interesting trivia for the biowar inclined :-) ---------- Forwarded message ---------- Date: Thu, 25 Oct 2001 10:37:28 -0700 From: Tim Sturgill Reply-To: EMED-L -- a list for emergency medicine practitioners. To: EMED-L@ITSSRV1.UCSF.EDU Subject: Re: [EMED-L] Airborne anthrax protection...

From JAMA. 1999;281:1735-1745. "Anthrax as a Biological Weapon: Medical and Public Health Management"

@ http://jama.ama-assn.org/issues/v281n18/ffull/jst80027.html "The nonflagellated vegetative cell is large (1-8 microns in length, 1-1.5 microns in breadth). Spore size is approximately 1 micron." The germinated B anthracis is _larger_ than the _singular_ spore (dormant) state (the gram positive rod). The spores are being milled to the "spherical" and "singular" spore size, around 1 micron. The spores unmilled may clump greatly (as reported for the Boca Raton letter) as part of the process that was used to cause sporulation of the growing B anthracis stock. Also they clump because of electrostatic charge (which is now being reported to have been defeated). My question is how do the TB and HEPA masks function with 1 micron size particles that are electrostatically neutral. I would assume that all these masks were designed from the premise that small particles will always have a electrostatic charges--since only artificially made particles (requiring great technical skill) can be made electrostatically neutral. Is the filter a physical barrier at 0.3 microns? Or is this a physical + electrostatic barrier at 0.3 microns (which means that the physical component may be much greater)? regards/t _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/_/_/ Tim Sturgill MD FACEP FAAEM logres@pobox.com _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/_/_/

-----Original Message----- From: EMED-L -- a list for emergency medicine practitioners. [mailto:EMED-L@ITSSRV1.UCSF.EDU] On Behalf Of James Li, M.D. Sent: October 25, 2001 04:26 To: EMED-L@ITSSRV1.UCSF.EDU Subject: [EMED-L] Airborne anthrax protection...

Anthrax spores are large, the smallest dimension around 0.7 microns (diameter) by 3.0 microns (length, but often much longer). "Spores may be larger than the diameter of the bacillus, but usually are not." [1] The Washington Post article refers to a diameter of 1.5 to 3.0 microns wide, but I think this may have been a misquote (and length instead).

Thus, a TB mask should be sufficient, as Dr. Siegelson states. Given the article from the Washington Post, and the postal cases that weren't supposed to happen (aerosolized particles from "low risk" letter sources), it's probably important to wear these in the ED in cases of suspected exposure, until decontamination is clearly confirmed. We use a standard N95 particulate mask at work (which is available at any hardware store for sanding and painting work). In addition, I would suggest using a HEPA (high efficiency particulate arrestance) filter, which actively removes particles at the sub ~0.3 micron level from ambient air, in areas that might become contaminated. These also are readily available, for under $100. I've been using a nice quiet desk top HEPA filter for regular dust in my own house for years, and got it from Wal-Mart for about $70.

James Li, M.D. Division of Emergency Medicine Mount Auburn Hospital Harvard Medical School

http://www.remotemedicine.org REF [1] Medical Microbiology, Sherris JC, ed. pp. 319. ----ORIGINAL MESSAGE----- I think that the TB mask is sufficient protective equipment from airborne spores, although there is no indication that it would be needed while treating a patient. Also, there is no reason to decontaminate the patient with soap and water. If he is worried, remove his clothes and send him home. He can take a shower there if he likes. If you wash the patient, the water can go down the drain. Henry Siegelson, MD, FACEP To unsubscribe, send the command "SIGNOFF EMED-L" to LISTSERV@ITSSRV1.UCSF.EDU To unsubscribe, send the command "SIGNOFF EMED-L" to LISTSERV@ITSSRV1.UCSF.EDU