The guidelines on severe acute respiratory syndrome (SARS) published by the British Infection Society (BIS) and the British Thoracic Society (BTS) in July 2003 recommend giving adult patients with suspected or probable SARS an N95 or equivalent mask and request that they wear this continuously.¹ This recommendation was apparently provided to prevent the spread of the SARS coronavirus from the patient to the surrounding environment.

An N95 respirator (mask) is a negative pressure respirator which only filters air entering the mask, not leaving it.² Those wearing this respirator will experience an additional burden on the breathing system in moving …