Dr. John Campbell (on Youtube) has been talking about using CO2 monitors as a proxy for understanding how recirculated (and therefore potentially full of fomites) indoor air is.<p>It's a good concept, since indoor CO2 is primarily generated by exhaling humans. It's important to keep your windows open!
There has been a lot of discussions here (Switzerland) regarding this and offices, shops etc having recirculating units without filters or UV sanitizers.<p>I would think that anything that spreads air without sanitation is an issue.
I think they mislabeled parts A and B of figure 2. The explanation from the text sounds like the opposite of what the figure is showing.<p>Interesting conclusion nonetheless.
Did the diamond princess and other cruise ships not provide a good example of transmission through have system as everyone stayed on board but isolated and continued to get sick for more than 14 days ?