Lots more research is necessary, here. Aerosols appear to be an important means of COVID-19 transmission, however the evidence still points to large droplet spread as being the predominant means of transmission. (Fomite transmission contributes also, but in minor way.) Thus, in public areas, the six foot distancing rule is an every effective for reducing transmission and should be one of our key messages, along with mask-wearing, hand washing and not touching one's face.
Regarding aerosols and droplets, we still don't know how many virus particles will cause an infection, but it is likely that a droplet will contain more of them than a finer particle. Further, distance, space, dispersion will all generally result in a lower probably of an infectious dose landing on your mucus membranes. Your risk will always be higher when standing within six feet from an infectious person than if standing twenty feet away.
p.s., Yale has 100,000 KN95 masks and we can't fit people to any of them.
p.s.s., We don't normally do spirometry as part of our respirator medical evaluations, unless the person's medical history indicates its necessity.
Pete Reinhardt, Yale EHS Director
Yes Peter, but the 6 foot rule for the obsolete droplet theory does assume zero velocity air movement. The droplets will NOT settle within 6 feet if the air is moving away from the source. What ever the speed of that air flow will shift the settling distance of those droplets. Do the math.
Monona
-----Original Message-----
From: pzavon**At_Symbol_Here**ROCHESTER.RR.COM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Sent: Wed, Aug 12, 2020 8:04 pm
Subject: Re: [DCHAS-L] Respirator physicals?
The 6' number is NOT based on zero air velocity. It is based on the Infection Control community's use of the obsolete concept that respiratory infections are spread only by "droplets" which they define as being what we would call the very large emitted aerosols that settle rapidly under the influence of gravity and so, theoretically, can travel no more than about 6 feet (2 meters) from the point of emission. The Industrial Hygiene community, on the other hand, recognizes a continuum of particle sizes from very large to micron size, all of which could contain viral particles, and some of which will not settle for hours, even after their water content has evaporated.
And individual incidents have shown that COVID19 can be spread by the smaller particles. No large scientific studies on that, yet, because of the stress on the entire system, and the difficulty of assessing such matters with precision.
You are more than welcome!
Adding to what Yaritza Binker (Thank you Yaritza!) has given you in the back-to-back eMails below with factual information and corresponding references, you should have enough ammunition to counter company management and legal counsel. Reaching out to OSHA and/or consultants would definitely help.
I'm not an expert in ventilation and I would certainly defer to D. Jeff Burton, Roger O. McClellan and others, but realize that that 6' number is based upon air movement or velocity equalling ZERO. So regardless of whether workers are side-by-side, 6', 12' or more apart from one another, the key consideration is always going to be the results from a workplace assessment which would include monitoring the air quality for contaminants. Monitoring the air quality for exposure to asbestos, benzene, beryllium, cadmium, - , and vinyl chloride is easy to do and COVID-19 not so easy to do. That's why some believe that blood and antigen body testing may be better for bioaerosols. In lieu of bioaerosol testing, you may want to base your decisions on an assumption that EVERYONE has COVID-19 in much the same way that healthcare institutions in the 1980's and early 1990's believed that ANYONE & EVERYONE who walked into their premises had HIV/AIDS.
Also, your query could not have come at a more opportune time with the publication today of August 2020 issue of Industrial Safety & Hygiene News (ISHN) and Dan Markiewicz' Column "Managing Best Practices" topic, "Check your OHS Legal requirements."
The four key words as a take-away from the article are "GENERAL DUTY CLAUSE" and "NEGLIGENCE." NEGLIGENCE and "FAILURE to WARN or TAKE ACTION" are words your legal counsel should know about.
Ber Safe, Secure & Sound, Vigilant and Well!
3M Personal Safety Division - Retired
OSHA standards are not really standards, they are requirements written into the CFR. OSHA guidance documents, in multiple places, reinforce the fact that N95s are respirators and must be issued within the framework of a respiratory protection program.
Here's a link to OSHA's National News Release from June.
Here is a link to OSHA's Covid-19 FAQ's page. Go to the Cloth Face Coverings section. It explains the distinction between the different types of masks and respirators, with CFR cross-references.
Here is a link to OSHA's Mask Fact Sheet.
I am so glad I read your post here. I have been fighting (to a degree) with my company about the mandatory use of KN-95 masks if workers have to work within 6 feet of each other. Instead of simply reaching out directly to OSHA with a letter of intent they are relying on in house counsel review and case law to justify suspension of ALL requirements for workers to be in the Resp. Prot. Program. That being said, management did say the likelihood of approval for work within 6 ft would be very hard to attain and anyone not comfortable doing the work and thus wearing the KN-95 would not be made to do so.
At this point I feel like I have more than done my due diligence in raising the concerns and frankly I am tired of sounding the proverbial horn and being ignored.
What are the possible ramifications that my company can look forward to and is there anything else I can do to point the company in the right direction to protect not only the workers but the company itself?
Thank you for your time and response,
Timothy A. Ellisor
What I relate below certainly dates me, but that is why you keep Monona and me around to "Stir the Pot."
You remind me of the Good O;' Days when we always took things very seriously (and not that people don't today) regarding respiratory protection regardless whether it was nuclear or non-nuclear. Those were the days when health physicists, industrial hygienists and safety professionals had the top authority and controlled the reins of respiratory protection equipment instead of differing to materials management and/or purchasing personnel or even distributors.
I had the privilege and honor of meeting and knowing K. Paul Steinmeyer, RRPT first when he worked at Northeast Utilities (1979 - 1984) and thereafter at Radiation Safety Associates, Inc. (Hebron, CT). He was part of the group of "Legends in Their Own Time" I knew back in the mid-1970's through 1980's as Alan Hack, Ed Hyatt and John Pritchard at Los Alamos, Larry Birkner (deceased) at Celanese Corporation/ARCO, Howard Cohen, Ph.D. at Olin Corporation/Yale University, Craig Colton at OSHA Training Institute/3M and Tom Nelson at DuPont/NIHS, Inc. and where they worked at that time.
It was at the time when I had responsibility for calling on and working together with health physicists, industrial hygienists and safety professionals at Consolidated Edison, Northeast Utilities and New York State Power Authority nuclear and fossil fuel sites. I even worked with Stone and Webster during the construction of Millstone III helping to train and fit test the construction workers on respiratory protection equipment. For all of these, NO medical clearance with spirometry, NO training with an exam (YES, an exam) and NO fit testing for tight-fitting respirators meant NO RESPIRATOR! Also and as a corollary for fit-testing, tight-fitting respirator wearers had to be clean shaven so that facial hair did not interfere with the sealing surface of the respirator faceiece or interfere with valve function. That meant NO 5 O'Clock shadow on up to a full beard with wiskers for men and NO "peach fuzz" for women (special case)!
I would strongly suggest that everyone as part of the Division of Chemical Health & Safety, regardless of current responsibilities, read and thoroughly understand the contents of USNRC 10 CFR 20, specifically Subpart H (Sections 20.1701 - 20.1705) and also NUREG/CR-0041 Revision 1. These documents are readily available online. I always carried around with me the paper copies of the 1980's editions (My Bibles), which dates me long before laptops and the internet.
Also Jim, going back to 1970's and until I am "blue in the face" in 2020 today, how many times I have had to repeat and repeat, "A Surgical Mask does not provide respiratory protection but rather helps provide asepsis, a physical barrier between the wearer and the work environment or sterile field." This certainly applies to the "creative masks or face shields" individuals or companies are making to "help" with the social distancing.
Be Safe, Sound, Vigilant and Well!
3M Personal Safety Division - Retired
ACS/DCHAS Founding Member
