https://www.dailymail.co.uk/news/articl ... finds.html
I thought I would share how I critique these kinds of articles. First I don't consider an article about a study to be a good source because all articles are going to have the bias of the writer. I want to come to my own conclusions, so I look for the study.
The article did not reveal the study source, but it did reveal a little information about where the study originated, so I used some of that info to search.
Searched for: universities of Göttingen and Cornell facemask study
That gave me this link:
and hooray - that was the study. Now I can see how they set up the study.
I go in with initial questions:
1. What was the purpose of the study? This is usually expressed in the first part of the study notes:
So that is the focus of this study and the question they seek to answer.... it is not clear how exactly the risk of infection is affected by wearing a mask during close personal encounters or by social distancing without a mask...
2. How did they conduct the study? This will give us information on whether this was just looking at other studies, doing experiments with live subjects in controlled situation or in real world situation, or other avenues.
Okay, so this is not going to actually take measurements from live subjects in real world situations but rather look at controlled lab experimentation. It seems like they had some human subjects, but the environment was controlled.To calculate exposure and infection risk, we use a comprehensive database on respiratory particle size distribution; exhalation flow physics; leakage from face masks of various types and fits measured on human subjects; consideration of ambient particle shrinkage due to evaporation; and rehydration, inhalability, and deposition in the susceptible airways.
'Upper bound' is how they calculate [ the particles of virus needed to produce and infection x the outward leakage of the mask x the way the environment messes with the virus particles x the inward leakage of the mask x effect on the respiratory tract ] (big ole calculation)While our quantitative analysis is limited to typical parameters for SARS-CoV-2, our approach also applies to other parameters and other respiratory infectious diseases. Here we answer the following questions:
• What is the upper bound on SARS-CoV-2 infection risk for near-field exposure?
• How does this upper bound change with the respiratory activities, that is, passive breathing vs. talking?
• How does this upper bound vary with the exposure duration?
• How do the type of face mask and the way it fits to the face affect the upper bound?
• Which intervention strategy, between masking and social distancing, is most effective?
From this information we can see they were taking into account a lot of potential variables. They indeed know that the actual risk of one on one exposure is extremely hard to calculate due to all the variables.
They went through several potential scenarios with people wearing different types of masks, no masks at all and also different lengths of distancing.The main idea behind the upper bound is that, if a scenario proves to be safe under the upper bounds defined here, there is no question of its effectiveness under real conditions.
3. What was the conclusion of the study?
It was summarized like this:
I found this study to be very self aware that it was not a 'real world' study. It took careful steps to evaluate in such a way that its conclusions could be valid in real world situations.Our results show that social distancing alone without masking is associated with a very high risk of infection, especially in situations where infectious is speaking. High infection risks are also expected when only the susceptible wears a face mask, even with social distancing. We show that universal masking is the most effective method for limiting airborne transmission of SARS-CoV-2, even when face seal leaks are considered.
This was a very well done study and my summary of it here does not reveal all the in depth information it generated. Even if you are not used to reading studies, you will find it worth the challenge of reading it.