Aug

14

Sanitizers and Masks

August 14, 2020 |

Stefan Jovanovich writes: 

Although mechanistic studies support the potential effect of hand hygiene or face masks, evidence from 14 randomized controlled trials of these measures did not support a substantial effect on transmission of laboratory-confirmed influenza. We similarly found limited evidence on the effectiveness of improved hygiene and environmental cleaning. We identified several major knowledge gaps requiring further research, most fundamentally an improved characterization of the modes of person-to-person transmission.

https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article  

Jeffrey Hirsch   writes: 

Wow! So then what was responsible for flattening the curves or slowing the spread? Nothing? Time?

Stefan Jovanovich writes: 

JH: The answers that the mask and shield-wearing medico who earns here daily bread by examining and diagnosing people at non-social distances offers are these: (1) no one knows exactly how viral infections "spread", (2) no one knows how or why they grow and then decline among populations, (3) people with poor health suffer more than people with good health, but, as with lung cancer and heart disease (to take the 2 most common examples), some people escape the likely consequences of their bad profiles and others who should be fine sicken and die, (4) exchanging the air and scrubbing it with filters AND requiring both patients and medical personnel, including office workers, offers the best odds of reducing general risks of infection because it increases the oxygen levels and reduces the "carbon" levels and that, in almost all situations, helps us human air-handling machines.  But the masks need to be changed almost as frequently as surgical gloves to be effective; wearing the same mask for hours at a stretch has zero likelihood of restricting any kind of airborne infection and is guaranteed to have the same kinds of adverse consequences that people get from not changing their water filters within the time limits of their functional capacities.  

What she and her Dad think was and is monumentally stupid is to have shut down and continued to reduce  access to doctors and medical treatment in the name of keeping emergency rooms free. That is what we have decided to call General Staff thinking of the first order - the same kind that discouraged the development of automatic weapons for soldiers on the grounds that they would "waste" the ammunition.

Henry Gifford writes: 

Part 4, about “exchanging” the air and scrubbing it with filters and increasing Oxygen levels and decreasing “Carbon” levels sounds flawed to me.

Most modern commercial buildings in North America, including office buildings and hospitals, typically have systems that gather air from many rooms and put it into a common tube (“duct”) from where it goes through a filter and then a fan and then something to heat or cool the air, and maybe mix in a small % of outdoor air, then return it to all the rooms the air was removed from. Described another way, any airborne viruses in one room will be distributed to all the rooms served by that system, with a small % sent outdoors. Just how many people get sick this way is something that is politically incorrect to discuss or research in the buildings or building design industries, as these systems are the most expensive and profitable to design and install.

Even the fanciest filters have only a small chance of trapping something as small as a virus. People’s respiratory systems expel viruses coated with some water and other materials, in droplets of widely varying sizes, some of which fancier filters can catch, many of which even the best filters will unlikely catch. And retrofitting the fancy filters requires greatly increasing the size of the fan and the motor and the wires that supply electricity to the fan, which almost never happens. A normal air filter is there mainly to keep the equipment free from clogging by relatively large dust particles.

As for adding Oxygen and removing “Carbon,” (Carbon Dioxide exhaled by people), normal leaks in a building provide sufficient Oxygen replacement and Carbon Dioxide removal. Actual ventilation is beneficial for other reasons, but is not necessary for adding Oxygen or (generally) removing Carbon Dioxide. Submarines in WW2 had zero ventilation when submerged, yet running out of Oxygen was never a problem – poisoning with Carbon Dioxide was a problem long before Oxygen deprivation. Absorbent chemicals were used to absorb Carbon Dioxide. Some research in modern buildings has advocated higher ventilation rates as a result of supposedly finding correlation between higher Carbon Dioxide levels (>1,000 PPM) and lower worker performance, but I haven’t heard any talk about adverse health implications at Carbon Dioxide levels found in buildings.

Systems do exist that provide 100% outdoor air to buildings of any type and size, but these systems use very little energy and save space and are quieter, but are inexpensive and simple to design and install and maintain, thus they are not very popular. Even with all the talk about ventilation now, nobody seems to distinguish between “exchanging” used air or new outdoor air – not even a part of the conversation so far.


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