The spread of aerosolized SARS-CoV-2, the virus that causes COVID-19, inside public buildings could be suppressed using engineering controls such as effective ventilation, possibly with air filtration and disinfection and avoidance of air recirculation and overcrowding, according to a research letter published yesterday in Environment International. The international group of researchers said the evidence is sufficiently strong for aerosols as an important mode of coronavirus transmission, most of which occurs indoors, and that indoor measures to slow the spread are often easily implemented at relatively low cost. The authors noted that, of two published hospital-based papers and five in press, four identified airborne SARS-CoV-2 RNA, two found very few positive samples, and only one found no evidence. Three of the studies also reported some quantitative viral RNA data, with one from Singapore identifying positive air samples in two of three patient isolation rooms and one from the United States reporting that 63% of air samples from patient rooms and hallways were positive. One study found that viral load decreased with increasing distance from infected patients. Viral loads were highest when air samplers were worn by the sampling team near a patient receiving supplementary oxygen via nasal cannula. A study in China detected airborne SARS-CoV-2 DNA in a bathroom and an area used to remove personal protective equipment (PPE). More than 50% of viral RNA in these samples was linked to aerosols, and viral RNA was found on passive samplers about 2 and 3 meters (6.6 and 9.8 feet) from infected patients.

 

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