On Apr 4, 2020, at 10:57 AM, Wright, Mike <mwright**At_Symbol_Here**USW.ORG> wrote:

Monona is right (as usual). The virus can live longer than one day on a hard surface. But probably not 17. That number is based on a study of surfaces in staterooms on the Diamond Princess that had been inhabited by confirmed positive cases. They were sampled 17 days later, but before any disinfection. What the researchers found was viral RNA, not live virus. That was no surprise. You'd expect viral fragments to persist long after the virus is broken up. CDC did a poor job of reporting this, so journalists got the impression that a fomite could be infectious for several weeks. The consensus seems to be that the maximum is 3 days on a hard surface, less on a porous, absorbent one.  But those numbers don't matter all that much. Surfaces where positive cases have been or in high-traffic areas ought to be disinfected a lot more often than every couple of days, and at the moment people ought to be washing up after touching anything outside their own house. 

 

I have one other small quibble. The video talks about droplet and fomite transmission, but not aerosol. Even the CDC now admits that possibility (although WHO isn't there yet). Droplets fall out fast. Aerosols are not as infectious, but they linger.

 

Nevertheless, it's a terrific teaching tool. The best I've seen.  

 

Mike Wright

 

 

 

Michael J. Wright

Director of Health, Safety and Environment

United Steelworkers

 

412-562-2580 office

412-370-0105 cell

 

"My friends, love is better than anger. Hope is better than fear. Optimism is better than despair. So let us be loving, hopeful and optimistic. And we'll change the world." 

                                                                                                                                                                                         Jack Layton

 

 

 

 

From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Monona Rossol
Sent: Saturday, April 04, 2020 9:02 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] Recommend: Video explaining COVID-19

 

Peter, Brilliant, beautiful and perfect for explaining to people.  But I have to tell you there is one error in it.  

 

Peter,  The statement that the bug lives for 24 hours on surfaces, is incorrect.  There are now 4 studies of COVID-19 on surfaces, and the people who did the studies, except for one, erred in not recording the humidity and temperature over the time of the tests.  So lengths of time that live virus was found on surfaces appear to be inconsistent ranging from hours to 17 days. But these results are not inconsistent when you factor in what is known about viruses.  For example, the 17 day and other long survival times were found on hard surfaces on a cruise ship study where the humidity is very high.  This is easy to explain when you look at the three major factors that influence survival time: 

 

a) humidity (higher humidities --> longer survival)

b) temperature (too low inactivates but may not kill; mid-range with an optimum temp some where; too hot kills)

c) the nature of the surface.  (porous = shorter life; hard surface = longer life; toxic surface , e.g., copper, = shorter)

 

So the NIOSH study for reusing N95s by putting them in paper bags for 5 days showed the virus dead in 2-3 days.  Paper bags are necessary to dry out the mask and keep humidity from being trapped in the bag.

 

The 24 hour number in the video unfortunately made it more difficult to convince our people who are subletting to HCWs that it would be best to disinfect hard contact surfaces after occupancy by virus positive/exposed tenants. 

 

Any chance this one wee boo could be repaired and a perfect video release?

 

Monona