Great editorial about "The COVID-19 crisis is almost certainly an indoor air crisis; it is very likely a ventilation crisis." (among other crises) onlinelibrary.wiley.com/doi/full/10.11… by Nazaroff @WBahnfleth @WargockiPawel Zhang /1
"The phenomenon of low risk outdoors and high risk indoors deserves some explanation. This is probably the most important observation in this pandemic. There is a simple explanation: dilution." /2
"For an ideal expired jet from a person breathing at rest, at a distance >1 m, there is >10-fold dilution from surrounding air because of...entrainment. If the surrounding air is totally free from infectious virus, as it is outdoors, the concentration beyond 1 m is very low." /3
"In any well-ventilated indoor environment...with an outdoor-air ventilation rate of 10 L/s/person or more, the background concentration in room air is similarly low. This means that...10 L/s/person ventilation is likely to produce a close-range inhalation risk like outdoors." /4
"Thus, in a well-ventilated indoor space, the infection risk is comparably low to risk outdoors....This reasoning supports an important conclusion: that SARS-CoV-2 transmission does not occur everywhere, but mostly indoors in poorly ventilated spaces." /5
"The dominant view in public health toward fearful airborne transmission fails to account for the power of dilution. Sufficient dilution of airborne infectious aerosols is the key to reducing inhalation transmission, both at close range and at room scale." /6
"Is this the right time for an indoor air revolution? For the first time in history, the COVID-19 pandemic has focused the world's attention on the roles of ventilation in disease transmission." /7
Forgot to list the first author: Yuguo Li. He has been prolific on the topic for a long time, and he understands what's happening with droplets and aerosols at close range better than almost anyone. /8
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