Journal Article

Characterization of hospital airborne SARS-CoV-2

Lemos, Bernardo, Koutrakis, Petros, Dowd, Scot E., Sunderland, Elsie M., Martins, Marco A. G., Stern, Rebecca A., Garshick, Eric

2021

Overview

Background The mechanism for spread of SARS-CoV-2 has been attributed to large particles produced by coughing and sneezing. There is controversy whether smaller airborne particles may transport SARS-CoV-2. Smaller particles, particularly fine particulate matter (≤ 2.5 µm in diameter), can remain airborne for longer periods than larger particles and after inhalation will penetrate deeply into the lungs. Little is known about the size distribution and location of airborne SARS-CoV-2 RNA. Methods As a measure of hospital-related exposure, air samples of three particle sizes (> 10.0 µm, 10.0–2.5 µm, and ≤ 2.5 µm) were collected in a Boston, Massachusetts (USA) hospital from April to May 2020 ( N  = 90 size-fractionated samples). Locations included outside negative-pressure COVID-19 wards, a hospital ward not directly involved in COVID-19 patient care, and the emergency department. Results SARS-CoV-2 RNA was present in 9% of samples and in all size fractions at concentrations of 5 to 51 copies m −3 . Locations outside COVID-19 wards had the fewest positive samples. A non-COVID-19 ward had the highest number of positive samples, likely reflecting staff congregation. The probability of a positive sample was positively associated ( r  = 0.95, p  < 0.01) with the number of COVID-19 patients in the hospital. The number of COVID-19 patients in the hospital was positively associated ( r  = 0.99, p  < 0.01) with the number of new daily cases in Massachusetts. Conclusions More frequent detection of positive samples in non-COVID-19 than COVID-19 hospital areas indicates effectiveness of COVID-ward hospital controls in controlling air concentrations and suggests the potential for disease spread in areas without the strictest precautions. The positive associations regarding the probability of a positive sample, COVID-19 cases in the hospital, and cases in Massachusetts suggests that hospital air sample positivity was related to community burden. SARS-CoV-2 RNA with fine particulate matter supports the possibility of airborne transmission over distances greater than six feet. The findings support guidelines that limit exposure to airborne particles including fine particles capable of longer distance transport and greater lung penetration.

• Publisher: BioMed Central,BioMed Central Ltd,Nature Publishing Group,BMC
• Subject: Aerosol / Aerosols / Air sampling / Airborne infection / Airborne sensing / Boston - epidemiology / Coronaviruses / COVID-19 / COVID-19 - diagnosis / COVID-19 - epidemiology / COVID-19 - transmission / Cross infection / Deoxyribonucleic acid / Diameters / Disease spread / Disease transmission / DNA / Emergency medical care / Emergency medical services / Emergency Service, Hospital - trends / Environmental aspects / Gene expression / Health aspects / Hospitals / Hospitals, Veterans - trends / Humans / Inhalation / Intensive Care Units - trends / Laboratories / Lungs / Mechanical properties / Medicine / Medicine & Public Health / Nosocomial infections / Pandemics / Particle Size / Particle size distribution / Particles / Particulate emissions / Particulate matter / Patients / Personal protective equipment / Pneumology/Respiratory System / Respiration / Ribonucleic acid / Risk factors / RNA / SARS-CoV-2 / SARS-CoV-2 - isolation & purification / Severe acute respiratory syndrome coronavirus 2 / Size distribution / Size fraction / Sneezing / Work stations