The largely finished plague mask, in all it's (sterile) glory.

This is a modern adaptation with an army-issue gas mask stitched onto an air filter mask, and a metal-plate 'miasmatic filter' protecting an amber vial underneath.

http://en.wikipedia.org/wiki/Plague_doctor
A blood-pressure Sphygmomanometer has been retrofitted to gauge the internal pressure of the mask. Whereas the brass caps on the cartridge ports are largely ornamental, they can easily be pulled off and fitted with the proper activated-carbon filter cartridges. These are currently in place for aesthetic purposes. Because one needs to be stylish when handling plague victims.