5 ms·

I certainly don't think you should be ridiculed for the notion, although I think my counter thought would be why should it be one or the other, and how confiden

I certainly don't think you should be ridiculed for the notion, although I think my counter thought would be why should it be one or the other, and how confident are we in the engineering side of the solution at a wide scale. To my knowledge masks are a low cost / lost risk way to reduce the spread, and countries that had faster uptake and higher rates of compliance in mask usage did see lower overall case counts. The building ventilation side to me seems more like a long term solution, with lots of details to implement. How can we be confident that someone did the retrofit correctly, and tested the air pathways to make sure there isn't droplets being pushed from one table to another in a restaurant. Can we be confident that small changes to dampers, rearrangement of the dining room, other changes don't affect the conditions and are maintained over time. Building HVAC systems are hard enough to maintain as is. This seems like a great addition to building codes, or if some standard can be developed for inspection, maintenance, testing, etc. And how can we be sure that businesses don't just try and cheat, would they be liable, can this be inspected, would the liability be collectable, etc, etc. I think as a society we should be looking at this problem holistically, I think part of the solution is masks, and part is vaccines, and part should probably be building codes and HVAC systems in public indoor spaces to reduce a variety of airborne pathogens.

bsder 5y ago
> And how can we be sure that businesses don't just try and cheat As someone who knows an HVAC inspector, they WILL cheat. He has appalling stories. The most appalling was him having to hold up opening a memory care facility because the HVAC was all shared when it was all supposed to be isolated. This was completely on the HVAC contractor as the plans were quite explicit about what needed to be done--which means that contractor did this before and got away with it. People who come into these kinds of facilities are not well, and get sick with things all the time. Many of them are immune compromised. But, nope, everybody wanted the facility open and banking money--this included the local politicians, the local community, the "oversight" committee, etc.--nobody gave a damn about the fact that the HVAC would KILL PEOPLE. So, don't hold your breath.
- dwaite 5y ago
  > So, don't hold your breath. Or, do.
timr 5y ago
> To my knowledge masks are a low cost / lost risk way to reduce the spread, and countries that had faster uptake and higher rates of compliance in mask usage did see lower overall case counts. 1) This isn't really true. There's not a lot of correlation between what nations/states did, and where they ended up. You can find observational papers on both sides of every question (for example, specific to masks, recently: [1]). 2) What else did nations with mask adoption do that could also explain the outcomes? Most places did many things at once, so we're going to be doing post-hoc analysis of this for years. Unfortunately, because nobody thought it appropriate to conduct actual clinical trials, we'll probably never know the answer. There are too many intermingled factors at play so we have to use models, and the modeling work so far has largely been garbage that reflects the assumptions used to create them [2]. (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. A cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) [1] https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v1.full.pdf https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v... [2] https://www.jclinepi.com/article/S0895-4356(21)00087-1/fulltext https://www.jclinepi.com/article/S0895-4356(21)00087-1/fullt...
- Izkata 5y ago
  > (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. a cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) There were studies done; all the way back in March 2020 there was an infographic making the rounds showing a rough estimate of percentage of particles filtered/let through by different types of cloth masks and N95/etc. If I remember right, all the cloth masks let through >50% of particles.
  - timr 5y ago
    There have been a number of laboratory studies performed that show varying levels of effectiveness for different kinds of masks and materials (where "effectiveness" is defined in all sorts of different ways that may or may not be relevant). Prior to Covid-19, there was a low-quality evidence base that didn't provide much signal either way: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.net/covid-19/masking-lack-of-evidence-with-... Strapping a mask on a mannequin or to a nozzle is, of course, very different than asking people to wear them everywhere. For evidence of real-world effectiveness of a medical intervention, you do a controlled trial. We could have done some, but we did not. It is notable -- but not at all perfect -- that the only RCT conducted with masks and Covid-19 in 2020 found no significant personal protective effect: https://www.acpjournals.org/doi/10.7326/M20-6817 https://www.acpjournals.org/doi/10.7326/M20-6817 It is a well-done study, and certainly limits the claims that can be made for masks, but doesn't answer every question. A good cluster RCT might have been able to address the question of whether or not masks protect others, for example.

bsder 5y ago

> And how can we be sure that businesses don't just try and cheat As someone who knows an HVAC inspector, they WILL cheat. He has appalling stories. The most appalling was him having to hold up opening a memory care facility because the HVAC was all shared when it was all supposed to be isolated. This was completely on the HVAC contractor as the plans were quite explicit about what needed to be done--which means that contractor did this before and got away with it. People who come into these kinds of facilities are not well, and get sick with things all the time. Many of them are immune compromised. But, nope, everybody wanted the facility open and banking money--this included the local politicians, the local community, the "oversight" committee, etc.--nobody gave a damn about the fact that the HVAC would KILL PEOPLE. So, don't hold your breath.

dwaite 5y ago
> So, don't hold your breath. Or, do.

timr 5y ago

> To my knowledge masks are a low cost / lost risk way to reduce the spread, and countries that had faster uptake and higher rates of compliance in mask usage did see lower overall case counts. 1) This isn't really true. There's not a lot of correlation between what nations/states did, and where they ended up. You can find observational papers on both sides of every question (for example, specific to masks, recently: [1]). 2) What else did nations with mask adoption do that could also explain the outcomes? Most places did many things at once, so we're going to be doing post-hoc analysis of this for years. Unfortunately, because nobody thought it appropriate to conduct actual clinical trials, we'll probably never know the answer. There are too many intermingled factors at play so we have to use models, and the modeling work so far has largely been garbage that reflects the assumptions used to create them [2]. (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. A cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) [1] https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v1.full.pdf https://www.medrxiv.org/content/10.1101/2021.05.18.21257385v... [2] https://www.jclinepi.com/article/S0895-4356(21)00087-1/fulltext https://www.jclinepi.com/article/S0895-4356(21)00087-1/fullt...

Izkata 5y ago
> (and before anyone says it: yes, it's entirely possible to have conducted clinical trials of masks. a cluster randomized trial, for example, could have been used to establish efficacy early in the pandemic. That we didn't even consider doing these "because it's a pandemic" is one of the biggest scientific lost opportunities of our lifetime.) There were studies done; all the way back in March 2020 there was an infographic making the rounds showing a rough estimate of percentage of particles filtered/let through by different types of cloth masks and N95/etc. If I remember right, all the cloth masks let through >50% of particles.
- timr 5y ago
  There have been a number of laboratory studies performed that show varying levels of effectiveness for different kinds of masks and materials (where "effectiveness" is defined in all sorts of different ways that may or may not be relevant). Prior to Covid-19, there was a low-quality evidence base that didn't provide much signal either way: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.net/covid-19/masking-lack-of-evidence-with-... Strapping a mask on a mannequin or to a nozzle is, of course, very different than asking people to wear them everywhere. For evidence of real-world effectiveness of a medical intervention, you do a controlled trial. We could have done some, but we did not. It is notable -- but not at all perfect -- that the only RCT conducted with masks and Covid-19 in 2020 found no significant personal protective effect: https://www.acpjournals.org/doi/10.7326/M20-6817 https://www.acpjournals.org/doi/10.7326/M20-6817 It is a well-done study, and certainly limits the claims that can be made for masks, but doesn't answer every question. A good cluster RCT might have been able to address the question of whether or not masks protect others, for example.