| About This Archive | | DCHAS-L 2020 Index | | DCHAS-L Yearly Index | |
Check out Safety Emporium for your N95, N99, and face shield needs.
|
Previous by Date: Subject: Re: [DCHAS-L] Sars-CoV2 infectivity Date: Saturday, June 27, 2020 at 11:56:55 AM Author: NEAL LANGERMAN <neal**At_Symbol_Here**CHEMICAL-SAFETY.COM> |
Next by Date: Subject: [DCHAS-L] Article Date: Sat, 27 Jun 2020 12:54:31 -0400 Author: Richard Palluzi |
To add to Peter's comments
It was found in 1965 that divers breathing heliox mixtures at depths below 500 feet developed nervous tremors known as High Pressure Nervous Syndrome (HPNS). A series of deep dives at the F.G. Hall laboratory at Duke University under the direction of Peter Bennett found that using small quantities of nitrogen in the heliox (termed tri-mix) helped eliminate this problem. In their Atlantis dive series, three divers reached a depth of 2132 feet breathing tri-mix.
It has been found that adding helium to hydrogen-oxygen mixes (termed Hydreliox) helps to eliminate the "hydrogen effect" narcosis associated with breathing only a hydrogen-oxygen mix. Theoretical limits of hydreliox are currently placed at about 1750 feet.
Diving With Gas Mixes Other Than Air by Larry "Harris" Taylor, Ph.D http://www-personal.umich.edu/~lpt/mixhistory.htm is an excellent summary on the history of diving gases
Other than medical gases, diving gases are the only compressed gas cylinders with a color code. Color code Guideline IMCA D043-07
Eugene Ngai
Chemically Speaking LLC
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of pzavon**At_Symbol_Here**ROCHESTER.RR.COM
Sent: Saturday, June 27, 2020 10:28 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity
Helium is used as the inert gas in diving gas mixture because of the problems connected with nitrogen narcosis, not so much because of carbon dioxide. In most SCUBA systems, the exhaled air is expelled into the water (all those bubbles), and where it isn't, the rebreathing systems are there to recover O2 from the CO2.
Peter Zavon, CIH
Penfield, NY
PZAVON**At_Symbol_Here**Rochester.rr.com
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Sambor, Andrew:(Exelon Nuclear)
Sent: Friday, June 26, 2020 4:01 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity
Thank you, I was unaware of the impacts under those conditions. Is that why helium is utilized as the inert portion of breathing air for deep diving operations?
Get Outlook for iOS
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> on behalf of Osprey, James <ospreyj**At_Symbol_Here**NOVATECH.CA>
Sent: Friday, June 26, 2020 1:19:42 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Subject: [EXTERNAL] Re: [DCHAS-L] Sars-CoV2 infectivity
EXTERNAL MAIL. Do not click links or open attachments from unknown senders or unexpected Email. |
I have enjoyed following this email train.
My last 40 odd years have been spent amongst other things in the development of techniques for the measurement of gases (including CO2) in controlled atmospheres and process conditions.
I am more than happy to concur with Monona's arithmetic.
I would point out that the toxicity of CO2 is related to the partial pressure, which at atmospheric pressure becomes quite significant at 5% leading to unconsciousness greater than 10%. As such, most alarm conditions in confined spaces are set at 5,000 ppm (0.5% v/v) at normal atmospheric pressure. However in hyperbaric environments (say 600ft, depth in diving bell) the operating pressure is around 20bar and the alarm condition must be set at 250ppm or less). There are additional risk factors associated with stratification and increased concentration at low lying locations in the diving bell.
It's important to note that the much vaunted statement that CO2 is a simple asphyxiant is profoundly untrue as exposure to such low levels (at pressure) which can hardly be considered as oxygen displacers, has resulted in immediate collapse and death.
