In the debate about the importance of SARS-CoV2 airborne transmission, researchers at the University of Amsterdam performed laser measurements and modeling of the laser light that exhales the smallest breath drop. Their results indicate that the virus does not spread well through them: they are too small to carry many virus particles. Nonetheless, the researchers agreed that “aerosols are important in the spread of coronavirus.” Your question is “is this the most important method”.
Aerosol droplets are small particles that stay in the air for a long time (from a few minutes to a few hours) after we talk, cough or sneeze, and may not be very effective in spreading the coronavirus.
This research shows that physicists and doctors Van der Waals Zeman Institute Research results from the University of Amsterdam (Netherlands) are published in the journal this week Fluid physics. Their model of spreading SARS-CoV-2 in confined spaces shows that aerosol transmission is not a very effective way.
The author used laser technology To measure the distribution of droplets released by various people when they talk or cough.They also used nozzle Produce a known number of aerosol particles that are the same as the aerosol particles emitted by the volunteers, Calculation and modeling How do they spread, how long they stay in the air, and the likelihood of spreading the coronavirus.
The results show that these air droplets are not without risks, but because of their small size, they contain less viruses than the larger droplets produced when someone coughs, talks or sneezes directly.In this work, it is considered that the size between the two types of droplets is limited to 5 microns, Although other scientists think it should be changed to 100 microns.
Lead author Daniel Bonn (Daniel Bonn) told SINC: “We all believe that aerosols are important for the spread of coronavirus, but the question is whether this is the most important way, and our estimation of this study shows that they are not Very effective method. The method of transmission because there are not many virus particles in the aerosol droplets.”
Low risk of well-ventilated aerosols
“Based on current knowledge, we have found that when using aerosols, it is relatively safe to enter Modern building Bonn pointed out that there is good ventilation, such as airports, railway stations, modern offices, etc. He emphasized: “Modern ventilation means that the risk of aerosol infection is not great.”
According to the author, due to the relatively small amount of virus in the small droplets, this means that you are only at risk if you stay in a poorly ventilated room with the infected person for a relatively long time or after they cough.
However, even if someone enters the space a few minutes after an individual carrier with mild symptoms of Covid-19 coughs, the possibility of infection is “very low”, and if the person is only talking, the possibility of infection is even lower.
The study pointed out that the currently known breeding data show that compared with measles, for example, SARS-CoV-2 is less infectious, and measles is a well-known airborne very effective vaccine, but in the case of coronavirus, “maybe” It is spread by aerosol, but there may not be a very effective way, especially from asymptomatic or mildly symptomatic individuals who exhibit low viral loads.”
“That just caught our attention Avoid crowded and poorly ventilated spaces Bonn insists that (for hyperdispersion events) and for people who produce large amounts of aerosols with large amounts of virus (hyperdispersion), the risk of being infected by aerosols is not great. elevator, Meeting rooms or other poorly ventilated spaces”.
The results of this study continue to support the use of mask, This Social isolation And other measures to reduce the spread of large droplets.The researchers recalled: “They are so large that they fall on the ground about 1 meter from the mouth. Therefore, if the risk of infection is to be minimized, not only Keep 1.5 meters ÿ Wash your handsAnd also make sure that the room you are in is well ventilated. “
The authors hope that this study will provide more context for people to consider their safety during the pandemic, although they point out that their results are based on current data and knowledge.
Bonn admitted: “We still don’t know enough about this virus (especially the number of virus particles that need to be inhaled before getting sick) to say that our risk analysis is completely correct.” Bonn concluded: “If new knowledge emerges, Our model will still retain the virus and its infectivity, but certain parameters must be modified.”
Daniel Bonn, Scott H Smith, Aernout Somsen, Cees van Rijn, Stefan Kooij, Lia van der Hoek and Reinout Alexander Bem. “Aerosol persistence related to the possible spread of SARS-CoV-2”. Fluid physics February 27, 2020 (DOI: 10.1063 / 5.0027844)