Saturday, April 25, 2020

role of HVAC systems ... potentially airborne virus (e g. SARS-CoV-2)

Click on the image to enlarge. Engineer menu items from the author's heating system showing system capacity cubic foot per minute for the heat pump on low (right image) and 'upstairs' zone cubic foot per minute capacity.
**Under Construction: First Test Post**
** This is from a letter (edited) I sent to BPS and other school administrators **
** Will update  this post soon with footnotes **

Something I and others are examining closely is role of HVAC systems and indoor/ outdoor air quality in the spread of upper respiratory illness. I (and others) haven't completed such investigations yet, but from early results it seems clear that a potentially airborne virus  (e g. SARS-CoV-2) is responsible for high volume infections in structures with closed HVAC return systems: nursing homes, high density urban housing, aircraft carriers, cruise lines, hospitals. I don't think this revelation will hit the press for awhile because of an unfortunate 'fixation' with a misunderstood 'droplet transmission theory' and a misunderstanding of aerosolized transmission of the highly reproductive, very small sized SARS-CoV-2 virus. In addition, both academic knowledge of the transmission and the etiology of COVID-19 are works in progress.

I recommend full duct cleaning of all BPS schools before students return, particularly of BHS where transient populations are now being housed. I am also recommending a full review of all of BPS air filtration systems and the addition/review of filtration and other air quality equipment as needed. HEPA standards (.3 microns) are not enough to fully stop a SARS-Cov-2 virus sized between .06 and .12 microns, despite some industry claims otherwise. Industrial full spectrum and UV light filtration systems focused on 'IAQ' should be mandatory additions to every public indoor space now. In addition, increased cleaning and filter change schedules should be implemented for every school. Probably, the more of such that you can afford, the less 'transmissive' of viruses BPS HVAC systems will be.

Because a number of (pre-print) studies are showing very high correlations between outdoor air quality (especially high levels of NO2) and COVID-19 spread,  there are probably a number of improvements the local government and community could be doing to improve both indoor and outdoor air quality: the banning of wood burning, the removal or upgrade of the cogen electrical plant downtown, subsidization of air source heat pumps with increased filtration  for residential and commercial housing, etc.

It is worth noting that Covid-19 deaths correlate highly with pre-existing health issues: heart, lungs, blood. However, recent observations have doctors noting how little pre-existing respiratory patients show up in COVID-19 distress compared to those suffering from obesity and cardiovascular illnesses. Although no one under age 60 has reputedly died from Covid-19 in Whatcom County yet, it will surprise no health professional I know if increased cardiovascular and respiratory health correlates with resistance to SARS-CoV-2 or other viral threats. The governor's orders maintain a stay at home exemption for exercise; most probably for the reason I cite above. I would advise all BHS families to use that exemption liberally to strengthen their health and immune systems.

It is unlikely that we will have a working anti-viral, vaccine, or other solution to SARS-CoV-2 if school reopens next fall amidst the backdrop of a busier society and economy.  Because of this, families, schools and our local government made need to take the lead in promoting immunologic health and viral resistance with what means they have available. I will have more information on this in the months to come. But I recommend budgeting for HVAC, student health, and all other immnulogic improvements to reduce infection rates of all respiratory illness when and if school returns this fall.

For whether we master bat originated SARs viruses is in some sense no more relevant than swine, avian, pangolin or whatever zoonotic flu like epidemic is coming down the pike next to sicken and kill us all.

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