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.
4/ The image to left is based on ion generators tested by @IAQinGWN in 2000s that emitted approximately 1 to 5 mg/hr of ozone. Newer bipolar units often emit less (by design), but may also be even LESS effective than their (fairly ineffective) predecessors at removing particles.
5/ We put this in the context of how much higher the 24-hour average outdoor ozone concentrations would have to be for a median-sized US home at different air exchange rates to yield the same indoor concentrations stemming from (older) ion generator emissions.

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More from @CorsIAQ

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
14 Mar
1/ Concerns about under-ventilation of indoor spaces are FAR from new. Here are just 3 of many examples.
2/ Ben Franklin (18th century): "I am persuaded that no common Air from without, is so unwholesome as the Air within a close Room, that has been often breath'd and not changed" Franklin advocated exposure to fresh air & including open windows when sleeping.
3/ Florence Nightingale (mid 19th century): “Keep the air the patient breathes as pure as the external air, without chilling him.”
Read 6 tweets
12 Mar
1/ Proven Technology. The cost to put a very good portable HEPA filtration system in a classroom that typically holds 24 or 25 students is approx $10/student/yr (year 1), with recurring filter & energy costs of around $7/student/yr. Per year. Not per day, week, or month.
2/ The system can often yield an equivalent of 3 or more ACH &, at ventilation rates I have seen in a majority of schools in Texas, 60-75% overall reduction in inhaled dose of virus-laden paricles in shared air.
3/ In the US we spend approximately $15,000/year to educate a SINGLE student. To effectively reduce virus-laden particles in classroom air would add a whopping $7-10/student each year to this total. Two Grande Frappaccunios, folks. Proven technology.
Read 4 tweets

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