There is none. People continue to parrot peer reviewed studies from outbreaks past, without recognizing that the anticipated protocols are not working to keep Healthcare workers safe.
The apparent inability of researchers to do anything but dogmatically utter the past conclusions in the face of contrary data is astounding, but the willingness to argue over the fine points of a dictionary definition while people continue to be infected is insane.
Droplet, airborne, powdered fomite, whatever, this travels at least short distances through the air, and therefore respiratory and mucosal contact protection must be provided at a level which will prevent contact with those virons in fine droplets, in dust, whatever, from making contact with mucosae.
Short of a full space suit with piped in air or SCBA, PAPR is best, because it is positive pressure, full face (fit tested) P-100 is likely adequate, provided the seal is tight and the filters aren't plugged (pulling air in around the mask). Anything less is asking for trouble.
The protocols described by the person in the link Black Agnes posted are suicide. Decontamination is nonexistent. If not directly infected, the fomites will get them.
Are healthcare workers are so despondent over the implementation of obamacare they are willing to die en masse in protest? Because they will, if that is what they are going to use for PPE and containment.