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Contamination of Surfaces with SARS-COV-2 during treatment of patients with COVID-19: exhaust fans and toilet seats are also covered with virus

2020-03-28

(image courtesy of pixabay and TheDigitalArtist)

Research on COVID-19 revealed viruses contaminating all surfaces in hospital rooms before cleaning that was removed by using 5000 ppm of sodium dichloroisocyanurate for “high-touch areas” and 1000 ppm on floors.  Areas where viruses were recovered included the blades of exhaust fans and toilet seats.  Recovery from exhaust fans showed that air is contaminated with droplets from exhaling (breathing out), coughing, and sneezing.  The size of these droplets varies from visible to extremely tiny, small enough so that only one or a few viruses could fit within a single particle.  Smaller particles can float in the air for long periods of time.  From the experience with measles transmission, we know that air remaining in a room for as long as two hours after a patient has left can contain infectious virus.  Whether SARS-COV-2 is as efficient as measles is unknown but considered unlikely.

Implications are that low-level infectiousness of ambient (remaining) air in areas through which patients have passed is entirely possible.  How long these infectious particles persist is unknown, but experts downplay the risks of transmission through the air after the larger droplets have settled out.

There is a significant risk of low-level exposure for susceptible individuals who pass through areas in which infectious patients have been breathing.  Whether this low-level exposure might lead to mild or inapparent disease is unknown.  I think that there is substantial risk for mild exposure, which might actually be a good thing, since patients with asymptomatic infection are likely to obtain immunity which might be sufficient to prevent later severe disease.

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