oven have a turning table and still it is advisable to stir your food in between of the heating process.
A paper or cloth, however, could catch fire!
The better idea to clean cloth is obviously a washing machine. Those usually have also a program to wash at 60°C / 140°Fahrenheit, which should be sufficient, or even higher. This will not only kill most germs (denaturation of many proteins or nucleic acids starts already below 50°C) but also wash away contamination.
Due to the current situation and the ongoing shortage of respirators the possibilities for decontamination are discussed broadly.
The best study on this topic seems to be from 2010:
Evaluation of Multiple (3-Cycle) Decontamination Processing for Filtering Facepiece Respirators
They tried eight different methods including microwave-oven-generated steam.
So it turns out, yes, it is possible to decontaminate respirators in a microwave. Two minutes with max power seem to be sufficient. But you should add a bowl with some water below the respirator. The generated steam ensures a more homogeneous temperature profile and prevents local hot spots.
But be aware that some respirators have metal brackets at the nose part. Those can not be put in a microwave.
Anyhow, it is always stated that decontamination is not ideal and should only be an emergency solution.