James Osprey
UK 07393 426915
Canada
514 339 5374, 208
905 569 9824, 208
1 800 465 5347, 208
Sent from my iPhone
On 26 Jun 2020, at 18:11, Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**lists.princeton.edu> wrote:
=EF=BB=BF
Ooops. 4-5% = 40,000 - 50,000 ppm. lungs are REALLY good at exchanging gases apparently. Monona
-----Original Message-----
From: Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Fri, Jun 26, 2020 12:25 pm
Subject: Re: [DCHAS-L] Sars-CoV2 infectivityHmm.. 0.04% = 400 ppm (world average now) and 4-5% is 4000-5000 ppm, soooo, when they exhale 3500 ppm CO2 that's about right. Monona
-----Original Message-----
From: Backus, Bruce <backusb**At_Symbol_Here**WUSTL.EDU>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Fri, Jun 26, 2020 11:39 am
Subject: Re: [DCHAS-L] Sars-CoV2 infectivityHi Ralph,
Is that breathing directly into a CO2 meter, or analyzing the air in the breathing zone under a mask? The air we breathe in contains about 0.04% CO2, but we exhale air that contains about 4 to 5% CO2.
Thanks,
Bruce
_____________________________________
Bruce Backus
Assistant Vice Chancellor | Environmental Health and Safety | Washington University in St. Louis
4533 Clayton Ave.| Campus Box 8229 | Saint Louis, MO 63110
S: 314.362.8976 | Cell C: 314.302.0466 | : backusb**At_Symbol_Here**wustl.edu
-----Original Message-----
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Stuart, Ralph
Sent: Friday, June 26, 2020 9:55 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: Re: [DCHAS-L] Sars-CoV2 infectivity
> 900 to 1000 ppm CO2 is also where documented effects on mental acuity can be shown. It's a nice number.
Is there a reference for this? I just had one of our librarians who had been wearing a cloth mask for an hour exhale into a CO2 meter and he hit 3500 ppm. After wearing a cloth mask for 20 minutes, I max out around 1500, so I suspect that the longer wearing periods could become productivty problem.
- Ralph
Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859
ralph.stuart**At_Symbol_Here**keene.edu
---
For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
---
For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org
Follow us on Twitter **At_Symbol_Here**acsdchas--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
Confidentiality Warning:
This message and any attachments are intended only for the use of the intended recipient(s), are confidential, and may contain privileged information. If you are not the intended recipient, you are hereby notified that any review, retransmission, conversion to hard copy, copying, circulation or other use of this message and any attachments is strictly prohibited. If you are not the intended recipient, please notify the sender immediately by return e-mail, and delete this message and any attachments from your system. Thank you.
Information confidentielle:
Le pre´sent message, ainsi que tout fichier qui pourrait y =C3=AAtre joint, sont envoye´s =C3 l'intention exclusive de son ou de ses destinataires; ils sont de nature confidentielle et peuvent constituer une information privile´gie´e. Nous avertissons toute personne autre que le destinataire pre´vu que tout examen, re´acheminement, impression, copie, distribution ou autre utilisation de ce message et de tout fichier qui y est joint est strictement interdit. Si vous n'=C3=AAtes pas le destinataire pre´vu, veuillez en aviser imme´diatement l'expe´diteur par retour de courriel et supprimer ce message et tout document joint de votre syste`me. Merci.
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
This Email message and any attachment may contain information that is proprietary, legally privileged, confidential and/or subject to copyright belonging to Exelon Corporation or its affiliates ("Exelon"). This Email is intended solely for the use of the person(s) to which it is addressed. If you are not an intended recipient, or the employee or agent responsible for delivery of this Email to the intended recipient(s), you are hereby notified that any dissemination, distribution or copying of this Email is strictly prohibited. If you have received this message in error, please immediately notify the sender and permanently delete this Email and any copies. Exelon policies expressly prohibit employees from making defamatory or offensive statements and infringing any copyright or any other legal right by Email communication. Exelon will not accept any liability in respect of such communications. -EXCIP
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
--- For more information about the DCHAS-L e-mail list, contact the Divisional membership chair at membership**At_Symbol_Here**dchas.org Follow us on Twitter **At_Symbol_Here**acsdchas
Previous post | Top of Page | Next post