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Subject: Re: [DCHAS-L] Community Protection Strategies in the COVID Era Webinar
Date: Saturday, August 15, 2020 at 11:14:02 AM
Author: "Stuart, Ralph" <Ralph.Stuart**At_Symbol_Here**KEENE.EDU> 		Next by Date:
Subject: Re: [DCHAS-L] Community Protection Strategies in the COVID Era Webinar
Date: Sat, 15 Aug 2020 12:41:57 -0400
Author: Steve

From: John Callen <jbcallen**At_Symbol_Here**GMAIL.COM>
Subject: Re: [DCHAS-L] ACGIH White Paper (August 2020)
Date: Sat, 15 Aug 2020 11:40:37 -0500
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: C5B0E423-B3C6-40D5-9519-D06DF1437478**At_Symbol_Here**gmail.com
In-Reply-To <2015942538.1966295.1597489410476**At_Symbol_Here**mail.yahoo.com>


Monona & ALL: 

Regarding your question, I have listed the NIOSH specifications below the "X's" and please note that micrometer = micron.  

The size of contaminants and particles are usually described in microns, a metric unit of measure where:

  • one micron is one-millionth of a meter
  • 1 micron = 10-6 m = 1 =CE=BCm
For example, viruses generally measure in the range of 0.005 microns - 0.300 microns, cough generating bioaerososl in the range of 0.01 microns to 10 microns, bacteria in the range of 0.300 microns  - 60.000 microns, and the average cross section of a human hair is about 50 microns. 

XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Filter Efficiency Tests (42 CFR 84.174) for Non-powered Series N, R and P Filtration 

Challenge Materials:

  • Sodium Chloride (N series)
  • DOP (R and P series)
  • Charge neutralized

Preconditioning: 

  • 38  =B1 2.5  =B0C and 85  =B1 5% humidity for 25  =B1 1 hours (N series only)

Particle Size Distribution [CMD = Count Median (geometric) Diameter]:

  • 0.075  =B1 0.020 Micrometer CMD sodium chloride, with a standard geometric deviation not exceeding 1.86 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent
  • 0.185  =B1 0.020 Micrometer CMD DOP, with a standard geometric deviation not exceeding 1.60 at the specified test conditions as determined with a scanning mobility particle sizer or equivalent
  • 0.3 Micrometer, MMAD, Mass Median Aerodynamic Diameter - the most difficult particle size to filter based upon the graph of %Efficiency versus Particle Size, Micrometer (MMAD) for the filtration mechanisms of impaction capture, interception capture and diffusion capture.

Challenge Concentration: 
  • =E2=89=A4 200 mg/m3

Airflow Rate:

  • 85  =B1 4 liters per minute (42.5  =B1 2 for filters tested in pairs)

Temperature: 

  • 25  =B1 5  =B0C

Humidity:

  • 30  =B1 10% (N series)
  • Unspecified (R and P series)

Test Duration:

  • Until 200  =B1 5 mg loading is reached (N and R series)
  • Until minimum efficiency is reached (P series)

Minimum Efficiency Allowed:

  • 95, 99, or 99.97% depending on desired classification. 
  • Efficiency is measured continuously throughout the test period. 
  • Twenty filters tested, all must pass. 


If you have any further questions, please let me know.  Please note that I am not an expert in particle physics and I defer those questions to others.  Thanks!

Be Safe, Secure and Sound, Vigilant as Always and Well,

All MY Best,

John B. Callen, Ph.D.
3M Personal Safety Division - Retired
ACS/DCHAS Founding Member
(312) 632-0195











On Aug 15, 2020, at 6:03 AM, Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU> wrote:

I not only had read it, I've already added two of the illustrations to a powerpoint I've already trained with!.  I'm a member of the committee so I get stuff right away.

It's not bad, but I sure would alter the drawing of the recirculating ventilation system unless I want to point out why they don't work well.  That's the little split drawing with the diffuser and return over head on the left, and the floor level diffuser on the right with the return right above it.  Those positions show the weak points of that kind of ventilation since they short circuit the pathway for the air.  We have use diffusers like that second one in the buildings I do including the one that won the AIA COTE award in 2016.

MY QUESTION FOR YOU:  is the saline aerosol test what is used for generation of a 0.3 micron test particle?  Attached find an N95 pressure cooker article.  I don't need anything but the info that is NOT present here which is whether or not the efficiency measured is at 0.3 microns.  Because that's the size of much of the virus aerosol.

Monona


-----Original Message-----
From: John Callen <jbcallen**At_Symbol_Here**GMAIL.COM>
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Fri, Aug 14, 2020 4:13 pm
Subject: [DCHAS-L] ACGIH White Paper (August 2020)

Monona, Roger & ALL:

The ACGIH just published a White Paper entitled, " Ventilation for Industrial Settings during the COVID-19 Pandemic."

https://www.acgih.org/docs/default-source/vent-committee/iv_position-test.pdf?sfvrsn=4b10ba0d_2

It is nice and easy reading for your weekend and make sure you read the "Important Suggested Measurers" and "Resources on Pages 15 - 16.

After you read it, "Comments, please!"  Thanks!

Be Safe, Secure and Sound, Vigilant as Always and Well! 

John B. Callen, Ph.D.
3M Personal Safety Division - Retired
ACS/DCHAS Founding Member
(312) 632-0195


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