Source / Disclosures
Carr-Locke D. Abstract Su008. Presented at: Digestive Disease Week; May 21-24, 2021 (virtual meeting).
Disclosures: Carr-Locke claims to have acted as an independent contractor for Boston Scientific and to hold patents with Steris Corporation.
Endoscopy suite exposes doctors to many breath droplets and amid COVID-19 pandemic, study at Digestive Disease Week found N95 and KN95 masks provide the best protection against inhalation of these droplets.
“Respiratory masks seem to protect us in a hospital environment, certainly in an endoscopy unit, which I was interested in.” David Carr-Locke, MD, of the Presbyterian Hospital in New York, said Healio. “This will allow the passage of very small particles that can be detected by taste and smell. This does not mean that the mask does not work and that surgical masks are almost as effective as respiratory masks, but the best protection is the respiratory mask, which is fitted over the face and is over 95% effective.
Using a low-pressure electrical impactor (ELPI, Dekati), Carr-Locke and his colleagues measured the two-way aerosol concentration generated by respiration and a nebulizer.
Carr-Locke reported that respiration produced particle concentrations ranging from 7 per cubic centimeter with diameters of 7 m to 10 m to 130,000 per cubic centimeter with diameters of 0.01 m to 0.02 m.
Cloth masks blocked the transmission of particles expired 0.76 m and larger while surgical and N95 masks blocked the transmission of all particle sizes with a few exceptions.
Looking at the nebulized saccharin, the researchers saw particles ranging from 2,000 per cubic centimeter with diameters of 7 m to 10 m to 14,500,000 per cubic centimeter with diameters of 0.01 m to 0.02 m.
Effective blockage of aerosols of all sizes was observed for all types of masks on the wearer’s side, but coming from the outer side, only respirators – N95 and KN95 – provided effective protection. Surgical masks blocked transmission at 0.4 m or more and non-medical masks were variable. Carr-Locke reported that filters built into non-medical masks improve blockage.