1/ Increased ventilation is critical. Period. But remember, it is NOT everything. Inhalation dose = D = C x B x t x f. Ventilation affects C (concentration of virus-laden aerosol particles in air - in #/L). A tripling of ventilation will reduce C by a maximum factor of 3.
2/ If ventilation is increased and that causes a person to stay in a building for more time (t in minutes), that will obviate some of the benefit of increased ventilation.
3/ If a person goes into a building and does aerobic exercise and increases their respiratory minute volume (B in L/min) by a factor of 10 they will receive a greater inhalation dose than if they were in the building at rest at the lower ventilation rate.
4/ It's inhalation dose that matters (repeat). Increasing ventilation is important for lowering C and should be job #1. Improved central filtration and portable HEPA filtration can also lower C. Required masks can dramatically lower C (often more so than any of the above).
5/ It is important to continue to use these as layered inhalation dose (and therefore risk) reduction. But we should NOT forget about the other important factors - time (t) and respiratory minute volume (B).
6/ The latter (B) has been woefully overlooked in this pandemic. See my blog from last August for more detail --- corsiaq.com.
Should have added here that C is the time-integrated concentration over exposure period t. It should be taken as size-dependent, as the term "f" is faction deposited in different parts of respiratory system, which varies by particle size. Details at corsiaq.com.
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