Thread by @CorsIAQ

1/ It would be easy to put a #CorsiRosenthalBox in a 3 m3 chamber with 0.05 ACH, inject particles, switch the system on, and show a dramatic downward trajectory of particle concentrations to effective 0 ug/m3 in 10s of seconds. But we do not do that, for it would be deceiving.

2/ Instead, studies are being done in actual classrooms, home environments, etc., and showing remarkable effectiveness at reducing aerosol concentrations. Further, experiments are being done to determine highly-relevant metrics like clean air delivery rate (CADR).

3/ Data indicate CADR of 400 to 800 cfm depending on fan and fan speed. These results can then be translated to estimate benefits in actual building spaces.

4/ At upper end (CADR = 800 cfm) this translates to an equivalent aerosol particle concentration reduction of between 25 to 30 ACH (air changes per hour) in a 2-person dorm room or small bedroom in home. As context, isolation rooms in hospitals are designed for at least 12 ACH.

5/ For 700 to 800 square foot classrooms a #CorsiRosenthalBox with CADR = 800 cfm translates to 7 to 8 ACH. When added to typical ventilation rates I have observed in classrooms, this leads to a combined ACH of 10 to 11/hr (getting close to hospital isolation room range).

6/ That some school districts are resisting these benefits is mind boggling, disappointing, and frustrating. I am inspired by the many who are finding ways of getting the #CorsiRosenthalBox into schools. Kudos to you.

7/ A fairly easy calculation of capital costs for materials, replacement filters once during school year, & recurring energy costs indicates a CR box serving 25 students & teacher in the same space costs less than $3 per student each yr (one tall Caffe Latte per student per yr).

8/ The actual cost would be even less per student if more than 25 students are in the classroom. Compare that with the average cost of educating ONE student in the US ($13K per year).

9/ The #CorsiRosenthalBox, even with replacement filters & energy costs, dramatically reduces the inhalation dose of students to virus-laden respiratory aerosol particles (and other particles form wildfire smoke, allergens, etc) at 0.02% of the cost of educating the student.

10/ Don't be looking for rocket science here, folks. There is none. This is a simple, inexpensive, highly effective approach based on sound engineering principles and testing. Just do it!