Coronaviruses and influenza Viren are sensitive to acidity of aerosol. pH-mediated rapid inactivation of coronaviruses is possible by enriching the indoor air with non-hazardous levels of nitric acid. Conversely, indoor air filter may unintentionally remove volatile acids thus prolonging persistence of airborne Virus. This new understanding can be very helpful in controlling airborne transmission especially in indoor environment such as hospital settings.
Atemwegsinfektionen verursacht durch beeinflussen und Coronaviren sind erhebliche anhaltende Probleme für die menschliche Gesundheit. Allein die Grippe ist weltweit für über 400,000 Todesfälle pro Jahr verantwortlich. Die anhaltende COVID-19-Pandemie ist darauf zurückzuführen Roman Coronavirus SARS CoV-2 has caused over 6 million deaths so far plus immense human suffering and unthinkable economic damages to world economy. Therefore, minimising transmission of these Viren is an extremely important priority.
It is known that their dominant mode of transmission is airborne. These infections are contracted by breathing in contaminated air. The expiratory aerosol particles act as vehicles for the transmission of influenza Virus und Roman Coronavirus SARS-CoV-2. Hence the importance of wearing face coverings. It is hypothesized that the Virus can remain in the air for about 3 hours with a half-life of 1.1 hours.
Needless to say, that rapid inactivation of these Viren would greatly contribute to limiting their transmission.
It is known that the enveloped Viren like influenza and corona Viren are inactivated in acidic conditions however level of acidity of expiratory aerosol particles and its role on inactivation of the Viren war unbekannt.
In a recent study published in the preprint medRxiv, the researchers examined this aspect for influenza and coronaviruses. They found that the aerosol particles exhaled into indoor air become mildly acidic (pH ≈ 4). This acidic condition rapidly inactivated influenza-A Virus within minutes but the novel Coronavirus SARS-CoV-2 required days for inactivation. Further, if the indoor air were enriched with non-hazardous levels of nitric acid, the acidity of the aerosol dropped by up to 2 units which in turn reduced the inactivation times for both Viren to below 30 seconds. This pH-mediated 99%- reduction in inactivation time could be of great significance in rapid inactivation of these Viren in indoor settings thus helping reduce community spread considerably.
Vor dem Hintergrund der oben genannten Erkenntnisse sollte der Einsatz von Raumluftfiltern sorgfältig erwogen werden, da jede unbeabsichtigte Entfernung flüchtiger Säuren aus der Raumluft den Säuregehalt des ausgeatmeten Aerosols verringern und die Ausbreitung in der Luft verlängern kann Virus Beharrlichkeit.
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References:
- COVID-19: What Does Confirmation of the Airborne Transmission of SARS-CoV-2 Virus Mean? Scientific European. Posted 17 April 2021. Available at http://scientificeuropean.co.uk/covid-19/covid-19-what-does-confirmation-of-the-airborne-transmission-of-sars-cov-2-virus-mean/
- Luo B., et al 2022. Acidity of expiratory aerosols controls the infectivity of airborne influenza Virus and SARS-CoV-2. Pre-print medRxiv. Posted March 14, 2022. DOI: https://doi.org/10.1101/2022.03.14.22272134
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