Quantity, Size Distribution, and Characteristics of Cough-generated Aerosol Produced by Patients with an Upper Respiratory Tract Infection

It is generally recognized that most nosocomial infections are spread by exposure to expelled particles at close range (usually within 1 m) or through contact. Although the Korea Centers for Disease Control established a 2-m cut-off for transmittance from patients during the Middle East Respiratory Syndrome (MERS) outbreak in Korea in 2015, questions have been raised regarding possible infection due to aerosols transported beyond this distance. The aim of this study was to characterize cough-generated aerosol emissions from cold patients and to determine the transmission distance of cough particles in indoor air. The study was conducted using subjects with acute upper respiratory infections. The number and size distribution of the particles generated from each cough were measured after participants coughed into a stainless steel chamber in a clean room. The total particle concentration was measured for each subject in the near field (＜ 1 m) and far field (＞ 2 m). The number of particles emitted by the cough of an infected patient was 560 ± 5513% greater than that generated by patients after recovery (P ＜ 0.001). The number of particles was also significantly higher (P ＜ 0.001) than the background concentration when infected patients were coughing, even in the far field. These results suggest that the 2-m cut-off should be reconsidered to effectively prevent airborne infections.