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Dr. Richard Corsi Profile picture
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17 May, 6 tweets, 2 min read
1/ Adapting Your Workplace for COVID-19

I will be teaching a two half-day workshop on June 9th and 10th w/ some great insights on field measurements from special guest @Wymelenberg.

pdx.edu/professional-e…
2/ This course will have 3 major modules: (1) basics on indoor air quality and particles in indoor air, (2) fundamentals of indoor transmission of COVID-19 by aerosols, and (3) layered inhalation dose (and thus risk) reduction. Modules 1 and 2 are primarily day 1. (3) = day 2.
3/ This is not a 1-hour webinar. The intent is to provide a robust 8-hour discussion that allows business or school leaders to understand & explain "why" to their employees (and patrons), and for employees and patrons to understand & explain "why" to business & school leaders.
4/ There will be a lot of practical information steeped in systematic background materials that are usually not available in 20 minute to 1 hour webinars.
5/ There is a cost for logistics of putting on this short course @Portland_State. The speakers are donating 100% of their share to support students working on separation of inhalation dose by close contact versus far field (shared air).
6/ We are very excited about this course and pleased with sign-ups to date. A great deal of planning. Hope to see some of you there!

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More from @CorsIAQ

Dr. Richard Corsi Profile picture
15 May
1/ Increased ventilation is critical. Period. But remember, it is NOT everything. Inhalation dose = D = C x B x t x f. Ventilation affects C (concentration of virus-laden aerosol particles in air - in #/L). A tripling of ventilation will reduce C by a maximum factor of 3.
2/ If ventilation is increased and that causes a person to stay in a building for more time (t in minutes), that will obviate some of the benefit of increased ventilation.
3/ If a person goes into a building and does aerobic exercise and increases their respiratory minute volume (B in L/min) by a factor of 10 they will receive a greater inhalation dose than if they were in the building at rest at the lower ventilation rate.
Read 7 tweets
Dr. Richard Corsi Profile picture
13 May
1/ "There is nothing remotely similar to the CAA (Clean Air Act) for nonindustrial indoor environments. In the opinion of the author, the time is long overdue to explicitly address indoor air quality in future CAA amendments ..." (next)
2/ "and to formally address what may be the most important and relatively overlooked environmental issue of our time." Note that "our time" was over two decades ago.
3/ Almost 20 years ago I postulated that we could do more to reduce population exposure to harmful air pollution of outdoor origin than several decades of (highly beneficial) efforts to improve outdoor air quality, by designing, constructing, & operating buildings correctly.
Read 4 tweets
Dr. Richard Corsi Profile picture
8 May
1/ Primer on Inhalation Dose

Remember that whether it is via close contact or far field (same indoor space but not close contact) inhalation dose associated with virus laden aerosol particles is defined by the same variables:
Dosei = Ci x B x t x fi

Let's take a closer look.
2/ For aerosol particles (as opposed to actual virions in those particles), Dosei is the number of particles in size range i that are inhaled and deposited in the respiratory system.
3/ These size-fractionated particle numbers can then be converted to size-fractionated particle volume or total volume in different parts of the respiratory system, as we have done with the safeairspaces.com model.
Read 25 tweets
Dr. Richard Corsi Profile picture
8 May
1/ I have been asked extensively during interviews and by the public about my own personal decisions during this pandemic. I never answer questions like "which air cleaner should I buy?" but do give guidance on those that are proven and what to look for. Some examples.
2/ Do you use a mask outdoors?
From the start of the pandemic I have carried a mask with me when I go outdoors but only wear it if it appears I might come in close contact with someone. This is perhaps 5% of the time. I have avoided crowds for the past 15 months.
3/ Do you have a portable air cleaner in your home?
Yes, we have two very good portable HEPA air cleaners (each with CADR greater than 300 scfm). We purchased these long before the pandemic.
Read 18 tweets
Dr. Richard Corsi Profile picture
8 May
1/ Excellent article by @zeynep. My take below ...

Why Did It Take So Long to Accept the Facts About Covid? nytimes.com/2021/05/07/opi…
2/ At the start of this pandemic transmission by direct contact, close contact via LARGE respiratory droplets, & fomites were emphasized. ...
3/ Airborne transmission by aerosol particles (in near or far fields) was ignored & even downplayed by @WHO and @CDC, despite the fact this pathway represented THE nightmare scenario. This effectively opened the gate for THE nightmare scenario to occur.
Read 12 tweets
Dr. Richard Corsi Profile picture
1 May
1/ Simple answer = very little for aerosol particles but possibly (in some cases) dispersion that reduces close contact dose. But depending on flow conditions, there can be a low pressure zone on the downstream side that leads to some accumulation of particles.
2/ The risk of people letting their guards down thinking that barriers are somehow effective for aerosol particles is much greater than any benefit, IMHO. Technical answer next.
3/ Is there a benefit in terms of far field exposure? Very minimal. Here's why. Indoor aerosol particle decay rates (k) to (integrated) indoor surfaces range from approx 0.2 to 10/hr for 0.3 to 10 um particles, respectively (higher for larger diameter particles).
Read 9 tweets

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