1/ It is important to recognize that as long as an infected individual is in an indoor space, virus-laden aerosol particles will accumulate to higher concentrations in that space until (in a well-mixed space) an approximate steady-state concentration occurs. more ....
2/ The steady-state condition is reached when the rate of emissions from the source is equal to the rate of removal by ventilation, deposition onto surfaces, & filtration. At this point the rate of change of concentration with time is zero. more ...
3/ The time to achieve 95% of steady-state is 3/B (where B is the sum of removal mechanisms, each w/ units of inverse hours). I have observed K-12 classrooms with outdoor air change rates as low as 0.5/hr. w/o filtration and little deposition this = 6 hrs to steady-state. ....
4/ When you walk into a space where an infector is present is important, particularly for far-field (not close contact) scenarios. This knowledge can be important for forensics analysis of infection events.
More to come (including classroom plots) ... in my overdue blogs!
More to come (including classroom plots) ... in my overdue blogs!
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