Richard Corsi, PhD, PE (Texas) Profile picture
Oct 14 6 tweets 1 min read Twitter logo Read on Twitter
1/ Just saw that a company w/ a relatively expensive air cleaner is criticizing #CorsiRosenthalBox es. I wonder why? There are more peer-reviewed journal articles on the CR-Box than their product.
2/ Critical or our @ucdavis study that showed CADR that BLOW other systems away, implying the results seem too good and need to be replicated. Would love to see their data, replicated and in a peer-reviewed journal.
3/ We used the same experimental process to test our CR Boxes in replicate as we did for commercial HEPA air cleaners and arrived at the same CADR listed by manufacturers for two commercial HEPA air cleaners (protocol worked!). Were those companies lying about their CADR?
4/ In fact, we are now showing similarly impressive and replicated results for four more CR Boxes and recently presented the results at #AAAR2013.
5/ Still waiting for those who make uninformed (at best) comments to show your data, including as many replicates as we have done. And it would be great if your protocols and results went through a rigorous peer-review process w/ publication in a high quality journal.
6/ We and others have done so for the CR Box. We'll keep waiting for yours.

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More from @CorsIAQ

Oct 11
A bit of preliminary data on the CR Box in the @UCDavisCOE dean's office suite - one of several in our on-campus field study. CADR & effectiveness. 1/ Image
Effectiveness (e) is defined as 1 - Cw/Cwo, where Cw = PM2.5 concentration with the air cleaner in place and Cwo is the PM2.5 concentration without the air cleaner in place. 2/
For a nearly 400 ft^2 shared space in our office suite the effectiveness remains at between 0.93 and (indiscernible from) 1.0. In other words, our CR Box is reducing the amount of PM2.5 we breathe in by 93% to nearly 100% relative to w/o the CR-Box in operation. 3/
Read 11 tweets
Sep 21
1/ After more than 15 mos & 3,300 hours of operation this CR-Box was tested & sent to CR-Box pasture about 2 mos ago. It was just recalled (with no hesitation) for service while its replacement is going through a suite of 2-month lab testing as part of our field study. Image
2/ Importantly, even after 15 mos and more than 3,300 hours of actual operation this CR-Box maintains an average CADR (high flow) of about 400 cfm (for particles between 0.35 and 3 microns) w/ over 500 cfm for particles greater than 2.3 microns.
3/ The PM2.5 concentrations outdoors and indoors have been relatively high the past couple of days and this extensively used CR Box with soiled filters dramatically reduces PM2.5 concentrations in the Dean's Suite when it is activated, even on medium flow setting.
Read 6 tweets
Sep 19
1/ The Dose Makes the (risk of) Infection

My blog entry from August 2020. Still some unknowns at that time, but the fundamentals have not changed.

corsiaq.com/2020/08/19/the…
2/ If you understand that with COVID-19 we have been dealing with an airborne infectious disease for almost 4 years, the concept of inhalation dose & key parameters that define it provides a roadmap for dramatically reducing infections.
3/ Unfortunately, the roadmap was never used (or used late and without significant clarity) by authorities charged w/ oversight of pandemic reduction, and has now been effectively shredded.
Read 5 tweets
Sep 11
1/ On the morning of 9/11 my wife & I like so many others were shocked & horrified. My wife reminded me this morning that on that day I was emphatic that large numbers of people would also get sick and die from ...
2/ extraordinary inhalation, dermal, & hand-to-mouth exposure to dust from fallen WTC towers & combustion products thereafter. Cement dust, asbestos, toxic metals, plasticizers, flame retardants, products of jet fuel combustion, products of smoldering building materials, & more.
3a/ This was obvious to Dr. Paul Lioy & colleagues of EOHSI/Rutgers who went to the scene to collect dust samples. They "scooped it from the windshields of nearby cars and secured it in Teflon bags" for laboratory analyses.
Read 10 tweets
Sep 10
1/ Been hearing of some push back by school districts over fears that fan motors on CR-Boxes may overheat and be a fire hazard. This thread addresses those concerns. Image
2a/ Resistance on the fan motor was considered in design of the original CR-Box. Clearly, resistance is greater if just one filter is duct-taped to a fan, and I wanted to get away from that simpler concept, even though such a design can be quite effective in right-sized spaces.
2b. Note that the 1-filter on fan design should be worst-case scenario for resistance (assuming similar filters as used in a 4 or 5-filter CR Box), yet Underwriters Lab (UL) tested this design and concluded that under normal and blockage conditions ...
Read 19 tweets
Sep 3
1/ College students returning to dorms across North America.

Just a reminder that a "classic" 4-5 MERV-13 filter #CorsiRosenthalBox in a 220 sq. ft x 9 ft can add between 15 to 27 ADDITIONAL equivalent ACH to the space (depending on flow setting, fan, etc.). Image
2/ That's more than what isolation rooms in hospitals are typically designed to achieve. If the starting point before CR Box is 2 ACH, the reduction in respiratory aerosol particles will be approx 90%. If the starting point is 1 ACH then CR-Box yields approx 95% reduction. Image
3/ It's not unreasonable to expect CO2 concentrations in a dorm room with 3 sleeping students & windows closed to exceed 5,000 ppm (>13% rebreathed fraction). Been measured. A CR-Box can reduce probability of infection during these & other prolonged exposure periods. Image
Read 4 tweets

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