It’s my impression that there’s some spread via aerosol in public spaces like buses and trains. By increasing ventilation in those spaces by opening more windows I find it plausible that we could reduce that transmission.
Why aren’t health orgs pushing for increasing ventilation of public spaces?
Not an answer, but fwiw, my impression is that there’s reasonable odds of at least some aerosol transmission, not just large droplets when coughing. Although I concede that close-contact during symptomatic periods (or a few days before/after) is probably the primary transmission mechanism, especially given how much it seems to circulate in families.
CIDRAP mentions that we don’t know that 6 feet is sufficient, and that aerosol transmission has been seen in MERS (a different coronavirus).
This preprint on surface survival mentioned that SARS-CoV-2 (which they called HCoV-19) seemed able to survive in an aerosol for several hours and remained viable (although also note gwillen’s comment on this.)
This seems like a reasonable question, especially given the extent to which we’ve seen cruise ships (where adequate ventilation is apparently challenging) get incredibly infected.
I initially guessed ventilation would only provide minor benefits. But I’ve decided now that it looks medium to high value.
I’ve been influenced in part by this Stat article and this J Storrs Hall blog post.
Boy, it’s been quite a while! Have a half-assed conclusion (/retrospective/answer).
Here’s an article with a lot of illustrations whose models suggest that increased ventilation (in several common scenarios) results in a reduction in infection rate by a factor of about 5-7x, even when compared to mask wearing.
A room, a bar and a classroom
https://www.microcovid.org/ ’s model seems to be using a 5x reduction number for indoor vs “almost-outdoor,” which seems to roughly line up with this.
For comparison, mCov’s factor-reductions for surgical-mask wearing are 2x, and n95s are 10x. So “open-windows and heavy ventilation” lands basically right between the two in reducing risk.
My impression at this point is that adequate ventilation was a pretty strong target for reducing spread.
So… Kudos or BayesPoints to ChristianKI (whichever you prefer) for calling that 8 months ago.
Here’s a paper on SARS-1 that seems highly-relevant:
Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong.
I have not read through all of it yet, but even the abstract seems to suggest that someone agrees with you, thinks it contributed to that outbreak, and has at least started looking into it.
I’m not sure how extensive the suggested edits were, but I do have to comment that in all likelihood, sporadic crisis-based funding is not conductive to altering the ventilation architecture of a large fraction of hospitals.
(It has been my weak impression that pandemic-related funding has historically relied heavily on a tiny handful of interested politicians and on taking full advantage of policy-windows whenever there’s an outbreak or a scare.)
If there is a good argument that a ventilation redesign would help prevent pneumonia or other common hospital-acquired-infections, I suspect that would be a good thing to look into and add to the proposal. If true, it would make the argument a lot stronger, and also likelier to get implemented and upkept.
Abstract:
Here’s a good op-ed on this topic: https://www.nytimes.com/2020/03/04/opinion/coronavirus-buildings.html
The author suggests that the lack of attention on building ventilation is due to uncertainty about how important close contact (i.e., close enough that a person’s respiratory droplets could directly land on you) is for transmission, vs. more indirect airborne transmission.
(E.g., from CDC website: “Early reports suggest person-to-person transmission most commonly happens during close exposure to a person infected with COVID-19, primarily via respiratory droplets produced when the infected person coughs or sneezes. Droplets can land in the mouths, noses, or eyes of people who are nearby or possibly be inhaled into the lungs of those within close proximity. The contribution of small respirable particles, sometimes called aerosols or droplet nuclei, to close proximity transmission is currently uncertain. However, airborne transmission from person-to-person over long distances is unlikely.”)
It seems to me like this is a potential dangerous error given that paper about the bus where people got infected despite having some distance.
Note that that paper was retracted for unclear reasons. So unsure how much we should weigh it.