1/ Great study. I used the results from this study and follow-up tracer experiments in restaurant X to estimate ranges of the volume of particles deposited in the respiratory systems of those infected.
2/ Results suggest as low as 1 picoliter (pL) (one-trillionth of a liter) and as high as low teens of pL for respirable particles (less than 4 microns in diameter) (greater particle sizes also modeled but volume mode is in particles less than 4 microns).
3/ This volume range was used to develop a new factor (omega) for simulations in other indoor environments, where the infector in Restaurant X is placed in a a gym, classroom, ride share vehicle, etc., and omega = inhalation dose in those settings divided by that in Restaurant X.
4/ This was the basis for previous tweets in spring/summer 2020 indicating high potential for infection in vehicles, gyms, choir rooms, bars, restaurants, and classrooms with insufficient ventilation and other forms of layered risk reduction.
5/ Due to higher respiratory minute volumes inhalation dose in poorly ventilated gyms without required mask wearing, as well as in vehicles with windows closed and little air intake have BY FAR the highest omega values.
6/ The infection risks predicted by safeairspaces.com are anchored on inhalation doses predicted in Restaurant X and linked to a dose (PFU) response curve for a human coronavirus similar to (but not the same) as the current corona virus.
7/ We have a paper in review that shows fairly good agreement between the model and several outbreaks with sufficient metadata to model. Hopeful to re-anchor once a good dose-response relationship is developed (if ever) for SARS-CoV-2 and its variants.
8/ I will dig up and retweet some of the old simulations for various environments.

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More from @CorsIAQ

6 Apr
1/ Outdoor education. This time of year and for the next two months many schools have an opportunity to have some class periods outdoors (weather, space, and local conditions permitting). Do it if you can.
2/ A very nice whiteboard on wheels costs roughly the same as an XLNT HEPA filtration system on wheels, about 2 Grande Frappuccinos per student per yr for a class of 25 students. An investment of $10/student for each is small given$15K cost of educating 1 student/yr in US.
3/ I used to occasionally teach outdoors as a faculty member at the U of Texas at Austin on nice fall and spring days. Students would bring towels to sit on. It was a wonderful way to teach, and the students seemed to like it as well.
Read 4 tweets
29 Mar
1/ Ozone has been regulated in the US for 43 years due to its adverse impacts on respiratory health. The image on the right shows a healthy lung tissue (top) and lung tissue exposed to ozone at only 20 ppb during four hours of moderate exercise. .....
2/ On the top image, the cilia on epithelial cells stand upright and orderly. This is important for clearing mucous that may convey deposited particles, including those that may contain pathogens. Bottom image ...
3/ In the bottom image the cilia look less ordered, less upright, and the epithelial cells appeal distorted. The arrows point to neutrophils, indicative of inflammation due to inhalation of ozone.
Read 5 tweets
27 Mar
1/ Schools and school districts across North America are making horrific mistakes, wasting precious resources, & doing little to protect their teachers, staff, students or families. It is disappointing and difficult to see all for this unfolding ....
2/ Universal masks, outdoors if at all possible, increased ventilation, improved MERV rating for filters in mechanical systems, appropriate-sized portable HEPA filtration systems, and UVGI (upper-room in larger spaces; in mechanical system if significant recirculated air). ...
3/ That's it, folks. I highly suggest that you NOT venture from these proven approaches and technologies. Doing so puts you at high risk of wasting your district's money and doing little to protect anyone. Use proven technologies. Just do it!
Read 4 tweets
20 Mar
1/ Distancing and Shared Air.

Full disclosure. I want children back in school for their mental, social, & physical health, & for their future.

But I continue to be deeply concerned by a lack of attention & messaging on what needs to be done to EFFECTIVELY make schools safer.
2/ IMO, 3 ft of physical distancing is probably fine with UNIVERSAL MASK WEARING in classrooms in terms of inhalation dose by close contact.
3/ I have some concern about such distancing when masks are NOT worn, e.g., while eating, particularly given a much more infectious virus now than "coronavirus classic". I provided some guidance on lunch periods in my EPA school webinar months ago - at corsiaq.com
Read 13 tweets
20 Mar
1/ As states struggle w/ funding higher education they should not look at this as allocation, but rather investment in both the short & long-term future. Investment in STEM education has a rapid and significant return on investment when students stay in-state after graduation.
2/ I've done a detailed analysis based on graduates of the Maseeh College of Engineering and Computer Science @Portland_State. Every $1 spent on a student yields a return on investment of 12%/yr ($320% over 10 yrs) in Oregon State income tax alone.
3/ This analysis is based on fraction of graduates employed in Oregon, starting salaries w/ annual increases, and use of the State's income tax calculator. The ROI would be much higher if property tax, start-up businesses, etc., are included.
Read 4 tweets
17 Mar
1/ I have spoken with dozens and dozens of school districts. My recommendations include universal masks, increased ventilation, and stick with PROVEN technologies.
2/ Improved filtration as per MERV rating (to MERV-13 if possible), portable HEPA filtration (appropriately-sized), and upper-room or in-mechanical-system UVGI (in-system if significant recirculation rates high). Add good DYI box-and-fan systems if sealed properly. Just Do It!
3/ When a district official says "Yes, but I hear that this ..." or "What about this ....". I just repeat - stick with PROVEN technologies (see above). "But we were told ..." stick with PROVEN technologies. "But ...." Stick with PROVEN technologies.
Read 7 tweets

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