Personal Protective Equipment: Reply

We thank Dr. Johnstone¹  for his insightful comments, in response to our article,²  about the practical implications of the loss of smell caused by personal protective equipment. We agree that healthcare professionals commonly rely on their sense of smell to facilitate diagnosis of some conditions. As Dr. Johnstone reported, the first indication that a vaporizer is leaking might be when a member of the surgical team detects the characteristic odor of a potent volatile anesthetic. Physicians’ use of smell has also been evaluated to diagnose pseudomonas infections,³  and this ability might also be impaired by personal protective equipment.

N95 filtering facepiece respirators are designed to eliminate 95% of “most transmissible” particles from inspired air but are not resistant to oil and do not eliminate nuisance organic vapors.⁴  A person wearing an N95 mask may therefore be able to detect the odor of potent volatile anesthetics. P100 filters remove 99.97% of airborne particles, are strongly resistant to oil, and are commonly used with elastomeric half-facepiece respirators. Manufacturers commonly include a layer of activated carbon to eliminate nuisance organic compounds.⁵  Although there are currently no studies of how various respirators affect a person’s ability to detect volatile anesthetic agents (e.g., from a leaking vaporizer), a P100 filter would reasonably be expected to eliminate the odor of sevoflurane in low concentrations. In the authors’ personal experience, P100 filters are highly effective in eliminating other offensive odors that may be found in the operating room.

We agree that use of the extensive personal protective equipment that is required to care for patients with COVID-19 or other respiratory illnesses can impair the user’s sense of smell. This reduction in a critical sense suggests an important research opportunity. New technologies that detect contamination by volatile organic compounds or infectious agents without relying on a person’s ability to detect an odor may help users of personal protective equipment during a future pandemic. As we stated in our review, personal protective equipment impairs human performance in sometimes unpredictable ways.²  We thank Dr. Johnstone for pointing out yet another opportunity for improvement.

The authors declare no competing interests.